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WO2008148807A1 - Procédé amélioré de transformation d'hydrocarbures sur un catalyseur en présence de vapeur d'eau - Google Patents

Procédé amélioré de transformation d'hydrocarbures sur un catalyseur en présence de vapeur d'eau Download PDF

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Publication number
WO2008148807A1
WO2008148807A1 PCT/EP2008/056922 EP2008056922W WO2008148807A1 WO 2008148807 A1 WO2008148807 A1 WO 2008148807A1 EP 2008056922 W EP2008056922 W EP 2008056922W WO 2008148807 A1 WO2008148807 A1 WO 2008148807A1
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mixture
reaction zone
reaction
hydrogen
carbon atoms
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English (en)
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Marco Bosch
Dirk Neumann
Regina Benfer
Hans-Günter Wagner
Harald BÄDER
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BASF SE
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BASF SE
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C4/00—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms
    • C07C4/08—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms by splitting-off an aliphatic or cycloaliphatic part from the molecule
    • C07C4/12—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms by splitting-off an aliphatic or cycloaliphatic part from the molecule from hydrocarbons containing a six-membered aromatic ring, e.g. propyltoluene to vinyltoluene
    • C07C4/14—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms by splitting-off an aliphatic or cycloaliphatic part from the molecule from hydrocarbons containing a six-membered aromatic ring, e.g. propyltoluene to vinyltoluene splitting taking place at an aromatic-aliphatic bond
    • C07C4/18—Catalytic processes
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C4/00—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms
    • C07C4/08—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms by splitting-off an aliphatic or cycloaliphatic part from the molecule
    • C07C4/12—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms by splitting-off an aliphatic or cycloaliphatic part from the molecule from hydrocarbons containing a six-membered aromatic ring, e.g. propyltoluene to vinyltoluene
    • C07C4/14—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms by splitting-off an aliphatic or cycloaliphatic part from the molecule from hydrocarbons containing a six-membered aromatic ring, e.g. propyltoluene to vinyltoluene splitting taking place at an aromatic-aliphatic bond
    • C07C4/20—Hydrogen being formed in situ, e.g. from steam
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • B01J21/066—Zirconium or hafnium; Oxides or hydroxides thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/90—Regeneration or reactivation
    • B01J23/96—Regeneration or reactivation of catalysts comprising metals, oxides or hydroxides of the noble metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J38/00—Regeneration or reactivation of catalysts, in general
    • B01J38/04—Gas or vapour treating; Treating by using liquids vaporisable upon contacting spent catalyst
    • B01J38/06—Gas or vapour treating; Treating by using liquids vaporisable upon contacting spent catalyst using steam
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J38/00—Regeneration or reactivation of catalysts, in general
    • B01J38/04—Gas or vapour treating; Treating by using liquids vaporisable upon contacting spent catalyst
    • B01J38/12—Treating with free oxygen-containing gas
    • B01J38/16—Oxidation gas comprising essentially steam and oxygen
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2521/00—Catalysts comprising the elements, oxides or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium or hafnium
    • C07C2521/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
    • C07C2523/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of noble metals
    • C07C2523/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of noble metals of the platinum group metals
    • C07C2523/42—Platinum
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
    • C07C2523/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of noble metals
    • C07C2523/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of noble metals of the platinum group metals
    • C07C2523/44—Palladium
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
    • C07C2523/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of noble metals
    • C07C2523/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of noble metals of the platinum group metals
    • C07C2523/46—Ruthenium, rhodium, osmium or iridium
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/584—Recycling of catalysts

Definitions

  • the present invention relates to a process for the preparation of benzene by dealkylation of mono- and poly-alkyl-substituted benzenes having 7 to 12 carbon atoms in the presence of a heterogeneous catalyst and water vapor.
  • Aromatic hydrocarbons are widely used in both the petrochemical and chemical industries. Large amounts of aromatic hydrocarbons are needed, for example, as additives for gasoline - to increase the octane number. In the chemical industry, benzene is a key starting material for a variety of organic compounds.
  • aromatic hydrocarbons takes place mainly by naphtha reforming and by steam cracking.
  • steam cracking the goal is to obtain short-chain olefins
  • aromatic hydrocarbons are obtained as by-products, which can be separated by complex separation operations and separated into the individual components such as benzene, toluene, etc.
  • the two processes mentioned have the disadvantage that the aromatic hydrocarbons are coupled with other products.
  • benzene In order to meet the great demand for benzene, processes have been developed which allow to dealkylate alkyl-substituted aromatic hydrocarbons, in particular toluene.
  • benzene can be produced from toluene and additional amounts of benzene can be provided or produced adapted to market needs.
  • hydrodealkylation in which the alkyl-substituted aromatic hydrocarbons are dealkylated with the addition of molecular hydrogen
  • dealkylation with the addition of water vapor which is also called steam dealkylation
  • alkyl-substituted aromatic hydrocarbons are passed together with hydrogen over a suitable catalyst.
  • the corresponding dealkylated aromatics and alkanes are formed. Heat is released in this reaction, ie it is exothermic.
  • the reaction equation is shown with toluene as an example under (1) below.
  • the other technically interesting dealkylation reaction in addition to the corresponding aromatics additionally hydrogen and carbon monoxide.
  • the reaction equation for the steam dealkylation is exemplified below under (2).
  • the resulting carbon monoxide reacts with the water vapor present to form carbon dioxide and another molecule of H 2 .
  • This reaction is called the water-gas shift reaction and is shown in (3).
  • Steam dealkylation is an endothermic reaction.
  • the heat needed to maintain the reaction temperature is supplied by, for example, overheating the reactant stream (s) or heating from the outside.
  • No. 3,829,519 describes the preparation of benzene and hydrogen from alkylated aromatic hydrocarbons, for example toluene, in the presence of steam and optionally hydrogen with the aid of a supported catalyst comprising alumina and at least one noble metal of groups 8, 9 or 10 of the Periodic Table of the Elements ,
  • synthesis gas is produced from a hydrocarbon-containing stream by dividing the reactant stream and reacting a part with water vapor in an endothermic reaction to hydrogen and CO, while the hydrocarbons contained in the other part of the reactant stream partially by means of oxygen be oxidized.
  • This exothermic reaction also produces hydrogen and CO.
  • the heat released during the exothermic reaction is used for indirect heating of the endothermic reaction and the two product streams are combined prior to further processing.
  • US 6,228,341 describes special reactors for optimum utilization of the heat generated during exothermic reactions.
  • a possibility shown in US Pat. No. 6,228,341 consists in the successive carrying out of an exothermic reaction and an endothermic reaction; wherein the two reactions take place spatially separated in adjacent channels or tubes, so that the endothermic reaction zone is indirectly heated by the heat generated during the exothermic reaction.
  • the two reactions are connected to each other, because after the reaction in the exothermic reaction, the product mixture is transferred to the endothermic reaction zone and there subjected to the endothermic reaction.
  • US Pat. No. 3,775,504 discloses a process combined from steam dealkylation and hydrodealkylation, in which the hydrogen formed in the steam dealkylation is used at least partly in the hydrodealkylation. The heat released in one reaction is used to meet the heat demand of the other reaction. According to US Pat. No. 3,775,504, hydrogen is already added to the reactant stream in order to allow the hydrodealkylation in the entire catalyst bed and to delay the deactivation of the catalyst. The molar ratio of water vapor used and hydrogen to hydrocarbon contained in the aromatic is given as 5: 1 to 20: 1. The reaction takes place in the presence of a supported catalyst which contains at least one noble metal of groups 8, 9 or 10 of the Periodic Table of the Elements and whose support consists essentially of aluminum oxide.
  • the object of the present invention is to provide an alternative process for the dealkylation of alkyl-substituted aromatic hydrocarbons, which is less expensive and less expensive in terms of apparatus than comparable processes known in the prior art.
  • the process should also have a positive effect on the catalyst life and thus on the operating times of the reactor.
  • heterogeneous catalyst in step a) and in step b) contains at least one element selected from subgroups 8, 9 and 10 of the Periodic Table of the Elements.
  • a hydrogen addition from the outside means below 10% by weight, preferably below from 5 wt .-% and more preferably below 1 wt .-% to the respective reaction zone.
  • the process according to the invention is carried out completely without the addition of external hydrogen.
  • the hydrogen produced according to the invention in the process is generally not completely consumed and, following the reactions in reaction zones I and II, can be separated from the reaction mixture obtained and into the process in reaction zones I or II or in the mixtures A or B, preferably in the reaction zone Il and / or mixture B, are recycled.
  • this recycled hydrogen does not fall within the definition of "external hydrogen” or "external addition of hydrogen” since this hydrogen is hydrogen produced in the process.
  • the process according to the invention essentially takes place without the addition of external hydrogen in step a) or b), this being advantageous in terms of the costs of the process, since hydrogen is nowadays frequently obtained from hydrocarbons and has therefore become a correspondingly expensive raw material.
  • the mixture A is desulfurized before entering the reaction zone I.
  • the decision Sulfurization is in some embodiments carried out with the addition of small amounts of hydrogen, the concentration of which is slightly above the stoichiometrically necessary concentration for the complete conversion of the mixture A contained sulfur compounds.
  • the slightly more than stoichiometric amount of hydrogen also prevents overcharging of the desulfurization catalyst.
  • the thereby registered in the mixture A hydrogen does not have to be removed consuming because it does not bother, but on the contrary may even be beneficial in dealkylation.
  • the reactions in steps a) and b) are carried out at very low molar ratios of water vapor to carbon atoms present in the mixture (S: C ratio), resulting in equipment and energy advantages. Since relatively little water is added, correspondingly less energy must be expended for evaporation. Also, significantly less water vapor is contained in the product gas stream, the condensation heat of which must be removed during the work-up. Overall, the heat exchanger surfaces can be significantly smaller dimensions, resulting in significant cost savings.
  • alkyl in the context of the present invention means branched and linear C 1 -C 6 -alkyl groups.
  • One or more alkyl-substituted aromatic hydrocarbons means that one, two or more of the H atoms bonded to the aromatic nucleus can be replaced by alkyl up to the case where all the corresponding H atoms have been replaced by alkyl.
  • one or more alkyl-substituted benzenes containing 7 to 12 carbon atoms may be dealkylated.
  • mono-alkyl-substituted benzenes such as toluene, ethylbenzene or propylbenzene, poly-alkylated benzenes such as o-, m- and p-xylenes or mesitylene and mixtures thereof are suitable.
  • toluene is used.
  • mixtures containing substantially mono- and polysubstituted alkyl-substituted benzenes are used; For example, the resulting in the steam cracking so-called TX cut.
  • Sources of the mono- and poly-alkyl-substituted benzenes having 7 to 12 carbon atoms to be used according to the present invention are:
  • Fully hydrogenated pyrolysis gasoline which is obtained as a by-product in the production of ethylene and propylene from naphtha in the presence of steam in a steam cracker, the so-called TX cut is obtained therefrom.
  • Cokererase extract obtained by scrubbing gas with higher boiling hydrocarbons and / or by adsorption on activated charcoal from raw coal resulting from the coking of coal,
  • coal extract obtained by extraction of coal and / or brown coal with solvent such as tetralin or toluene at 350-400 0 C and 100-300 bar,
  • Aromatic fraction which is formed during the reaction of synthesis gas with methanol on zeolite catalysts or directly from synthesis gas by reaction on a bifunctional catalyst such as ZSM-5 / zinc chromite,
  • Aromatic fraction obtained by a dehydrocyclization of methane, ethane, propane and / or butane, this process is also called cyclic process, as well
  • the mixture A may contain sulfur-containing compounds and have impurities contained in the mono- and poly-alkyl-substituted benzenes and / or compounds which are obtained or are not completely separated during preparation or workup of the alkyl-substituted benzenes.
  • mixture A may also contain non-aromatic hydrocarbons containing from 6 to 12 carbon atoms.
  • the non-aromatic hydrocarbons are a mixture of branched linear and cyclic alkanes containing from 6 to 12 carbon atoms.
  • the linear and branched alkanes are called paraffins and the cyclic alkanes naphthenes.
  • Typical examples of the above mentioned paraffins are n-hexane, n-heptane, n-octane, n-nonane and n-decane as well as alkanes having 5 to 9 carbon atoms, which contain one or more More methyl, ethyl and / or propyl group (s) contain, wherein the total number of carbon atoms of 6 does not fall below 12 and is not exceeded.
  • Typical examples of the above-mentioned naphthenes are cyclohexane, cycloheptane, cyclooctane and cyclopentanes, cyclohexanes and cycloheptanes containing one or more methyl, ethyl and / or propyl group (s), wherein the total number of carbon atoms does not exceed 12.
  • the ratio of paraffins to naphthenes is usually between 10: 90 and 90: 10 wt .-%, preferably between 20: 80 and 80: 20 wt .-%, more preferably between 40: 60 and 60: 40 wt .-%.
  • the mixture A is prepared by separating a mixture containing mono- and polysubstituted alkyl-substituted aromatic hydrocarbons having at least 7 carbon atoms and non-aromatic hydrocarbons into two fractions.
  • a first fraction contains mono- and polysubstituted alkyl-substituted benzenes having 7 to 12 carbon atoms and at the same temperatures and pressures boiling non-aromatic hydrocarbons and can be used according to the invention as mixture A, wherein optionally the non-aromatic hydrocarbons can be separated beforehand.
  • the second fraction are the mono- and polysubstituted benzenes having at least 13 carbon atoms and the boiling at higher temperatures non-aromatic hydrocarbons.
  • the proportion of non-aromatic hydrocarbons having 6 to 12 carbon atoms in the mixture A is in the range between 0 and 50 wt .-%, preferably between 1 and 25 wt .-% and particularly preferably between 5 and 15 wt .-%.
  • the mixture A used according to the invention as feed contains at least one monosubstituted or polysubstituted alkyl-substituted benzene having 7 to 12 carbon atoms.
  • the amount of mono- and / or poly-alkyl-substituted benzenes having 7 to 12 carbon atoms in mixture A is usually at least 50% by weight, preferably at least 65% by weight, particularly preferably at least 80% by weight.
  • the mixture A can contain as sulfur-containing aromatic impurities, for example, thiophene, benzothiophene, dibenzothiophene or corresponding alkylated derivatives, in particular thiophenes.
  • sulfur-containing aromatic compounds for example, thiophene, benzothiophene, dibenzothiophene or corresponding alkylated derivatives, in particular thiophenes.
  • other sulfur-containing impurities such as hydrogen sulfide, mercaptans such as methyl mercaptan and tetrahydrothiophene, disulfides such as dimethyl disulfide and COS and CS 2 - hereinafter called non-aromatic sulfur compounds - may be present in mixture A.
  • the sulfur content may vary depending on the origin of the alkyl-substituted benzenes.
  • the mixture A is desulfurized prior to its use in step a) of the process according to the invention.
  • the content of aromatic sulfur-containing compounds is reduced prior to step a) to ⁇ 100 ppb, and the total sulfur content to a total of ⁇ 300 ppb.
  • the desulfurization of the mixture A prior to its use in step a) of the process according to the invention is preferably carried out on a copper-containing desulfurizing agent, with a copper and zinc-containing desulphurising agent (copper-zinc desulphurising agent) being particularly preferred.
  • the desulfurization may be carried out in the presence or absence of hydrogen, with the presence of hydrogen being preferred. Particularly preferred is the embodiment in the presence of hydrogen on a copper-containing desulfurizing agent.
  • the copper-zinc desulfurizing agent contains at least copper and zinc, wherein the copper: zinc atomic ratio is in the range of 1: 0.3 to 1:10, preferably 1: 0.5 to 1: 3 and especially 1: 0, 7 to 1: 1, 5 lies. It is obtained by a co-precipitation process and can be used in oxidized as well as in reduced form.
  • the copper-zinc desulfurizing agent contains at least copper, zinc and aluminum, wherein the copper: zinc: aluminum atomic ratio ranges from 1: 0.3: 0.05 to 1: 10: 2, preferably 1: 0, 6: 0.3 to 1: 3: 1, and more preferably 1: 0.7: 0.5 to 1: 1, 5: 0.9.
  • the desulfurizing agents can be prepared by various methods. For example, an aqueous solution containing a copper compound, in particular a water-soluble, such as copper nitrate or copper acetate, and a zinc compound, in particular a water-soluble, such as zinc nitrate or zinc acetate, with an aqueous solution of an alkaline substance (such as sodium carbonate, potassium carbonate). carbonate) are mixed together to form a precipitate (co-precipitation method). The precipitate formed is filtered off, washed with water or washed first, then filtered and then dried. The mixture is then calcined at about 270 to 400 0 C. Subsequently, the resulting solid is slurried in water, filtered off and dried. The resulting copper-zinc desulfurizing agent ("oxidized form”) can be used in this form in the desulfurization.
  • oxidized form can be used in this form in the desulfurization.
  • the mixed oxide thus obtained it is possible to subject the mixed oxide thus obtained to a hydrogen reduction.
  • This is conducted at about 150 to 350 0 C, preferably at about 150 to 250 ° C, carried out in the presence of hydrogen, wherein the hydrogen is diluted with an inert gas such as nitrogen, argon, methane, particularly nitrogen, so that the hydrogen content is 10% by volume or less, preferably 6% by volume or less, especially 0.5 to 4% by volume.
  • an inert gas such as nitrogen, argon, methane, particularly nitrogen
  • the copper-zinc desulfurizing agent may also contain metals belonging to Group VIII of the Periodic Table (such as Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt), Group IB (such as Ag, Au), or Group VIB (such as Cr, Mo, W) belong. These can be prepared by adding the corresponding metal salts in the above-mentioned preparation processes.
  • metals belonging to Group VIII of the Periodic Table such as Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt
  • Group IB such as Ag, Au
  • Group VIB such as Cr, Mo, W
  • Binders such as graphite
  • a solution containing a copper compound, in particular a water-soluble, such as copper nitrate or copper acetate, a zinc compound, in particular a water-soluble, such as zinc nitrate or zinc acetate, and an aluminum compound, such as aluminum hydroxide, aluminum nitrate, sodium aluminate, with an aqueous solution of an alkaline substance, such as sodium carbonate, potassium carbonate, are mixed together to form a precipitate (co-precipitation method).
  • the precipitate formed is filtered off, washed with water or first washed, then filtered and dried. Then calcium is defined at about 270 to 400 0 C.
  • the solid obtained is slurried in water, filtered and dried.
  • the resulting copper-zinc desulfurizing agent ("oxidized form") can be used in this form in the desulfurization.
  • the mixed oxide thus obtained it is possible to subject the mixed oxide thus obtained to a hydrogen reduction.
  • This is carried out at about 150 to 350 ° C., preferably at about 150 to 250 ° C., in the presence of hydrogen, the hydrogen being diluted by an inert gas such as nitrogen, argon, methane, in particular nitrogen, so that the hydrogen content is 10% by volume or less, preferably 6% by volume or less, especially 0.5 to 4% by volume.
  • the resulting copper-zinc desulfurizing agent (“reduced form") can be used in this form in the desulfurization.
  • the copper-zinc desulfurizing agent may also contain metals belonging to Group VIII of the Periodic Table (such as Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt), Group IB (such as Ag, Au), or Group VIB (such as Cr, Mo, W) belong. These can be prepared by adding the corresponding metal salts to the above-mentioned preparation processes. It is also possible to form or extrude the solid obtained after the calcination or also after the hydrotreatment into tablets or other forms, it being helpful to add additives such as binders, for example graphite.
  • binders for example graphite.
  • the co-precipitation can be carried out under pH control, for example by adjusting the feed rate of the salt solutions so that a pH of about 7 to 7.5 is maintained during the precipitation. It is also possible to subject the precipitate formed during precipitation to spray drying after washing.
  • catalysts e.g. the catalyst R 3-12 from BASF or G-132A from Süd-Chemie.
  • the copper-zinc desulfurizing agent is used in the reduced form. It may be advantageous to subject the mixed oxide obtained by the processes described above to a hydrogen reduction which can be carried out as follows (in the following, [cat] stands for catalyst):
  • the composite oxide is at 100 to 140 0 C, particularly at 120 ⁇ 5 ° C in a nitrogen Ström of 200 to 400 Nm 3 / m 3 [KA ⁇ ] # h, in particular of 300 ⁇ 20 Nm 3 / m 3 [ KAT] * h, warmed up.
  • the hydrogen stream is increased to 2.0 ⁇ 0.2 vol .-%, wherein the temperature of the catalyst should not rise above 230 0 C, preferably 225 ° C.
  • the hydrogen flow is now increased to 4.0 ⁇ 0.4 vol .-% and at the same time the temperature of the nitrogen to 200 ⁇ 10 ° increases, and here the temperature of the catalyst does not rise above 230 0 C, preferably 225 ° C. should. 5. Now the hydrogen flow is increased to 6.0 ⁇ 0.6 vol .-% while the temperature of the catalyst is maintained at 220 ⁇ 10 0 C.
  • the copper-zinc desulfurizing agent thus obtained is now in the "reduced form" and can be used. But it can also be stored under inert gas until it is used. Furthermore, it is also possible to store the copper-zinc desulfurizing agent in an inert solvent. On a case-by-case basis it may be advantageous to store the copper-zinc desulphurising agent in its oxidised form and to perform the activation "just-in-time". In this context, it may also be advantageous to perform a drying step before activation.
  • the water can be cooled to 100 to 140 ° C, in particular to 120 ⁇ 5 ° C, wherein the cooling rate should not exceed 50 K / h and the activation be carried out as described above.
  • a copper-zinc desulfurizing agent which contains 35 to 45 wt .-%, preferably 38 to 41 wt .-%, copper oxide, 35 to 45 wt .-%, preferably 38 to 41 wt .-% , Zinc oxide, and 10 to 30 wt .-%, preferably 18 to 24 wt .-%, aluminum oxide and optionally further metal oxides.
  • a copper-zinc desulfurizing agent containing 38 to 41% by weight, copper oxide, 38 to 41% by weight of zinc oxide, and 18 to 24% by weight of alumina is used.
  • copper-zinc desulfurizing agents are available from corresponding calcined mixed oxides according to the above-mentioned production methods.
  • the desulfurization of Mixture A is carried out on the copper-zinc desulfurizing agent in oxidized form without the addition of hydrogen. In a further embodiment, the desulfurization of the mixture A is carried out on the copper-zinc desulfurizing agent in oxidized form in the presence of hydrogen.
  • the desulfurization of the mixture A is carried out on the copper-zinc desulfurizing agent in reduced form without the addition of hydrogen.
  • the desulfurization of the mixture A is carried out on the copper-zinc desulfurizing agent in reduced form in the presence of hydrogen.
  • the performance of desulfurization in the presence of hydrogen is preferred according to the present invention.
  • the desulfurization in a temperature range of 40 to 200 0 C, especially at 50 to 180 0 C, in particular at 60 to 160 0 C, preferably at 70 to 120 0 C, at a pressure of 1 to 40 bar, especially at 1 to 32 bar, preferably at 1, 5 to 5 bar, in particular carried out at 2 to 4.5 bar.
  • the desulfurization is carried out in the liquid phase.
  • the desulfurization can be carried out in the presence of inert gases, such as nitrogen, argon or methane. In general, however, the desulfurization is carried out without the addition of inert gases.
  • hydrogen is used in the desulfurization with a purity of ⁇ 99.8% by volume, in particular of ⁇ 99.9% by volume, preferably of ⁇ 99.95% by volume. These degrees of purity apply analogously to the hydrogen which is used in the activations of the desulfurization catalysts which may have been carried out.
  • the hydrogen is added in slightly more than stoichiometric amounts with respect to the sulfur-containing compounds, thereby also avoiding overcharging of the copper-containing desulfurization catalyst, thus achieving a longer running time
  • the weight ratio of monosubstituted and polysubstituted alkyl-substituted benzenes in hydrogen in the range of 40,000: 1 to 1,000: 1, especially in the range of 38,000: 1 to 5,000: 1, especially in the desulfurization Range from 37,000: 1 to 15,000: 1, preferably in the range 36,000: 1 to 25,000: 1, especially in the range of 35,000: 1 to 30,000: 1.
  • the Liquid Hourly Space Velocity ranges from 0.5 to 10 kg of aromatic hydrocarbon per part by volume of desulfurization catalyst and Hour (kg / (m 3 [cat] (h)), in particular in the range of 1 to 8 kg / (m 3 [cat] (h) preferably in the range of 2 to 6 kg / (m 3 [cat] (h).
  • the thus desulfurized mixture A now has a content of aromatic sulfur compounds of at most 100 ppb, preferably of at most 70 ppb, and the total sulfur content is a total of ⁇ 300 ppb, preferably ⁇ 150 ppb, in particular ⁇ 100 ppb.
  • the desulfurizing agents described above also make it possible to reduce or completely remove the proportion of chlorine, arsenic and / or phosphorus or corresponding chlorine, arsenic and / or phosphorus-containing compounds in the mixture A.
  • the desulfurization of the mixture A can take place in one or more reactors connected in parallel or in series. These reactors are commonly used in
  • Liquid in cocurrent or in countercurrent, preferably in countercurrent, are performed.
  • the mixture A is desulfurized in the liquid phase.
  • the desulfurizing agent may also be removed from the desulfurization reactor. If the desulfurizing agent is present in reduced form, it may be advantageous to subject the desulfurizing agent to oxidation prior to removal.
  • oxygen or mixtures of oxygen with one or more inert gases, e.g. Air, used.
  • the oxidation takes place by conventional methods known to the person skilled in the art. For example, the oxidation can be carried out as follows:
  • the desulfurizing agent is first flushed with a stream of nitrogen of 200 to 400 Nm 3 / m 3 [ ⁇ at] * h, in particular of 300 ⁇ 20 Nm 3 / m 3 [K at] * h.
  • the air flow is increased to 120 to 180 Nm 3 / m 3 [Ka t ] # h, in particular to 150 ⁇ 10 Nm 3 / m 3 [ ⁇ at ] * h, and at the same time the nitrogen flow to likewise 120 to 180 Nm 3 / m 3 [ ⁇ at] * h, in particular to 150 ⁇ 10 Nm 3 / m 3 [K at] # h, wherein the temperature of the desulfurizing agent should not exceed 230 0 C, preferably 225 ° C should rise. This procedure is maintained until the temperature decreases and the content of oxygen in the exhaust gas corresponds to the input content.
  • the copper-zinc desulfurizing agent thus obtained can now be removed.
  • step a) the mixture A is reacted in the presence of water vapor on a heterogeneous catalyst to a mixture B, wherein the catalyst is present as a solid, while the reaction is carried out in the gas phase.
  • the water in the form of vapor or liquid is usually added to mixture A prior to introduction into reaction zone I or upon entry into reaction zone I.
  • the molar ratio of water vapor to carbon atoms (S: C) in mixture A when entering the reaction zone I is 0.1 to 2, preferably 0.2 to 1, particularly preferably 0.2 to 0.5.
  • the molar ratio of hydrogen to methane in the reaction zone I is below 25, and preferably between 0.1 and 20, and particularly preferably between 0.5 and 5.
  • the molar ratio of hydrogen to methane is a measure of the proportion of the endothermic Dampfdealkyl michsre neglect (2) and the exothermic Methanmaschinesreak- tion (5) in the overall reaction.
  • the molar H 2 / CH 4 ratio can be influenced.
  • the molar ratio of hydrogen and methane is also a measure of the respective proportions of the steam and hydrodealkylation reaction in the total conversion.
  • the water is added in liquid state to the mixture A before entering the reaction zone I and the contained in the mixture A alkyl-substituted benzenes having 7 to 12 carbon atoms and the water in an evaporator at 100 to 400 0 C evaporated ,
  • This steam is brought to the inlet temperature in a preheater and then introduced into the reaction zone I.
  • the water is added to the mixture A in the form of water vapor.
  • the inlet temperature is in the reaction zone I at temperatures of 475 to 600 0 C
  • the exit temperature from the reaction zone I is preferably at temperatures of 400 to 550 0 C.
  • the temperature of entry or exit temperature is the temperature immediately before or immediately after the reaction zone, a reaction zone begins at the beginning of the first and optionally the single catalyst bed of this reaction zone and ends at the end of the last, possibly single catalyst bed in this reaction zone.
  • the mono- and poly-alkyl-substituted benzenes having 7 to 12 carbon atoms are reacted mainly according to the steam dealkylation reaction, while at least part of the mono- and poly-alkyl-substituted benzenes are completely and / or partially dealkylated, ie Ben - zol and mono- and polysubstituted alkyl-substituted benzenes having a lower number of carbon atoms.
  • By-products are hydrogen, carbon monoxide, carbon dioxide and methane.
  • the reaction is endothermic and deprives the reaction zone I heat.
  • a small part of the mono- and poly-alkyl-substituted benzenes having 7 to 12 carbon atoms can react with the hydrogen contained in the mixture A from the desulfurization in small amounts according to the Hydrodealkyl istsretician.
  • the reaction is exothermic and gives heat to reaction zone I. Since this makes it possible to compensate for part of the heat consumed by the vapor disposition directly in the reaction zone I, the superstoichiometric metering of the hydrogen in the desulfurization before step a) proves to be advantageous.
  • the mixture B is obtained.
  • the mixture B is reacted in step b) of the process in the reaction zone II on a heterogeneous catalyst to a mixture C, wherein at least a portion of the hydrogen formed in step a) is consumed.
  • step b) according to the invention in step a) unreacted as well as partially dealkylated mono- and polysubstituted alkyl-substituted benzenes having 7 to 12 carbon atoms by hydrodealkylation with consumption of the present in the mixture B hydrogen as well as by reaction with the water vapor present according to Dealkylated steam dealkylation reaction.
  • the mixture B may be added before introduction into the reaction zone II or on entering the reaction zone II further water in the form of vapor or liquid.
  • the molecular ratio of water vapor to mono- or poly-alkyl-substituted benzenes having 7 to 12 carbon atoms when entering the reaction zone II is from 0.1 to 2, preferably from 0.2 to 1, preferably from 0.2 to 0.5.
  • the molar ratio of hydrogen to methane in the reaction zone II is below 20, preferably at 0.1 to 15, particularly preferably between 0.1 and 3.
  • the ratio of hydrogen to methane in the reaction zone II is below 25, preferably at 0.1 to 15.
  • the inlet temperature in the reaction zone II is preferably 450 to 750 0 C, the outlet temperature preferably at 400 to 800 0 C.
  • At least one supported catalyst is used both in step a) and in step b).
  • Supported means that a catalytically active compound is applied to an optionally catalytically active carrier.
  • the catalyst contains at least one metal selected from the 8th, 9th and 10th group of the Periodic Table of the Elements (IUPAC nomenclature) or a mixture thereof, preferably the catalyst contains at least one metal selected from the group palladium, rhodium, iridium, Platinum and mixtures thereof.
  • the catalyst contains, based on its total weight according to the present invention, 0.1 to 5 wt .-% of at least one metal selected from the group 8, 9 and 10 of the Periodic Table of the Elements or a mixture thereof, preferably 0.2 to 3 wt. %, particularly preferably 0.3 to 1, 2 wt .-%.
  • catalysts are used in which the dispersity of the Group 8 or 9 and 10 metals contained in the catalyst is at least 20%. The dispersity is measured by volumetric measurement of the CO uptake after reduction of the metal atoms in the presence of hydrogen.
  • the metals or metals of groups 8, 9 and 10 of the Periodic Table of the Elements have a radial concentration distribution on the carrier material, with the main part, ie at least 55% of the metals, or directly below the surface of the carrier material ,
  • Such catalysts are also referred to as shell catalysts.
  • the layer in which the metals are on the carrier material usually has a thickness of 50 to 350 microns.
  • the support material contained in the catalyst contains at least one oxide of one or more elements selected from the group AI, Si, Ti, Zr, Ce, Y, Cr, Fe, Mg, Ni, Zn, Ga and La.
  • the support material particularly preferably comprises oxides from the tetragonal crystal structure zirconium oxide in the XRD spectrum, stabilized zirconium oxide having a tetragonal crystal structure in the XRD spectrum, zirconium oxide having a monoclinic crystal structure in the XRD spectrum and Al, X spinel, where X is one or more elements ( e) represent from the group Ca, Zn, Mg and the proportion of X, measured as the weight fraction of the corresponding oxide XO relative to Al 2 O 3 , between 10 and 60 wt .-% is.
  • zirconium oxide having a tetragonal crystal structure in the XRD spectrum particularly preference is given to zirconium oxide having a tetragonal crystal structure in the XRD spectrum, stabilized zirconium oxide having a tetragonal crystal structure in the XRD spectrum, and Al, Mg spinel having a MgO content of from 10 to 50% by weight.
  • the inclusion of an XRD spectrum serves to determine the crystal structure of the zirconium oxide and is a known method of X-ray diffraction.
  • At least one further compound which stabilizes the zirconium oxide in the tetragonal crystal structure is added to the zirconium oxide.
  • compounds of lanthanum, cerium and / or silicon are used as stabilizers.
  • the support material contains less than 50 wt .-% ⁇ -alumina, more preferably less than 40 wt .-% and most preferably less than 30 wt .-% ⁇ -alumina.
  • the oxides may be mixed oxides, i. H. to oxides, which are also present at a microscopic level substantially as different oxides each with one atom of derived cations, as well as mixed oxides in which the cations are derived in an oxide of different atoms act.
  • mixed oxides may be wholly or partially converted to the mixed oxide form.
  • the carrier can be prepared by the methods known to those skilled in the art.
  • the oxide-containing support from suitable compounds which convert to the corresponding oxides upon calcining.
  • suitable compounds which convert to the corresponding oxides upon calcining.
  • hydroxides, carbonates and carboxylates are suitable.
  • the oxides or the corresponding precursors, which are converted into oxides during calcining can be isolated by methods known to those skilled in the art, for example by the sol-gel process, by precipitation, dehydration of the corresponding carboxylates, Dry mixing, slurrying or spray drying.
  • the corresponding soluble salts are used, such as halides, chlorides, alkoxides, nitrates, etc., preferably nitrates, chlorides and alkoxides.
  • precursors for silicon dioxide are tetraalkyl orthosilicates and colloidal silica, for example boehmites can be used as aluminum oxide precursors.
  • the carrier contains zirconium oxide, it is also possible to use commercially available zirconium oxide, which usually contains less than 1% impurities in relation to the commercial product.
  • the above-described oxides or the corresponding precursors can be mixed with auxiliaries which are suitable for facilitating the shaping of the support.
  • auxiliaries are, for example, graphite, wax and pore-forming agent.
  • the shaping of the carrier is then carried out by methods known to those skilled in the art, for example in "Preparation of Solid Catalysts", eds .: G. Ertel, H. Knoeginger, J. Weitkamp, Wiley-VCH, Weinheim 1999, chapter
  • the carrier can be chosen arbitrarily, usually strands, tablets, balls, SpNt, monoliths, etc. are produced.
  • the moldings described above, which are optionally mixed with auxiliaries, are calcined. This is usually done with air or a mixture of air and nitrogen at a temperature of 300 to 800 0 C, preferably at 500 to 600 0 C. It may be advantageous to add water vapor to the air or the air / nitrogen mixture.
  • the support usually has a BET surface area (determined according to DIN 66131) of at least 10 m 2 / g, preferably from 50 to 300 m 2 / g, in particular from 50 to 250 m 2 / g.
  • the pore volume of the support (determined by means of Hg porosimetry according to DIN 66133) is at least 0.1 ml / g, preferably 0.2 to 0.8 ml / g.
  • the support preferably has a monomodal or bimodal pore size distribution, the proportion of pores having a diameter greater than 10 nm being at least 30% by volume.
  • the cutting hardness of the carrier is at least 5 N / mm.
  • the cutting hardness can be measured, for example, on an apparatus from Zwick, type BZ2.5 / TS1S. It can with a pre-load of 0.5 N, a Vorkraftschub york of
  • the device has a fixed turntable and a freely movable punch with built-in cutting edge of 0.3 mm thickness.
  • the movable punch with the cutting edge is connected to a load cell for force absorption and, during the measurement, moves against the fixed turntable on which the shaped catalyst body to be examined is located.
  • the tester is controlled by a computer that registers and evaluates the measurement results.
  • the values obtained can be represented as the mean value from the measurements of 10 shaped catalyst bodies each.
  • the shaped catalyst bodies have a cylindrical geometry for the measurement, their average length being approximately equal to two to three times the diameter, and are loaded with the cutting edge of 0.3 mm thickness with increasing force until the shaped body has been severed , The cutting edge is applied perpendicular to the longitudinal axis of the molding on the molding.
  • the required force per mm diameter of the carrier is the cutting hardness (unit N / mm).
  • At least one metal of the subgroups 8, 9 and 10 or a mixture thereof can now be applied to the oxide-containing supports. This is carried out by methods known to those skilled in the art, for example in “Preparation of Solid Catalysts", G. Ertel, H. Knoeginger, J. Weitkamp, Wiley-VCH, Weinheim 1989, chap. 5.2; “Industrial Catalysis, A Practical Approach”; J. Hagen, 2 nd Edition, Wiley-VCH, Weinheim 2006, chap. 5.1).
  • the carrier is impregnated with a solution of a corresponding metal precursor.
  • the impregnation can be carried out by the incipient wetness method, wherein the porous volume of the support is filled by approximately the same volume of impregnating solution and - optionally after maturation - dries the support; or you work with an excess of solution, the volume of this solution is greater than the porous volume of the carrier.
  • the carrier is mixed with the impregnating solution and stirred for a sufficient time.
  • Suitable metal precursors are the metal salts, including halides, in particular chloride, nitrate, acetate, alkaline carbonates, formate, oxalate, citrate, tartrate, organometallic compounds, but also metal complexes.
  • the latter may contain as ligands acetylacetonate, amino alcohols, carboxylates such as oxalates, citrates, etc. or hydroxycarboxylic acid salts, etc.
  • the corresponding nitrate salts of the metals of groups 8, 9 and 10 are worked at a pH of between 4 and 12.
  • the catalyst contains more than one metal of groups 8, 9 and 10 or a mixture thereof, these metals may be applied together or in succession. be gene. In successive application, it may be advantageous to apply the individual metals in a certain order.
  • the oxide-containing support to which at least one of Group 8, 9 and 10 metals or a mixture thereof has been applied is calcined.
  • the calcination is usually carried out with air or a mixture of air and nitrogen, at a temperature of 300 to 800 0 C, preferably at 400 to 600 0 C. It may be advantageous to add water vapor to the air or the air / nitrogen mixture .
  • the catalyst thus obtained is usually activated before its use in the dealkylation of alkyl-substituted benzenes.
  • it is treated with hydrogen or a mixture of hydrogen and nitrogen at temperatures of 100 to 800 0 C, preferably at 400 to 600 0 C, treated.
  • the activation process is carried out in the presence of water vapor.
  • the activation of the catalyst is usually carried out in the reactor in which the dealkylation of the alkyl-substituted benzenes is to take place. But it is also possible to carry out the activation of the catalyst before installation in the corresponding reactor.
  • Coke and / or coke precursors may form at the active centers and in the pores of the catalyst.
  • Coke is usually high-boiling unsaturated hydrocarbons.
  • Coke precursors are typically low boiling alkenes, alkynes and / or saturated high molecular weight hydrocarbons.
  • the deposition of the coke or the coke precursor causes the activity and / or selectivity of the catalyst is adversely affected.
  • the aim of the regeneration is the removal of the coke or coke precursor without adversely affecting the physical properties of the catalyst.
  • the coke precursors can be obtained by evaporation in the presence of an intergas at elevated temperature (T> 250 ° C.) and / or hydrogenation in the presence of a water. containing gas mixture and / or combustion in the presence of an oxygen-containing gas mixture are removed.
  • the regeneration of the catalyst can be carried out in-situ or ex-situ, preference is given to in situ regeneration.
  • the inlet temperature for the oxidative regeneration is usually between 350 and 550 ° C.
  • the oxygen concentration of the oxygen-containing gas mixture is usually between 0.1 and 10% by volume.
  • the pressure is typically between 0.1 and 10 bar.
  • the oxidative regeneration of the catalyst is carried out in the presence of water vapor.
  • the catalysts described above can be used both in the reaction zone I and II. In each case the same but also different catalysts can be used. Likewise, in each case one or more different catalysts may be present in a reaction zone, these catalysts may be spatially separated, consecutive, in layers or as a common bed in the reaction zone.
  • the reaction zones I and II follow one another spatially, wherein the reaction zones I and II can each independently contain one or more serially and / or parallel-arranged reactors, which in turn independently of one another arrange one or more serially and / or parallelly arranged reactors.
  • te may have catalyst beds.
  • the catalyst beds can also be present in divided form.
  • the catalyst beds are preferably arranged in series. If a reaction zone contains more than one reactor, the reactors are preferably arranged in series.
  • reaction zones I (step a)) and II (step b)) are carried out according to the invention at pressures of 1 to 100 bar, preferably from 5 to 50 bar.
  • the reaction takes place in the reaction zones I (step b)) and II (step c)) at catalyst loadings, indicated as LHSV (Liquid Hourly Space Velocity), from 1 to 10 (l / l • h).
  • LHSV Liquid Hourly Space Velocity
  • the reaction in the reaction zone I (step a)) can be carried out isothermally or adiabatically, the reaction in the reaction zone II (step b)) takes place adiabatically.
  • an adiabatic reactor because of its usually simpler design, has significant cost advantages over an isothermal reactor, and the control of an adiabatic reactor is usually simpler.
  • the mixture A is at least initially reacted essentially in accordance with the steam dealkylation reaction, since upon entry into the reaction zone I according to the invention the molar ratio of water vapor to hydrogen is at least 10. If the steam dealkylation is carried out under adiabatic conditions, the reaction temperature drops and the reaction rate is reduced if the temperature drop is not counteracted. In straight throughput under adiabatic conditions, the conversion of endothermic reactions is generally lower than under isothermal conditions. Depending on the embodiment, it can therefore be weighed according to the present invention by the person skilled in the art whether reaction in the reaction zone I under adiabatic or isothermal conditions is more advantageous for the overall process.
  • reaction zone II In the mixture B used in reaction zone II, hydrogen is present from the reaction in reaction zone A, so that both steam and hydrodealkylation can take place in the reaction zone II.
  • the heat of reaction can at least partially compensate, as explained below. Therefore, the reaction in the reaction zone II according to the present invention is preferably carried out under adiabatic conditions.
  • the reaction in step b) in the reaction zone II becomes thermally neutral, i. with complete compensation of the reaction heat.
  • an isothermal reaction By an isothermal reaction according to the present invention is meant a reaction in which, in the case of an exothermic reaction, the resulting heat is for the most part compensated by active cooling. In the case of an endothermic reaction, the heat consumed by the reaction is largely balanced by active heating.
  • the absolute temperature difference between the inlet and output is outlet temperature of the reaction zone I, preferably less than 50 0 C, preferably less than 25 0 C and most preferably less than 10 0 C.
  • Adiabatic conversion according to the present invention refers to a reaction in which the heat generated during an exothermic reaction is largely retained in the system. This has the consequence that the exit temperature in an exothermic reaction with adiabatic implementation is higher than the inlet temperature. When performing an adiabatic endothermic reaction, the heat removed from the system by the reaction is for the most part not balanced from the outside. The outlet temperature is in this case below the inlet temperature.
  • the Einrittstemperatur reaction under adiabatic conditions in an endothermic reaction preferably by a maximum of 150 0 C, preferably to a maximum of 100 0 C and most preferably by a maximum of 50 0 C above the outlet temperature.
  • the Einrittstemperatur according to the invention is preferably a maximum of 150 0 C, preferably to a maximum of 100 0 C and most preferably by a maximum of 50 0 C below the exit temperature.
  • the absolute temperature difference in the reaction under adiabatic conditions is thus a maximum of 150 0 C.
  • this second reaction may consist in the oxidation of the hydrogen formed in the dealkylation and / or the remaining hydrocarbons and / or the carbon monoxide formed during dealkylation and / or the coke formed in the dealkylation with oxygen.
  • the heat-providing oxidation usually takes place in the same reaction zone in which the heat-consuming reaction is carried out. This has the advantage that the heat is transferred directly and only small heat losses occur.
  • oxygen and / or an oxygen-containing gas is supplied to carry out the reaction zone according to air.
  • the reaction is controlled in such a way that the heat of reaction (hydrodealkylation) produced during the exothermic reaction just covers the heat requirement of the endothermic reaction (steam dealkylation).
  • the control can be geared to heat equalization taking place within the reaction zone II between the two dealkylation reactions taking place there, but the process can also be carried out in such a way that the autothermal mode of operation extends to the reaction zones I and II, ie the heat gain by the Hydrodeal- kylierung in reaction zone II covers both the heat demand of Dampfdealkyl réelle in reaction zone I and II.
  • mixtures A in addition to at least one mono- or poly-alkyl-substituted benzene having 7 to 12 carbon atoms between 1 and 25 wt .-%, preferably between 5 and 15 Wt .-% non-aromatic hydrocarbons having 6 to 12 carbon atoms, wherein at least a portion of the non-aromatic hydrocarbons having 6 to 12 carbon atoms in the reaction zone I and / or II to carbon monoxide, carbon dioxide, methane and hydrogen.
  • Reactors used in the reaction zones I (step a)) and II (step b)) are generally fixed bed reactors, tube bundle reactors, fluidized bed reactors, shaft reactors, tube bundle reactors or fluid bed reactors, preferably tube bundles and fixed bed reactors.
  • a fixed-bed reactor in the case of an adiabatic procedure, preference is given to a fixed-bed reactor; in the case of an isothermal procedure, a tube-bundle reactor is preferably used.
  • the mixtures A and B can be heated from the outside. This can be done by an intermediate heater.
  • Reaction zones II may be followed by further reaction zones in which the dealkylation of the alkyl-substituted aromatics still present in mixture C is continued in an adiabatic manner using the same catalysts under the same reaction conditions as in reaction zone II.
  • Intermediate or intercooling may be incorporated between the reaction zones, optionally permitting heat exchange with other reaction zones or other units used in the process of the invention, such as evaporators and distillation units.
  • Coke and / or coke precursors may form at the active centers and in the pores of the catalyst.
  • Coke is usually high-boiling unsaturated hydrocarbons.
  • Coke precursors are typically low boiling alkenes, alkynes and / or saturated high molecular weight hydrocarbons.
  • the deposition of the coke or the coke precursor causes the activity and / or selectivity of the / the catalyst is adversely affected.
  • the aim of the regeneration is the removal of the Coke or the coke precursor without the physical properties of the / the catalysts are adversely affected.
  • the coke precursors can be removed in the presence of an oxygen-containing gas mixture by evaporation in the presence of an inter gas at elevated temperatures (T> 250 0 C) and / or hydrogenation in the presence of a hydrogen-containing gas mixture and / or incineration.
  • Regeneration of the catalyst (s) may be in situ or ex situ, preferably in situ regeneration.
  • the inlet temperature for the oxidative regeneration is usually between 350 and 550 0 C.
  • the oxygen concentration of the oxygen-containing gas mixture is usually between 0.1 and 10 vol .-%.
  • the pressure is typically between 0.1 and 10 bar.
  • the oxidative regeneration of the catalyst (s) is carried out in the presence of water vapor.
  • the mixture C contains after the reaction of the mixture B in the reaction zone II according to step b) benzene, unreacted water vapor and unreacted mono- and polysubstituted alkyl-substituted benzenes having 7 to 12 carbon atoms, only partially dealkylated mono- and polysubstituted alkyl-substituted Lower number of benzenes
  • Addition of air, oxygen or an oxygen-containing gas may be present or formed compounds, for example nitrogen.
  • the mixture C is worked up by the customary methods known to the person skilled in the art.
  • the mixture C is passed in a heat exchanger and cooled therein, preferably to 10 to 100 0 C. It is expedient that each heat released in the process Center to inte- (heat system), for example, the mixture A, B or other streams to be heated (for example evaporator a column) to heat.
  • inte- heat system
  • the mixture A, B or other streams to be heated for example evaporator a column
  • heat exchanger form a liquid and a gaseous phase, which are separated by gas-liquid separation in the gas stream D and liquid mixture E.
  • the gas stream D contains carbon monoxide, carbon dioxide, hydrogen and alkanes
  • in the mixture E are benzene, mono- and polysubstituted alkyl-substituted benzenes with 7 to 12 carbon atoms and water.
  • the mixture E is fed to a phase separator, the substantially water-containing aqueous phase separated and mixture F obtained, the organic compounds benzene and unreacted and only partially dealkylated mono- and poly-alkyl-substituted benzenes containing 7 to 12 carbon atoms.
  • the mixture F can be further separated, for example by distillation.
  • the benzene is separated from the mixture F.
  • Particular preference is given in this case to separating the benzene and, if appropriate, impurities over the top and aromatic and nonaromatic hydrocarbons having more than 6 C atoms via the bottom in a distillation column.
  • the benzene fraction can be passed into a further distillation column in which the dissolved water and the low boilers are passed overhead via azeotropic distillation and pure benzene are separated via sump.
  • the unreacted and only partially dealkylated mono- and poly-alkyl-substituted benzenes having 7 to 12 carbon atoms obtained in the purification of the mixture F apart from benzene are recycled back into the process.
  • these mono- and poly-alkyl-substituted benzenes are added to the mixture A or the mixture B.
  • the mixture F can be wholly or partially recycled and the mixture A or B are added.
  • the water-containing aqueous phase obtained on separation of the mixture E is likewise used completely or partially again in the process. It is preferably fed to mixture A or B before or when it enters the reaction zones I or II.
  • the in the phase separation (in the heat exchanger or in the phase separator) separated gas stream D contains hydrogen, carbon dioxide, carbon monoxide, alkanes, optionally in autothermal driving registered components such as nitrogen and oxygen.
  • Gas stream D can be recycled if desired.
  • a compressor or a nozzle can be interposed.
  • the recirculated gas stream D can be preheated (for example by thermal bonding). Gas stream D can also be recycled, for example, by using it for heat generation.
  • Embodiment 1 is a diagrammatic representation of Embodiment 1:
  • FIG. 1 A schematic drawing of Embodiment 1 is shown in FIG.
  • a mixture (1) containing mono- and polysubstituted alkyl-substituted benzenes and nonaromatic hydrocarbons having 7 to 20 carbon atoms is by means of the distillation D1 in a mixture (2) containing mono- and polysubstituted alkyl-substituted benzenes and non-aromatic hydrocarbons with 7 to 12 carbon atoms and a mixture (3) containing higher-boiling alkyl-substituted aromatic hydrocarbons and non-aromatic hydrocarbons separately.
  • Mixture (2) is separated by means of extractive distillation ED1 in mixture (4) containing non-aromatic hydrocarbons having 7 to 12 carbon atoms and mixture (5) containing aromatic hydrocarbons having 7 to 12 carbon atoms. Residues of sulfur-containing components in mixture (5) can be removed in the desulfurization stage DS. This gives an almost sulfur-free mixture (6), which, optionally after addition of recycled alkyl-substituted benzenes from the distillation column D2 (13), the mixture A forms.
  • reaction zone I At least a portion of the mono- and poly-alkyl-substituted benzenes are reacted to form mixture B to form benzene, carbon monoxide, carbon dioxide, methane and hydrogen. If appropriate, mixture B can be added to recycled water (12) from the phase separator WHS (10) before it is passed into the reaction zone II following the reaction zone I.
  • reaction zone II in addition to the reaction described for reaction zone I, at least a portion of the hydrogen formed in reaction zone I is consumed for the conversion of the alkyl-substituted benzenes to benzene.
  • a mixture C containing water vapor, unreacted and partially dealkylated mono- and poly-alkyl-substituted benzenes, benzene, carbon monoxide, carbon dioxide, alkanes and hydrogen is obtained.
  • GLS gas liquid separation
  • the water, alkyl-substituted benzenes and benzene contains, separately.
  • a portion of the mixture D is taken from the system (8) to prevent concentration of the gases in the circulation, the mixture (9) is optionally recycled to the reaction zone II.
  • the constituents contained in the liquid mixture E are separated in the phase separator WHS into an alkyl-substituted benzenes and benzene-containing mixture F and water (10).
  • the mixture F in benzene (14) and mono- and polysubstituted alkyl-substituted benzenes (13) is separated.
  • the mono- and poly-alkyl-substituted benzenes (13) can optionally be reused in mixture A.
  • Embodiment 2 is a diagrammatic representation of Embodiment 1:
  • FIG. 1 A schematic drawing of embodiment 2 is shown in FIG.
  • reaction zone I At least a portion of the mono- and polyalkylene-substituted benzenes is converted to carbon monoxide, carbon dioxide, methane and hydrogen to form benzene, carbon monoxide, carbon dioxide, methane and hydrogen and at least a portion of the non-aromatic hydrocarbons, and obtained the mixture B.
  • the mixture B is, optionally with the addition of recycled from the phase separator WHS recycled water (10), led into the reaction zone I following reaction zone II.
  • reaction zone II in addition to the reactions described for the reaction zone I, at least a portion of the hydrogen formed in the reaction zone I is used for the reaction of the and multiple alkyl-substituted benzenes to benzene with elimination of the corresponding alkane consumed.
  • a mixture C is obtained which comprises steam, unreacted and partially dealkylated mono- and polysubstituted alkyl-substituted benzenes, benzene, carbon monoxide, carbon dioxide, alkanes, in particular methane and hydrogen.
  • Part of the mixture D is withdrawn from the system (6) to prevent concentration of the gases in the circulation, the remainder (7) is optionally recycled to the reaction zone II. It is also possible to isolate certain gas components from mixture D or (7) and to return it to the reaction zone II. Particular preference is given to recycling alkanes and in particular methane and hydrogen.
  • the liquid components separated from the GLS as mixture E are separated in the phase separator WHS into a mixture F containing mono- and poly-alkyl-substituted benzenes and benzene and also water (8).
  • the mixture F is subsequently separated into benzene (12) and mono- and poly-alkyl-substituted benzenes (11).

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

L'invention concerne un procédé de production de benzol par désalkylation de benzols une ou plusieurs fois substitués en alkyle et comportant 7 à 12 atomes de carbone en présence d'un catalyseur hétérogène et de vapeur d'eau.
PCT/EP2008/056922 2007-06-08 2008-06-04 Procédé amélioré de transformation d'hydrocarbures sur un catalyseur en présence de vapeur d'eau Ceased WO2008148807A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP07109902.2 2007-06-08
EP07109902 2007-06-08

Publications (1)

Publication Number Publication Date
WO2008148807A1 true WO2008148807A1 (fr) 2008-12-11

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PCT/EP2008/056922 Ceased WO2008148807A1 (fr) 2007-06-08 2008-06-04 Procédé amélioré de transformation d'hydrocarbures sur un catalyseur en présence de vapeur d'eau

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WO (1) WO2008148807A1 (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110275868A1 (en) * 2010-05-07 2011-11-10 Basf Se Process for preparing at least one low molecular weight aromatic material of value from a lignin-comprising starting material
US20110275869A1 (en) * 2010-05-07 2011-11-10 Basf Se Process for producing synthesis gas and at least one organic liquid or liquefiable material of value
WO2011138357A1 (fr) 2010-05-07 2011-11-10 Basf Se Procédé de préparation d'au moins une matière valorisable aromatique de faible poids moléculaire à partir d'une matière de départ contenant de la lignine
WO2011138355A2 (fr) 2010-05-07 2011-11-10 Basf Se Procédé de production de cellulose et d'au moins une matière valorisable organique liquide ou liquéfiable avec recyclage des effluents gazeux
WO2011138356A1 (fr) 2010-05-07 2011-11-10 Basf Se Procédé de production de gaz de synthèse et d'au moins une matière valorisable organique liquide ou liquéfiable
WO2012013735A1 (fr) 2010-07-29 2012-02-02 Basf Se Composition contenant un catalyseur et de la lignine, et utilisation de ladite composition pour la production d'une composition aromatique
WO2012160072A1 (fr) 2011-05-24 2012-11-29 Basf Se Procédé de production de polyisocyanates à partir de biomasse
US8933262B2 (en) 2011-05-24 2015-01-13 Basf Se Process for preparing polyisocyanates from biomass

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1933897A1 (de) * 1968-07-05 1970-01-08 Shell Int Research Verfahren zur Desalkylierung von Alkylaromaten
US3775504A (en) * 1971-05-07 1973-11-27 Ici Ltd Production of benzene

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1933897A1 (de) * 1968-07-05 1970-01-08 Shell Int Research Verfahren zur Desalkylierung von Alkylaromaten
US3775504A (en) * 1971-05-07 1973-11-27 Ici Ltd Production of benzene

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110275868A1 (en) * 2010-05-07 2011-11-10 Basf Se Process for preparing at least one low molecular weight aromatic material of value from a lignin-comprising starting material
US20110275869A1 (en) * 2010-05-07 2011-11-10 Basf Se Process for producing synthesis gas and at least one organic liquid or liquefiable material of value
WO2011138357A1 (fr) 2010-05-07 2011-11-10 Basf Se Procédé de préparation d'au moins une matière valorisable aromatique de faible poids moléculaire à partir d'une matière de départ contenant de la lignine
WO2011138355A2 (fr) 2010-05-07 2011-11-10 Basf Se Procédé de production de cellulose et d'au moins une matière valorisable organique liquide ou liquéfiable avec recyclage des effluents gazeux
WO2011138356A1 (fr) 2010-05-07 2011-11-10 Basf Se Procédé de production de gaz de synthèse et d'au moins une matière valorisable organique liquide ou liquéfiable
WO2012013735A1 (fr) 2010-07-29 2012-02-02 Basf Se Composition contenant un catalyseur et de la lignine, et utilisation de ladite composition pour la production d'une composition aromatique
WO2012160072A1 (fr) 2011-05-24 2012-11-29 Basf Se Procédé de production de polyisocyanates à partir de biomasse
US8933262B2 (en) 2011-05-24 2015-01-13 Basf Se Process for preparing polyisocyanates from biomass

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