FI89477B - Method for production of methyl-tert-butyl-ether - Google Patents

Description

1 89477

The invention relates to a process for the preparation of methyl tert-butyl ether by reacting isobutene and methanol in an ether formation zone in the presence of a catalyst under ether formation conditions. Methyl tert-butyl ether is used as an additive in high octane gasoline.

10

The conversion of paraffins to olefins is a well-known method that has been extensively studied and described. U.S. Patent 4,229,609 describes a process in which a dehydrating hydrocarbon is dehydrated using 15 layers of a steam active dehydrogenation catalyst that is repeatedly regenerated.

In the present invention, the dehydration of isobutane in a novel manner to isobutene forms part of an integrated process for the preparation of methyl tert-butyl ether.

20

The process of the invention is characterized in that it comprises a) contacting a isobutane-containing stream and steam with a reforming catalyst containing a catalyst base and a Group VIII metal in an isomerization and reforming zone at a temperature in the range of about 510-621 ° C to convert at least a portion of isobutane b) removing the reaction agent from this isomerization and reforming zone, c) introducing at least a portion of the reaction agent into the ether formation zone and reacting the isobutene therein with methanol in the presence of an ether formation catalyst in the presence of methyl ether-tert-butyl y9477 d) removing the product containing methyl tert-butyl ether from this ether formation zone and directing it to the separation zone, 5 e) separating the ether-containing effluent in this separation zone, aa) methyl tert-butyl ether (bb) a stream containing 1-butene and (cc) a by-product stream containing 2-butene; the 1-butene in the stream is converted to 2-butene, which is removed from the separation zone as a by-product stream.

Other features, details, and embodiments of the invention, as well as the advantages thereof, will be apparent to those skilled in the art from the following detailed description of the invention and the drawings, in which Figure 1 shows a flow chart for preparing methyl tert-butyl ether from isobutane and methanol and Figure 2 shows a bar graph of butene products.

In accordance with the invention, it has been found that the catalyst described in more detail below, which is known to be an effective dehydrogenation catalyst, is also an excellent isomerization catalyst for the conversion of 1-butene to 2-butene.

The isomerization and reforming conditions used in the process of the invention are preferably in the following ranges: 35 3 b 9 4 7 7

Isomerization and reforming conditions

Generally Preferably used Used 5 Temperature (° C) 510-621 582-605

Pressure (kp / cm2) 0-14 0-7 10 Steam / hydrocarbon 1 / 1-25 / 1 2 / 1-15 / 1 (molar ratio) 1-15 1.5-8 LHSV * (or 1-10)

Hydrogen / hydrocarbon ** 15 (molar ratio) 0-1.3 / 1 0-0.8 / 1 * volume rate of hydrocarbon per hour, i.e. volume of hydrocarbon per volume of catalyst per hour.

** No H2 is added during isomerization and hydrogen removal.

20

The catalyst that can be used in all embodiments of the invention is generally a supported Group VIII metal catalyst. The most preferred Group VIII metal is platinum. The support may be alumina, silica, magnesium oxide, zirconia, alumina silicate, Group II alumina spinel, or a mixture of these supports. Group VIII metals are those classified in this group in the Periodic Table of the Elements set forth in Chemical Rubber Companies, Handbook of Chemistry and Physics, 45th 45th Edition (1964), page B-2.

The amount of Group VIII metal is not critical. In general, any amount that provides the catalytic activity of the support / metal combination can be used.

Typically, the Group VIII metal in the catalyst is in the range of about 0.01 to 10 parts by weight per 100 parts by weight of the support, and often this amount is in the range of about 0.1 to 5 parts by weight.

4 89477

Accelerator metals can be used in the catalyst together with a Group VIII metal. The most preferred accelerator metals are lead, tin and germanium, which are generally used up to 10, preferably 5 parts by weight per 100 parts by weight of support.

When an accelerator metal is used, it is usually used in the range of 0.01 to 10 parts by weight and often in the range of 0.1 to 1 part by weight per 100 parts by weight of the support. Accelerator metals can be used as chemical compounds such as halides, nitrates, oxalates, acetates, carbonates, propionates, tartrates, bromates, chlorates, oxides, hydroxides, etc. Of the accelerator metals, tin is the most preferred and tin halide is preferred.

The catalysts used in the invention are obtained by known methods, such as by impregnating the support with a metal compound. The compounds used should be such that, after calcination of the catalyst, no significant amounts of excess material remain, in particular no other metals which could affect the desired catalytic treatment.

The most preferred catalyst used in the process of the invention is one formed by a platinum zinc alumina account, especially and preferably by zinc aluminate spinel. Most preferably, the catalyst comprises an accelerator metal tin. Thus, the most preferred catalyst of the invention consists mainly of zinc aluminate spinel, platinum and tin. A typical catalyst may contain from about 0.1 to 5 parts by weight of platinum and from about 0.1 to 1 part by weight of tin per 100 parts by weight of zinc aluminate spinel support. The most preferred catalyst has a pore volume in the range of 0.23 to 0.55 ml / g and a surface area in the range of 12 to 30 m 2 / g.

In the ether reaction of the invention to form methyl tert-butyl ether, isobutene is reacted with methanol. This reaction is well known and has been extensively described in various contexts. Unreacted isobutane 89477 can be (after removal of ether) recycled to the reforming process to convert isobutane to isobutylene. The difficulty with such treatment, however, is that other hydrocarbons with a near boiling point 5 also recirculate so that these hydrocarbons, which do not take part in the ether formation reaction, rapidly accumulate in such circulation in excessive amounts. Although fractionation can be used, e.g., to remove 2-butene, 1-butene cannot be efficiently removed because its boiling point is very close to the boiling point of isobutene.

However, according to the invention, it has now been found that the recirculation of 1-butene to the reforming reaction (a catalytic reaction in which isobutane is converted to isobutene) does not cause such an accumulation because 1-butene is converted to 2-butene under reforming conditions, and this 2-butene can be easily removed by fractionation from unreacted isobutane and isobutene. The catalyst thus described and defined above has a dual function according to the invention: it acts normally in dehydrogenation to convert isobutane to isobutene and also acts as an isomerization catalyst to convert 1-butene to 2-butene. The reforming zone is therefore both a reforming and an isomerization zone, and the catalyst acts both as a catalyst to give the desired product, namely isobutene, which is converted to ether, and as a by-product removal catalyst, converting 1-butene to 2-butene.

The ether formation reaction step according to the invention is a step known per se. The reaction takes place between isobutene and methanol. Typical ether formation conditions are shown; · In the following table.

! 35 6> 94: 7

Eetterinmuodostusolosuhteet

Generally Preferably used 5 Temperature (° C) 32-93 38-77

Pressure (kp / cm2) 2.8-42 6-18.2 * 10 LHSV ** 0.2-30 0.5-20

Isobutene / methanol (molar ratio) 0.2-2 0.8-1.3 15 * The pressure is sufficient to keep the reactants in the liquid phase.

** Hydrocarbon volume rate per hour, i.e. volume of hydrocarbon per volume of catalyst per hour.

20

The catalyst used in the ether formation reaction is also a conventional ether formation catalyst. Such catalysts are described in U.S. Patents 3,979,461 and 3,902,870. Specific examples include hydrogen fluoride, sulfuric acid, AlCl 3, and acidic ion exchange resins.

In an embodiment of the invention in which the 1-butene-containing stream is contacted with a reforming catalyst both for the dehydrary isobutane isobutene crude isobutane for the ether formation reaction and for the isomerization of 1-butene to 2-butene, which allows the removal of 1-butene that would otherwise accumulate therein. the ratio of the total amount of isobutane to the total amount of 1-butene in general and preferably as shown in the following tau-35.

7 Λ 9 47 7

Table

Generally Preferred used 5 1-butene / isobutane (molar ratio) 1/10 to 1/10,000 1/100 to 1/1000 (1) of 1-butene in a stream containing 1-butene was removed from the ether formation stream.

10 (2) Total isobutane, including the isobutane feedstock and unreacted isobutane in the 1-butene stream from the ether formation reaction.

15

Other details and preferred embodiments of the invention will become apparent from the following description of the drawing and specific examples.

The drawing shows a flow chart of the method according to the invention. A feed stream containing mainly isobutane is fed to the steam-active reformer 1 containing the steam-active reforming catalyst via line 2. 25 steam is fed to the reforming device 1 via a line 3. The stream leaving the steam-active reformer is passed via line 11 to the MTBE reactor and separation system 4. Methanol is also passed to this MTBE reactor and separation system 4 via line 5. Methyl tertiary butyl ether (MTBE) is removed from the MTBE reactor and separation system 4 via line 6. The by-product stream containing the following compounds: unreacted isobutane, unreacted isobutene, butene-1, butene-2 and n-butane is passed through line 7 to fractionation tower 8. This fractionation tower 8 operates in such. .35 conditions that at least most of the butene-2, n-butane and heavier fractions are discharged as the upper stream. This upstream stream, which mainly contains butene-1, isobutane and isobutene, is led back via line 9 to a steam-active reformer 1. The bottom stream, which contains butene-2 and n-butane and other by-products, is removed from fractionator 8. through line 10.

5

The butene-1 contained in the upstream stream 9 is converted to butene-2 in the steam-active reformer 1 to an extent that depends on the equilibrium conditions to prevent the accumulation of butene-1 in the circulation line 9. The isobutane 10 in the stream 9 is at least partially converted to isobutene in the steam reactor. 1, while isobutene is converted at least in part to MTBE in the MTBE reactor and separation system 4. Thus, according to the invention, the steam-active reformer 1 has two different functions, being both a reformer and a by-product removal unit in which butene-1 is converted to internal olefins. in this case to butene-2, which are removed as a bottom stream from the fractionator 8.

20 Example 1

The butene-1 stream was treated in this example under steam active reforming conditions in contact with a steam active reforming catalyst. The composition of the feedstock, as well as the composition of the mixture leaving the reactor, is shown in the table below. This example was carried out at a liquid volume rate of 4.0 per hour, a steam to hydrocarbon ratio of 6/1, a pressure of 3.5 kp / cm 2 and an average bed temperature of 565 ° C. The reactor was filled with 3 mm preferred catalyst spheres.

The catalyst of this example contained 0.6 parts by weight of platinum, 1.0 part by weight of tin and 98.4 parts by weight of zinc aluminate spinel support. The pore volume was 0.29 ml / g and the surface area was 16 m2 / g. The catalyst layer had a diameter of 5 cm and a height of 35 cm, and 900 g of said preferred catalyst was introduced. The feed and discharge rates to the reactor shown in the following table were measured using calibrated gas chromatography. The analysis obtained from this gas chromatography is shown in the following table.

9 89477

Table _Mole -% _

Reactor feed Reactor outlet 5 C £ 0.138 C2 0.590 CO2 7.351 C3 0.496 10 1.570 C4 0.245 0.066 nC4 0.047 7.725

Cl1 99.032 14.793 trans-CJ2 0.125 16.914 15 cis-C42 13.130 butadiene 6.851 H2 25.526 02 0.085 N2 0.466 0.967 20 methane 3.682 CO 0.200

It can be seen from the above table that the steam active reforming catalyst is an effective isomerization catalyst that converts a significant amount of 1-butene to 2-butenes. Since 2-butenes boil at a much higher temperature than isobutane, isobutene and 1-butene, they can be easily removed from the stream leaving the ether formation reaction in the process of the invention.

30

Example 2

To determine the effect of isobutene recirculation on the steam-active reforming step, as well as to determine the effect of recycled l-butene on the steam-35 reactive reforming step, the following experiments were performed.

10 * 9 4 "7

In the first experiment, 95 mol% of isobutane raw material was confirmed with 5 mol% of isobutene. This mixture was passed to a steam active reforming test facility. As expected, the change was reduced by 1 to 3% compared to the change 5 obtained when pure raw material was used. Various experiments were performed using a liquid volume rate of 4 per hour and a steam to hydrocarbon ratio of 5: 1. The average bed temperature and the amount of isobutane conversion are shown in the following tables, as is the effect of 10% isobutene in the isobutane feed on the steam active reforming treatment with different treatment of isobutane. These values are also based on the volume volume of the liquid per hour 4 and the molar ratio of steam to hydrocarbon 5: 1.

15

Table _Isobutane change% 20 Inlet temperature no inlet 5% ° C_isobutene_isobutene 549 43.3 41.2: 25 560 46.9 44.8 571 50.4 48.0 582 53.9 51.6 30 Table

Isobutene selectivity%

% Change of isobutane in the feed not in the feed 5% of 35 fresh feeds_isobutene_isobutene * 42 95.7 94.4 44 95.1 93.8 46 94.5 93.3> 0 48 93.9 92.6 50 93.3 92, 1 H 09477 * Calculation of selectivity: sei (%) = (isobutene in product - isobutene in feed) τ isobutane changed; thus, "selectivity" is considered to be reduced.

A second experiment was performed to determine the effect of recirculating butene-1 with isobutane on the steam-active reforming treatment. In this series of experiments, 5 mol% of 1-butene was used as a raw material together with 95 mol% of isobutane in the experimental plant 10 described above. The following table shows the results obtained when comparing the pure raw material, i. pure isobutane, to a fortified raw material, i.e. to one containing 95 mole% isobutane and 5 mole% 1-butene. The values in this table are based on the liquid volume volume-15 per hour at 4 hours and the steam to hydrocarbon ratio at 5: 1, with an average bed temperature of 565 ° C.

The following table shows the conversion of isobutane obtained using pure feedstock compared to feedstock 20 fortified with 5 mole percent 1-butene as described above at various bed temperatures.

Table 25 _Isobutane change% _ Feed temperature no feed 5% ° C__ isobutene-1 butene-1 30 564 48.4 565 - 49.7 567 48.8 575 52.2 .35 576 - 51.0 577 50.8 579 51.8

The above results show that the steam-active reforming treatment can be used efficiently as well as the regular steam-active reforming, i. conversion of isoparaffin to an iso-olefin, that isomerization treatment, i.

to effect the conversion of 1-butene to 2-butenes. It should be noted that a certain portion of 1-butene is hydrogenated back to 5 normal butane. The isobutane fed to the reforming part contains a small amount of n-butane, this amount being 0.5 to 5 mol%. However, normal butane can be easily removed from isobutylene, isobutane and 1-butene due to its higher boiling point.

10

Example 3

Comparative experiments were performed using the same catalyst and the conditions shown in Figure 2. The experiments were performed using pure 1-butene and a fortified feed (isobutane and 5 mol% 1-butene). The results are shown in Figure 2. As can be seen, the leaving mixture is essentially unchanged. Thus, a reformer can be used to convert recycled l-butene to 2-butene and prevent the accumulation of l-butene.

20

Various changes and modifications may be made to the invention which will be apparent to those skilled in the art without departing from the scope of the invention.

25

Claims (3)

13 a 9 4 7 7 l. Process for the preparation of methyl tert-butyl ether by reacting isobutene and methanol in an ether-forming zone in the presence of a catalyst under ether-dosing conditions, characterized in that it comprises a) contacting the isobutane-containing stream and vapor with containing a catalyst base and a Group Vili metal, in the isomerization and reforming zone at a temperature in the range of about 510 to 6210 ° C, for converting at least a portion of isobutane to isobutene, b) removing the reaction agent from this isomerization and reforming zone, c) removing at least a portion of the reaction effluent to a tertiary formation zone and reacting isobutene therein with methanol in the presence of an ether formation catalyst to form methyl tert-butyl ether, d) removing the product containing methyl tert-butyl ether therefrom. from the zone and passing it to the separation zone, 25 e) separating the ether-containing effluent in this separation zone, aa) into a product stream containing methyl tert-butyl ether, 30 bb) into a stream containing 1-butene and cc) into a stream containing 2-butene f) passing the l-butene-containing stream to the isomerization and reforming zone and contacting the reforming catalyst 35 so that at least a portion of the l-butene in the l-butene-containing stream is converted to 2-butene, which is removed from the separation zone as a by-product stream. 14 ·, · 94 7 7 2. A patent according to claim 1, comprising 20 molar halides with 1-buten and isobutane and isomerization and reforming in the range of 1/10 to 1/10 000. Process according to Claim 1, characterized in that the molar ratio of 1-butene to isobutane in said isomerization and reforming zone is in the range from 1/10 to 10/10,000. Process according to Claim 1, characterized in that the catalyst base is zinc aluminate-Spinelli, the Group VIII metal is platinum in an amount of about 0.1 to 5 parts by weight per 100 parts by weight of the catalyst base 10 and in that the reforming catalyst additionally contains 0.01 - 1 part by weight per 100 parts by weight of carrier. 15. A patent for the preparation of the methyl tert-butyl ether genome by the reaction of isobutene and methanol in the reaction of a mixture with an ether mixture under the action of a catalyst and a catalyst for the reaction of a mixture of 20 and a). , which is an isobutane, and is contacted by a catalyst catalyst, which is a catalyst and a catalyst from the group 25 VIII, i en isomeriserings- och reformeringszon inom tempera-turintervallen av ca. 510-621 ° C for the reaction of the isomers with the reaction of isobutane, b) the reaction of the reaction with the reaction of the material is 30 times, c) the reaction with the reaction of the reaction with the isothermal and the addition of a reagent from methanol to an ether with an ether-35 reaction catalyst for the formation of methyl tert-butyl ether, is' -> 9 4/7 d) preparation of a product with methyl tert-butyl ether frdn denna eterbildningson and ledning av densamma account en separationszon, 5 e) avkiljning av en etherhaltig avloppsströmning i denna separationszon aa) account en produktströmning innehdllande methyl-tert -butyl-ether, 10 bb) account en l-butenhaltig strömning och cc) account en 2-butenhaltig biproduktströmning; utenen i den den 1-butenhaltiga strömningen omvandlas account 2-buten som avlägsnas frdn separszonen som en biproduktströmning. 3. A preferred embodiment of claim 1, which comprises a substrate for a catalyst having a zinc potassium spinel, a metal of Group VIII having a platinum stem of about 0.1 to 5 wires per 100 wafers for a catalyst substituent and a reformer. - 1 warrant for each 100 winners. 30