CN106984294B - A kind of oxidative carbonylation synthesis technique, its liquid waste processing catalyst and preparation method thereof - Google Patents

Abstract

The invention discloses a kind of oxidative carbonylation synthesis technique, its liquid waste processing catalyst and preparation method thereof.The synthesis technique, use nitric oxide to generate nitrous acid ester for nitric acid caused by the reaction of reducing agent reduction-oxidation carbonylation and put into oxidative carbonylation synthesis again, form the lossless circulation of nitrogen.The liquid waste processing catalyst, is carbon attachment material, including matrix and the carbon material layer for being covered in stromal surface；The carbon material layer is loose structure, including the carbon material of mass fraction 85%~95% and 5%~15% binding agent；The matrix is tower structured packing or random packing.The catalyst can greatly improve nitric acid transformation efficiency.

Description

A synthesis process of oxidative carbonylation method, its waste liquid treatment catalyst and its preparation method

technical field

The invention belongs to the field of chemistry and chemical engineering, and more specifically relates to an oxidative carbonylation synthesis process, a waste liquid treatment catalyst and a preparation method thereof.

Background technique

The chemical waste liquid containing dilute nitric acid and nitrogen monoxide waste gas will be produced in the ester synthesis process of oxidative carbonylation method. Take the industrial synthesis of oxalate ester and carbonate ester as an example: the following reactions occur during the synthesis process:

(1) 2RONO+2CO＝ROOCCOOR+2NO

(2) 2RONO+CO＝ROOCOR+2NO

Reaction 1 and 2 are the reaction formulas of oxalate and carbonate respectively. The nitric oxide (NO) formed in the reaction must be converted into nitrite to maintain the continuous reaction. During the conversion of NO into nitrite, there are The following reaction occurs:

(3) 4ROH+4NO+O ₂ ＝4RONO+2H ₂ O

Wherein R: represents an alkyl group, such as CH3-, C2H5 etc.

(4) 4NO+3O ₂ +2H ₂ O＝4HNO ₃

Reaction 3 is the regeneration reaction of nitrite ester, and reaction 4 is a side reaction in the regeneration process of nitrite ester. The water generated in reaction 3 is mixed with the by-product nitric acid and unreacted methanol in reaction 4 to form dilute nitric acid. Generally between 0.5 and 10%. Reaction 4 is not expected to occur during the regeneration of nitrite. Although many studies have aimed to improve the selectivity of nitrite, it is still impossible to completely avoid the occurrence of reaction 4.

At present, these chemical waste liquids containing dilute nitric acid use methods such as rectification recovery and neutralization to treat the nitric acid in the mixed solution, but these methods have many shortcomings. React with other components such as alcohols, esters, etc. to generate aldehydes and acids, and nitric acid will decompose at high temperature; while nitric acid neutralization will consume a large amount of alkali, and the by-product nitrate needs further treatment. Patent CN03120703.0 describes a synthetic method for the synthesis of nitrite by using oxalate by-product nitric acid. This method is suitable as a supplement for nitrite in the synthesis of oxalate and cannot be used to treat dilute nitric acid. In its embodiment, nitric acid The highest conversion rate is only 80%, and the concentration of dilute nitric acid remains at 1.9%. Recently, the patent CN104945262A uses methanol to catalytically reduce dilute nitric acid to generate methyl nitrite. This method has the characteristics of mild reaction conditions and high conversion rate of nitric acid by using methanol to reduce dilute nitric acid. Higher; patent CN104338550A uses activated carbon covered with molecular sieve membrane as a carrier, and by supporting additives such as iron and copper, the catalyst is used for dilute nitric acid treatment in the synthesis of oxalate esters, and the conversion rate of nitric acid is 70%. Due to the addition of copper and iron as additives , copper and iron are easily dissolved by nitric acid in dilute nitric acid environment, thus affecting the stability of the catalyst.

At present, there is no good method for the treatment of chemical waste liquid containing dilute nitric acid in the synthesis of oxidative carbonylation. There are problems such as incomplete treatment of dilute nitric acid, unstable catalyst and high treatment cost. The process is costly and environmentally unfriendly.

Contents of the invention

In view of the above defects or improvement needs of the prior art, the present invention provides a synthesis process of oxidative carbonylation method, its waste liquid treatment catalyst and its preparation method, the purpose of which is to reduce nitric acid produced by the synthesis reaction to finally generate nitrogen The nitrate is used as a synthetic raw material for the oxidative carbonylation method to form a non-destructive cycle of N elements, thereby solving the technical problem of the loss of N elements in the existing oxidative carbonylation method.

In order to achieve the above object, according to one aspect of the present invention, a catalyst for the treatment of synthetic waste liquid by oxidative carbonylation method is provided, which is characterized in that it is a carbon-adhered material; Carbon material layer; the carbon material layer is a porous structure, including 85% to 98% carbon material and 2% to 15% binder; the matrix is a structured packing or a random packing of a tower.

Preferably, in the catalyst, the carbon material layer further includes an additive with a mass fraction of 0.1%-10%, preferably B, or Pt.

Preferably, in the catalyst, the binder is tar or epoxy resin; the substrate is ceramic, stainless steel and/or plastic; the carbon material is.

According to another aspect of the present invention, a kind of preparation method of described catalyst is provided, comprising the following steps:

A. Disperse the carbon material to form a dispersion system. Gas dispersion such as air dispersion or liquid dispersion can be used, such as uniformly mixing the carbon material, dispersant, and binder to form a carbon material dispersion;

B. Uniformly attaching the carbon material dispersion system obtained in step A to the surface of the matrix to obtain a carbon material-matrix composite;

C. Subjecting the carbon material-matrix composite obtained in step B to conformal treatment to obtain the carbon-based catalyst.

According to another aspect of the present invention, a kind of oxidative carbonylation synthesis technique is provided, it comprises the following steps:

Synthesis by oxidative carbonylation method: the synthesis of oxidative carbonylation reaction takes place with the gas containing nitrite and carbon monoxide as the raw material, and the generated nitrogen monoxide is subjected to the regeneration reaction of nitrite to obtain the chemical waste liquid containing alcohol and dilute nitric acid and the waste liquid containing monoxide Nitrogen synthesis cycle gas;

Waste liquid nitric acid treatment:

(1) The chemical waste liquid containing alcohol and dilute nitric acid produced in the synthetic reaction of oxidative carbonylation and the synthesis cycle gas containing nitric oxide are passed through the catalyst bed in parallel or countercurrent to obtain the treated liquid phase and gas phase;

(2) reclaiming the alcohol in the treated liquid phase obtained in step (1), to obtain a dealcoholized liquid phase;

(3) The liquid phase after the dealcoholation obtained in step (2) is input as the liquid raw material containing nitrite synthesized by oxidative carbonylation;

(4) Put the treated gas phase obtained in step (1) into the carbon monoxide-containing gas raw material for oxidative carbonylation synthesis.

Preferably, in the oxidative carbonylation synthesis process, the catalyst bed, the filled catalyst is activated carbon or the catalyst as claimed in claims 1 to 3.

Preferably, in the oxidative carbonylation synthesis process, in the chemical waste liquid, the concentration of nitric acid is less than or equal to 10%; in the synthesis cycle gas, the volume percentage of nitric oxide is between 1% and 20%; Preferably, the chemical waste liquid and synthetic cycle gas are preheated.

Preferably, in the oxidative carbonylation synthesis process, when co-flowing through the catalyst bed, the chemical waste liquid and synthesis cycle gas are premixed.

Preferably, in the oxidative carbonylation synthesis process, when the co-current or counter-current passes through the catalyst bed, the space velocity of the liquid phase is between 0.1h ^-1 and 3h ^-1 , and the space velocity of the gas phase is between 100h ^-1 and 3000h ^- between ¹ .

Preferably, in the oxidative carbonylation synthesis process, the temperature of the catalyst bed is controlled between 30°C and 120°C, and the reaction pressure is between 0.1Mpa and 1.50Mpa.

Generally speaking, compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

The present invention uses the nitric oxide produced by the oxidative carbonylation synthesis process as a reducing agent to treat the nitric acid in the waste liquid to finally generate nitrite and put it into the oxidative carbonylation reaction to form N elements for non-destructive recycling, and to treat the regeneration of nitrite with high efficiency and low cost. The by-product of nitric acid is environmentally friendly. By adopting the catalyst provided by the invention, the treatment efficiency of nitric acid is greatly improved.

Description of drawings

Fig. 1 is the synthesizing process flow diagram of oxidative carbonylation method provided by the present invention;

Fig. 2 is the schematic structural diagram of the waste liquid nitric acid treatment device adopted in Embodiment 1, 2 and 4 of the present invention;

Fig. 3 is a schematic structural diagram of a waste liquid nitric acid treatment device used in Examples 3 and 5 of the present invention.

In all drawings, the same reference numerals are used to represent the same elements or structures, wherein: 1 is a mixing tower, 2 is a feed preheater, 3 is a tower bottom circulation pump, 4 is a packed tower, 5 is a reaction tower.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

The catalyst for treating synthetic waste liquid in the oxidative carbonylation method provided by the invention is a carbon-based catalyst, which is a carbon-adhered material; the carbon-adhered material includes a matrix and a carbon material layer covering the surface of the matrix. The carbon material layer has a porous structure and includes 85%-98% carbon material, 2%-15% binder, and 0.1%-10% auxiliary agent. The carbon material is preferably carbon powder, activated carbon, and/or carbon nanomaterials; the binder is preferably tar or epoxy resin; the auxiliary agent is B or Pt.

The matrix can be the existing column structured packing or random packing, preferably made of ceramic, stainless steel and/or plastic.

The carbon-based catalyst is prepared as follows:

A. Disperse the carbon material to form a dispersion system. Gas dispersion such as air dispersion or liquid dispersion can be used, such as uniformly mixing the carbon material, dispersant, and binder to form a carbon material dispersion;

B. Uniformly attaching the carbon material dispersion system obtained in step A to the surface of the matrix to obtain a carbon material-matrix composite;

C, subjecting the carbon material-matrix composite obtained in step B to a shape-attaching treatment to obtain the carbon-based catalyst;

The conformal treatment includes drying, roasting, and/or activation treatment.

The carbon-based catalyst provided by the invention is specially used for the oxidative carbonylation method synthesis provided by the invention

Oxidative carbonylation synthesis technique provided by the present invention, as shown in Figure 1, comprises the following steps:

Synthesis by oxidative carbonylation method: oxidative carbonylation reaction synthesis takes place with nitrite-containing liquid and carbon monoxide-containing gas as raw materials, and the generated nitrogen monoxide undergoes nitrite regeneration reaction to obtain chemical waste liquid containing alcohol and dilute nitric acid and Synthetic recycle gas containing nitric oxide; the regeneration reaction is as follows:

4ROH+4NO+O ₂ ＝4RONO+2H ₂ O (I)

4NO+3O ₂ +2H ₂ O＝4HNO ₃ (II)

Wherein formula (I) is the nitrate ester regeneration reaction formula, formula (II) is the side reaction, R represents an alkyl group, such as CH ₃ -, C ₂ H ₅ and so on.

Waste liquid nitric acid treatment:

(1) The chemical waste liquid containing alcohol and dilute nitric acid produced in the synthesis reaction of oxidative carbonylation and the synthesis cycle gas containing nitric oxide are passed through the catalyst bed in parallel or countercurrent to obtain the treated liquid phase and gas phase; The chemical reaction is as follows:

2HNO ₃ +4NO＝6N ₂ O ₃ +H ₂ O (Ⅲ)

2ROH+N ₂ O ₃ ＝2RONO+H ₂ O (Ⅳ)

The chemical waste liquid, wherein the concentration of nitric acid is less than or equal to 10%; the synthetic cycle gas, wherein the volume percentage of nitric oxide is between 1% and 20%; preferably, the chemical waste liquid and the synthetic cycle gas are pre-treated The chemical waste liquid and synthetic recycle gas are premixed when using co-current flow through the catalyst bed.

When passing through the catalyst bed in parallel or countercurrent, the space velocity of the liquid phase is between 0.1h ^-1 and 3h ^-1 , the space velocity of the gas phase is between 100h ^-1 and 3000h ^-1 , and the space velocity of the liquid phase is preferably 0.5 to 2h ^{- 1.} The gas phase space velocity is preferably 100-1000h ^-1 ; the temperature of the catalyst bed is controlled between 30-120°C, and the reaction pressure is between 0.1Mpa and 1.50Mpa.

When the concentration of nitric acid is less than or equal to 5%, it is preferred to flow through the catalyst bed in parallel; when the concentration of nitric acid is greater than 5%, it is preferred to flow through the catalyst bed in countercurrent.

In the catalyst bed, the filled catalyst is activated carbon or the carbon-based catalyst provided by the present invention.

(2) reclaiming the alcohol in the treated liquid phase obtained in step (1), to obtain a dealcoholized liquid phase;

(3) The liquid phase after the dealcoholation obtained in step (2) is dropped into as the oxidative carbonylation synthesis reaction raw material;

(4) Put the treated gas phase obtained in step (1) into the carbon monoxide-containing gas raw material for oxidative carbonylation synthesis.

The synthesis process of oxidative carbonylation method provided by the present invention is suitable for chemical synthesis including the industrial synthesis process of oxalate ester and carbonate ester, because its industrial synthesis process produces waste gas containing the same nitrogen, it is just used as a reducing agent and then specified Under the action of the catalyst, the dilute nitric acid in the chemical waste liquid is reduced to obtain nitrogen dioxide, which further reacts with nitric oxide and alcohol to form nitrate ester, and the dilute nitric acid produced by the synthesis side reaction is reused to realize the complete nitrogen element Circulation, solve the cost problem of dilute nitric acid waste liquid and the environmental problems caused by incomplete treatment.

On the other hand, the catalyst provided by the invention combined with the process conditions of the invention can greatly increase the catalytic conversion rate of dilute nitric acid, and the conversion rate of nitric acid exceeds 90%, and the preferred solution reaches 98%.

The following are examples:

Example 1 Synthesis of oxalate by oxidative carbonylation

The catalyst used in this example is activated carbon modified by B. The specific method is to add the activated carbon to the mass ratio of B:AC=1:20 to add boric acid aqueous solution and impregnate it in an equal volume, dry it at 120°C for 2 hours, and then dry it at 500-600°C Roasting in air isolation for 2 hours, cooling in air isolation, immersion and washing with nitric acid aqueous solution etc. for 3 times can obtain the catalyst used in this example.

The process flow used in this embodiment, waste liquid nitric acid treatment Figure 2, uses a mixing tower as a reactor, the upper section of the tower is used as a packing device, and the filler is catalyst particles, which are packed in two sections; the lower section is a plate tower.

The process of this embodiment is shown in Figure 2:

Synthesis by oxidative carbonylation:

The liquid containing nitrite and the gas containing carbon monoxide are used as raw materials to undergo oxidative carbonylation reaction to synthesize oxalate, and the generated nitric oxide undergoes nitrite regeneration reaction to obtain chemical waste liquid containing alcohol and dilute nitric acid and chemical waste liquid containing monoxide Synthetic recycle gas of nitrogen; the regeneration reaction is as follows:

4ROH+4NO+O ₂ ＝4RONO+2H ₂ O (I)

4NO+3O ₂ +2H ₂ O＝4HNO ₃ (II)

Wherein formula (I) is the nitrate ester regeneration reaction formula, formula (II) is the side reaction, R represents CH ₃ , or C ₂ H ₅ .

Waste liquid nitric acid treatment:

(1) The chemical waste liquid produced in the above process is heated to 80° C. through the feed preheater and added from the top of the mixing tower 1 with a liquid space velocity of 1.0 h ⁻¹ ; The synthesis cycle gas enters from the bottom of the mixing tower 1 through the valve 4, the gas phase space velocity is 200h ^-1 , and the reactor pressure is 0.1Mpa; The reaction gas is poured and heated into the tower, and the reaction gas is heated to 85°C by the liquid in the tower kettle, and enters the catalyst layer from the bottom of the filler, so that the gas and the liquid are in countercurrent contact with the catalyst bed; the temperature of the catalyst bed is controlled at 80-90°C.

The chemical waste liquid is determined to contain (mass fraction) 1% nitric acid, 55% methanol, and 43% water.

The synthetic cycle gas is measured, and its specific composition (volume percentage) is as follows: 12% nitric oxide, 5% methyl nitrite, 15% carbon monoxide, 10% carbon dioxide, 8% methanol, and 50% nitrogen.

(2) The liquid phase after the reaction is mixed with the circulating liquid of the tower kettle on the tray, and sent to the methanol recovery system outside the boundary through the tower kettle circulating pump 3.

(3) The liquid phase after methanol recovery treatment is used as the reaction raw material of oxalate ester, and is put into the oxidative carbonylation system again.

(4) After the synthesis cycle gas is in contact with the reaction solution on the catalyst layer, about 95% of the nitric acid in the reaction solution is reduced, and the reacted gas enters the oxalate ester synthesis through the overhead valve 3 .

In this embodiment, other conditions remain unchanged, only when the liquid space velocity is adjusted to 0.1h ^-1 ~ 0.5h ^-1 , about 90% to 93% of the nitric acid in the reaction solution is reduced.

Example 2 Synthesis of oxalate by oxidative carbonylation

The carbon-based catalyst used in this embodiment is a carbon-adhered material; the carbon-adhered material includes a substrate and a carbon material layer covering the surface of the substrate. The carbon material layer has a porous structure, including 90%-95% carbon powder and 5%-10% tar by mass fraction.

The matrix is a ceramic filler treated with 5% potassium hydroxide at 100°C for 3-5 hours.

The carbon-based catalyst is prepared as follows:

A. Heat the mixture of carbon powder and tar in the formula ratio to 120°C, and stir evenly to form a carbon material dispersion;

B. Immerse the ceramic filler treated with 5% potassium hydroxide at 100°C for 3 to 5 hours into the above dispersion liquid, take it out after immersion for 0.5 hour and drain it for 2 hours, so that the carbon material is dispersed and evenly attached to the surface of the ceramic filler to obtain Carbon material-matrix composites;

C. Calcining the carbon material-matrix composite at 600-750° C. in the absence of air for 4 hours, and then raising the temperature to 900° C. and activating it with water vapor for 0.5 hours to obtain the catalyst used in this example.

The process flow adopted in this embodiment, the treatment of waste liquid nitric acid is shown in Figure 2 for details, the packed tower is used as the reactor, the upper part of the tower is a packing device, and the packing is a carbon-coated ceramic packing catalyst, which is packed in four stages; the bottom part of the tower body is filled with stainless steel Metal corrugated packing.

The process of this embodiment is shown in Figure 2:

Synthesis by oxidative carbonylation:

Using gas containing nitrite and carbon monoxide as raw materials, oxalate is synthesized by oxidative carbonylation reaction, and the generated nitric oxide undergoes nitrite regeneration reaction to obtain chemical waste liquid containing alcohol and dilute nitric acid and synthesis of nitric oxide Recycle gas; the regeneration reaction is as follows:

4ROH+4NO+O ₂ ＝4RONO+2H ₂ O (I)

4NO+3O ₂ +2H ₂ O＝4HNO ₃ (II)

Wherein formula (I) is the nitrate ester regeneration reaction formula, formula (II) is the side reaction, R represents CH ₃ , or C ₂ H ₅ .

Waste liquid nitric acid treatment:

(1) The chemical waste liquid produced in the above process is heated to 75°C through the feed preheater 2, and fed from the top of the tower with a liquid space velocity of 1.5h ^-1 ; the synthesis cycle gas produced in the above oxidative carbonylation process is The valve 4 enters from the bottom of the mixing tower 1, the gas phase space velocity is 500h ^-1 , and the reactor pressure is 0.3Mpa; the liquid in the bottom of the tower is heated to 90-100°C by the feed preheater 2, sprayed from the top of the stainless steel metal corrugated packing and heated into the Tower reaction gas, the reaction gas is heated to 85°C by the liquid in the tower kettle, and enters the catalyst layer from the bottom of the filler; the gas and liquid are in countercurrent contact on the catalyst bed; the temperature of the catalyst bed is controlled at 80°C to 90°C.

The chemical waste liquid is determined to contain (mass fraction) 1.5% nitric acid, 57% methanol, and 41.5% water.

The synthetic cycle gas is measured, and its specific composition (volume percentage) is as follows: 16% nitric oxide, 4% methyl nitrite, 12% carbon monoxide, 10% carbon dioxide, 8% methanol, and 50% nitrogen.

(2) The liquid phase after the reaction is mixed with the circulating liquid of the tower reactor on the tray, and sent to the methanol recovery system outside the boundary through the tower reactor circulating pump 3.

(3) The liquid phase after methanol recovery treatment is used as the reaction raw material of oxalate ester, and is put into the oxidative carbonylation system again.

(4) After the synthesis cycle gas is in contact with the reaction solution on the catalyst layer, about 90% of the nitric acid in the reaction solution is reduced, and the reacted gas enters the oxalate ester synthesis through the overhead valve 3 .

In this embodiment, other conditions remain unchanged, only when the gas phase space velocity is adjusted to 1000h ⁻¹ , about 93% of the nitric acid in the reaction is also reduced.

Example 3 Synthesis of oxalate by oxidative carbonylation

The carbon-based catalyst used in this embodiment is a carbon-adhered material, specifically carbon-coated stainless steel wire mesh filler; the carbon-adhered material includes a substrate and a carbon material layer covering the surface of the substrate. The carbon material layer has a porous structure, including 85%-90% carbon powder, 10%-15% tar, and 0.1%-0.3% platinum as an auxiliary agent.

The matrix is stainless steel wire mesh packing.

The carbon-based catalyst is prepared as follows:

A. Heat the mixture of carbon powder and tar in the proportion of the formula to 150°C, and stir evenly to form a carbon material dispersion;

B. Treat the stainless steel wire mesh with 20% nitric acid solution at 100°C for 1 to 3 minutes, rinse until neutral, then treat it with 3% potassium hydroxide solution at 80°C for 15 minutes, and immerse the treated stainless steel mesh filler into the above dispersion , take it out after soaking for 0.5 hours and drain for 2 hours, so that the carbon material is dispersed and evenly attached to the surface of the stainless steel wire mesh filler, and a carbon material-matrix composite is obtained;

C. Roast the carbon material-matrix composite at 600-650° C. in isolation from air for 3 hours, then lower it to normal temperature under nitrogen protection, impregnate the chloroplatinic acid solution according to the material ratio of 30gPt/ ^m3 filler, and then the stainless steel filler 120 ℃ under the protection of nitrogen for 2 hours, and then heated up to 200 ℃ with hydrogen-containing 10% hydrogen and nitrogen for 2 hours to obtain the catalyst used in this example.

The technical process adopted in this example, the waste liquid nitric acid treatment part is shown in Figure 3 for details, it is a two-tower process, one tower is a packed tower 4, and stainless steel wire mesh packing is installed inside. The second tower is the reaction tower 5, and the filler is a carbon-coated stainless steel mesh packing catalyst, which is packed in three stages.

The process of this embodiment is shown in Figure 3:

Synthesis by oxidative carbonylation:

The liquid containing nitrite and the gas containing carbon monoxide are used as raw materials to undergo oxidative carbonylation reaction to synthesize oxalate, and the generated nitric oxide undergoes nitrite regeneration reaction to obtain chemical waste liquid containing alcohol and dilute nitric acid and chemical waste liquid containing monoxide Synthetic recycle gas of nitrogen; the regeneration reaction is as follows:

4ROH+4NO+O ₂ ＝4RONO+2H ₂ O (I)

4NO+3O ₂ +2H ₂ O＝4HNO ₃ (II)

Wherein formula (I) is the nitrate ester regeneration reaction formula, formula (II) is the side reaction, R represents CH ₃ , or C ₂ H ₅ .

Waste liquid nitric acid treatment:

(1) The chemical waste liquid produced in the above process is heated to 75°C through the feed preheater 2, and added from the top of the reaction tower 5 with a liquid space velocity of 1.5h ^-1 ; the synthetic waste liquid produced in the above oxidative carbonylation process The circulating gas enters from the bottom of the packed tower 4, and the gas phase space velocity is 3000h ^-1 (relative to the volume of the catalyst in the reaction tower 5); Spray and heat the reaction gas entering the tower; the reaction gas is preheated to 80°C through the liquid in the packed tower 4, and enters the catalyst layer from the bottom of the reaction tower 5, and the pressure at the top of the reaction tower 5 is 1.5Mpa; so that the gas and liquid are in the catalyst bed layer countercurrent contact; the temperature of the catalyst bed is controlled at 85-95°C

The chemical waste liquid is determined to contain (mass fraction) 8.5% nitric acid, 45.5% methanol, and 46% water.

The synthetic cycle gas is measured, and its specific composition (volume percentage) is as follows: 3% nitric oxide, 7% methyl nitrite, 22% carbon monoxide, 10% carbon dioxide, 8% methanol, and 50% nitrogen

(2) The liquid in the 5th tower of the reaction tower is pumped to the top of the 4th tower of the packed tower, and mixed with the circulating liquid of the 4th tower of the packed tower on the tray; the liquid of the 4th tower of the packed tower is sent to the outside through the 3rd part of the tower still circulating pump Methanol recovery system.

(3) The liquid phase after methanol recovery treatment is used as the reaction raw material of oxalate ester, and is put into the oxidative carbonylation system again.

(4) After the synthesis cycle gas is in contact with the reaction solution at the catalyst layer, about 98% of the nitric acid in the reaction solution is reduced, and the gas after the reaction enters the oxalate ester synthesis through the packed tower 4 overhead valve 6 .

Example 4 Synthesis of oxalate by oxidative carbonylation

The carbon-based catalyst used in this embodiment is a carbon-adhesive material, specifically a carbon-coated plastic filler; the carbon-adherent material includes a substrate and a carbon material layer covering the surface of the substrate. The carbon material layer has a porous structure, including activated carbon powder with a mass fraction of 95% to 98%, and epoxy resin at 2% to 5%.

The matrix is a plastic filler.

The carbon-based catalyst is prepared as follows:

A. Disperse the activated carbon powder with nitrogen;

B. Immerse the plastic filler treated with acetone for 3-5 minutes into the epoxy resin binder, take out the plastic filler after soaking for 0.5 hour and drain it for 10 minutes, blow the 200-400 mesh activated carbon powder with nitrogen gas To the surface of the above-mentioned plastic filler coated with a binder, a carbon-coated layer is formed on the surface of the filler, and a carbon material-matrix composite is obtained;

C. Curing the carbon material-matrix composite at 60° C. to 80° C. for 2 hours to obtain the catalyst used in this example.

The process flow used in this example, the nitric acid treatment part is shown in Figure 2 for details, using the mixing tower 1 as the reactor, the upper part of the tower is a packing device, and the packing is a catalyst carbon-coated plastic packing catalyst, which is packed in three stages; the lower part is a tray tower.

The process of this embodiment is shown in Figure 2:

Synthesis by oxidative carbonylation:

The liquid containing nitrite and the gas containing carbon monoxide are used as raw materials to undergo oxidative carbonylation reaction to synthesize oxalate, and the generated nitric oxide undergoes nitrite regeneration reaction to obtain chemical waste liquid containing alcohol and dilute nitric acid and chemical waste liquid containing monoxide Synthetic recycle gas of nitrogen; the regeneration reaction is as follows:

4ROH+4NO+O ₂ ＝4RONO+2H ₂ O (I)

4NO+3O ₂ +2H ₂ O＝4HNO ₃ (II)

Wherein formula (I) is the nitrate ester regeneration reaction formula, formula (II) is the side reaction, R represents CH ₃ , or C ₂ H ₅ .

Waste liquid nitric acid treatment:

(1) The chemical waste liquid produced in the above process is heated to 70°C through the feed preheater 2, and added from the top of the mixing tower 1 with a liquid space velocity of 1.0h ^-1 ; the synthetic waste liquid produced in the above oxidative carbonylation process The circulating gas enters from the bottom of the mixing tower 1, the gas phase space velocity is 500h ^-1 , and the reactor pressure is 0.5Mpa; the liquid in the bottom of the tower is heated to 90-100°C by the feed preheater, and the reaction gas is sprayed and heated into the tower from the upper tray, The reaction gas is preheated to 60°C through the liquid in the tower pot, and enters the catalyst layer from the top of the packing layer; the gas and the liquid are in co-current contact on the catalyst bed; the temperature of the catalyst bed is controlled at 80°C to 85°C.

The chemical waste liquid is determined to contain (mass fraction) 2.5% nitric acid, 55% methanol, and 41.5% water.

The synthetic cycle gas is measured, and its specific composition (volume percentage) is as follows: 20% nitric oxide, 2% methyl nitrite, 10% carbon monoxide, 5% carbon dioxide, 8% methanol, and 55% nitrogen.

(2) The liquid phase after the reaction is mixed with the circulating liquid of the tower kettle on the tray, and sent to the methanol recovery system outside the boundary through the tower kettle circulating pump 3.

(3) The liquid phase after methanol recovery treatment is used as the reaction raw material of oxalate ester, and is put into the oxidative carbonylation system again.

(4) After the synthesis cycle gas is in contact with the reaction solution on the catalyst layer, about 95% of the nitric acid in the reaction solution is reduced, and the reacted gas is de-oxalated through the tower top valve 3 for synthesis.

Example 5 Synthesis of oxalate by oxidative carbonylation

The carbon-based catalyst used in this embodiment is a carbon-adhered material, specifically a carbon-coated stainless steel plate corrugated filler; the carbon-adhered material includes a substrate and a carbon material layer covering the surface of the substrate. The carbon material layer has a porous structure, including 87%-93% carbon powder and 7%-13% tar.

The matrix bit corrugated packing of stainless steel plate

The carbon-based catalyst is prepared as follows:

A. Heat the mixture of carbon powder and tar in the proportion of the formula to 150°C, and stir evenly to form a carbon material dispersion;

B. Treat stainless steel plate corrugated packing with 20% nitric acid solution for 4-6 minutes, rinse with water until neutral, then treat with 3% potassium hydroxide solution at 80°C for 30 minutes, and immerse the treated stainless steel packing into the above carbon material dispersion , after impregnating the stainless steel filler for 5-10 hours, take it out and drain for 2 hours to obtain a carbon material-matrix composite;

C. Roast the carbon material-matrix composite at 600°C to 650°C for 3 hours in isolation from air, and lower it to room temperature under nitrogen protection

Repeat the above carbon coating process for 2 to 3 times to obtain the catalyst used in this example.

The process flow used in this embodiment, the nitric acid treatment part is shown in Figure 3. The first tower is a packed tower 4 with ceramic filler inside, and the second tower is a reaction tower 5 with a carbon-coated stainless steel corrugated packing catalyst inside, which is packed in three stages.

The process of this embodiment is shown in Figure 3

Synthesis by oxidative carbonylation:

The liquid containing nitrite and the gas containing carbon monoxide are used as raw materials to undergo oxidative carbonylation reaction to synthesize oxalate, and the generated nitric oxide undergoes nitrite regeneration reaction to obtain chemical waste liquid containing alcohol and dilute nitric acid and chemical waste liquid containing monoxide Synthetic recycle gas of nitrogen; the regeneration reaction is as follows:

4ROH+4NO+O ₂ ＝4RONO+2H ₂ O (I)

4NO+3O ₂ +2H ₂ O＝4HNO ₃ (II)

Wherein formula (I) is the nitrate ester regeneration reaction formula, formula (II) is the side reaction, R represents CH ₃ , or C ₂ H ₅ .

Waste liquid nitric acid treatment:

(1) After the chemical waste liquid produced in the above process is heated to 80°C by the feed preheater 2, it is sprayed from the top of the reaction tower 5 to the catalyst bed, and the liquid space velocity is 3h ^-1 ; the above-mentioned oxidative carbonylation The synthetic cycle gas generated in the process enters from the bottom of the packed tower 4, and the gas phase space velocity is 100h ^-1 (relative to the volume of the catalyst in the reaction tower 2); 4. Spray the middle and upper trays and heat the reaction gas into the tower, and preheat the reaction gas to 85°C; the heated reaction gas enters the catalyst bed from the top of the reaction tower 5, so that the gas and liquid are in parallel contact with the catalyst bed; The temperature of the catalyst bed is controlled at 90°C to 95°C.

The chemical waste liquid is determined to contain (mass fraction) 1.0% nitric acid, 60% methanol and 39% water.

The synthetic cycle gas is measured, and its specific composition (volume percentage) is as follows: 15% nitric oxide, 5% methyl nitrite, 12% carbon monoxide, 10% carbon dioxide, 8% methanol, and 50% nitrogen.

(2) The liquid in the 5th tower of the reaction tower is sent to the top of the packed tower 4 with the tower still circulating pump 3, and mixed with the circulating liquid in the 4th tower of the packed tower on the tray; the liquid in the 1st tower of the packed tower is passed through the 2 parts of the tower still pump Send out of bounds to methanol recovery system.

(3) The liquid phase after methanol recovery treatment is used as the reaction raw material of oxalate ester, and is put into the oxidative carbonylation system again.

(4) After the synthesis cycle gas is in contact with the reaction liquid on the catalyst layer, about 90% of the nitric acid in the reaction liquid is reduced, and the reacted gas is de-oxalated through the overhead valve 6 to synthesize.

The nitric acid treatment process in Examples 1 to 5 is also suitable for the synthesis of carbonate by oxidative carbonylation, and the methanol in Examples 1 to 5 can also be replaced by ethanol.

It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (9)

1. a kind of catalyst of oxidative carbonylation synthesis liquid waste processing, it is characterised in that be carbon attachment material；The carbon attachment Material includes matrix and is covered in the carbon material layer of stromal surface；The carbon material layer is loose structure, the carbon material layer by The carbon material of mass fraction 85%~98%, 2%~15% binding agent and 0.1%~10% auxiliary agent composition, the auxiliary agent are B, or Pt；The matrix is tower structured packing or random packing.

2. catalyst as claimed in claim 1, it is characterised in that the binding agent is tar or epoxy resin；The matrix For ceramics, stainless steel and/or plastic material.

3. the preparation method of catalyst as claimed in claim 1 or 2, it is characterised in that comprise the following steps：

A, by carbon material carry out it is scattered form dispersion, using gas dispersion air is scattered or liquid dispersion, by carbon material and Dispersant, binding agent are uniformly mixed to form carbon material dispersion liquid；

B, the carbon material dispersion obtained in step A is uniformly attached to stromal surface, obtains carbon material-substrate complex；

C, the carbon material obtained in step B-substrate complex is subjected to attached shape processing, obtains carbon-supported catalysts；At the attached shape Reason includes drying, roasting, and/or activation process.

4. a kind of oxidative carbonylation synthesis technique, it is characterised in that comprise the following steps：

Oxidative carbonylation synthesizes：Oxidation and carbonylation is occurred as raw material using the liquid containing nitrous acid ester and the gas containing carbon monoxide Synthesis, the nitric oxide of generation carry out nitrous acid ester regenerative response, obtain the chemical waste liquid of containing alcohol and dust technology and containing an oxygen Change the synthetic cyclic gas of nitrogen；

Waste liquid nitric acid treatment：

(1) by the caused chemical waste liquid containing alcohol and dust technology in oxidative carbonylation synthetic reaction with containing nitric oxide production synthesis Circulating air, cocurrent or countercurrent pass through catalyst bed, the liquid and gas after being handled；

(2) alcohol in the liquid phase after the processing obtained in recycling step (1), obtains the liquid phase after dealcoholysis；

(3) liquid phase after the dealcoholysis that will be obtained in step (2) is thrown as the liquid charging stock containing nitrous acid ester that oxidative carbonylation synthesizes Enter；

(4) gas phase after the processing that will be obtained in step (1), it is former with the gas containing carbon monoxide to put into the oxidative carbonylation synthesis Material；

The catalyst bed, the catalyst of filling is activated carbon or the catalyst as described in right wants 1 or 2.

5. oxidative carbonylation synthesis technique as claimed in claim 4, it is characterised in that the chemical waste liquid, wherein nitric acid are dense Degree is less than or equal to 10%；The synthetic cyclic gas, wherein nitric oxide production percent by volume is between 1% to 20%.

6. oxidative carbonylation synthesis technique as claimed in claim 4, it is characterised in that the chemical waste liquid and synthetic cyclic gas By preheating.

7. oxidative carbonylation synthesis technique as claimed in claim 4, it is characterised in that pass through catalyst bed when using cocurrent When, the chemical waste liquid and synthetic cyclic gas are by premix.

8. oxidative carbonylation synthesis technique as claimed in claim 4, it is characterised in that cocurrent or countercurrent passes through catalyst bed When, wherein liquid phase air speed is in 0.1h^-1~3h^-1Between, gas phase air speed is in 100h^-1~3000h^-1Between.

9. oxidative carbonylation synthesis technique as claimed in claim 4, it is characterised in that the catalyst bed temperature control is 30 Between~120 DEG C, reaction pressure is in 0.1Mpa between 1.50Mpa.