CN102500410A - Catalyst for ethylbenzene and ethanol synthesis to realize shape-selectivity alkylation for diethylbenzene - Google Patents

Abstract

The invention relates to a shape-selective alkylation catalyst for synthesizing p-diethylbenzene from ethylbenzene and ethanol, which mainly solves serious side reactions such as disproportionation reaction and isomerization reaction of ethylbenzene in the existing technology of synthesizing p-diethylbenzene from ethylbenzene and ethanol problems, and bioethanol can be used to replace ethylene to solve the shortage of petrochemical raw materials. The present invention adopts 50-90 parts by weight of hydrogen-type silica-alumina zeolite with a ten-membered ring hole structure containing SiO ₂ /Al ₂ O ₃ molar ratio of 20-200, at least one of rare earth or alkaline earth metal oxides The technical scheme of the catalyst composed of 1-10 parts of two kinds of metal oxides and an oxide binding agent preferably solves the above problems. The reaction conditions for synthesizing p-diethylbenzene are reaction temperature 350-450°C; total pressure 0.2MPa-2.0MPa; ethylbenzene/ethanol ratio 2.0-6.0; space velocity 1-8h ^-1 . The catalyst is used in the ethylbenzene alkylation process for synthesizing p-diethylbenzene from ethylbenzene and ethanol, and has good catalytic reaction selectivity and yield.

Description

Shape-selective Alkylation Catalyst for the Synthesis of p-Diethylbenzene from Ethylbenzene and Ethanol

technical field

The invention relates to a shape-selective alkylation catalyst for synthesizing p-diethylbenzene from ethylbenzene and ethanol. The catalyst can be used in the chemical production of synthesizing p-diethylbenzene, and can especially catalyze the synthesis of para-alkyl with high selectivity. Ethylbenzene, and avoid the generation of m- and ortho-diethylbenzene by-products; and bioethanol can be used to replace ethylene to solve the shortage of petrochemical raw materials.

Background technique

P-divinylbenzene can be obtained by dehydrogenation of p-diethylbenzene, and p-divinylbenzene comonomer is widely used in the production of existing polystyrene plastics. The produced polymers have excellent specific gravity, heat resistance, transparency and shrinkage. Efficiency and other aspects are better than pure polystyrene. At the same time, divinylbenzene can also be used as a crosslinking agent in the polymerization production of new plastic materials. In addition, p-methylstyrene can be copolymerized with other monomers, which can improve the heat resistance and flame retardancy of some polymers, and can be used in large quantities. It is widely used in the manufacture of engineering plastics and alkyd resin coatings. On the other hand, p-diethylbenzene is also widely used as a desorption eluent in the production of p-xylene by adsorptive separation of mixed xylenes. For a long time, there is no satisfactory method to obtain high-concentration p-diethylbenzene. To obtain p-position products, there must be a shape-selective catalyst with good performance. It is required that the pore size, grain size and acid center strength in the zeolite catalyst are suitable. , and the acidity of the outer surface is suppressed, it is possible to cause the ethylbenzene alkylation reaction to break the thermodynamic equilibrium concentration distribution of p-diethylbenzene, m-diethylbenzene, and o-diethylbenzene products, and mainly generate p-diethylbenzene. Catalytic theory speculates that the chemically modified ZSM-5 molecular sieve can make the gas-phase alkylation reaction of ethylbenzene and ethylene break through the limitation of thermodynamic equilibrium, and can obtain p-diethylbenzene with a concentration of more than 90%, and basically do not form ortho- and meta-diethylbenzene. Diethylbenzene. In recent years, research on this subject has aroused widespread interest from various companies and scientific research institutions, and some progress has been made. If further success can be achieved, it will bring about a huge change in the production process of p-diethylbenzene, which will have a great impact on energy conservation, It is of great significance to simplify equipment, reduce production costs and improve economic benefits. The catalyst technology in this application patent is developed and invented for obtaining p-diethylbenzene production process with high selectivity.

Chinese patent CN1045930 provides a ZSM-5 zeolite catalyst suitable for the direct synthesis of p-diethylbenzene by ethylbenzene/ethanol alkylation. Magnesium-aluminum zeolite molecular sieve catalyst made by modification, drying and roasting; the modified catalyst is used in the alkylation reaction of ethylbenzene/ethanol as raw material to directly synthesize p-diethylbenzene at a temperature of 360°C~ Under the reaction conditions of 390°C, mass space velocity of 6~9 h ^-1 , and styrene-ene ratio of 6~8, the conversion rate of ethylbenzene can reach 5~10%, and the selectivity of p-diethylbenzene can reach 95~98%.

Chinese patent CN1605390 relates to a catalyst and preparation method for the alkylation of ethanol and ethylbenzene to synthesize p-diethylbenzene. Based on the HZSM-5 molecular sieve with a Si/Al ratio of 50, the surface acidity and pores of the catalyst are adjusted by B, Mg and Co. It has ideal pore size distribution, acidity distribution in the pores and strong anti-coking ability. Catalyst for benzene synthesis. The precursor of B is boric acid, the precursor of Mg is magnesium nitrate, and the precursor of Co is cobalt nitrate. The mass ratio of B to HZSM-5 molecular sieve is 1%-3%, the mass ratio of Mg to HZSM-5 molecular sieve is 0.1%-1%, and the mass ratio of Co to HZSM-5 molecular sieve is 1%-3%. Compared with the current similar catalysts, the present invention has the characteristics of simple preparation method, low cost, good selectivity to diethylbenzene, high yield and the like.

The above documents have improved the para-selectivity of the product to diethylbenzene, but the ethylbenzene conversion rate of the total selectivity of the product is still low, which cannot meet the actual production needs, and has not been bonded as a fixed bed catalyst. Molding treatment, also can not adopt hydrous ethanol as reaction raw material, thereby has limited its practical value of realizing industrial application.

Contents of the invention

The invention mainly solves serious side reactions such as disproportionation reaction and isomerization reaction in the existing technology of synthesizing p-diethylbenzene from ethylbenzene and ethylene, thereby improving the effect of ethylbenzene alkylation reaction; The shortage of petrochemical raw materials. The object of the present invention is to provide a kind of efficient ethylbenzene and ethanol synthesis p-diethylbenzene shape-selective alkylation catalyst.

In order to solve the above-mentioned technical problems, the technical scheme adopted by the present invention is as follows: a shape-selective alkylation catalyst for synthesizing p-diethylbenzene from ethylbenzene and ethanol comprises the following components in parts by weight:

(1) 50-90 parts of hydrogen-type silica-alumina zeolite with a ten-membered ring structure with a molar ratio of SiO ₂ /Al ₂ O ₃ of 20-200;

(2) 1 to 10 parts of at least two metal oxides selected from alkaline earth or rare earth metal oxides;

(3) The rest is an oxide binder, so that the total parts by weight of the catalyst is 100 parts in total.

In the present invention, the hydrogen-type silica-alumina zeolite is selected from any one of HZSM-5, HZSM-35, HZSM-11, HSAPO-11 or HMCM-22, and is selected in the liquid phase silicon deposition surface modification treatment of zeolite Polysiloxane is used as a modifier, and the deposition amount of silicon dioxide is 3wt% to 20wt% of the weight of hydrogen-type silicon aluminum; the polysiloxane modifier is selected from active hydrogen siloxane. the

In the present invention, the alkaline earth or rare earth metal oxides are at least two metal oxides selected from lanthanum, cerium, strontium, calcium, barium or magnesium oxides.

In the present invention, the oxide binder is selected from alumina or silica. the

In the present invention, ethanol can be selected from 40 wt% to 95 wt% hydrous ethanol or absolute ethanol as the reaction raw material.

The reaction conditions for the synthesis of p-diethylbenzene from ethylbenzene and ethanol using the shape-selective alkylation catalyst are: reaction temperature 350-450°C; total pressure 0.2MPa-2.0 MPa; ethylbenzene/ethanol 2.0-8.0; space velocity 1-8h ^{- 1} .

The preparation method of the shape-selective alkylation catalyst described in the present invention, the specific steps are: through the method of mixing and molding hydrogen-type silica-alumina zeolite and oxide binder, or forming into powder or into balls or granulation or extrusion molding, The preferred solution adopts the mixed extrusion molding method, after molding, it is dried at 120°C for 3 hours, and then fired at 400-600°C for 4 hours. In the liquid-phase silicon deposition surface modification treatment of zeolite, the n-hexane solution of active hydrogen siloxane is used for impregnation, and the shape-selective modification effect is obtained through drying and roasting treatment. The further metal oxide loading operation method can be impregnated with metal nitrate solution before forming or impregnated with metal nitrate solution after forming, preferably after forming. After impregnation, it is dried at 120°C for 3 hours, and then calcined at 450-600°C for 4 hours to make a catalyst.

The catalyst of the present invention uses a fixed-bed reactor to investigate the catalytic reaction performance. The inner diameter of the reactor is 20mm, and the length is 400mm. It is made of stainless steel. Electric heating is adopted, and the temperature is automatically controlled. The bottom of the reactor was filled with a section of glass beads with a diameter of 2 mm as a support, the reactor was filled with 15 ml of catalyst, and the upper part was filled with 2 mm glass beads to preheat and vaporize the raw materials. After the ethylbenzene and ethylene gas in the raw material are mixed, the alkylation reaction occurs through the catalyst bed from top to bottom, and p-diethylbenzene and a small amount of by-products are mainly o-diethylbenzene, m-diethylbenzene, benzene , methylbenzene and dimethylbenzene, etc. The catalytic reaction conditions are as follows: temperature 350-450°C; total pressure 0.2MPa-2.0 MPa; ethylbenzene/ethanol ratio 2.0-8.0; space velocity 1-8h ^-1 .

The experimental data obtained by the reaction were calculated using the following formula.

×100%

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×100%

×100%

×100%

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In the present invention, one of medium-strongly acidic HZSM-5, HZSM-35, HZSM-11, HSAPO-11 or HMCM-22 zeolite is used as an active component in the catalyst, and its non-shape-selective zeolite is passivated. The functional acidic sites on the outer surface are added with at least two basic metal oxides selected from alkaline earth or rare earth oxides as catalytic activity promoters, which further improves the selectivity of the molecular sieve carrier. The above-mentioned features make the catalyst use ethylbenzene and ethanol in the process of synthesizing p-diethylbenzene, which can meet the high selectivity and conversion rate of alkylation, and maintain a low loss rate of ethylbenzene and good stability. A better practical process effect has been achieved.

The shape-selective alkylation catalyst of the present invention is used as raw materials for ethylbenzene and ethanol, and undergoes alkylation reaction to generate p-diethylbenzene. Ethanol is used as a reaction raw material, and the catalyst has good stability.

Detailed ways

The present invention is described further below by embodiment.

Example 1:

Mix 42 grams of hydrogen-type HZSM-5 molecular sieve with a molar ratio of SiO ₂ /Al ₂ O ₃ of 140 and 12 grams of r-Al ₂ O ₃ , then add 1.8 grams of Tianqing powder and mix evenly, then add a certain amount of 3% dilute Nitric acid is used as a binder to fully knead evenly, carry out extrusion molding, dry at 120°C for 2 hours, and then bake at 540°C for 1 hour. The shaped zeolite is impregnated with a n-hexane solution of 15% active hydrogen siloxane modifier, dried at 120°C for 2 hours, and then calcined at 500°C for 3 hours, and the surface is modified by liquid-phase silicon deposition. Catalyst I was processed and the deposition amount of silicon dioxide was 6.7wt%.

Example 2:

The HZSM-5 molecular sieve prepared by the method described in Example 1 was impregnated with the obtained molecular sieve in 7.0% concentration of magnesium nitrate and 2.3% concentration of barium nitrate aqueous solution. After the impregnation, the remaining impregnation solution was filtered off. It was dried at 120°C for 3 hours, and then calcined at 540°C for 4 hours. The temperature was programmed to rise at a rate of 3°C/min. It was designated as catalyst II, with a loading of magnesia of 3.2% and a loading of barium oxide of 1.5%.

Example 3:

The HZSM-5 molecular sieve prepared by the method described in Example 1 was impregnated with the obtained molecular sieve in 6.5% concentration of cerium nitrate and 5.1% concentration of lanthanum nitrate aqueous solution. After the impregnation, the remaining impregnation solution was filtered off. It was dried at 120°C for 3 hours, and then calcined at 540°C for 4 hours. The temperature was programmed at a rate of 3°C/min. It was designated as Catalyst III, with a loading of cerium oxide of 3.5% and a loading of lanthanum oxide of 2.4%.

Example 4:

Adopt the former powder of hydrogen type HZSM-11 molecular sieve to replace the former powder of HZSM-5 molecular sieve, make the HZSM-11 molecular sieve of molding according to the method program and condition described in example 1, use the strontium nitrate of 6.2% concentration and 1.2% strontium nitrate with the molecular sieve that makes Concentrated calcium nitrate aqueous solution for immersion, after immersion, filter off the remaining immersion solution. It was dried at 120°C for 3 hours, and then calcined at 540°C for 4 hours. The temperature was programmed to rise at a rate of 3°C/min. It was designated as catalyst IV. The loading capacity of strontium oxide was 3.8% and the loading capacity of calcium oxide was 0.5%. .

Example 5:

Adopt the former powder of hydrogen type HSAPO-11 molecular sieve to replace the former powder of HZSM-5 molecular sieve, and replace aluminum oxide with silica sol as binding agent, make the HSAPO-11 molecular sieve of molding according to the method procedure and condition described in example 1, use The obtained molecular sieve is impregnated in 9.5% concentration of cerium nitrate and 1.5% concentration of magnesium nitrate aqueous solution, after impregnation, the remaining impregnation solution is filtered off. Dry at 120°C for 3 hours, then calcined at 540°C for 4 hours, adopt temperature program, the heating rate is 3°C/min, denote as catalyst Ⅴ, its loading capacity of cerium oxide and magnesium oxide are 7.1% and 1.0%, respectively. %.

Embodiment 6:

Adopt the former powder of hydrogen type HMCM-22 molecular sieve to replace the former powder of HZSM-5 molecular sieve, make the HMCM-22 molecular sieve of molding according to the method procedure and condition described in example 1, use the lanthanum nitrate of 4.5% concentration and 2.4% lanthanum nitrate with the prepared molecular sieve Dip in a concentrated magnesium nitrate aqueous solution, after dipping, filter off the remaining dipping solution. It was dried at 120°C for 3 hours, and then calcined at 540°C for 4 hours. The temperature was programmed to rise at a rate of 3°C/min. It was designated as catalyst VI, and the loadings of lanthanum oxide and magnesium oxide were 3.3% and 1.3%, respectively.

Embodiment 7:

Adopt the former powder of hydrogen type HZSM-35 molecular sieve to replace the former powder of HZSM-5 molecular sieve, make the ZSM-35 molecular sieve of molding according to the method procedure and condition described in example 1, use the lanthanum nitrate of 3.6% concentration, 7.3% lanthanum nitrate with the prepared molecular sieve Concentration of barium nitrate and 6.2% concentration of calcium nitrate aqueous solution, after immersion, filter off the remaining impregnation solution. It was dried at 120°C for 3 hours, then calcined at 540°C for 4 hours, and the temperature was programmed at a rate of 3°C/min. The loading of lanthanum oxide was 2.6%.

Embodiment 8:

Use catalysts I, II, III, IV, V, VI, and VII to investigate their alkylation activity and selectivity in a fixed-bed reactor, and the extent to which side reactions are mainly isomerization and disproportionation reactions (measured by total selectivity) express). Reaction conditions adopted: reaction temperature 400°C; total pressure 1.2 MPa; ethylbenzene/ethanol ratio 4.0; space velocity 3.0 h ^-1 ; shown.

catalyst Conversion rate of ethylbenzene/% Selectivity of p-diethylbenzene/% Total selectivity to p-diethylbenzene/% I (95 wt% aqueous ethanol) 24.1 51.8 46.0 II (95 wt% ethanol with water) 21.3 96.9 90.6 III (40 wt% ethanol with water) 21.0 97.1 91.3 IV (absolute ethanol) 21.2 96.4 91.5 V (65 wt% ethanol with water) 21.3 97.2 91.1 VI (82 wt% aqueous ethanol) 20.9 96.7 91.6 VII (56 wt% ethanol with water) 20.7 99.0 91.9 .

the

It can be seen that the HZSM-5 molecular sieve modified by two or three kinds of metal oxides in alkaline earth or rare earth metal oxides, compared with the catalyst without silicon deposition modification, due to the adjustment of the pore size and the catalyst surface Due to the acidity of the surface, the selectivity of the modified HZSM-5 molecular sieve to diethylbenzene is obviously improved; the modified HZSM-5 molecular sieve catalyst still maintains a high conversion rate of p-diethylbenzene, and the total selectivity of the product is also high.

From the above results, it can be seen that the HZSM-35, HZSM-11, HZSM-11, HZSM-11, HSAPO-11 or HMCM-22 molecular sieve catalysts can also play a similar catalytic effect, and also have high p-diethylbenzene selectivity and total product selectivity; reaching the index requirements for industrial production applications.

Claims (6)

1. a shape-selective alkylation catalyst for the synthesis of p-diethylbenzene from ethylbenzene and ethanol, characterized in that it comprises the following components in parts by weight: (1) 50-90 parts of hydrogen-type silica-alumina zeolite with a ten-membered ring structure with a molar ratio of SiO ₂ /Al ₂ O ₃ of 20-200; (2) 1 to 10 parts of at least two metal oxides selected from alkaline earth or rare earth metal oxides; (3) The rest is an oxide binder, and the total parts by weight of the catalyst is 100 parts in total. 2. The shape-selective alkylation catalyst for synthesizing p-diethylbenzene from ethylbenzene and ethanol according to claim 1, wherein said hydrogen-type silica-alumina zeolite is selected from HZSM-5, HZSM-35, HZSM-11, In any of HSAPO-11 or HMCM-22, polysiloxane is used as a modifier in the liquid-phase silicon deposition surface modification treatment of zeolite, and the deposition amount of silicon dioxide is 5wt relative to the weight of hydrogen-type silica-alumina zeolite %～20wt%. 3. The shape-selective alkylation catalyst for synthesizing p-diethylbenzene from ethylbenzene and ethanol according to claim 1, characterized in that the alkaline earth or rare earth metal oxide is selected from lanthanum, cerium, strontium, calcium, barium or magnesium At least two metal oxides in the oxide. 4. The shape-selective alkylation catalyst for synthesizing p-diethylbenzene from ethylbenzene and ethanol according to claim 1, characterized in that the oxide binder is selected from alumina or silica. 5. The shape-selective alkylation catalyst for synthesizing p-diethylbenzene from ethylbenzene and ethanol according to claim 1, characterized in that ethanol is selected from 40 wt% to 95 wt% hydrous ethanol or absolute ethanol as the reaction raw material. 6. According to claim 2, the polysiloxane modifier is used in the surface modification treatment of the liquid phase silicon deposition of zeolite, characterized in that the polysiloxane modifier is selected from active hydrogen siloxanes.