CN102976892B - Method for preparing ethanol through acetic ester hydrogenation - Google Patents

Abstract

The invention relates to a method for preparing ethanol through acetic ester hydrogenation. The method performs an acetic ester hydrogenation reaction to generate ethanol under the conditions of certain temperature, pressure, hydrogen/ester molar ratio and hydrogen circulation in a fixed-bed reactor filled with a copper-based catalyst, wherein in the copper-based catalyst, a mesoporous molecular sieve MCM-41 is used as a carrier, copper is used as an active component, and the oxide of at least one element of La and Ce is used as an auxiliary; and the MCM-41 accounts for 40-90% of the catalyst by weight, the active component copper accounts for 10-50% of the catalyst by weight, and the auxiliary accounts for 0.1-20% of the catalyst by weight. According to the method for preparing ethanol through acetic ester hydrogenation, provided by the invention, when the reaction temperature is 220 DEG C, the reaction pressure is 3MPa, the hydrogen/ester molar ratio is 30 and the mass airspeed of acetic ester is 2h<-1>, the conversion rate of acetic ester is 98.5%, and the ethanol selectivity is as high as 99.6%, thereby showing extremely high hydrogenation activity, selectivity and stability.

Description

Method for preparing ethanol by hydrogenation of acetate

technical field

The invention relates to a method for preparing ethanol through hydrogenation of acetate.

Background technique

Ethanol, commonly known as alcohol, as an important chemical raw material, is widely used in food, medicine, chemical industry, national defense and other fields. Since the oxygen content of ethanol is as high as 34.7%, it can also be added to gasoline as a substitute for methyl tert-butyl ether (MTBE) to obtain ethanol gasoline. While reducing gasoline consumption, it can also make gasoline burn more fully, thereby reducing combustion emissions of pollutants such as CO.

Mature ethanol production technologies mainly include two routes. One is the petroleum route that uses ethylene, a product of petroleum cracking, as raw material, and obtains ethanol through hydration. Another route refers to the biological fermentation method that uses various sugar-containing agricultural products, agricultural and forestry by-products and wild plants as raw materials, and converts disaccharides and polysaccharides into monosaccharides and further into ethanol through hydrolysis and fermentation.

Due to the limitations of our country's national conditions, the large-scale use of sugarcane or corn to produce fuel ethanol is limited, and the ethanol production technology using cellulose as raw material is not yet mature. Based on the fact that my country is relatively rich in coal, the production of ethanol from syngas has received extensive attention. The reported method of producing ethanol directly from synthesis gas is that the synthesis gas first reacts on the Rh/SiO ₂ catalyst at 3-10MPa and 300°C to generate acetaldehyde, ethanol, ethyl acetate and acetic acid-based carbon dioxide products, and then Cu/SiO ₂ [JP6259632], Pd-Fe/SiO ₂ [JP61178940, JP61178942] or CuO/Al ₂ O ₃ [CN1230458A] and other catalysts modified by alkali metal or transition metal oxide additives, acetaldehyde, ethyl acetate By-products such as esters and acetic acid are further hydrogenated to ethanol. Due to the disadvantages of harsh process conditions, poor catalyst stability, and low selectivity, this technology has not been widely used so far.

Chinese patent CN101934228A reports a copper-based catalyst for the hydrogenation of acetate to ethanol, the carrier is alumina or silicon oxide, and the additives are oxides of zinc, manganese, chromium, calcium, barium, iron, nickel, magnesium and other elements. Among them, the highest conversion rate of acetate is 88%, and the reaction efficiency is low.

Chinese patent CN102327774A reports that a copper-based catalyst is applied to the reaction system of hydrogenation of acetate to ethanol. The preparation method is to add silica sol or soluble aluminum salt to the mixed solution of copper soluble salt and additive metal soluble salt, and stir After uniformity, the mixed solution is added to the solution of the precipitating agent under the condition of 50-95° C., and then aged, filtered, washed, dried, calcined, formed and reduced to obtain the catalyst. The highest conversion rate of the prepared catalyst in the hydrogenation reaction of acetate was 85%, and the ethanol selectivity was 91%.

Chinese patent CN101941887A uses silicon oxide or aluminum oxide as a carrier, copper as an active component, Zn, Mn, Cr, Ca, Ba and other metals or metal oxides as auxiliary agents to prepare a copper-based catalyst, in the hydrogenation reaction of acetate The selectivity is up to 99%, while the conversion rate is up to 92%.

Chinese patent CN101411990A discloses a preparation method of oxalate ester hydrogenation ethylene glycol copper silicon catalyst, the method is to add mesoporous silica molecular sieve with a specific surface area of ^600-1200m2 /g in the copper ammonium complex powder, and then filtered, washed, dried, roasted and reduced to make a catalyst.

Chinese patent CN1935375A discloses a catalyst for the hydrogenation of dimethyl maleate to 1,4-butanediol. The catalyst uses a large specific surface mesoporous molecular sieve MCM-41 as a carrier to impregnate a Cu salt solution to prepare a catalyst precursor. body, and then calcined to obtain Cu/MCM-41 catalyst. In the hydrogenation reaction of dimethyl maleate, the catalyst has high activity and high selectivity of 1,4-butanediol.

In view of the fact that copper-based catalysts are prone to aggregation and sintering of copper grains under high temperature conditions, the development of copper-based catalysts with high temperature sintering resistance, high activity and high selectivity is one of the difficulties in the hydrogenation of acetate to ethanol technology.

Contents of the invention

The object of the present invention is to provide a method for producing ethanol by hydrogenation of acetate, using the catalyst of the present invention for the reaction of hydrogenation of acetate to produce ethanol, which can obtain higher ethanol production capacity and ethanol selectivity, and has a longer life , significantly reducing the production cost of ethanol.

The invention provides a catalyst for the hydrogenation of acetate to ethanol, which has a large amount of layered silicate structure before reduction, so that the dispersion of copper is greatly improved, and the thermal stability is also enhanced. At the same time, rare earth additives La and The electronic modification of Ce regulates the valence state of copper, so that the catalyst not only has an ideal valence state distribution, but also has good resistance to high temperature sintering. The catalyst greatly improves the high dispersion of copper, has high thermal stability, hydrogenation activity and stability in the hydrogenation reaction of acetate, reduces waste discharge and greatly reduces subsequent separation costs.

The preparation method of a catalyst for the hydrogenation of acetate to ethanol provided by the present invention is to add active components and auxiliary agents to the mother liquor of mesoporous molecular sieves during the synthesis of mesoporous silica molecular sieves, and then jointly aging and reacting for a period of time, Elevate the temperature to distill ammonia, then pour it into a crystallization kettle for crystallization for a certain period of time, then filter, wash, dry and roast to form the catalyst of the present invention. Adopting the method helps to improve the dispersion degree of copper in the catalyst, and promotes the stability of the valence state and the grain size of the active components.

Technical scheme of the present invention:

A method for hydrogenation of acetate to ethanol, in a fixed-bed reactor filled with a copper-based catalyst, under the conditions of certain temperature, pressure, hydrogen ester molar ratio and hydrogen circulation, the hydrogenation reaction of acetate is carried out produce ethanol;

The copper-based catalyst is based on mesoporous silica molecular sieve MCM-41 as a carrier, copper as an active component, and oxides of at least one element in La and Ce as an auxiliary agent; each component accounts for the weight percentage of the catalyst It is: silicon oxide=50-90wt%, active component copper=10-50wt%, auxiliary agent=0.1-20wt%.

The preparation method of the copper-based catalyst for the hydrogenation of acetate to ethanol provided by the present invention comprises the following steps: under stirring conditions, slowly add the soluble silicon source dropwise to the aqueous solution in which CTAB is dissolved, and continuously add the alkali solution to make the pH value Keep it between 11~11.5. After the dropwise addition is completed, continue to stir to form the MCM-41 mesoporous molecular sieve mother liquor; add cuproammonia solution and soluble additive precursor to the mother liquor; after fully stirring, raise the temperature to distill ammonia, When the pH value of the liquid phase is lower than 7, stop heating and lower the temperature; put the cooled material liquid into a stainless steel crystallization kettle to crystallize, cool, filter and wash the precipitate until neutral; finally dry and roast the filter cake The catalyst of the invention is formed.

Optionally, the mesoporous silica MCM-41 in the catalyst accounts for 60-90% of the weight of the catalyst. The active component copper accounts for 20-40% by weight of the catalyst. The auxiliary agent accounts for 1-10% of the weight of the catalyst.

The preparation method of the copper-based catalyst of a kind of acetate hydrogenation system ethanol provided by the invention is through the following steps:

1) Under the condition of stirring, slowly add the soluble silicon source to the aqueous solution in which CTAB is dissolved, and at the same time continuously add NaOH to keep the pH value between 11-11.5. After the addition is completed, stir for 0.5-2 hours to form MCM-41 medium Molecular sieve mother liquor;

2) A soluble precursor of copper is selected and dissolved in ammonia water;

3) Select one or two soluble precursors of additives to prepare an aqueous solution;

4) Pour the solution in step 2) and the solution in step 3) into the mother liquor in step 1), and stir at room temperature for 4-24 h;

5) Raise the temperature of the slurry generated in step 4) to 50-100°C for ammonia distillation, and stop heating when the pH value of the liquid phase is lower than 7;

6) Put it into a stainless steel crystallization kettle, and then crystallize at 80-140°C for 24-72 hours;

7) After cooling the stainless steel crystallization kettle in step 6), filter and wash the precipitate until neutral;

8) Dry the filter cake in step 7) at 50-120°C;

9) After the filter cake dried in step 8) is crushed, it is calcined at 350-600° C. to form the catalyst of the present invention.

Wherein, the soluble silicon source is one or both of tetraethyl orthosilicate and water glass.

The additives are soluble salts of La and Ce, such as nitrates, chlorides or acetates.

The steps provided by the present invention to provide a method for hydrogenation of acetate to ethanol include:

1) Put the prepared copper-based catalyst supported on MCM-41 molecular sieve into a fixed bed reactor after molding, and perform reduction in an atmosphere with a volume ratio of 5-10% H ₂ /N ₂ , and the reduction temperature is 350-500 ℃, reduction time 2-24 hours;

2) After the reduction, replace the whole system with pure hydrogen, adjust the reaction temperature to 160-260°C, the pressure to 1.0-4.0MPa, the mass space velocity of acetate to 0.5-3 h ^-1 , and the material containing acetate to be vaporized in the vaporization chamber Then enter the reactor and react with hydrogen to generate ethanol;

3) After the product is condensed, the gas-liquid separation is carried out. The liquid phase product is collected into the product tank, and the gas phase is pressurized by the booster and then circulated into the reactor for reaction. The molar hydrogen-ester ratio is 20-200; fresh hydrogen is automatically replenished according to the pressure change .

The acetate includes one or both of methyl acetate and ethyl acetate.

The acetate-containing material may also contain one or two solvents of ethanol and methanol.

The composition of the circulating gas phase includes hydrogen, a small amount of acetate and ethanol, and the volume ratio is: 100:0.01-0.2:0.01-0.2.

The composition of the circulating gas phase includes hydrogen, trace amounts of acetate, ethanol and methanol, and the volume ratio is: 100:0.01-0.2:0.01-0.2:0.01-0.4.

The reaction temperature in step 2) is 180-240°C.

The reaction pressure in step 2) is 2-4MPa.

The molar ratio of hydrogen to ester in the reaction described in step 3) is 20-100.

In the present invention, copper is supported on the mesoporous silica molecular sieve by ammonia distillation-crystallization method, and at the same time, La and Ce are used to regulate the valence distribution, specific surface area and pore size distribution of copper in the catalyst, thereby significantly improving the sintering resistance of the catalyst ability.

The shaped catalyst of the present invention is used in the hydrogenation reaction of acetate to ethanol, when the reaction temperature is 220°C, the reaction pressure is 3MPa, the molar hydrogen-to-ester ratio is 50, and the mass space velocity of acetate is ^1.2h The conversion rate is 98.6%, the ethanol selectivity is as high as 99.6%, and the ethanol space-time yield reaches 628g/Lh, showing extremely high hydrogenation activity and selectivity.

The present invention combines the unique structure of the mesoporous molecular sieve MCM-41 in the formation process, and adopts the method of combining ammonia distillation and crystallization to prepare copper-silicon-based catalysts. This method promotes the formation of more stable layered silicic acid from copper and silicon. Salt structure, thus greatly improving the high dispersion of copper. The obtained catalyst has high thermal stability, hydrogenation activity and stability in the acetate hydrogenation reaction. The catalyst is used for the hydrogenation of acetate to ethanol. Under optimized conditions, the conversion rate of ethyl acetate reaches 98.6%, and the selectivity of ethanol reaches 99.6%. While reducing waste emissions, it also greatly reduces the cost of subsequent separation. In addition, the catalyst operated stably for 1500 hours without significant change in activity, indicating that the catalyst has excellent thermal stability.

Description of drawings

Figure 1. Mold test stability of acetate hydrogenation to ethanol catalyst.

Fig. 2. Low-temperature nitrogen adsorption and desorption curves of acetate hydrogenation to ethanol catalyst.

Figure 3. Mesopore size distribution curve of acetate hydrogenation ethanol catalyst.

Figure 4. Micropore pore size distribution curve of acetate hydrogenation ethanol catalyst.

Detailed ways

The present invention will be further described below by specific examples, but they do not limit the present invention in any way. It is also pointed out that the reagents and equipment used in the examples are all commercially available unless the source is clearly stated.

Example 1:

Catalyst preparation

Weigh 11 g of CTAB (cetyltrimethylammonium bromide) and place it in a beaker of 270 g of water and fully dissolve it, add 51.4 g of TEOS (tetraethyl silicate); then add 2.2 g of NaOH to make The pH value is between 11-11.5; increase the temperature of the water bath to 80°C and stir for 2 h to form the mother liquor of MCM-41 molecular sieve; weigh 15.2g Cu(NO ₃ ) ₂ ·3H ₂ O and 51.7ml of 25% ammonia water, add Add cuproammonia solution to 150ml of water; pour the cuproammonia solution into the mother liquor of MCM-41 molecular sieves at room temperature and stir for 4 hours; weigh 0.53g La(NO ₃ ) ₃ 6H ₂ O and add to the slurry; Heat the water bath to 80°C to volatilize the ammonia gas, stop heating when the pH value is lower than 7; then put the slurry into a stainless steel crystallization kettle, and crystallize at 120°C for 24 hours; take it out and cool it after the crystallization is completed , filtered, washed until neutral; then dried at 120°C for 6 h; finally calcined at 500°C for 6 h to form a catalyst with 20% copper loading and 1% La ₂ O ₃ loading, labeled as 20Cu-1La -MCM-41. The adsorption and desorption performance and pore size distribution of the catalyst were characterized by a low-temperature nitrogen physical adsorption instrument (Tristar3000 and ASAP2020, Micromeritics, USA). The results are shown in Figures 2, 3 and 4, respectively.

Catalyst evaluation

Sieve the prepared catalyst tablet into 40-60 mesh, then weigh 0.8g and put it into a fixed-bed isothermal reactor, use 20% H ₂ /N ₂ atmosphere for reduction, the total amount of gas is controlled at 200ml/min, The reduction temperature is 400°C, and the reduction time is 4 hours. After the reduction, replace the system with pure hydrogen, and adjust the temperature to about 215°C, the pressure at 2.5MPa, the molar hydrogen-ester ratio at 50, and the liquid mass space velocity of ethyl acetate (EAC) at 1.5 h ^-1 , using a liquid-phase high-pressure pump Feed. Samples were taken at intervals of 1 hour and the product composition was analyzed by gas chromatography with FID detector, and EAC conversion and ethanol selectivity were calculated. The reaction results are shown in Table 1.

Example 2

Catalyst preparation

Weigh 11 g of CTAB and place it in a beaker of 270 g of water and fully dissolve it, add 59.4 g of TEOS; then add 2.2 g of NaOH to make the pH value between 11-11.5; increase the temperature of the water bath to 80 ° C and stir for 2 h Form the mother liquor of MCM-41 molecular sieve; weigh 7.6g Cu(NO ₃ ) ₂ 3H ₂ O and 25.8ml 25% ammonia water, add it to 150ml water to form a copper ammonia solution; pour the copper ammonia solution into MCM at room temperature -41 molecular sieve mother liquor and stirred for 4h; Weigh 1.06g La(NO ₃ ) ₃ 6H ₂ O and add it to the slurry; Stop heating; then put the slurry into a stainless steel crystallization kettle and crystallize at 120°C for 24 hours; after the crystallization is complete, take it out to cool, filter, and wash until neutral; then dry at 120°C for 6 h, and finally in The catalyst was calcined at 500℃ for 6 h to form a catalyst with 10% Cu loading and 2% La ₂ O ₃ loading, labeled as 10Cu-2La-MCM-41.

Catalyst evaluation

Sieve the prepared catalyst tablet into 40-60 mesh, then weigh 0.8g and put it into a fixed-bed isothermal reactor, use 20% H ₂ /N ₂ atmosphere for reduction, the total amount of gas is controlled at 200ml/min, The reduction temperature is 400°C, and the reduction time is 4 hours. After the reduction, replace the system with pure hydrogen, and adjust the temperature to about 215°C, the pressure at 2.5MPa, the molar hydrogen-ester ratio at 50, and the liquid mass space velocity of ethyl acetate (EAC) at 1.2 h ^-1 , using a liquid-phase high-pressure pump Feed. Samples were taken at intervals of 1 hour and the product composition was analyzed by gas chromatography with FID detector, and EAC conversion and ethanol selectivity were calculated. The reaction results are shown in Table 1.

Example 3

Catalyst preparation

Weigh 11 g of CTAB, place it in a beaker of 270 g of water and fully dissolve it, add 40 g of TEOS; then add 2.2 g of NaOH to make the pH value between 11-11.5; increase the temperature of the water bath to 80 °C and stir for 2 h Form the mother liquor of MCM-41 molecular sieve; weigh 22.8g Cu(NO ₃ ) ₂ 3H ₂ O and 77.5ml of 25% ammonia water, add it to 150ml water to make copper ammonia solution; pour the copper ammonia solution into MCM-41 at room temperature Molecular sieve mother liquor and stirred for 4 h; weighed 2.7g La(NO ₃ ) ₃ 6H ₂ O and added to the slurry; then heated the water bath to 80°C to volatilize the ammonia gas, and stopped when the pH value was lower than 7 Heating; then put the slurry into a stainless steel crystallization kettle and crystallize at 120°C for 24 hours; after the crystallization was completed, take it out to cool, filter, and wash until neutral; then dry at 120°C for 6 h; The catalyst was calcined at ℃ for 6 h to form a catalyst with 30% Cu loading and 5% La ₂ O ₃ loading, which was labeled as 30Cu-5La-MCM-41.

Catalyst evaluation

Sieve the prepared catalyst tablet into 40-60 mesh, then weigh 0.8g and put it into a fixed-bed isothermal reactor, use 20% H ₂ /N ₂ atmosphere for reduction, the total amount of gas is controlled at 200ml/min, The reduction temperature is 400°C, and the reduction time is 4 hours. After the reduction, replace the system with pure hydrogen, adjust the temperature to about 220°C, the pressure to 3MPa, the molar hydrogen-to-ester ratio to 30, and the liquid mass space velocity of ethyl acetate (EAC) to be 2h ^-1 , using a liquid-phase high-pressure pump to feed . Samples were taken at intervals of 1 hour and the product composition was analyzed by gas chromatography with FID detector, and EAC conversion and ethanol selectivity were calculated. The reaction results are shown in Table 1.

Example 4

Catalyst preparation

Weigh 11 g of CTAB and put it in a beaker of 270 g of water and dissolve it fully, add 34.4 g of TEOS; then add 2.2 g of NaOH to make the pH value between 11-11.5; increase the temperature of the water bath to 80 °C and stir for 2 h to form the mother liquor of MCM-41 molecular sieve; weigh 30.4g Cu(NO ₃ ) ₂ 3H ₂ O and 103.4ml of 25% ammonia water, and add it to 150ml water to form a copper ammonia solution; pour the copper ammonia solution into MCM- 41 molecular sieve mother liquor and stirred for 4 hours; Weigh 0.27g La(NO ₃ ) ₃ 6H ₂ O and add to the slurry; After that, raise the temperature of the water bath to 90°C to volatilize the ammonia gas, and stop when the pH value is lower than 7 Heating; then put the slurry into a stainless steel crystallization kettle and crystallize at 120°C for 24 hours; after the crystallization was completed, take it out to cool, filter, and wash until neutral; then dry at 120°C for 6 h; Calcined at ℃ for 6 h to form a catalyst with a copper loading of 40% and a La ₂ O ₃ loading of 0.5%, labeled as 40Cu-0.5La-MCM-41.

Catalyst evaluation

Sieve the prepared catalyst tablet into 40-60 mesh, then weigh 0.8g and put it into a fixed-bed isothermal reactor, use 20% H ₂ /N ₂ atmosphere for reduction, the total amount of gas is controlled at 200ml/min, The reduction temperature is 400°C, and the reduction time is 4 hours. After the reduction, replace the system with pure hydrogen, and adjust the temperature to about 220°C, the pressure to 3MPa, the molar hydrogen-to-ester ratio to 30, and the liquid mass space velocity of ethyl acetate (EAC) to be 2 h ^-1 . material. Samples were taken at intervals of 1 hour and the product composition was analyzed by gas chromatography with FID detector, and EAC conversion and ethanol selectivity were calculated. The reaction results are shown in Table 1.

Example 5

Catalyst preparation

Weigh 11 g of CTAB and place it in a beaker of 270 g of water and dissolve it fully, add 43.3 g of TEOS; then add 2.2 g of NaOH to make the pH value between 11-11.5; increase the temperature of the water bath to 80 °C and stir for 2 h to form the mother liquor of MCM-41 molecular sieve; weigh 22.8g Cu(NO ₃ ) ₂ 3H ₂ O and 77.5ml of 25% ammonia water, and add it to 150ml water to form a copper ammonia solution; pour the copper ammonia solution into MCM- 41 molecular sieve mother liquor and stirred for 4 h; weighed 0.1g Ce(NO ₃ ) ₃ 6H ₂ O and added to the slurry; then heated the water bath to 80°C to volatilize the ammonia gas, when the pH value was lower than 7 Stop heating; then put the slurry into a stainless steel crystallization kettle and crystallize at 120°C for 24 hours; after the crystallization is completed, take it out to cool, filter, and wash until neutral; then dry at 120°C for 6 h; Calcined at 500 °C for 6 h to form a catalyst with a Cu loading of 30% and _a CeO loading of 0.2%, labeled as 30Cu-0.2Ce-MCM-41.

Catalyst evaluation

Sieve the prepared catalyst tablet into 40-60 mesh, then weigh 0.8g and put it into a fixed-bed isothermal reactor, use 20% H ₂ /N ₂ atmosphere for reduction, the total amount of gas is controlled at 200ml/min, The reduction temperature is 400°C, and the reduction time is 4 hours. After the reduction, replace the system with pure hydrogen, adjust the temperature to about 200°C, the pressure to 3MPa, the molar hydrogen-to-ester ratio to 50, and the liquid mass space velocity of methyl acetate (MAC) to be 2 h ^-1 . material. After the product is condensed and gas-liquid separated, the gas phase is circulated through the booster and enters the reactor for reaction. Liquid samples were taken at intervals of 1 hour and the product composition was analyzed by gas chromatography with FID detector, and MAC conversion and ethanol selectivity were calculated. The reaction results are shown in Table 1.

Example 6

Catalyst preparation

Weigh 11 g of CTAB and place it in a beaker of 270 g of water and fully dissolve it, add 61.6 g of Na ₂ SiO ₃ .9H ₂ O; then add 2.2 g of NaOH to make the pH between 11-11.5; increase the temperature of the water bath After reaching 80°C, stir for 2 h to form the mother liquor of MCM-41 molecular sieve; weigh 15.2g Cu(NO ₃ ) ₂ 3H ₂ O and 51.7ml of 25% ammonia water, and add it to 150ml of water to make copper ammonia solution; Pour the cuproammonia solution into the mother liquor of MCM-41 molecular sieve and stir for 4 h; weigh 5g Ce(NO ₃ ) ₃ 6H ₂ O and add it to the slurry; Stop heating when the pH value is lower than 7; then put the slurry into a stainless steel crystallization kettle and crystallize at 120°C for 24 hours; after the crystallization is completed, take it out to cool, filter, and wash until neutral; Dry for 6 h; finally calcined at 500 °C for 6 h to form a catalyst with 20% Cu loading and 10% CeO ₂ loading, labeled as 20Cu-10Ce-MCM-41.

Catalyst evaluation

Sieve the prepared catalyst tablet into 40-60 mesh, then weigh 0.8g and put it into a fixed-bed isothermal reactor, use 20% H ₂ /N ₂ atmosphere for reduction, the total amount of gas is controlled at 200ml/min, The reduction temperature is 400°C, and the reduction time is 4 hours. After the reduction, replace the system with pure hydrogen, and adjust the temperature to about 210°C, the pressure to 3MPa, the molar hydrogen-to-ester ratio to 50, the liquid mass space velocity of methyl acetate to 1.3h ^-1 , and a liquid-phase high-pressure pump to feed. Liquid samples were taken at intervals of 1 hour and the product composition was analyzed by gas chromatography with FID detector, and MAC conversion and ethanol selectivity were calculated. The reaction results are shown in Table 1.

Example 7

Catalyst preparation

Weigh 5.5kg CTAB, place it in a 130L water reactor and fully dissolve it, add 25.7kg of TEOS; then add 1.1kg of NaOH to make the pH between 11-11.5; increase the liquid phase temperature in the kettle to 80°C and stirred for 4 h to form the mother liquor of MCM-41 molecular sieve; weigh 7.6kg Cu(NO ₃ ) ₂ 3H ₂ O and 26L of 25% ammonia water, and add it to 135L water to form a cuproammonia solution; The solution was poured into the mother liquor of MCM-41 molecular sieve and stirred for 4 hours; 266g La(NO ₃ ) ₃ ·6H ₂ O was weighed and added to the reaction kettle; then the temperature in the kettle was raised to 80°C to volatilize the ammonia gas, when the pH When the value is lower than 7, stop heating; then raise the temperature to 120°C under airtight conditions to crystallize for 24 hours; after the crystallization is completed, cool, filter, and wash until the water is neutral; then dry in an oven at 120°C 6 h; finally, it was calcined at 500℃ for 6 h to form a catalyst with 20% copper loading and 1% La ₂ O ₃ loading.

Catalyst evaluation

The prepared catalyst was punched into Φ3*3mm columnar particles, then weighed 47g and placed in a fixed-bed model reactor with an inner diameter of 27mm, and the reduction was carried out in a 20% H ₂ /N ₂ atmosphere. The amount is controlled at 10 L/min, the reduction temperature is 400°C, and the reduction time is 10 hours. After the reduction, replace the system with pure hydrogen, and adjust the bed center temperature to about 220°C, the pressure at 3MPa, the molar hydrogen-ester ratio at 50, and the liquid mass space velocity of ethyl acetate (EAC) at 1.2 h ^-1 . High pressure pump feeding. After the product is condensed and gas-liquid separated, the gas phase is circulated through the booster and enters the reactor for reaction. Fresh hydrogen is automatically replenished according to pressure changes. Liquid samples were taken at intervals of 1 hour and the product composition was analyzed by gas chromatography with FID detector, and the EAC conversion and ethanol selectivity were calculated. The reaction results are shown in Table 1. The reaction stability data are shown in Figure 1.

Embodiment 8:

Except that reaction pressure adopts 2MPa, other is with embodiment 8, and reaction result is shown in Table 1.

Embodiment 9:

Except that reaction pressure adopts 1MPa, other is with embodiment 8, and reaction result is shown in Table 1.

Example 10:

Except that reaction temperature adopts 205 ℃, other is the same as embodiment 8, and reaction result is shown in Table 1.

Example 11:

Except that reaction temperature adopts 185 ℃, other is the same as embodiment 8, and reaction result is shown in Table 1.

Example 12:

Except that reaction temperature adopts 235 ℃, other is the same as embodiment 8, and reaction result is shown in Table 1.

Example 13:

Except that the reaction molar hydrogen ester ratio adopts 20, other is with embodiment 8, and reaction result is shown in Table 1.

Example 14:

Except that the reaction molar hydrogen ester ratio adopts 10, other is with embodiment 8, and reaction result is shown in Table 1.

Example 15:

Except that methyl acetate was used instead of ethyl acetate and the temperature was 215° C., the others were the same as in Example 8, and the reaction results are shown in Table 1.

Table 1 Ethyl acetate hydrogenation ethanol reaction result

Example raw material temperature, ℃ pressure, MPa Molar Hydrogen Ester Ratio Airspeed, h ^-1 Conversion rate selectivity Space-time yield, g/L.h Example 1 ethyl acetate 215 2.5 50 1.5 98.8% 99.8% -- Example 2 ethyl acetate 215 2.5 50 1.2 95.5% 99.5% -- Example 3 ethyl acetate 220 3 30 2 98.5% 99.6% -- Example 4 ethyl acetate 220 3 30 2 97.2% 99.2% -- Example 5 Methyl acetate 200 3 50 2 88.6% 99.5% -- Example 6 Methyl acetate 210 3 50 1.3 98.7% 99.4% -- Example 7 ethyl acetate 220 3 50 1.2 98.6% 99.6% 628.34 Example 8 ethyl acetate 220 2 50 1.2 97.5% 99.8% 622.58 Example 9 ethyl acetate 220 1 50 1.2 75.7% 99.8% 483.37 Example 10 ethyl acetate 205 3 50 1.2 96.5% 100.0% 617.42 Example 11 ethyl acetate 185 3 50 1.2 61.8% 100.0% 395.41 Example 12 ethyl acetate 235 3 50 1.2 98.8% 99.8% 630.88 Example 13 ethyl acetate 220 3 20 1.2 96.5% 99.9% 616.81 Example 14 ethyl acetate 220 3 10 1.2 87.1% 99.8% 556.17 Example 15 Methyl acetate 215 3 50 1.2 98.4% 99.5% 372.47

Claims (9)

1. a method for acetic ester preparation of ethanol by hydrogenating, is characterized in that the step that it comprises:

1) by prepare load on the copper-based catalysts moulding on MCM-41 molecular sieve after put into fixed-bed reactor, be 5-10%H in volume ratio ₂/ N ₂in atmosphere, reduce, reduction temperature 350-500 DEG C, recovery time 2-24 hour;

2) after reduction finishes, with pure hydrogen displacement whole system, adjust temperature of reaction to 160-260 DEG C, pressure is 1.0-4.0MPa, and acetic ester mass space velocity is 0.5-3h ^-1, the material that contains acetic ester enters reactor after vaporizing chamber vaporization and hydrogen reaction generates ethanol;

3) product is through the laggard row gas-liquid separation of condensation, and liquid-phase product is collected products pot, and gas phase circulates and enters reactor and react after supercharger supercharging, and mole hydrogen ester is than being 20-200;

Described copper-based catalysts is taking mesoporous silicon oxide molecular sieve MCM-41 as carrier, taking copper as active ingredient, taking the oxide compound of at least one element in La, Ce as auxiliary agent; Each component accounts for catalyst weight per-cent: silicon oxide=50-90wt%, and active ingredient copper=10-50wt%, auxiliary agent=0.1-20wt%, each weight percentages of components sum is 100%;

The preparation method of described copper-based catalysts is:

1), by measuring tetraethoxy or water glass and cetyl trimethylammonium bromide aqueous solution, with NaOH adjust pH=11-11.5, at 80 DEG C, stirring reaction 0.5-2h, forms MCM-41 mesopore molecular sieve mother liquor;

2), under room temperature, add successively at least one the soluble salt aqueous solution in copper ammon solution and La, Ce; And stirring reaction 4h;

3) 80 DEG C of heating make ammonia volatilization, when pH value stops heating lower than 7 time;

4) crystallization 24 hours at 120 DEG C; After crystallization completes taking-up cooling, filter, washing is to neutral; Then dry 6h at 120 DEG C; Finally roasting 6h at 500 DEG C.

2. in accordance with the method for claim 1, it is characterized in that described acetic ester is one or both in ritalin and vinyl acetic monomer.

3. in accordance with the method for claim 1, it is characterized in that the described acetic ester material that contains also includes one or both solvents in ethanol and methyl alcohol.

4. in accordance with the method for claim 1, it is characterized in that described circulation gas phase composite comprises hydrogen, acetate in minute ester and ethanol, volume ratio is: 100: 0.01-0.2: 0.01-0.2.

5. in accordance with the method for claim 1, it is characterized in that described circulation gas phase composite comprises hydrogen, acetate in minute ester, ethanol and methyl alcohol, volume ratio is: 100: 0.01-0.2: 0.01-0.2: 0.01-0.4.

6. in accordance with the method for claim 1, it is characterized in that step 2) described temperature of reaction is 180-240 DEG C.

7. in accordance with the method for claim 1, it is characterized in that step 2) described reaction pressure is 2-4MPa.

8. in accordance with the method for claim 1, it is characterized in that step 3) mole hydrogen ester of described reaction is than being 20-100.

9. for a method for acetic ester preparation of ethanol by hydrogenating, it is characterized in that the step that it comprises:

1) by prepare load on the copper-based catalysts moulding on MCM-41 molecular sieve after put into fixed-bed reactor, be 5-10%H in volume ratio ₂/ N ₂in atmosphere, reduce, reduction temperature 350-500 DEG C, recovery time 2-24 hour;

2) after reduction finishes, with pure hydrogen displacement whole system, adjust temperature of reaction to 220 DEG C, pressure is 3MPa, and acetic ester mass space velocity is 1.2h ^-1, the material that contains acetic ester enters reactor after vaporizing chamber vaporization and hydrogen reaction generates ethanol;

3) product is through the laggard row gas-liquid separation of condensation, and liquid-phase product is collected products pot, and gas phase circulates and enters reactor and react after supercharger supercharging, and a mole hydrogen ester ratio is 50;

Described copper-based catalysts is taking mesoporous silicon oxide molecular sieve MCM-41 as carrier, taking copper as active ingredient, taking the oxide compound of at least one element in La, Ce as auxiliary agent; Each component accounts for catalyst weight per-cent: silicon oxide=50-90wt%, and active ingredient copper=10-50wt%, auxiliary agent=0.1-20wt%, it is 100% that each component accounts for catalyst weight per-cent sum;

The preparation method of described copper-based catalysts is:

1), by measuring tetraethoxy or water glass and cetyl trimethylammonium bromide aqueous solution, with NaOH adjust pH=11-11.5, at 80 DEG C, stirring reaction 0.5-2h, forms MCM-41 mesopore molecular sieve mother liquor;

2), under room temperature, add successively at least one the soluble salt aqueous solution in copper ammon solution and La, Ce; And stirring reaction 4h;

3) 80 DEG C of heating make ammonia volatilization, when pH value stops heating lower than 7 time;

4) crystallization 24 hours at 120 DEG C; After crystallization completes taking-up cooling, filter, washing is to neutral; Then dry 6h at 120 DEG C; Finally roasting 6h at 500 DEG C.