CN116023205A - Method for preparing butadiene from ethanol and acetaldehyde - Google Patents
Method for preparing butadiene from ethanol and acetaldehyde Download PDFInfo
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Abstract
The invention provides a method for preparing butadiene from ethanol and acetaldehyde, which comprises the following steps: in a fixed bed reactor, the mixed solution raw material of ethanol-acetaldehyde-water passes through a bed layer of a supported catalyst loaded with metal element A-metal element B, hydrogen is simultaneously introduced into the reactor, the space velocity of the hydrogen is 24-243 mL/h/(g raw material), the metal element A is hydrogenation active component element, the metal element B is one or more of Ta, zr, Y, hf and Ir, and the metal element A and the metal element B are different. The catalyst of the invention loads metal with hydrogenation activity, hydrogen is added in the reaction atmosphere, so that the acetaldehyde polymerization product which is easy to form carbon deposit is hydrogenated, the carbon deposit formation is slowed down, the regeneration interval time of the catalyst is prolonged, the hydrogen flow is controlled, and the reversible reaction of ethanol dehydrogenation to generate acetaldehyde and acetaldehyde hydrogenation to generate ethanol is balanced. Therefore, the aim of slowing down the formation of carbon deposit and prolonging the regeneration interval time of the catalyst is realized.
Description
Technical Field
The invention relates to a method for preparing butadiene from ethanol and acetaldehyde.
Background
1, 3-butadiene is widely used in the chemical industry, butadiene being the main raw material for synthetic Styrene Butadiene Rubber (SBR), polybutadiene rubber (BR), neoprene and nitrile rubber. The largest used for styrene-butadiene rubber is, in turn, polybutadiene rubber (mainly butadiene rubber). Butadiene is also used in the production of styrene-butadiene latex, ABS resins, adiponitrile, etc., which is a raw material for the production of nylon 66. At present, a byproduct C4 fraction produced in ethylene by steam cracking is a main source of butadiene, and about 97% of devices worldwide adopt a cracking C4 mixture extraction process. However, in recent years, the price of petroleum has increased, and the global lightening of steam cracking raw materials has an influence on the yield of butadiene, and development of alternative methods for producing butadiene has become important.
The method for preparing butadiene from ethanol mainly comprises two production methods of a one-step method and a two-step method: the one-step method is to separately feed ethanol and produce butadiene in one step; the two-step process first dehydrogenates ethanol to acetaldehyde in one reactor and then converts the mixture of ethanol and acetaldehyde as a feedstock to butadiene in another reactor. The complete reaction path for preparing butadiene from ethanol is as follows: (1) Firstly, performing anaerobic dehydrogenation on a part of ethanol to generate acetaldehyde; (2) Two molecules of acetaldehyde are subjected to aldol condensation reaction to generate 3-hydroxybutyraldehyde; (3) subsequent dehydration of 3-hydroxybutyraldehyde to 2-butenal; (4) The 2-butenal and ethanol undergo an intermolecular hydrogen transfer reaction of MPVO, and are converted into 2-butenol, and the ethanol is dehydrogenated to generate acetaldehyde again; (5) finally, 2-butenol is dehydrated to form butadiene.
(1)CH 3 CH 2 OH→CH 3 CHO+H 2
(2)2CH 3 CHO→CH 3 -CHOH-CH 2 -CHO
(3)CH 3 -CHOH-CH 2 -CHO→CH 3 -CH＝CH-CHO+H 2 O
(4)CH 3 -CH＝CH-CHO+CH 3 CH 2 OH→CH 3 -CH＝CH-CH 2 OH+CH 3 CHO
(5)CH 3 -CH＝CH-CH 2 OH→CH 2 ＝CH-CH＝CH 2
In the reaction process, various side reactions exist, particularly, ethanol is dehydrated to generate ethylene, diethyl ether and aldehyde to generate more than five-carbon heavy components, and other reactions (such as cracking, hydrogenation, cyclization, diels-Alder reaction and the like) can also occur.
U.S. Union carbide Co (PEP Report 35E// On-Purpose Butadiene production IHS Markit, california 2012) uses 2% Ta 2 O 5 /SiO 2 The catalyst has butadiene selectivity of 63% and catalyst life of 120h at 325-350deg.C by two-step process. Dumeignil et al (Green chem.,2018, 20:3203-3209) used a ZnTa-TUD-1 catalyst, and after 60 hours of continuous reaction, butadiene selectivity was reduced from 73% to below 60%, and after calcination regeneration, catalyst activity was restored, but after 15 hours, it was reduced to the pre-regeneration activity level.
However, since the side reaction which causes carbon deposition is very easy to occur in the process of preparing butadiene from ethanol, the regeneration interval time of the catalyst for preparing butadiene is short and the regeneration is frequent, and thus, a method for slowing down the carbon deposition and prolonging the regeneration interval time of the catalyst for preparing 1, 3-butadiene from ethanol needs to be researched and developed to overcome the problems.
Disclosure of Invention
The invention aims to solve the problems of short catalyst regeneration interval time and frequent regeneration of the existing butadiene preparation method, and provides a method for preparing butadiene from ethanol and acetaldehyde so as to slow down carbon deposit formation and prolong the catalyst regeneration interval time.
The invention discovers for the first time that the mixed solution of ethanol, acetaldehyde and water is taken as a raw material, and passes through a bed layer filled with a metal (A) -metal (B) -silicon dioxide catalyst, hydrogen is simultaneously introduced into a reactor, the metal (A) is metal with hydrogenation activity, and hydrogen is added in a reaction atmosphere, so that an acetaldehyde multimerization product which is easy to form carbon deposit is hydrogenated, and the carbon deposit formation is slowed down. The present invention has been made.
The invention provides a method for preparing butadiene from ethanol and acetaldehyde, which comprises the following steps: in a fixed bed reactor, the mixed solution raw material of ethanol-acetaldehyde-water passes through a bed layer of a supported catalyst loaded with metal element A-metal element B, hydrogen is simultaneously introduced into the reactor, the space velocity of the hydrogen is 24-243 mL/h/(g raw material), the metal element A is hydrogenation active component element, the metal element B is one or more of Ta, zr, Y, hf and Ir, and the metal element A and the metal element B are different.
The catalytic process is characterized in that metal with hydrogenation activity is loaded, hydrogen is added in the reaction atmosphere, so that an acetaldehyde multimerization product which is easy to form carbon deposition is hydrogenated, the carbon deposition formation is slowed down, the regeneration interval time of a catalyst is prolonged, the hydrogen flow is controlled, and the ethanol dehydrogenation is balanced to generate acetaldehyde and the reversible reaction of the acetaldehyde hydrogenation to generate ethanol is balanced. Therefore, the aim of slowing down the formation of carbon deposit and prolonging the regeneration interval time of the catalyst is realized.
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
The invention provides a method for preparing butadiene from ethanol and acetaldehyde, which comprises the following steps: in a fixed bed reactor, the mixed solution raw material of ethanol-acetaldehyde-water passes through a bed layer of a supported catalyst loaded with metal element A-metal element B, hydrogen is simultaneously introduced into the reactor, the space velocity of the hydrogen is 24-243 mL/h/(g raw material), the metal element A is hydrogenation active component element, the metal element B is one or more of Ta, zr, Y, hf and Ir, and the metal element A and the metal element B are different. The invention provides a method for preparing the catalyst for hydrogenation of the acetaldehyde polymer product, which is easy to form carbon deposition, by loading the metal with hydrogenation activity on the catalyst and adding hydrogen in the reaction atmosphere for the first time, the formation of carbon deposition is slowed down, the regeneration interval time of the catalyst is prolonged, the hydrogen flow is controlled, and the ethanol dehydrogenation is balanced to generate acetaldehyde and the reversible reaction of the acetaldehyde hydrogenation to generate ethanol is balanced. Therefore, the aim of slowing down the formation of carbon deposit and prolonging the regeneration interval time of the catalyst is realized.
According to a preferred embodiment of the invention, the metallic element a is preferably selected from one or more of noble metals, cu, ni, preferably Cu and/or Ag and/or Au. The preferred A element species is adopted, so that the carbon deposition of the catalyst can be further delayed, and the regeneration interval time of the catalyst can be prolonged.
According to a preferred embodiment of the present invention, it is preferred that the metallic element B is selected from one or more of Ta, zr, hf and Y, preferably Ta and/or Zr. The adoption of the preferred B element species can further delay the carbon deposition of the catalyst and prolong the regeneration interval time of the catalyst.
The support of the supported catalyst according to the present invention may be various supports, for example, one or more of silica and dealuminated molecular sieves, and for the present invention, silica is preferable. By adopting the preferable carrier, the carbon deposition of the catalyst can be further delayed, and the regeneration interval time of the catalyst can be prolonged.
According to a preferred embodiment of the present invention, the molar ratio of the metal element B to the metal element a is 4 to 400:1, preferably 5-320:1. by adopting the preferable proportion, the carbon deposition of the catalyst can be further delayed, and the regeneration interval time of the catalyst can be prolonged.
According to a preferred embodiment of the present invention, the total content of the metal element a in elemental form and the metal element B in oxide form is 2 to 5% by weight based on the total weight of the catalyst. By adopting the preferable content, the carbon deposition of the catalyst can be further delayed, and the regeneration interval time of the catalyst can be prolonged.
According to a preferred embodiment of the present invention, the metal element a is present in the form of simple substance in the catalyst and the metal element B is present in the form of oxide in the catalyst.
According to a preferred embodiment of the present invention, the preparation method of the supported catalyst comprises: impregnating the carrier with a solution containing a metal A compound and a metal B compound, and then drying, roasting and reducing; preferably an isovolumetric infusion; or the metal A-containing compound is impregnated on the support carrying the metal B, and then dried, calcined, and reduced, preferably by an isovolumetric impregnation. By adopting the preferable preparation method, the carbon deposition of the catalyst can be further delayed, and the regeneration interval time of the catalyst can be prolonged.
According to a preferred embodiment of the present invention, the preferred drying conditions include: the temperature is 50-120 ℃ and the time is 12-24h.
According to a preferred embodiment of the present invention, preferably considering safety, when using ethanol isovolumetric infusion, the drying conditions include: drying in a vacuum drying oven at 50-60deg.C for 1-2 hr, and drying in a forced air drying oven at 100-120deg.C for 18-30 hr.
According to a preferred embodiment of the present invention, the conditions of calcination include: 450-550 ℃ for 3-5h.
According to a preferred embodiment of the present invention, when using an equal volume impregnation with an ethanol solution, the equal volume impregnation is preferably performed under sealed conditions.
According to a preferred embodiment of the invention, the time of the isovolumetric infusion is determined as desired, typically from 1 to 20 hours.
According to a preferred embodiment of the invention, the conditions of the reduction are preferably such that the metal component a is reduced to the elemental form and the metal component B remains in the oxidized form. For example, the reduction is carried out at a temperature of 300 to 400 c, preferably 310 to 350 c, the reduction step of the catalyst also being carried out at the time of use of the catalyst. For example, hydrogen is introduced into the fixed bed reactor for reduction.
According to a preferred embodiment of the invention, the hydrogen space velocity is from 24 to 243 mL/h/(g of feedstock). By adopting the preferable hydrogen airspeed, the carbon deposition of the catalyst can be further delayed, and the regeneration interval time of the catalyst can be prolonged.
According to a preferred embodiment of the present invention, the operating conditions within the fixed bed reactor include: the temperature is 300-400 ℃, preferably 310-350 ℃. Therefore, the carbon deposition of the catalyst can be further delayed, and the regeneration interval time of the catalyst can be prolonged.
According to a preferred embodiment of the present invention, the operating conditions within the fixed bed reactor include: the pressure is normal pressure. Therefore, the carbon deposition of the catalyst can be further delayed, and the regeneration interval time of the catalyst can be prolonged.
According to a preferred embodiment of the present invention, the operating conditions within the fixed bed reactor include: the mass airspeed of the raw material is 0.5 to 5 hours -1 Preferably, the mass space velocity of the raw material is 0.8-3h -1 . Therefore, the carbon deposition of the catalyst can be further delayed, and the regeneration interval time of the catalyst can be prolonged.
According to a preferred embodiment of the invention, the molar ratio of ethanol to acetaldehyde in the raw material solution is 2:1-5:1, and the mass of water is 5-50% of the total solution mass. Therefore, the carbon deposition of the catalyst can be further delayed, and the regeneration interval time of the catalyst can be prolonged.
According to a preferred embodiment of the invention, the molar ratio of ethanol to acetaldehyde in the raw material solution is 2.5:1-4:1, and the mass of water is 8-20% of the total solution mass. Therefore, the carbon deposition of the catalyst can be further delayed, and the regeneration interval time of the catalyst can be prolonged.
According to a preferred embodiment of the invention, the method comprises: in a fixed bed reactor, under the conditions of the temperature of 300-400 ℃ and normal pressure, the ethanol-acetaldehyde-water mixed solution is taken as a raw material to pass through a bed layer loaded with a metal (A) -metal (B) -silicon dioxide catalyst, and meanwhile, hydrogen is introduced into the reactor, wherein the hydrogen space velocity is 24-243 mL/h/(g raw material). Therefore, the carbon deposition of the catalyst can be further delayed, and the regeneration interval time of the catalyst can be prolonged.
According to a preferred embodiment of the invention, the catalyst is prepared by mixing and dissolving precursor salts of metal A and metal B in absolute ethanol solution, and then carrying out equal volume impregnation on silicon dioxide; or the precursor salt solution of the metal (A) is immersed and supported on the silicon dioxide loaded with the metal B in an equal volume. Therefore, the carbon deposition of the catalyst can be further delayed, and the regeneration interval time of the catalyst can be prolonged.
According to a preferred embodiment of the invention, the method of the invention comprises: in a fixed bed reactor, under the conditions of the temperature of 300-400 ℃ and normal pressure, the ethanol-acetaldehyde-water mixed solution is taken as a raw material to pass through a bed layer filled with a metal (A) -metal (B) -silicon dioxide catalyst, and meanwhile, hydrogen is introduced into the reactor, wherein the hydrogen space velocity is 24-243 mL/h/(g raw material).
According to a preferred embodiment of the present invention, the catalyst is preferably a catalyst prepared by mixing a metal (A) with a precursor salt of a metal (B) in an absolute ethanol solution, and then carrying the catalyst in an equivolume impregnation manner with silica or carrying the catalyst in an equivolume impregnation manner with a metal (A) on metal (B) -silica, wherein the metal (A) is one or both of Cu and Ag having hydrogenation activity, and the metal (B) is Ta 2 O 5 、ZrO 2 One or two of them. Therefore, the carbon deposition of the catalyst can be further delayed, and the regeneration interval time of the catalyst can be prolonged.
According to a preferred embodiment of the present invention, preferably, the molar ratio of ethanol to acetaldehyde in the reaction feed solution is from 2:1 to 5:1, preferably, the molar ratio of ethanol to acetaldehyde in the feed is from 2.5:1 to 4:1; the water content is 5-50% of the total solution mass, preferably the water mass fraction in the raw material is 8% -20%. Therefore, the carbon deposition of the catalyst can be further delayed, and the regeneration interval time of the catalyst can be prolonged.
According to a preferred embodiment of the present invention, preferably, the fixed bed reaction conditions are as follows: the mass airspeed of the raw material is 0.5 to 5 hours -1 The temperature of the reaction is 320-400 ℃, and the reaction raw materials react under the action of a catalyst to obtain 1, 3-butadiene; preferably, the space velocity of the raw material mass is 0.8-3h -1 The reaction temperature is 310-350 ℃ and the pressure is 100kPa-200kPa, such as normal pressure. Therefore, the carbon deposition of the catalyst can be further delayed, and the regeneration interval time of the catalyst can be prolonged.
The invention has no special requirement on a fixed bed reactor, and a common fixed bed can be used for the invention, and aiming at the invention, the temperature of the reactor is controlled by adopting a tubular furnace with three heating areas, and liquid feeding is carried out by using a double plunger pump.
The following examples are provided for illustrative purposes only and are not intended to limit the invention in any way, as the process for preparing 1, 3-butadiene from ethanol and acetaldehyde is provided in the present invention.
Definition of terms:
description of catalyst Performance test
The reactor used in the examples below was a fixed bed reactor, the temperature of the reactor was controlled using a tube furnace with three heating zones, liquid feed was performed using a double plunger pump, and the product formed during the reaction was maintained in a gas phase, so that the product could be analyzed on line using gas chromatography to identify the product formed and the content as accurately as possible. Specific operating conditions are described in the following application examples.
Example 1
0.972g of tantalum pentachloride and 0.063g of anhydrous copper chloride were dissolved in absolute ethanol. Placing 30g of C-type silica gel carrier in a beaker, rapidly dropwise adding the precursor solution into the beaker under stirring, mixing with the silica carrier (isovolumetric impregnation), sealing and standing for 2 hours, and then at 50 DEG CDrying in a vacuum oven for 1 hour, and drying in a forced air oven at 120deg.C for 24 hours. Finally, the dried solid is put into a muffle furnace air atmosphere for roasting, the roasting temperature is 500 ℃, the roasting is carried out for 5 hours, and the reduction (325 ℃ hydrogen atmosphere is reduced for 0.5 hour) is carried out to obtain 0.1 percent Cu/2 percent Ta 2 O 5 /SiO 2 A catalyst.
The catalyst was charged into a fixed bed reactor, the molar ratio of ethanol/acetaldehyde fed was 3.5:1, the water content was 10wt%, the reaction temperature was 325 ℃, the pressure was normal, the flow rate of the feed was 1g/g of WHSV per hour based on the total mass of ethanol and acetaldehyde, the flow rate of the hydrogen was 120 mL/h/(g of raw material), and the total conversion of ethanol and acetaldehyde and the carbon selectivity of butadiene were measured under the process conditions.
Example 2
1.458g of tantalum pentachloride and 0.024g of silver nitrate were dissolved in absolute ethanol. 30g of the type B silica gel carrier is placed in a beaker, the precursor solution is quickly added dropwise into the beaker under stirring, mixed with the silica carrier (equal volume impregnation), then sealed and kept stand for 2 hours, then dried in a vacuum drying oven at 60 ℃ for 1 hour, and then dried in a forced air drying oven at 110 ℃ for 24 hours. Finally, the dried solid is put into a muffle furnace air atmosphere for roasting, the roasting temperature is 450 ℃, the roasting time is 5 hours, and the reduction (325 ℃ hydrogen atmosphere reduction for 0.5 hour) is carried out to obtain 0.05 percent of Ag/3 percent of Ta 2 O 5 /SiO 2 A catalyst.
The catalyst was charged into a fixed bed reactor, the molar ratio of ethanol/acetaldehyde fed was 3.5:1, the water content was 10wt%, the reaction temperature was 325 ℃, the pressure was normal, the flow rate of the feed was 1.5g/g of WHSV per hour based on the total mass of ethanol and acetaldehyde, the flow rate of hydrogen was 240 mL/h/(g of raw material), and the total conversion of ethanol and acetaldehyde and the carbon selectivity of butadiene were measured under the process conditions.
Example 3
4.181g of zirconium nitrate pentahydrate was dissolved in deionized water. Placing 30g of B-type silica gel carrier in a beaker, adding the precursor solution into the beaker dropwise under stirring, mixing with the silica carrier, standing for 2 hours, and thenDrying was carried out in a forced air drying oven at 100℃for 24 hours. Finally, the dried solid is put into a muffle furnace air atmosphere for roasting at 550 ℃ for 5 hours to obtain 4 percent ZrO 2 /SiO 2 。
Then, the aqueous chloroauric acid solution was immersed in the obtained 4% ZrO by the same immersing method 2 /SiO 2 On top of this, it was left to stand for 2 hours and then dried in a forced air drying oven at 80℃for 12 hours. Finally, the dried solid is put into a muffle furnace air atmosphere for roasting, the roasting temperature is 550 ℃, the roasting is carried out for 5 hours, and the reduction (325 ℃ hydrogen atmosphere is reduced for 0.5 hour) is carried out to obtain 0.02 percent of Au/4 percent of ZrO 2 /SiO 2 A catalyst.
The catalyst was charged into a fixed bed reactor, the molar ratio of ethanol/acetaldehyde fed was 3.5:1, the water content was 10wt%, the reaction temperature was 325 ℃, the pressure was normal, the flow rate of the feed was 3g/g of WHSV per hour based on the total mass of ethanol and acetaldehyde, the flow rate of the hydrogen was 24 mL/h/(g of raw material), and the total conversion of ethanol and acetaldehyde and the carbon selectivity of butadiene were measured under the process conditions.
Example 4
0.972g tantalum pentachloride was dissolved in absolute ethanol. The 30gB type silica gel carrier is placed in a beaker, the precursor solution is quickly and dropwise added into the beaker under the condition of stirring, the precursor solution is mixed with the silica carrier, then the mixture is sealed and kept stand for 2 hours, then the mixture is dried in a vacuum drying box at 50 ℃ for 1 hour, and then the mixture is dried in a blast drying box at 120 ℃ for 24 hours. Finally, the dried solid is put into a muffle furnace air atmosphere for roasting at the temperature of 450 ℃ for 5 hours to obtain 2 percent Ta 2 O 5 /SiO 2 。
Yttrium nitrate (in such an amount that Y is supported on a carrier) 2 O 3 Is dissolved in absolute ethanol (the amount of absolute ethanol is such that the mass concentration of yttrium nitrate is 5%). Thereto was further added 2% Ta 2 O 5 /SiO 2 Stirring at 50℃until the ethanol had evaporated to dryness. And dried in a forced air drying oven at 110℃for 12 hours. Finally, the dried solid is put into a muffle furnace air atmosphere to be roasted for 3 hours at the roasting temperature of 500 ℃ to obtain 2%Y 2 O 3 /2％Ta 2 O 5 /SiO 2 A catalyst.
Copper nitrate (in an amount such that the amount of Cu supported on the carrier is 0.1 wt%) was dissolved in deionized water, 2%Y 2 O 3 /2％Ta 2 O 5 /SiO 2 Placing in a beaker, adding the above copper nitrate water solution into the beaker dropwise under stirring, and mixing with 2%Y 2 O 3 /2％Ta 2 O 5 /SiO 2 Mix, then rest for 12h and dry in a blow-dry oven at 110 ℃ for 24 hours. Finally, the dried solid is put into a muffle furnace air atmosphere for roasting, the roasting temperature is 500 ℃, the roasting is carried out for 3 hours, and the solid is reduced (325 ℃ hydrogen atmosphere is reduced for 0.5 hour) to obtain 0.1 percent Cu/2%Y 2 O 3 /2％Ta 2 O 5 /SiO 2 A catalyst.
The catalyst was charged into a fixed bed reactor, the molar ratio of ethanol/acetaldehyde fed was 3.5:1, the water content was 10wt%, the reaction temperature was 325 ℃, the pressure was normal, the flow rate of the feed was 1.5g/g of WHSV per hour based on the total mass of ethanol and acetaldehyde, the flow rate of hydrogen was 120 mL/h/(g of raw material), and the total conversion of ethanol and acetaldehyde and the carbon selectivity of butadiene were measured under the process conditions.
Example 5
0.972g tantalum pentachloride was dissolved in absolute ethanol. 30g of C-type silica gel carrier is placed in a beaker, the precursor solution is quickly added dropwise into the beaker under stirring, mixed with the silica carrier (isovolumetric impregnation), then sealed and kept stand for 2 hours, then dried in a vacuum drying oven at 50 ℃ for 1 hour, and then dried in a forced air drying oven at 120 ℃ for 24 hours. Finally, the dried solid is put into a muffle furnace air atmosphere for roasting at 500 ℃ for 5 hours to obtain 2 percent Ta 2 O 5 /SiO 2 。
Nickel nitrate (in an amount such that the amount of Ni supported on the carrier is 0.1 wt%) was dissolved in deionized water, 2% Ta 2 O 5 /SiO 2 Placing the solution in a beaker, rapidly dropwise adding the nickel nitrate aqueous solution into the beaker under the condition of stirring,with 2% Ta 2 O 5 /SiO 2 Mix, then rest for 12h and dry in a blow-dry oven at 110 ℃ for 24 hours. Finally, the dried solid is put into a muffle furnace air atmosphere for roasting, the roasting temperature is 500 ℃, the roasting is carried out for 3 hours, and the solid is reduced (325 ℃ hydrogen atmosphere is reduced for 0.5 hour) to obtain 0.1 percent Ni/2 percent Ta 2 O 5 /SiO 2 A catalyst.
The catalyst was charged into a fixed bed reactor, the molar ratio of ethanol/acetaldehyde fed was 3.5:1, the water content was 10wt%, the reaction temperature was 325 ℃, the pressure was normal, the flow rate of the feed was 1g/g of WHSV per hour based on the total mass of ethanol and acetaldehyde, the flow rate of the hydrogen was 120 mL/h/(g of raw material), and the total conversion of ethanol and acetaldehyde and the carbon selectivity of butadiene were measured under the process conditions.
Example 6
The catalyst preparation was identical to example 1, except that the reaction temperature of the fixed bed reactor was 360℃and the other conditions were identical.
Example 7
The catalyst preparation was identical to example 1, except that the ethanol/acetaldehyde molar ratio of the feed was 2.4:1, all other conditions being identical.
Example 8
The catalyst preparation was identical to example 1, except that the support used was a dealuminated Beta molecular sieve, all other conditions being identical.
Comparative example 1
The catalyst preparation method and the activity test method of example 1 were the same except that the hydrogen flow rate was 0 mL/h/(g of raw material).
Comparative example 2
The catalyst preparation and activity test methods of example 1 were identical, except that the hydrogen flow was 480 mL/h/(g of raw material).
Comparative example 3
The catalyst is 1% CuO/MgO-SiO 2 The activity test method was the same as that of example 1.
Comparative example 4
Preparation of catalyst 4% ZrO as in example 3 2 /SiO 2 The method is characterized by comprising the following steps:
4.181g of zirconium nitrate pentahydrate was dissolved in deionized water. The 30g B type silica gel carrier is placed in a beaker, and the precursor solution is quickly added dropwise into the beaker under stirring, mixed with the silica carrier, then allowed to stand for 2 hours, and then dried in a 100 ℃ forced air drying oven for 24 hours. Finally, the dried solid is put into a muffle furnace air atmosphere for roasting at 550 ℃ for 5 hours to obtain 4 percent ZrO 2 /SiO 2 。
The catalyst was charged into a fixed bed reactor, the molar ratio of ethanol/acetaldehyde fed was 3.5:1, the water content was 10wt%, the reaction temperature was 325 ℃, the pressure was normal, the flow rate of the feed was 3g/g of WHSV per hour based on the total mass of ethanol and acetaldehyde, the flow rate of the hydrogen was 24 mL/h/(g of raw material), and the total conversion of ethanol and acetaldehyde and the carbon selectivity of butadiene were measured under the process conditions.
The results of the catalyst activity test are summarized in Table 1.
TABLE 1
As can be seen from the above table, in example 1, compared with comparative example 1, the catalyst does not decrease the selectivity of butadiene at a proper hydrogen flow rate after adding a small amount of Cu, and at the same time, the reduction of the conversion rate is slowed down, the single pass life of the catalyst is prolonged, and the catalyst regeneration interval time is prolonged. Example 1 compared to comparative example 2, comparative example 3 showed a too high hydrogen flow rate which reduced conversion and selectivity.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (10)
1. A process for preparing butadiene from ethanol and acetaldehyde, the process comprising: in a fixed bed reactor, the mixed solution raw material of ethanol-acetaldehyde-water passes through a bed layer of a supported catalyst loaded with metal element A-metal element B, hydrogen is simultaneously introduced into the reactor, the space velocity of the hydrogen is 24-243 mL/h/(g raw material), the metal element A is hydrogenation active component element, the metal element B is one or more of Ta, zr, Y, hf and Ir, and the metal element A and the metal element B are different.
2. The method of claim 1, wherein,
the metal element A is selected from one or more of noble metals, cu and Ni, preferably Cu and/or Ag and/or Au;
the metal element B is selected from one or more of Ta, zr, hf and Y, preferably Ta and/or Zr;
the carrier of the supported catalyst is one or more of silicon dioxide and dealuminated molecular sieve, preferably silicon dioxide.
3. The method according to claim 1 or 2, wherein,
the molar ratio of the metal element B to the metal element A is 4-400:1, preferably 5-320:1, a step of; and/or
The metal element A exists in the catalyst in the form of simple substance, and the metal element B exists in the catalyst in the form of oxide; and/or
The total content of the metal element A in terms of simple substance and the metal element B in terms of oxide is 2 to 5% by weight based on the total weight of the catalyst.
4. A process according to any one of claims 1 to 3, wherein the process for preparing the supported catalyst comprises:
impregnating the carrier with a solution containing a metal A compound and a metal B compound, and then drying, roasting and reducing; preferably an isovolumetric infusion; or alternatively
Impregnating a metal-containing A compound on a carrier loaded with a metal B, and then drying, roasting and reducing, preferably, carrying out equal volume impregnation;
preferred conditions for drying include: the temperature is 50-120 ℃ and the time is 12-24 hours;
the roasting conditions include: 450-550 ℃ for 3-5h;
the conditions of the reduction are preferably such that the metal component a is reduced to the elemental form and the metal component B remains in the oxidized form.
5. The process according to any one of claims 1 to 4, wherein the hydrogen space velocity is 24 to 243 mL/h/(g of feedstock).
6. The method according to any one of claims 1 to 5, wherein,
the operating conditions within the fixed bed reactor include:
the temperature is 300-400 ℃, preferably 310-350 ℃; and/or
The pressure is normal pressure; and/or
The mass airspeed of the raw material is 0.5 to 5 hours -1 Preferably, the mass space velocity of the raw material is 0.8-3h -1 。
7. The process according to any one of claims 1 to 6, wherein the molar ratio of ethanol to acetaldehyde in the feed solution is from 2:1 to 5:1, the mass of water being from 5 to 50% of the total solution mass.
8. The process according to any one of claims 1 to 7, wherein the molar ratio of ethanol to acetaldehyde in the feed solution is 2.5:1 to 4:1, the mass of water being 8 to 20% of the total solution mass.
9. A method according to any one of claims 1-8, wherein the method comprises: in a fixed bed reactor, under the conditions of the temperature of 300-400 ℃ and normal pressure, the ethanol-acetaldehyde-water mixed solution is taken as a raw material to pass through a bed layer loaded with a metal (A) -metal (B) -silicon dioxide catalyst, and meanwhile, hydrogen is introduced into the reactor, wherein the hydrogen space velocity is 24-243 mL/h/(g raw material).
10. The method according to claim 9, wherein the catalyst is prepared by mixing and dissolving precursor salts of metal A and metal B in absolute ethanol solution, and then carrying out equal volume impregnation on silicon dioxide; or the precursor salt solution of the metal (A) is immersed and supported on the silicon dioxide loaded with the metal B in an equal volume.
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