A strip-type ester hydrogenation catalyst

Abstract

The application discloses an extruded ester hydrogenation catalyst; a copper source solution and a silicon source solution are added into an aqueous urea solution to stir and react under temperature rising; when the pH of the reaction solution approaches to neutral, heating is stopped to obtain a catalyst slurry; the obtained slurry is cooled and modified high-activity nano-silicon dioxide additives are added to stir and age; suction filtration, washing and squeezing are carried out; after the blocky catalyst precursor after squeezing is crushed, extrusion molding is carried out; meanwhile, the extruded material is passed through a conveying belt and immersed through a sol containing PVA; after complete aging under constant temperature and humidity, drying is carried out to a reasonable moisture content, and then isotactic pelletizing treatment is carried out to form a shape; the isotactic material is subjected to programmed temperature calcination in a nitrogen atmosphere, and the extruded ester hydrogenation catalyst is obtained. By adding the modified high-activity nano-silicon dioxide to the slurry, the gaseous methanol is preferentially reacted with the high-activity nano-silicon dioxide in the application process, the elapse of the silicon of the layered copper silicate is protected, the agglomeration of the high-activity copper grains is delayed, and the generation of side reactions is reduced.

Description

Technical Field

[0001] This invention relates to catalysts for the hydrogenation of esters to alcohols, and more specifically to an extruded ester hydrogenation catalyst. Background Technology

[0002] The syngas-to-ethylene glycol route has gradually become a research hotspot for non-petroleum-based ethylene glycol synthesis due to its advantages of abundant raw materials, good economics, and more rational processes. This route starts with syngas, uses CO gas-phase catalytic coupling to synthesize oxalate esters, and then hydrogenates them to produce ethylene glycol. This approach eliminates dependence on petroleum resources and actively follows the trend of ethylene glycol production technology development. Developing coal-based processes is of particular importance in this regard.

[0003] One of the key technologies for the production of ethylene glycol from coal-based syngas is the development of catalysts for the hydrogenation of oxalate esters to ethylene glycol. A search of existing patent literature revealed that CN 103433039 discloses a method for preparing a hydrogenation catalyst for oxalate esters, which includes the following steps: (1) preparing a silicon source solution, a copper source solution, or a mixed solution of a copper source and a catalyst M source containing a Cu precursor and a catalyst M precursor; (2) under heating conditions, adding the copper source solution or the mixed solution of the copper source and M source dropwise to the silicon source solution, while adjusting the pH value to produce a uniform precipitate, thereby obtaining a catalyst precursor gel; (3) aging the gel under heating conditions; (4) washing, filtering and drying the aged gel; (5) calcining the dried gel to obtain the catalyst, wherein in step (1), the silicon source solution contains urea, and the copper source solution or the mixed solution of the copper source and M source contains ammonium salt; in step (2), the pH value is adjusted by adding alkaline solution or by pre-adjusting the amount of urea and / or ammonium salt. However, the preparation steps are quite complex and the catalyst shaping after preparation is not mentioned. Whether the catalyst is shaped or not is a necessary condition for its industrial application and has a great impact on the catalyst's performance and activity.

[0004] Based on years of industrial experience and research, this invention focuses on the pain points of industry application technology and actively conducts research and innovation in order to create a stable, efficient and more valuable ester hydrogenation catalyst. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the prior art by providing an extruded ester hydrogenation catalyst.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] This invention provides an ester hydrogenation catalyst, which is prepared by a method comprising the following steps:

[0008] S1. Slurry preparation: Add copper source solution and silicon source solution to urea aqueous solution and stir. Heat the reaction solution until the pH of the reaction solution is close to neutral, then stop heating to obtain catalyst slurry.

[0009] S2. Preparation of modified additives: Nano silica powder is added to deionized water with adjusted pH, stirred, and spray-dried to obtain modified high-activity nano silica additives.

[0010] S3. Catalyst molding and preparation: Cool the slurry obtained in step S1 and add the modified high-activity nano silica additive, stir and age;

[0011] S4. Filter the slurry obtained in step S3, wash and press it; crush the pressed block catalyst precursor and extrude it into shape through a twin-screw extruder (feeded by a forced feeder); at the same time, immerse the extruded material in a sol containing PVA through a conveyor belt.

[0012] S5. After the material obtained in step S4 is fully aged under constant temperature and humidity conditions, it is conveyed to a pre-dryer by a conveyor belt and dried to a reasonable moisture content. Then, it isodactic pelletizing is performed and the isodactic material is calcined in a nitrogen atmosphere by programmed temperature rise to obtain the catalyst.

[0013] In step S5, aging under constant temperature and humidity conditions can reduce physical channels between precursor particles caused by insufficient kneading in the freshly extruded strip catalyst, thereby improving the catalyst's strength performance. Controlling the moisture content in the pre-dryer can improve the efficiency of isotactic processing, reduce losses during catalyst forming, and save costs.

[0014] As one embodiment of the present invention, the copper source includes at least one of copper nitrate, copper acetate, copper sulfate, and copper chloride.

[0015] As one embodiment of the present invention, the silicon source includes at least one of tetraethyl silicate, silica sol, sodium silicate, and fumed silica.

[0016] As one embodiment of the present invention, the molar ratio of the copper source, silicon source and urea is 1:1~3:1~3.

[0017] In one embodiment of the present invention, in step S1, the temperature of the heating reaction is 80-90°C, and the time is 8-16 hours. This temperature is within the range for the initiation of urea hydrolysis. This can control the uneven precipitation caused by excessively rapid hydrolysis of the precipitant, which in turn affects the formation of copper oxide flakes and thus the catalyst activity. If the reaction time is less than 8 hours, the reaction may be incomplete, resulting in the loss of active components. If the reaction time is too long, it will affect the production yield and increase the consumption of utilities.

[0018] In one embodiment of the present invention, in step S2, the spray drying process controls the inlet air temperature to be 120~260℃ and the feed rate to be 100~1500mL / h.

[0019] As one embodiment of the present invention, in step S2, the pH range of the deionized water is 1.5 to 5, and the acid used for preparation is one or a mixture of several of nitric acid, oxalic acid, and glycolic acid.

[0020] In one embodiment of the present invention, in step S2, nano-silica powder is added to deionized water with adjusted pH, wherein the mass percentage of nano-silica powder is controlled at 5-20%. In step S2, the mixture is stirred for 1-12 hours.

[0021] In one embodiment of the present invention, in step S3, the temperature is lowered to 20~50℃. The modified highly active nano-silica additive is added while the temperature is lowered to 20~50℃, wherein the mass percentage of the modified highly active nano-silica additive is controlled at 0.1~5%.

[0022] In one embodiment of the present invention, in step S3, the stirring time is 0.5~2h and the aging time is 1~3h.

[0023] In one embodiment of the present invention, in step S4, the crushing is to crush to 5-30 mesh; the washing is to wash with deionized water until the conductivity is less than 1500 μS / cm.

[0024] In one embodiment of the present invention, in step S4, the washing is performed with deionized water until the conductivity is below 1500 μS / cm.

[0025] In one embodiment of the present invention, in step S4, the immersion is performed in a PVA-containing sol with a concentration of 1-30% for 3-30 seconds.

[0026] As one embodiment of the present invention, in step S5, the shaping process includes pressing the filter cake and extruding it into strips.

[0027] As one embodiment of the present invention, in step S5, the constant temperature and humidity conditions have a constant temperature range of 20~80℃ and a humidity range of 30~80%.

[0028] In one embodiment of the present invention, in step S5, the aging time is 2 to 10 hours.

[0029] In one embodiment of the present invention, in step S5, the moisture content is controlled at 20-60%.

[0030] In one embodiment of the present invention, in step S5, the drying temperature is 50°C to 110°C and the time is 1 to 3 hours.

[0031] In one embodiment of the present invention, in step S5, the sample is calcined at 500°C for 3-8 hours under a nitrogen atmosphere.

[0032] The use of the above-mentioned ester hydrogenation catalyst in ester hydrogenation synthesis reactions also falls within the scope of protection of this invention. This includes: the hydrogenation of dimethyl oxalate to ethylene glycol, the hydrogenation of dimethyl oxalate to ethanol, and the hydrogenation of dimethyl malonate to 1,3-propanediol.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1) This invention adds modified high-activity nano-silica to the slurry, so that the methanol in the gas phase reacts preferentially with the high-activity nano-silica during the application process, thereby protecting the loss of silicon in the layered copper silicate, delaying the agglomeration of high-activity copper grains, and reducing the generation of side reactions.

[0035] 2) PVA sol is used to modify the material during the molding process, which improves the toughness of the strip precursor catalyst under adhesive conditions, making it easier to achieve regularization, reducing the generation of broken material during molding, and saving costs.

[0036] 3) Due to the use of PVA, during the inert gas atmosphere calcination process, it can be mostly carbonized into hollow activated carbon fibers, which has a certain confinement effect on active metals, reducing sintering and agglomeration, while improving the strength performance of the entire catalyst and increasing the heat transfer efficiency and appropriately reducing the hot spot temperature.

[0037] 4) Without reducing the performance of the original catalyst, the simple and low-cost method of extrusion strip regularization will greatly enhance its commercial value and improve the catalyst's start-up performance. Detailed Implementation

[0038] The present invention will be described in detail below with reference to embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several adjustments and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0039] Example 1

[0040] Step 1: Weigh 91.24g of copper nitrate trihydrate into a beaker, add 500mL of deionized water and stir to dissolve, preparing solution I. Weigh 226.02g of tetraethyl orthosilicate into a beaker for later use, designated solution II. Add 5L of deionized water to a reaction vessel and add 33.98g of urea, stirring to dissolve. Pour solutions I and II separately into the reaction vessel and stir for 20 minutes. Heat to 80℃ and react for 8 hours. When the pH of the reaction solution reaches neutral, stop heating and age for 2 hours to obtain catalyst slurry L.

[0041] Step 2: Add 0.5g of nano silica powder to 10mL of deionized water with adjusted pH (adjusted to pH 3 with oxalic acid) (the mass percentage of nano silica powder is controlled at 10%) and stir for 2h. After spray drying, the modified high-activity nano silica additive B is obtained.

[0042] Step 3: After cooling the slurry L to 35℃, add the modifier B (the mass percentage of modifier B is 3%), stir for 2 hours, age at room temperature for 3 hours, and then filter. The catalyst precursor was washed with deionized water until its conductivity was below 1500 μS / cm. The filter cake was then pressed, and the pressed block catalyst precursor was crushed to 10 mesh. It was then fed into a twin-screw extruder at a uniform speed through a forced feeder and extruded into shape. At the same time, the extruded material was conveyed through a conveyor belt and immersed in a 15% PVA-containing sol solution for 15 seconds. After the treated strip material was aged completely under constant temperature and humidity conditions of 50°C and 50% (5h), it was conveyed to a pre-dryer and dried at 80°C for 2h until the moisture content was about 45%. Then, the strip precursor was processed into standard 5*5mm cylindrical particles using a pelletizing device. The shaped catalyst precursor was dried at 105°C for 2h in the pre-dryer. The dried material was then calcined in a calcining furnace at 500°C for 4h in a nitrogen atmosphere to obtain catalyst A.

[0043] Comparative Example 1

[0044] This comparative example is basically the same as Example 1, except that in step three, the extruded material is not immersed in the PVA-containing sol solution after passing through the conveyor belt, but is directly aged (5h) under constant temperature and humidity conditions of 50°C and 50% before being transported by the conveyor belt to the pre-dryer for subsequent operations to obtain catalyst B.

[0045] Comparative Example 2

[0046] This comparative example is basically the same as Example 1, except that in step three, isotactic pelletizing was not performed. The material was conveyed to a pre-dryer and dried at 80°C for 2 hours until the moisture content was about 45%. It was then dried at 105°C for 2 hours in the pre-dryer. The dried material was then calcined in a calcining furnace at 500°C for 4 hours in a nitrogen atmosphere to obtain catalyst C.

[0047] Comparative Example 3

[0048] This comparative example is basically the same as Example 1, except that: the nano silica powder is not modified, i.e., there is no step two; in step three, after the slurry L is cooled to 35°C, 0.5g of nano silica powder is added, stirred for 2 hours, filtered and then carried out for subsequent operations to obtain catalyst D.

[0049] Test Example 1

[0050] The prepared catalyst products A, B, C, and D were compared with the commercially available H-CAT type catalyst from Jiangsu Jinjuhejin Materials Co., Ltd. using a grain hardness tester in terms of strength and sieve powder ratio. The data are shown in Table 1 below:

[0051] Table 1

[0052]

[0053] Test Example 2

[0054] The prepared catalyst products A, B, C, and D were first activated with commercially available catalysts. Twenty original granular catalyst particles were taken from each catalyst and loaded into the constant temperature zone of the reactor. The reactor was filled with inert quartz sand at both the top and bottom. The catalysts were activated at atmospheric pressure and a hydrogen space velocity of 1000 h⁻¹. -1 The catalyst was activated at 180℃ and 250℃ for 8 hours and 20 hours, respectively. After activation, the temperature was lowered to room temperature. Once the catalyst oxidation was complete, samples were taken and tested for strength using a grain hardness tester. The data are shown in Table 2 below.

[0055] Table 2

[0056]

[0057] Test Example 3

[0058] Catalyst evaluation: Catalyst A and the same commercially available catalyst were used in the hydrogenation reaction of dimethyl oxalate to ethylene glycol.

[0059] The application conditions are as follows:

[0060] The 20-40 mesh catalyst, after being ground and sieved, was packed into a fixed-bed reactor. After activation, the reaction pressure was controlled at 2.0-3.0 MPa, the reaction temperature at 170-200℃, and the hydrogen / ester molar ratio at 80:1. Oxalate and hydrogen were metered using a plunger pump and a mass flow meter. Under these conditions, dimethyl oxalate was hydrogenated to produce crude ethylene glycol. The reaction solution was quantitatively analyzed using a calibrated gas chromatograph. The pressure drop before and after the reactor was recorded after 720 h. The results are shown in Table 3.

[0061] Table 3 Catalyst evaluation results and performance test data

[0062]

[0063] As shown in Table 1, the strength performance of catalyst A is superior to that of commercially available catalysts and catalysts B, C, and D, with a reasonable data distribution. Catalyst A exhibits more stable strength than commercially available catalysts, and its finished product powder ratio (less than 1 mm) is also optimal, significantly reducing losses during the molding process and saving costs. After reduction, strength performance tests were conducted. Analysis of Table 2 shows that the strength of catalysts A, B, C, D, and the commercially available catalysts all decreased to varying degrees after activation and reduction. The strength decrease of the commercially available catalysts was less than that of catalysts A, B, C, and D. The excessively low strength performance after activation is detrimental to the operation of large-scale industrial plants. The catalyst stability and lifespan of the catalyst are significantly negatively affected. The activated catalyst strength is too low, and during large-scale industrial operation, the catalyst bed in the reactor is prone to pulverization and loss under high space velocity, high temperature, high pressure, and scouring by gaseous materials. This causes hot spots to shift downwards, further affecting the catalyst's lifespan. Under the same operating conditions, comparative operation in a small-scale unit showed that, with almost the same space-time yield, catalyst A exhibited selectivity almost equivalent to commercially available catalysts, while its reaction temperature was lower (Table 3). This reduces the possibility of coking and lowers energy costs while maintaining high selectivity. After a 720-hour evaluation test, the pressure drop before and after the reactor increased to varying degrees, with catalyst A showing the smallest pressure change. Therefore, the catalyst prepared using this invention possesses high activity, selectivity, and strength, greatly enhancing its application prospects.

[0064] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. An ester hydrogenation catalyst, characterized in that, The catalyst is prepared by a method comprising the following steps: S1. Slurry preparation: Add copper source solution and silicon source solution to urea aqueous solution and stir. Heat the reaction solution until the pH of the reaction solution is close to neutral, then stop heating to obtain catalyst slurry. S2. Preparation of modified additives: Nano-silica powder is added to deionized water with adjusted pH, stirred, and spray-dried to obtain modified high-activity nano-silica additives; the pH range of the deionized water is 1.5~5, and the acid used for preparation is one or a mixture of several of nitric acid, oxalic acid, and glycolic acid; S3. Catalyst molding and preparation: Cool the slurry obtained in step S1 and add the modified high-activity nano silica additive, stir and age; S4. Filter the slurry obtained in step S3, wash and press it; crush the pressed block catalyst precursor and extrude it into shape through a twin-screw extruder; at the same time, immerse the extruded material in a sol containing PVA through a conveyor belt. S5. After the material obtained in step S4 is fully aged under constant temperature and humidity conditions, it is conveyed to a pre-dryer by a conveyor belt and dried to a reasonable moisture content. Then, it isodactic pelletizing is performed and the isodactic material is calcined in a nitrogen atmosphere by programmed temperature rise to obtain the catalyst.

2. The ester hydrogenation catalyst according to claim 1, characterized in that, In step S1, the copper source includes at least one of copper nitrate, copper acetate, copper sulfate, and copper chloride; the silicon source includes at least one of tetraethyl silicate, silica sol, sodium silicate, and fumed silica; and the molar ratio of the copper source, silicon source, and urea is 1:1~3:1~3.

3. The ester hydrogenation catalyst according to claim 1, characterized in that, In step S1, the temperature of the heating reaction is 80–90°C, and the time is 8–16 hours.

4. The ester hydrogenation catalyst according to claim 1, characterized in that, In step S2, nano-silica powder is added to deionized water with adjusted pH, wherein the mass percentage of nano-silica powder is controlled at 5-20%, and the mixture is stirred for 1-12 hours.

5. The ester hydrogenation catalyst according to claim 1, characterized in that, In step S3, the temperature is lowered to 20~50℃ and the modified high-activity nano silica additive is added, wherein the mass ratio of the modified high-activity nano silica additive is controlled at 0.1~5%; the stirring time is 0.5~2h and the aging time is 1~3h.

6. The ester hydrogenation catalyst according to claim 1, characterized in that, In step S4, the crushing is to crush to 5-30 mesh; the washing is to wash with deionized water until the conductivity is below 1500 μs / cm.

7. The ester hydrogenation catalyst according to claim 1, characterized in that, In step S4, the sample is immersed in a PVA-containing sol with a concentration of 1-30% for 3-30 seconds.

8. The ester hydrogenation catalyst according to claim 1, characterized in that, In step S5, the constant temperature and humidity conditions are: temperature range 20~80℃, humidity range 30~80%; aging time 2~10h; moisture content controlled at 20~60%; drying temperature 50℃~110℃, time 1~3h; and calcination at 500℃ for 3~8h in a nitrogen atmosphere.

9. Use of an ester hydrogenation catalyst according to any one of claims 1-8 in an ester hydrogenation synthesis reaction.

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