A large-pore Cu / SiO 2 catalyst and its preparation and application

Abstract

The present invention discloses a large-pore Cu / SiO2 catalyst and its preparation and application. The large-pore Cu / SiO2 catalyst includes a carrier and copper oxide loaded on the inner and outer surfaces of the carrier. The carrier is a large-pore silica carrier. In the large-pore Cu / SiO2 catalyst, the mass percentage contents of the carrier and the active component are as follows: the carrier is 62.5% - 99.5%, and the copper oxide is 0.5% - 37.5%. The large-pore Cu / SiO2 catalyst is granular, with a specific surface area of 150 - 300m 2 / g, a pore volume of 0.8 - 1.2 ml / g, and an average pore diameter of 15 - 25 nm. The present invention provides the application of the large-pore Cu / SiO2 catalyst in the dehydrogenation lactonization reaction of diglycol, ultimately greatly improving the selectivity of the target product, and the catalyst has a low production cost, a simple and reliable preparation method, and relatively mild reaction conditions.

Description

(1) Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to a large-pore Cu / SiO 2 catalyst, its preparation, and its application in the dehydrogenation lactonization reaction of diglycol. (2) Background Art

[0002] 1,4-Dioxan-2-one (PDO) is an important organic chemical product with a wide range of uses. It can not only be directly used as a fragrance and food additive, but also be a synthetic monomer of poly(1,4-dioxan-2-one) (PPDO). Poly(1,4-dioxan-2-one) can be used to manufacture the housing of electronic components to protect circuit boards and electronic components and improve the high-temperature resistance of products. In the construction industry, it can be used to manufacture building materials such as heat insulation, sound insulation, fire resistance, and waterproofing to improve the service life and quality of buildings. In the automotive industry, it can be used to manufacture automotive parts such as engine hoods and doors to improve the durability and safety performance of automobiles. In the chemical industry, it can even be used as a manufacturing material for corrosion-resistant containers, pipelines, valves, and other chemical equipment. In the medical industry, it can be used to manufacture surgical sutures, drug sustained-release materials, orthopedic fixation materials, and tissue repair materials, etc.

[0003] There are three methods for synthesizing 1,4-dioxan-2-one: The first method is to prepare it by an organic synthesis method, which uses ethylene glycol, sodium metal, and chloroacetic acid as raw materials to synthesize 1,4-dioxan-2-one. This method has cumbersome operations and high production costs, which is not conducive to industrial production.

[0004] The second method is the catalytic carbonylation reaction method: carbon monoxide, formaldehyde, and 1,2-ethylene glycol or 1,3-dioxolane, etc. are used as raw materials for carbonyl addition to synthesize 1,4-dioxan-2-one. The catalysts used mainly include carbonyl complexes of hydrogen fluoride, copper, and silver, etc.

[0005] The third method is a catalytic oxidative dehydrogenation cyclization method, which usually uses diethylene glycol as a reaction raw material for synthesis, and uses a transition metal such as copper, silver, platinum, zinc or a composite oxide catalyst of the above elements supported by an inert carrier such as alumina, activated carbon, silicon dioxide, etc. For example, US Pat. 2,142,033 uses a copper-chromium composite oxygenate catalyst (chromium content ≤ 5wt%) to obtain the target product by gas phase dehydrogenation lactonization of diethylene glycol, with a selectivity of 75.0%, but a yield of only 25%. US Pat. 2,807,629 increases the selectivity to 94.0% and the yield to 84% by changing the chromium content in the copper-chromium catalyst. US Pat. 3,119,840 also uses a copper-chromium catalyst. When the molar ratio of hydrogen to the raw material is 3 to 100, the yield of the target product dioxanone can reach up to 96%. Japanese Patent Laid-Open No. 58-99476 uses activated carbon, silicon dioxide or aluminum oxide to load platinum or palladium metal catalysts, and uses oxygen in the air as an oxidant to make diethylene glycol undergo oxidative dehydrogenation and self-condensation to synthesize p-dioxanone, but its selectivity can only reach 75% at most. Fetizon.M. et al. (Fetizon M, et al., Tetrahedron, 1975, 31, 171-176) used silver carbonate loaded on a diatomaceous earth carrier as a catalyst, and refluxed diethylene glycol in benzene for 10 hours, and the yield of p-dioxanone could reach 95%. In CN 1739852A, Wang Yuzhong et al. used a coprecipitation method to load copper, zinc and other alkali metal or alkaline earth metal compounds on an inert carrier, and the mass percentage of active components was 20-90%; the activity and selectivity of the catalyst were high, but the catalyst preparation process was relatively complicated, which was not conducive to industrial expansion of production.

[0006] It can be seen from the published literature that most catalysts cannot have both activity and selectivity, and the method for preparing the catalyst is still relatively complicated, using precious metal components or chromium with high toxicity, which is not conducive to its industrial application. The present invention uses a simple impregnation method to load the copper active component on macroporous silica to obtain a large-pore Cu / SiO 2 The catalyst does not add any chemical additives other than the copper catalytic active substance, and in particular, the larger catalyst pore size facilitates the diffusion of raw material and target product molecules, so that it not only has high activity in the dehydrogenation lactonization reaction of diethylene glycol, but also can significantly reduce the generation of by-products, thereby making it have high selectivity at the same time. (III) Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a large-pore Cu / SiO 2 Catalyst, preparation thereof and application in dehydrogenation lactonization of diethylene glycol.

[0008] To solve the above technical problems, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a large-pore Cu / SiO 2 catalyst, wherein the large-pore Cu / SiO 2 catalyst comprises a carrier and copper oxide loaded on the inner and outer surfaces of the carrier. The carrier is a large-pore silica carrier. In the large-pore Cu / SiO 2 catalyst, the mass percentage contents of the carrier and the active component are as follows:

[0010] Carrier 62.5% - 99.5%

[0011] Copper oxide 0.5% - 37.5%

[0012] The large-pore Cu / SiO 2 catalyst is granular, with a specific surface area of 150 - 300 m 2 / g, a pore volume of 0.8 - 1.2 ml / g, and an average pore diameter of 15 - 25 nm.

[0013] Preferably, the large-pore Cu / SiO 2 catalyst comprises the following components in weight percentages:

[0014] Carrier 70% - 99%

[0015] Copper oxide 1% - 30%.

[0016] In a second aspect, the present invention provides a preparation method of the large-pore Cu / SiO 2 catalyst described in the first aspect, comprising the following steps:

[0017] (1) Immerse the large-pore silica carrier in a mixed solution of a copper precursor and a complexing agent, and oscillate and impregnate for 1 - 48 h;

[0018] (2) Dry the mixture obtained in step (1) to uniformly load the copper precursor onto the inner and outer surfaces of the alumina carrier;

[0019] (3) Put the dried catalyst precursor obtained in step (2) into a muffle furnace and carry out calcination treatment in an air atmosphere. The calcination treatment conditions are: heat up to 150 - 800 °C at a heating rate of 0.5 - 20 °C / min and calcine for 1 - 10 h to obtain the large-pore Cu / SiO 2 catalyst.

[0020] In the above preparation method, the macroporous silica support can be obtained in the following manner: Commercial coarse-pore silica gel (type C silica gel) with a mesh size of 20 - 40 is added to a sodium hydroxide solution with a concentration of 0.4 - 0.7 M, treated at 70 - 90 °C for 7 - 9 h, filtered, washed with water until the filtrate is neutral, and then dried in a forced-air drying oven to obtain the macroporous silica support. The copper precursor can be a soluble copper salt such as copper nitrate, copper chloride, copper acetate, or copper acetylacetonate. The complexing agent is ammonia, ethylenediamine, ethylenediaminetetraacetic acid, or citric acid. The molar ratio of the complexing agent to the copper precursor is 1 - 150:1, preferably 5 - 100:1. The drying treatment is carried out in a rotary evaporator and an oven. First, it is dried in the rotary evaporator at 10 - 60 °C and 0.005 - 0.1 MPa for 1 - 24 h, and then dried in the oven at 50 - 150 °C for 1 - 48 h. The calcination treatment conditions are preferably: heated to 300 - 600 °C at a heating rate of 3 - 15 °C / min and calcined for 2 - 6 h.

[0021] In the third aspect, the present invention provides the application of the macroporous Cu / SiO 2 catalyst described in the first aspect in the dehydrogenation lactonization reaction of diglycol. Before the dehydrogenation lactonization reaction of diglycol is carried out, the macroporous Cu / SiO 2 catalyst needs to be pre-reduced: Using a hydrogen-nitrogen mixture (v / v = 1:1 - 9) with an airspeed of 100 - 800 h -1 as the reducing agent, reduction is carried out under atmospheric pressure and at a temperature of 280 - 350 °C for a reduction time of 1 - 12 h.

[0022] The catalyst of the present invention has a relatively large pore size, so it is beneficial for the diffusion of the relatively large molecule raw material diglycol and the product p-dioxanone inside the catalyst particles. It can not only improve the activity of the catalyst, but also reduce the residence time of the raw material diglycol inside the catalyst pores, thus significantly reducing the generation of the main reaction by-product 1,4-dioxane and other by-products, and ultimately greatly improving the selectivity of the target product at the same time. Experimental results show that when the catalyst pore size is greater than 15 nm, the selectivity of the target product is significantly improved; however, when the catalyst pore size is too large (greater than 25 nm), the dispersion of the active component Cu decreases and the particle size becomes larger, resulting in an increase in other by-products.

[0023] Preferably, the dehydrogenation lactonization reaction of diglycol of the present invention is carried out in a fixed-bed reactor.

[0024] Preferably, the conditions for the dehydrogenation lactonization reaction of diglycol are: the temperature is 220 - 280 °C, the reaction pressure is 0.1 - 1 MPa, and the liquid hourly space velocity of the raw material is 0.2 - 1.5 h -1, the hydrogen space velocity of the carrier is 100 - 800 h -1 .

[0025] Compared with the prior art, the beneficial effects of the present invention are embodied in:

[0026] (1) When the large-pore Cu / SiO 2 catalyst provided by the present invention is applied to the dehydrogenation lactonization of diglycol to prepare p-dioxanone, its larger pore diameter is beneficial to the diffusion of the raw material diglycol with larger molecules and the product p-dioxanone inside the catalyst particles. It can not only improve the activity of the catalyst, but also reduce the residence time of the raw material diglycol inside the catalyst pores, thereby significantly reducing the generation of the main reaction by-product 1,4-dioxane and other by-products, and ultimately greatly improving the selectivity of the target product.

[0027] (2) The catalyst provided by the present invention, in addition to having high activity and selectivity, has low catalyst production cost, simple and reliable preparation method, and relatively mild reaction conditions, bringing great advantages for the industrial application of this catalyst. (IV) BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of a fixed-bed reaction device used when the catalyst is applied to the dehydrogenation lactonization reaction of diglycol: 1 - hydrogen cylinder, 2 - nitrogen cylinder, 3 - raw material bottle, 4 - high-pressure constant flow pump, 5 - three-way valve, 6 - pressure reducing valve, 7 - stop valve, 8 - mass flowmeter, 9 - check valve, 10 - reaction tube, 11 - reaction furnace, 12 - condenser, 13 and 14 - condensate inlet and outlet, 15 - filter, 16 - back pressure valve, 17 - product collection tank, 18 - catalyst bed. (V) SPECIFIC EMBODIMENTS

[0029] The present invention will be further described below through specific examples, but the protection scope of the present invention is not limited thereto.

[0030] Example 1

[0031] 5 g of 20 - 40 mesh commercial macroporous silica gel (type C silica gel, specific surface area 390 m 2 / g, pore volume 0.9 cm 3 / g, average pore diameter 9.8 nm) was added to 20 ml of a sodium hydroxide solution with a concentration of 0.6 M and treated at 80 °C for 8 h, filtered and washed with water until the filtrate was neutral, and then dried in a blast drying oven at 110 °C for 24 h to obtain a macroporous silica gel support.

[0032] 0.5703 g of copper nitrate trihydrate was weighed and added to 20 ml of ammonia water solution. After it was completely dissolved, 2 g of the above-mentioned large-pore silica support was added, and the mixture was shaken at room temperature for 2 h. The solvent was evaporated under reduced pressure at 60 °C until dry, and the dried catalyst precursor was placed in a forced-air drying oven and dried at 110 °C for 4 h, and then calcined in a muffle furnace at 500 °C for 4 h to obtain catalyst A. The weight content of CuO was 9.4%, and the rest was silica gel support. The specific surface area of catalyst A was measured to be 240 m 2 / g, the pore volume was 1.02 cm 3 / g, and the average pore diameter was 18.0 nm.

[0033] Example 2

[0034] The preparation method of catalyst B was the same as that of Example 1, but the mass of copper nitrate trihydrate added was 0.7604 g, and the prepared catalyst was denoted as catalyst B. The weight content of CuO was 12.5%, and the rest was silica gel support. The specific surface area of catalyst B was measured to be 242 m 2 / g, the pore volume was 0.99 cm 3 / g, and the average pore diameter was 17.8 nm.

[0035] Example 3

[0036] The preparation method of catalyst C was the same as that of Example 1, but the amount of copper nitrate trihydrate added was 0.9505 g, and the prepared catalyst was denoted as catalyst C. The weight content of CuO was 15.6%, and the rest was silica gel support. The specific surface area of catalyst C was measured to be 245 m 2 / g, the pore volume was 0.99 cm 3 / g, and the average pore diameter was 17.5 nm.

[0037] Example 4

[0038] The preparation method of catalyst D was the same as that of Example 1, but the amount of copper nitrate trihydrate added was 1.1406 g, and the prepared catalyst was denoted as catalyst D. The weight content of CuO was 18.8%, and the rest was silica gel support. The specific surface area of catalyst D was measured to be 246 m 2 / g, the pore volume was 0.98 cm 3 / g, and the average pore diameter was 17.4 nm.

[0039] Example 5

[0040] The preparation method of catalyst E was the same as that of Example 3, but the catalyst calcination temperature was 400 °C, and the prepared catalyst was denoted as catalyst E. The weight content of CuO was 15.6%, and the rest was silica gel support. The specific surface area of catalyst E was measured to be 247 m 2 / g, the pore volume was 0.98 cm 3 / g, the average pore size is 17.4 nm.

[0041] Example 6

[0042] The preparation method of catalyst F is the same as that of Example 3, but the calcination temperature of the catalyst is 600 °C. The obtained catalyst is denoted as catalyst F. Among them, the weight content of CuO is 15.6%, and the rest is silica gel carrier. The specific surface area of catalyst F is measured to be 239 m 2 / g, the pore volume is 1.01 cm 3 / g, and the average pore size is 17.8 nm.

[0043] Example 7

[0044] The preparation method of catalyst G is the same as that of Example 3, but the temperature for treating commercial macroporous silica gel with sodium hydroxide solution is 60 °C. The obtained catalyst is denoted as catalyst G. Among them, the weight content of CuO is 15.6%, and the rest is silica gel carrier. The specific surface area of catalyst G is measured to be 295 m 2 / g, the pore volume is 1.08 cm 3 / g, and the average pore size is 15.3 nm.

[0045] Example 8

[0046] The preparation method of catalyst H is the same as that of Example 3, but the temperature for treating commercial macroporous silica gel with sodium hydroxide solution is 90 °C. The obtained catalyst is denoted as catalyst H. Among them, the weight content of CuO is 15.6%, and the rest is silica gel carrier. The specific surface area of catalyst H is measured to be 198 m 2 / g, the pore volume is 0.95 cm 3 / g, and the average pore size is 24.6 nm.

[0047] Comparative Example 1

[0048] The preparation method of catalyst I is the same as that of Example 3, but the temperature for treating commercial macroporous silica gel with sodium hydroxide solution is 90 °C, and the treatment time is 12 h. The obtained catalyst is denoted as catalyst I. Among them, the weight content of CuO is 15.6%, and the rest is silica gel carrier. The specific surface area of catalyst I is measured to be 152 m 2 / g, the pore volume is 0.94 cm 3 / g, and its average pore size is 29.8 nm.

[0049] Comparative Example 2

[0050] The preparation method of catalyst J is the same as that of Example 3, but the temperature for treating commercial macroporous silica gel with sodium hydroxide solution is 50 °C. The obtained catalyst is denoted as catalyst J. Among them, the weight content of CuO is 15.6%, and the rest is silica gel carrier. The specific surface area of catalyst J is measured to be 327 m 2 / g, the pore volume is 1.05 cm3 / g, the average pore size is 13.6 nm.

[0051] Comparative Example 3

[0052] The preparation method of catalyst K is the same as that of Example 3, but the temperature of the commercial macroporous silica gel treated with sodium hydroxide solution is 30 °C, and the concentration of the sodium hydroxide solution is 0.5 M. The prepared catalyst is denoted as catalyst K. Among them, the weight content of CuO is 15.6%, and the rest is the silica gel carrier. The specific surface area of catalyst K is measured to be 345 m 2 / g, the pore volume is 1.02 cm 3 / g, and its average pore size is 11.8 nm.

[0053] Comparative Example 4

[0054] The preparation method of catalyst L is the same as that of Example 3, but the silica gel carrier used is commercial macroporous silica gel (type C silica gel). The prepared catalyst is denoted as catalyst L. Among them, the weight content of CuO is 15.6%, and the rest is the silica gel carrier. The specific surface area of catalyst L is measured to be 378 m 2 / g, the pore volume is 0.88 cm 3 / g, and the average pore size is 9.9 nm.

[0055] Comparative Example 5

[0056] The preparation method of catalyst M is the same as that of Example 3, but the silica gel carrier used is commercial type B silica gel. The prepared catalyst is denoted as catalyst M. Among them, the weight content of CuO is 15.6%, and the rest is the silica gel carrier. The specific surface area of catalyst M is measured to be 521 m 2 / g, the pore volume is 0.70 cm 3 / g, and the average pore size is 5.2 nm.

[0057] Example 9

[0058] The reaction device is as Figure 1 shown. The catalysts A, B, C, D, E, F, G, H, I, J, K, L, and M prepared in the above examples and comparative examples are respectively loaded into the reaction tubes of the fixed-bed reaction device. First, the catalysts are subjected to reduction treatment. The reduction conditions are: 320 °C, atmospheric pressure, the space velocity of the hydrogen-nitrogen mixed gas (1:9, v / v) is 900 h -1 , the reduction time is 4 h, and then the dehydrogenation lactonization reaction of diglycol is carried out. The reaction conditions are set as: 260 °C, 0.1 MPa, LHSV = 0.5 h -1 , the space velocity of the carrier hydrogen is 480 h -1 , and the results are shown in the following table.

[0059] Table 1 Reaction performance of different catalysts in the dehydrogenation lactonization reaction of diglycol

[0060]

[0061] [a]DEG-diethylene glycol; [b]PDO-p-dioxanone; [c]Diox-1,4-dioxane; [d]Mainly includes 2-(2-hydroxyethoxy)acetaldehyde, ethanol, etc.

[0062] From the results in Table 1, it can be seen that when Cu / SiO 2 When the average pore size of catalysts (A-F) is in the range of 15-25 nm, the catalysts not only have high activity but also have high selectivity for the target product. When the average pore size of catalysts (J-M) drops below 15 nm, although the catalyst activity does not change significantly, the selectivity for by-product Diox and other by-products increases significantly. When the average pore size of catalyst (I) is greater than 25 nm, the feedstock conversion rate decreases significantly and the selectivity for the target product PDO decreases.

Claims

1. Application of a large-pore Cu / SiO2 catalyst in the dehydrogenation lactonization of diethylene glycol to prepare p-dioxanone, characterized in that: The large-pore Cu / SiO2 catalyst comprises a carrier and copper oxide loaded on the inner and outer surfaces of the carrier, wherein the carrier is a large-pore silica carrier. In the large-pore Cu / SiO2 catalyst, the mass percentage contents of the carrier and the active component are as follows: Carrier 62.5%~99.5% Copper oxide 0.5%~37.5% The large-pore Cu / SiO2 catalyst is in granular form with a specific surface area of ​​150 to 300 m 2 / g, pore volume is 0.8~1.2ml / g, and average pore diameter is 15~25nm; The preparation method of the large-pore Cu / SiO2 catalyst comprises the following steps: (1) immersing the macroporous silica support in a mixed solution of a copper precursor and a complexing agent, and shaking and immersing for 1 to 48 hours; (2) drying the mixture obtained in step (1) so that the copper precursor is evenly loaded on the inner and outer surfaces of the silica carrier; (3) placing the dried catalyst precursor obtained in step (2) into a muffle furnace for calcination in an air atmosphere, wherein the calcination conditions are: heating the temperature to 150-800°C at a heating rate of 0.5-20°C / min and calcining for 1-10h to obtain the large-pore Cu / SiO2 catalyst.

2. The use according to claim 1, characterized in that: The macroporous Cu / SiO2 catalyst comprises the following components in weight percentage: Carrier 70%~99% Copper oxide 1%~30%.

3. The use according to claim 1, characterized in that: The copper precursor is a soluble copper salt, the complexing agent is ammonia water, ethylenediamine, ethylenediaminetetraacetic acid or citric acid, and the molar ratio of the complexing agent to the copper precursor is 1-150:

1.

4. The use according to claim 3, characterized in that: The molar ratio of the complexing agent to the copper precursor is 5-100:

1.

5. The use according to claim 1, characterized in that: The drying treatment is carried out in a rotary evaporator and an oven, first drying for 1 to 24 hours at 10 to 60° C. and 0.005 to 0.1 MPa in the rotary evaporator, and then drying for 1 to 48 hours at 50 to 150° C. in an oven.

6. The use according to claim 1, characterized in that: The calcination treatment conditions are: heating to 300-600° C. at a heating rate of 3-15° C. / min and calcining for 2-6 hours.

7. The use according to claim 1 or 2, characterized in that: Before the dehydrogenation of diethylene glycol, the large-pore Cu / SiO2 catalyst needs to be pre-treated by reduction: -1 The hydrogen-nitrogen mixed gas is used as the reducing agent, and the reduction is carried out under normal pressure and a temperature of 280-350°C for 1-12 hours.

8. The use according to claim 7, characterized in that: The diethylene glycol dehydrogenation lactonization reaction is carried out in a fixed bed reactor.

9. The use according to claim 7, characterized in that: The reaction conditions of the dehydrogenation of diethylene glycol are as follows: temperature of 220-280°C, reaction pressure of 0.1-1 MPa, liquid space velocity of the raw material of 0.2-1.5 h -1 , carrier hydrogen space velocity is 100~800h -1 .

Images