Catalyst, preparation method and application thereof, and method for synthesizing acrolein

Abstract

The present invention discloses a catalyst, a preparation method and an application thereof, and a method for synthesizing acrolein, belonging to the technical field of dehydration processes. The catalyst comprises a carrier and an active component supported on the carrier, the carrier is zirconium phosphate, and the active component is lanthanum oxide and potassium oxide. By modifying the zirconium phosphate catalyst with potassium and lanthanum, the catalyst is used for catalyzing the dehydration of glycerol to produce acrolein, the catalyst has good anti-coking ability, both the conversion rate of glycerol and the selectivity of acrolein are relatively high, and the stability of the catalyst is excellent, and the single operation time is longer than 24 days. It is verified that, for a catalyst with the mass percentage contents of potassium oxide and lanthanum oxide being 0.5% and 1.1% respectively, an aqueous glycerol solution with a mass fraction of 50% is used as a raw material in a fixed bed, nitrogen is used as a carrier gas, the volume space velocity is controlled at 1.2 h-1, and the reaction is carried out for 26 days under such reaction conditions, the average conversion rate of glycerol is more than 98.4%, and the average selectivity of acrolein is 87.6%.

Description

Technical Field

[0001] The invention belongs to the technical field of dehydration process, and specifically relates to a catalyst and a preparation method and application thereof, and a method for synthesizing acrolein. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Acrolein is the simplest unsaturated aldehyde. It has high reactivity due to the presence of two reactive functional groups, which can react individually or simultaneously. For this reason, acrolein has many applications, such as as a synthetic intermediate, especially as a key intermediate for the synthesis of methionine. In addition, acrolein can also produce D-methionine, L-methionine, folic acid, acrylic acid, glutaraldehyde required for animal feed additives, and pyrimidine drugs used to treat asthma.

[0004] The industrial production of acrolein mainly includes: formaldehyde-acetaldehyde gas phase condensation, propylene ether pyrolysis and propylene catalytic oxidation. With the increasing shortage of petroleum resources and the continuous rise in oil prices, the process of preparing acrolein using petroleum-based products as raw materials is facing severe challenges. In recent years, the research on the direct preparation of acrolein using glycerol as raw material through selective dehydration has attracted the attention of many scientists. Among them, zirconium phosphate catalysts have attracted the attention of researchers due to their advantages of simple preparation, low price and high activity. For example, patent CN104368368A discloses the use of zirconium phosphate as a catalyst to catalyze the preparation of acrolein from glycerol. After the catalyst is operated for 100 hours, the acrolein yield remains above 70%. However, for continuous flow reactions, the life of the zirconium phosphate catalyst needs to be improved. Patent CN107115877A discloses that on the basis of zirconium phosphate, the activity of the zirconium phosphate catalyst is improved by loading other metal elements, such as copper nitrate, cobalt nitrate, cerium nitrate, nickel nitrate, etc., but the improvement of the catalyst life and selectivity is limited.

[0005] Therefore, there is still a need to develop catalysts with high activity, good selectivity and good stability to improve the conversion rate of glycerol and the selectivity of acrolein, reduce the content of by-product propionaldehyde, and thus improve the post-processing efficiency of acrolein and reduce production costs. Summary of the invention

[0006] In order to solve the deficiencies of the prior art, the purpose of the present invention is to provide a catalyst and a preparation method and application thereof, and a method for synthesizing acrolein. The catalyst provided by the present invention has a long life and high selectivity.

[0007] In order to achieve the above object, the technical solution of the present invention is:

[0008] In a first aspect of the present invention, a catalyst is provided, comprising a carrier and an active component supported on the carrier, wherein the carrier is zirconium phosphate, and the active component is lanthanum oxide and potassium oxide.

[0009] In some embodiments of the present invention, the particle size of the catalyst is 90-100 nm.

[0010] In some embodiments of the present invention, the loading amount of the lanthanum oxide is 0.1-10%, and the loading amount of the potassium oxide is 0.1-8%.

[0011] In some embodiments of the present invention, the loading amount of the lanthanum oxide is 0.5-2%, and the loading amount of the potassium oxide is 0.5-1.5%.

[0012] In some embodiments of the present invention, the loading amount of the lanthanum oxide is 1.1%, and the loading amount of the potassium oxide is 0.5%.

[0013] The second aspect of the present invention provides a method for preparing the above-mentioned catalyst, comprising:

[0014] In a solvent, ammonium dihydrogen phosphate and zirconium oxychloride are mixed, stirred, heated and aged, and the precipitate is washed, filtered, dried, and calcined to obtain zirconium phosphate;

[0015] The zirconium phosphate is immersed in a lanthanum salt solution, taken out and the solvent is removed, and then calcined to obtain zirconium phosphate loaded with lanthanum oxide;

[0016] The zirconium phosphate loaded with lanthanum oxide is immersed in a potassium salt solution, taken out and the solvent is removed, and then calcined to obtain a catalyst.

[0017] In some embodiments of the present invention, when the ammonium dihydrogen phosphate and zirconium oxychloride are mixed, the molar ratio of phosphorus to zirconium is 1.5-2.5:1.

[0018] In some embodiments of the present invention, the heating aging is heating the solution to 50-90° C. for 1.5-2.5 h;

[0019] In some embodiments of the present invention, the calcination is performed at 400-500° C. for 2-4 h.

[0020] In some embodiments of the present invention, the lanthanum salt comprises one of lanthanum chloride and lanthanum nitrate;

[0021] The potassium salt includes one of potassium chloride, potassium hydroxide, potassium carbonate and potassium nitrate.

[0022] The third aspect of the present invention provides a use of the above catalyst or the catalyst prepared by the above preparation method in synthesizing acrolein from glycerol.

[0023] The fourth aspect of the present invention provides a method for synthesizing acrolein, comprising: using the above catalyst or the catalyst prepared by the above preparation method as a catalyst, using a glycerol aqueous solution as a raw material and nitrogen as a carrier in a fixed bed reactor, the reaction temperature is 250-330°C, and the volume space velocity is controlled at 0.5-1.5 h -1 Reaction to obtain acrolein.

[0024] In some embodiments of the present invention, the mass fraction of glycerol in the glycerol aqueous solution is 10-60%.

[0025] The beneficial effects of the present invention are:

[0026] The present invention utilizes a potassium and lanthanum modified zirconium phosphate catalyst to catalyze the dehydration of glycerol to generate acrolein. The catalyst has good anti-coking ability, high glycerol conversion rate and acrolein selectivity, and excellent catalyst stability, with a single operation time of more than 24 days.

[0027] Specifically, it has been verified that K / La / ZrP with a potassium oxide and lanthanum oxide content of 0.5% and 1.1% respectively is used as a catalyst, a 50% mass fraction of glycerol aqueous solution is used as a raw material, nitrogen is used as a carrier gas, and the volume space velocity is controlled at 1.2 h -1 Under the reaction conditions, after 26 days of reaction, the average conversion rate of glycerol was above 98.4%, and the average selectivity of acrolein was 87.6%. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0029] Figure 1 This is the infrared spectrum of the catalyst prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0031] Example 1

[0032] A method for synthesizing acrolein comprises the following steps:

[0033] At room temperature, an aqueous solution of ammonium dihydrogen phosphate and an aqueous solution of zirconium oxychloride are mixed in parallel and stirred continuously. The dropping time is 1 h, and the molar ratio of phosphorus to zirconium is 2. After the dropping, the solution is heated to 60°C and aged for 2 h. After the aging, the precipitate is washed and filtered until the filtrate is tested with a silver nitrate solution without precipitation. Then, the white solid is dried in an oven at 80°C for 12 h. The dried white solid is calcined in a muffle furnace at 450°C for 3 h to obtain zirconium phosphate.

[0034] Weigh a certain amount of lanthanum nitrate and dissolve it in a certain amount of deionized water, and immerse the zirconium phosphate in the lanthanum nitrate solution. After the impregnation, place the carrier on a rotary evaporator at 50°C to remove water. The loaded solid is calcined in a muffle furnace at 450°C for 3 hours to obtain zirconium phosphate loaded with lanthanum oxide. The loading amount of lanthanum oxide on the zirconium phosphate is 2%.

[0035] Weigh a certain amount of potassium hydroxide and dissolve it in a certain amount of deionized water, and immerse the zirconium phosphate loaded with lanthanum oxide in the potassium hydroxide solution. After the impregnation, place the carrier on a rotary evaporator at 50°C to remove water. The solid after the secondary loading is calcined in a muffle furnace at 450°C for 3 h to obtain a catalyst. The loading amount of potassium oxide on the catalyst is 0.5%.

[0036] The catalyst prepared in Example 1 was reacted in a fixed bed reactor with a 50% mass fraction of glycerol aqueous solution as raw material and nitrogen as carrier gas at a volume space velocity of 1.2 h -1 The reaction temperature was 300°C. Under this reaction condition, the reaction lasted for 14 days. The average conversion rate of glycerol was above 96.6%, and the average selectivity of acrolein was 82.8%.

[0037] Figure 1 is the infrared spectrum of the catalyst obtained in this Example 1. Figure 1 It can be seen that the potassium and lanthanum loaded zirconium phosphate catalyst was successfully prepared. The infrared spectrum mainly shows the characteristic diffraction peaks of zirconium phosphate. The loading of K and La has little effect on the structure of zirconium phosphate and will not destroy the structure of zirconium phosphate.

[0038] Furthermore, according to testing, the particle size of the catalyst obtained in Example 1 is about 96 nm.

[0039] Example 2

[0040] A method for synthesizing acrolein, which differs from Example 1 in that the loading amount of lanthanum oxide is changed to 1.5%, the loading amount of potassium oxide is changed to 1%, and the remaining steps are the same as Example 1. After running for 14 days, the average conversion rate of glycerol is above 96.1%, and the average selectivity of acrolein is 85.3%.

[0041] Example 3

[0042] A method for synthesizing acrolein, which differs from Example 1 in that the loading amount of lanthanum oxide is changed to 1%, the loading amount of potassium oxide is changed to 0.5%, and the remaining steps are the same as Example 1. After running for 24 days, the average conversion rate of glycerol is above 98.3%, and the average selectivity of acrolein is 87.3%.

[0043] Example 4

[0044] A method for synthesizing acrolein, which differs from Example 1 in that the loading amount of lanthanum oxide is changed to 1.1%, the loading amount of potassium oxide is changed to 0.5%, and the volume space velocity is controlled at 1.2 h -1 , and the remaining steps were the same as those in Example 1. After 26 days of operation, the average conversion rate of glycerol was above 98.4%, and the average selectivity of acrolein was 87.6%.

[0045] Comparative Example 1

[0046] A method for synthesizing acrolein is different from Example 4 in that potassium oxide and lanthanum oxide are not loaded, and the remaining steps are the same as those of Example 4. After running for 5 days, the average conversion rate of glycerol is above 50.7%, and the average selectivity of acrolein is 45.2%.

[0047] Comparative Example 2

[0048] A method for synthesizing acrolein, which differs from Example 4 in that the loading amount of lanthanum oxide is changed to 1.6%, potassium oxide is not loaded, and the remaining steps are the same as Example 4. After running for 16 days, the average conversion rate of glycerol is above 64.3%, and the average selectivity of acrolein is 72.8%.

[0049] Comparative Example 3

[0050] A method for synthesizing acrolein, which differs from Example 4 in that the loading amount of potassium oxide is changed to 1.6%, lanthanum oxide is not loaded, and the remaining steps are the same as Example 4. After 19 days of operation, the average conversion rate of glycerol is above 68.0%, and the average selectivity of acrolein is 58.4%.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Use of a catalyst in the synthesis of acrolein from glycerol, characterized in that: The catalyst comprises a carrier and an active component loaded on the carrier, wherein the carrier is zirconium phosphate, and the active component is lanthanum oxide and potassium oxide; The loading amount of the lanthanum oxide on the zirconium phosphate is 0.5-2%, and the loading amount of the potassium oxide on the catalyst is 0.5-1.5%.

2. Use of the catalyst according to claim 1 in the synthesis of acrolein from glycerol, characterized in that: The particle size of the catalyst is 90-100 nm.

3. Use of the catalyst according to claim 1 in the synthesis of acrolein from glycerol, characterized in that: The loading amount of the lanthanum oxide on the zirconium phosphate is 1.1%, and the loading amount of the potassium oxide on the catalyst is 0.5%.

4. Use of the catalyst according to any one of claims 1 to 3 in the synthesis of acrolein from glycerol, characterized in that: The preparation method of the catalyst comprises: In a solvent, ammonium dihydrogen phosphate and zirconium oxychloride are mixed, stirred, heated and aged, and the precipitate is washed, filtered, dried, and calcined to obtain zirconium phosphate; The zirconium phosphate is immersed in a lanthanum salt solution, taken out and the solvent is removed, and then calcined to obtain zirconium phosphate loaded with lanthanum oxide; The zirconium phosphate loaded with lanthanum oxide is immersed in a potassium salt solution, taken out and the solvent is removed, and then calcined to obtain a catalyst.

5. Use of the catalyst as claimed in claim 4 in the synthesis of acrolein from glycerol, characterized in that: When the ammonium dihydrogen phosphate and zirconium oxychloride are mixed, the molar ratio of phosphorus to zirconium is 1.5-2.5:1; The heating aging is to heat the solution to 50-90° C. and age it for 1.5-2.5 h; The calcination is carried out at 400-500° C. for 2-4 h.

6. Use of the catalyst as claimed in claim 4 in the synthesis of acrolein from glycerol, characterized in that: The lanthanum salt includes one of lanthanum chloride and lanthanum nitrate; The potassium salt includes one of potassium chloride, potassium hydroxide, potassium carbonate and potassium nitrate.

7. A method for synthesizing acrolein, characterized in that: The catalyst in any one of claims 1 to 6 is used as a catalyst, a glycerol aqueous solution is used as a raw material, nitrogen is used as a carrier, the reaction temperature is 250-330°C, and the volume space velocity is controlled at 0.5-1.5 h -1 , reaction to obtain acrolein.

8. The method for synthesizing acrolein according to claim 7, characterized in that: The mass fraction of glycerol in the glycerol aqueous solution is 10-60%.

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