Hydrocracking catalyst as well as preparation method and application thereof

Abstract

The invention provides a preparation method of a hydrocracking catalyst. The preparation method comprises the following steps: obtaining a molybdenum source and a complexing agent; the method comprises the following steps: adding a molybdenum source and a complexing agent into a preset deionized water solution for dissolving, and continuously stirring within first time to obtain a uniform solution; adding a carrier into the uniform solution, and continuously stirring within second time to obtain a solution containing solid particles; filtering the solution containing the solid particles, and drying the filtered solid particles in a vacuum box to obtain a catalyst precursor; and placing the catalyst precursor in a fixed bed, and continuously introducing a mixed gas containing hydrogen and hydrogen sulfide in a target ratio so as to realize a reaction in a heating process, thereby obtaining the single-layer molybdenum disulfide hydrocracking catalyst. The invention also provides a single-layer molybdenum disulfide hydrocracking catalyst and application thereof. According to the method, the single-layer molybdenum disulfide hydrocracking catalyst can be efficiently obtained, and the problems that the synthesis time of the molybdenum disulfide catalyst is long and the single-layer molybdenum disulfide with high hydrogenation activity is difficult to prepare are solved.

Description

Technical Field

[0001] This invention relates to the field of biomass-based syngas for aviation fuel production, specifically to a hydrocracking catalyst, its preparation method, and its application. Background Technology

[0002] Biomass-based syngas technology for producing aviation fuel is a key breakthrough for the aviation industry towards carbon neutrality. Its core significance lies in constructing a closed-loop system of "waste-energy-emission reduction" by converting renewable biomass resources such as agricultural and forestry waste into clean aviation fuel. This technology not only solves the dependence of traditional aviation fuel on fossil resources but also achieves a 55%-92% reduction in carbon dioxide emissions throughout its entire life cycle through a carbon-neutral cycle mechanism (CO2 absorbed by biomass growth offsets combustion emissions). This provides the aviation industry with a zero-carbon fuel solution that can be used directly without engine modifications.

[0003] The Fischer-Tropsch reaction, as one of the important methods for converting syngas into aviation fuel, plays a central role in the production of aviation fuel from biomass-based syngas. However, during the catalytic conversion into hydrocarbons, this reaction inevitably generates a large amount of high-carbon (C50) hydrocarbons. 20+ Straight-chain alkanes. Because these large molecules have excessively high boiling points and cannot be used directly as aviation fuel, they need to be cracked into C8-C6 hydrocarbons suitable for aviation fuel through hydrocatalytic cracking technology. 20 Distillate fraction.

[0004] In high-carbon-number hydrocracking catalytic cracking processes, catalysts are a core technology. MoS2 catalysts have attracted attention due to their high hydrocracking activation performance. In MoS2 crystals, molybdenum atoms are located between two sulfur atom layers (S-Mo-S). The atoms in the crystal are bonded by strong covalent bonds, and the layers are connected by van der Waals forces. The hydrogenation model of MoS2, namely the rim-edge model, indicates that the basal surface atoms are not reactive due to coordination saturation, and the edge positions of the top or bottom surface are the main active centers for hydrogenation. Reducing the number of stacked layers can increase the exposed edges of the bottom and bottom atomic layers; therefore, monolayer MoS2 is often synthesized to enhance the exposure of its active sites.

[0005] The synthesis of MoS2 catalysts is often achieved through hydrothermal or solvothermal methods, which require a long crystallization process and make it difficult to prepare monolayer MoS2 with high hydrogenation activity. The effect on the hydrocracking of straight-chain alkanes with high carbon number is not ideal. Summary of the Invention

[0006] The first aspect of the present invention provides a method for preparing a hydrocracking catalyst, comprising: obtaining a molybdenum source and a complexing agent; dissolving the molybdenum source and the complexing agent in a preset deionized aqueous solution and continuously stirring for a first time to obtain a homogeneous solution; adding a support to the homogeneous solution and continuously stirring for a second time to obtain a solution containing solid particles; filtering the solution containing solid particles and drying the filtered solid particles in a vacuum chamber to obtain a catalyst precursor; placing the catalyst precursor in a fixed bed and continuously introducing a mixed gas containing a target proportion of hydrogen and hydrogen sulfide to achieve a reaction during heating to obtain a monolayer molybdenum disulfide hydrocracking catalyst.

[0007] In the above scheme, the molybdenum source is any one of sodium molybdate, ammonium heptamolybdate, and ammonium tetrathiomolybdate.

[0008] In the above scheme, the complexing agent is either humic acid or glucose.

[0009] In the above scheme, the carrier is any one of activated carbon, aluminum oxide, and titanium oxide.

[0010] In the above scheme, the target ratio in the mixture of hydrogen and hydrogen sulfide is the volume ratio of hydrogen and hydrogen sulfide, and the volume ratio ranges from 1:1 to 1:4.

[0011] In the above scheme, the value range of the first time is 20 to 60 minutes, and the value range of the second time is 5 to 30 minutes.

[0012] In the above scheme, the filtered solid particles are placed in a vacuum chamber for drying, including: placing the filtered solid particles in a vacuum chamber and drying them continuously for 2 to 4 hours at a temperature range of 100-130°C.

[0013] In the above scheme, the heating process includes heating to 300-450℃ at a heating rate of 2-8℃ / min; during the heating process, hydrogen and hydrogen sulfide complete the Mo... 6+ Sulfidation and reduction.

[0014] A second aspect of the present invention provides a monolayer molybdenum disulfide hydrocracking catalyst prepared by the above-described method for preparing hydrocracking catalysts.

[0015] A third aspect of the present invention provides an application of the above-mentioned monolayer molybdenum disulfide hydrocracking catalyst in the hydrocracking of long-chain alkanes to achieve the production of aviation fuel from biomass-based syngas.

[0016] The technical solutions of the embodiments of the present invention have at least the following beneficial effects:

[0017] (1) This preparation method utilizes Mo 6+A complex is formed between the complexing agent and the carrier, thereby achieving a uniform distribution of Mo.

[0018] (2) This preparation method can achieve rapid Mo preparation under high temperature conditions using hydrogen and hydrogen sulfide. 6+ The sulfidation and reduction processes enable the efficient preparation of monolayer molybdenum disulfide hydrocracking catalysts. Attached Figure Description

[0019] Figure 1 A flowchart illustrating a method for preparing a hydrocracking catalyst according to an embodiment of the present invention is shown. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0021] Figure 1 A flowchart illustrating a method for preparing a hydrocracking catalyst according to an embodiment of the present invention is shown.

[0022] like Figure 1 As shown in the embodiment of the present invention, the preparation method of the hydrocracking catalyst specifically includes steps S1 to S5.

[0023] In step S1, a molybdenum source and a complexing agent are obtained.

[0024] In step S2, the molybdenum source and complexing agent are added to a pre-set deionized aqueous solution to dissolve, and the mixture is continuously stirred within a first time period to obtain a homogeneous solution.

[0025] In step S3, a carrier is added to the homogeneous solution and stirred continuously for a second time period to obtain a solution containing solid particles.

[0026] Specifically, a molybdenum source and a complexing agent are first obtained. For example, the molybdenum source is any one of sodium molybdate, ammonium heptamolybdate, and ammonium tetrathiomolybdate. The complexing agent is any one of humic acid and glucose.

[0027] Furthermore, the molybdenum source and complexing agent are dissolved in a deionized water solution under stirring, and the stirring is continued for a short period of time to form a homogeneous solution. It should be noted that this continuous stirring occurs for a short period of time, for example, the range of which is 20-60 minutes.

[0028] Further, a carrier is added to the homogeneous solution obtained in step S2 and stirring continues to yield a solution containing solid particles. For example, the carrier can be any one of activated carbon, alumina, and titanium dioxide. It should be noted that the second stirring time ranges from 5 to 30 minutes.

[0029] In step S4, the solution containing solid particles is filtered, and the filtered solid particles are dried in a vacuum chamber to obtain the catalyst precursor.

[0030] Specifically, the solution containing solid particles is filtered, the filtered solid particles are removed, and the fixed particles are dried in a vacuum chamber to obtain a catalyst precursor. For example, the filtered solid particles are placed in a vacuum chamber and dried continuously at a temperature range of 100-130°C for 2-4 hours to obtain the catalyst precursor.

[0031] In step S5, the catalyst precursor is placed in a fixed bed and a mixture of hydrogen and hydrogen sulfide in a target ratio is continuously introduced to achieve the reaction during the heating process, thereby obtaining a monolayer molybdenum disulfide hydrocracking catalyst.

[0032] Specifically, the catalyst precursor obtained in step S4 is placed in a fixed bed, and a mixture of hydrogen and hydrogen sulfide in a target ratio is continuously introduced. Here, the target ratio in the mixture of hydrogen and hydrogen sulfide is the volume ratio of hydrogen and hydrogen sulfide. In this embodiment, the volume ratio ranges from 1:1 to 1:4.

[0033] Furthermore, the temperature is increased to create a high-temperature reaction environment, for example, by increasing the temperature to 300-450°C at a rate of 2-8°C / min, and reacting under these high-temperature conditions for 1-3 hours, during which hydrogen and hydrogen sulfide completely react to form Mo. 6+ The sulfidation and reduction processes ultimately yield a monolayer molybdenum disulfide hydrocracking catalyst.

[0034] Based on the above method for preparing hydrocracking catalysts, specific embodiments are described below.

[0035] In one embodiment of the present invention, 0.3 g of sodium molybdate and 0.2 g of humic acid were obtained and dissolved in 300 ml of deionized water solution under continuous stirring for 20 min to form a homogeneous solution. Then, 2 g of activated carbon was added to the homogeneous solution, and stirring was continued for 10 min to obtain a solution containing solid particles. Further, the solid particles were filtered out and dried in a vacuum drying oven at 110°C for 2 h to obtain a catalyst precursor. Further, the obtained catalyst precursor was placed in a fixed bed, and a mixture of hydrogen and hydrogen sulfide in a volume ratio of 1:1 was continuously introduced, and the temperature was increased to 350°C at 2°C / min for 1 h to obtain a monolayer molybdenum disulfide hydrocracking catalyst. Through the embodiments of the present invention, the obtained monolayer molybdenum disulfide hydrocracking catalyst can be applied to the hydrocracking of long-chain alkanes, enabling C8-C… 20 The aviation fuel distillate is increased by 50-60%, and it has excellent recycling performance.

[0036] In another embodiment of the present invention, 0.3 g of ammonium heptamolybdate and 0.5 g of glucose were obtained and dissolved in 200 ml of deionized water solution under continuous stirring for 30 min to form a homogeneous solution. Then, 6 g of aluminum oxide was added to the homogeneous solution, and stirring was continued for 10 min to obtain a solution containing solid particles. Further, the solid particles were filtered out and dried in a vacuum drying oven at 120°C for 2 h to obtain a catalyst precursor. Further, the obtained catalyst precursor was placed in a fixed bed, and a mixture of hydrogen and hydrogen sulfide in a volume ratio of 1:2 was continuously introduced, and the temperature was increased to 450°C at 4°C / min for 1 h to obtain a monolayer molybdenum disulfide hydrocracking catalyst. Through the embodiments of the present invention, the obtained monolayer molybdenum disulfide hydrocracking catalyst can be applied to the hydrocracking of long-chain alkanes, enabling C8-C… 20 The aviation fuel distillate is increased by 45-65%, and it has excellent recycling performance.

[0037] In another embodiment of the present invention, 0.1 g of ammonium tetrathiomolybdate and 0.3 g of humic acid were obtained and dissolved in 250 ml of deionized water solution under continuous stirring for 30 min to form a homogeneous solution. Then, 8 g of titanium dioxide was added to the homogeneous solution, and stirring was continued for 5 min to obtain a solution containing solid particles. Further, the solid particles were filtered out and dried in a vacuum drying oven at 100°C for 3 h to obtain a catalyst precursor. Further, the obtained catalyst precursor was placed in a fixed bed, and a mixture of hydrogen and hydrogen sulfide in a volume ratio of 1:3 was continuously introduced, and the temperature was increased to 400°C at 5°C / min for 1 h to obtain a monolayer molybdenum disulfide hydrocracking catalyst. Through the embodiments of the present invention, the obtained monolayer molybdenum disulfide hydrocracking catalyst can be applied to the hydrocracking of long-chain alkanes, enabling C8-C… 20 The aviation fuel distillate is increased by 40-50%, and it has excellent recycling performance.

[0038] Through the above embodiments, a monolayer MoS2 catalyst precursor was synthesized using a molybdenum source, complexing agent, and support, and monolayer MoS2 was generated in the presence of hydrogen and hydrogen sulfide. This preparation method utilizes Mo... 6+ The complex formed between the complexing agent and the carrier is uniformly distributed by Mo; at the same time, it enables the rapid reaction of hydrogen and hydrogen sulfide to form Mo under high temperature conditions. 6+ The sulfidation and reduction processes can efficiently prepare monolayer molybdenum disulfide hydrocracking catalysts.

[0039] The above specific embodiments further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0040] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A method for preparing a hydrocracking catalyst, characterized in that, include: Obtain the molybdenum source and complexing agent; The molybdenum source and complexing agent are dissolved in a pre-set deionized aqueous solution, and the mixture is continuously stirred within a first time to obtain a homogeneous solution. A carrier is added to the homogeneous solution, and the mixture is continuously stirred for a second time period to obtain a solution containing solid particles. The solution containing solid particles is filtered, and the filtered solid particles are dried in a vacuum chamber to obtain a catalyst precursor. The catalyst precursor is placed in a fixed bed and a mixture of hydrogen and hydrogen sulfide in a target ratio is continuously introduced to achieve the reaction during the heating process, thereby obtaining a monolayer molybdenum disulfide hydrocracking catalyst.

2. The method for preparing the hydrocracking catalyst according to claim 1, characterized in that, The molybdenum source is any one of sodium molybdate, ammonium heptamolybdate, and ammonium tetrathiomolybdate.

3. The method for preparing the hydrocracking catalyst according to claim 1, characterized in that, The complexing agent is either humic acid or glucose.

4. The method for preparing the hydrocracking catalyst according to claim 1, characterized in that, The carrier is any one of activated carbon, aluminum oxide, and titanium oxide.

5. The method for preparing the hydrocracking catalyst according to claim 1, characterized in that, The target ratio in the mixture of hydrogen and hydrogen sulfide is the volume ratio of hydrogen to hydrogen sulfide, and the volume ratio ranges from 1:1 to 1:

4.

6. The method for preparing the hydrocracking catalyst according to claim 1, characterized in that, The first time interval is in the range of 20 to 60 minutes, and the second time interval is in the range of 5 to 30 minutes.

7. The method for preparing the hydrocracking catalyst according to claim 1, characterized in that, The step of drying the filtered solid particles in a vacuum chamber includes: The filtered solid particles are placed in a vacuum chamber and dried continuously at a temperature range of 100-130°C for 2-4 hours.

8. The method for preparing the hydrocracking catalyst according to claim 1, characterized in that, The heating process includes heating to 300-450°C at a heating rate of 2-8°C / min; during the heating process, the hydrogen and hydrogen sulfide complete the Mo... 6+ Sulfidation and reduction.

9. A monolayer molybdenum disulfide hydrocracking catalyst prepared by the method described in any one of claims 1 to 8.

10. An application of the monolayer molybdenum disulfide hydrocracking catalyst of claim 9 in the hydrocracking of long-chain alkanes to achieve the production of aviation fuel from biomass-based syngas.

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