Nickel-molybdenum high-dispersity coal tar slurry bed hydrogenation catalyst and preparation method thereof

Abstract

The invention discloses a nickel-molybdenum high-dispersity coal tar slurry bed hydrogenation catalyst and a preparation method thereof. The nickel-molybdenum catalyst with high dispersibility, high coke inhibition performance and high hydrogenation activity is synthesized from the composite acid, ammonium heptamolybdate, thiourea and nickel sulfate through a two-step method. The preparation method comprises the following steps: (1) preparing a composite acid solution according to the mass ratio of concentrated acid A to concentrated acid B under the condition of cold bath, and preparing a dilute acid solution with the pH value of 1-4 by adopting the composite acid solution and deionized water; and (2) adding ammonium heptamolybdate, thiourea and nickel sulfate into the dilute acid solution, reacting at room temperature for 6-15 hours, and then reacting in a hydrothermal kettle at 180-200 DEG C for 24-36 hours. And (3) after the reaction is completed, taking out the hydrothermal reaction kettle, naturally cooling to room temperature, opening the reaction kettle, taking out a black reaction product, standing and centrifuging to obtain a solid product, and drying for 1 hour at 110 DEG C under a vacuum condition to obtain the high-dispersity NiMoSx catalyst.

Description

Technical Field

[0001] The invention belongs to the field of coal tar hydrogenation, and specifically relates to a nickel-molybdenum high-dispersion coal tar slurry bed hydrogenation catalyst and a preparation method thereof. Background Art

[0002] Coal tar is an important product of the coking industry. It has the characteristics of high density, heteroatom content, and mechanical impurity content. It also has a complex chemical composition and is rich in polycyclic aromatic hydrocarbons and heterocyclic compounds. After hydrogenation, the RON of gasoline and the cetane number of diesel are low, both of which fail to meet the national fuel standards. In addition, the processing cost is high, the hydrogen consumption is large, and the catalyst is easily deactivated. In addition, since 2016, coal tar has been listed as a national hazardous waste in my country. The rational and clean utilization of coal tar resources has become a current research hotspot.

[0003] Catalytic hydroconversion is a more efficient method for upgrading coal tar to liquid transportation fuels in modern refineries. Various hydroconversion reactor technologies using fixed bed, ebullating bed, moving bed and slurry bed have been designed for the hydroconversion of coal tar. Hydroconversion using fixed bed, ebullating bed or moving bed reactors usually suffers from the disadvantages of coking and heavy metal deposition leading to catalyst deactivation, especially for the hydroprocessing of heavier feedstocks. In addition, there are also critical issues such as feedstock diffusion, pressure drop and mass transfer in fixed bed, ebullating bed or moving bed reactors. Slurry bed reactors can overcome the limitations of the above processes.

[0004] For more than 50 years, effective catalysts for the hydroconversion process to convert coal tar into high-value products with lower boiling points have been widely studied. Among these catalysts, MoS2, as one of the main active catalysts, has been favored by people because of its superior hydrogenation ability for coal tar (including high sulfur content, impurities and heavy components) even under harsh reaction conditions such as high pressure and high temperature, and its ability to effectively prevent the damage caused by deposited coke to equipment. Although alumina-supported Ni-Mo and Co-Mo heterogeneous catalysts have been used in fixed bed and fluidized bed reactors, unsupported Mo-based dispersed catalysts are used in slurry bed reactors because of their strong resistance to deactivation, ability to inhibit coking and no diffusion limitation of reactants.

[0005] However, until recently, it has been difficult to manufacture MoS2 catalysts with high dispersion, high hydrogenation activity and good coking suppression performance for slurry beds. Summary of the invention

[0006] The purpose of the present invention is to propose a slurry bed hydrogenation catalyst with high dispersibility, high hydrogenation activity and good coke suppression performance, which is prepared by mixing a composite acid with ammonium heptamolybdate, thiourea and nickel sulfate through a two-step method.

[0007] The technical solution adopted by the present invention to solve the above technical problems is as follows: (1) Prepare a composite acid solution in a cold bath according to the mass ratio of concentrated acid A: concentrated acid B, and then use the composite acid solution and deionized water to prepare a dilute acid solution with a pH of 1-4. (2) Add ammonium heptamolybdate, thiourea and nickel sulfate to the dilute acid solution and react at room temperature for 6-15 hours. (3) After the reaction is completed, place the solution in (2) in a hydrothermal reactor and react at 180-200°C for 24-36 hours. (4) After the reaction is completed, take out the hydrothermal reactor, cool it naturally to room temperature, open the reactor, take out the black reaction product, and obtain a solid product after standing and centrifugation. Dry it at 110°C under vacuum conditions for 1 hour to obtain a highly dispersed NiMoSx catalyst. Add the NiMoSx catalyst to coal tar for catalytic hydrogenation.

[0008] The concentrated acid A in step (1) is concentrated sulfuric acid or sulfurous acid, and the concentrated acid B is concentrated hydrochloric acid or concentrated phosphoric acid.

[0009] The mass ratio of the composite acid in step (1) is concentrated acid A: concentrated acid B = 1:1-1:5.

[0010] Compared with the prior art, the technical solution provided by the present invention has the following technical advantages: hydrochloric acid was previously used to adjust the pH of the entire hydrothermal system, which resulted in a waste of acid anions after washing and drying, and was not conducive to the sulfurization of molybdenum and difficult to generate a large amount of molybdenum disulfide. The technical solution provided by the present invention uses a composite acid to participate in the two-step method to synthesize a molybdenum disulfide catalyst. In the preparation process, a strong acid containing S is added, which not only efficiently utilizes the strong acid anions, but also improves the generation efficiency of molybdenum disulfide. At the same time, the prepared nickel-loaded molybdenum disulfide hydrogenation catalyst has high dispersibility, hydrogenation activity and coke suppression performance. DETAILED DESCRIPTION

[0011] The present invention is further illustrated by way of examples below, but they do not constitute any limitation to the present invention. Any limited number of modifications made by anyone within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0012] Implementation Case 1 A composite acid solution was prepared in a cold bath at a mass ratio of 1:1 for concentrated sulfuric acid and concentrated hydrochloric acid, and 300 ml of a dilute acid solution with a pH of 3 was prepared using the composite acid solution and deionized water. 3.0 mmol of ammonium heptamolybdate, 12.0 mmol of thiourea, and 0.6 mmol of nickel sulfate were added to the dilute acid solution and reacted at room temperature for 6 hours. After the reaction was completed, the solution was placed in a hydrothermal reactor for reaction at 180°C for 24 hours. After the reaction was completed, the hydrothermal reactor was taken out and naturally cooled to room temperature. The reactor was opened and the black reaction product was taken out. After standing and centrifugation, a solid product was obtained. The highly dispersed NiMoSx catalyst was obtained by drying at 110°C under vacuum conditions for 1 hour. The NiMoSx catalyst was added to coal tar for catalytic hydrogenation.

[0013] Implementation Case 2 According to the mass ratio of sulfurous acid: concentrated hydrochloric acid of 3:1, a composite acid solution was prepared under cold bath conditions, and then 300 ml of dilute acid solution with a pH of 4 was prepared using the composite acid solution and deionized water. 3.0 mmol ammonium heptamolybdate, 12.0 mmol thiourea, and 0.6 mmol nickel sulfate were added to the dilute acid solution and reacted at room temperature for 12 h. After the reaction was completed, the solution was placed in a hydrothermal reactor for reaction at 200°C for 24 h. After the reaction was completed, the hydrothermal reactor was taken out and naturally cooled to room temperature. The reactor was opened and the black reaction product was taken out. After standing and centrifugation, a solid product was obtained, which was dried at 110°C under vacuum conditions for 1 h to obtain a highly dispersed NiMoSx catalyst. The NiMoSx catalyst was added to coal tar for catalytic hydrogenation.

[0014] Implementation Case 3 A composite acid solution was prepared in a cold bath with a mass ratio of concentrated sulfuric acid to concentrated phosphoric acid of 1:1, and then 300 ml of a dilute acid solution with a pH of 2 was prepared using the composite acid solution and deionized water. 3.0 mmol of ammonium heptamolybdate, 12.0 mmol of thiourea, and 0.6 mmol of nickel sulfate were added to the dilute acid solution and reacted at room temperature for 15 h. After the reaction was completed, the solution was placed in a hydrothermal reactor for reaction at 200 ° C for 36 h. After the reaction was completed, the hydrothermal reactor was taken out and naturally cooled to room temperature. The reactor was opened and the black reaction product was taken out. After standing and centrifugation, a solid product was obtained. The highly dispersed NiMoSx catalyst was obtained by drying at 110 ° C under vacuum conditions for 1 h. The NiMoSx catalyst was added to coal tar for catalytic hydrogenation.

Claims

1. A nickel-molybdenum highly dispersed coal tar slurry bed hydrogenation catalyst and a preparation method thereof, the specific steps of which are: (1) Prepare a composite acid solution in a cold bath according to the mass ratio of concentrated acid A: concentrated acid B, and then use the composite acid solution and deionized water to prepare a dilute acid solution with a pH of 1-4. (2) Add ammonium heptamolybdate, thiourea and nickel sulfate to the dilute acid solution and react at room temperature for 6-15 hours. (3) After the reaction is completed, place the solution in (2) in a hydrothermal reactor and react at 180-200°C for 24-36 hours. (4) After the reaction is completed, take out the hydrothermal reactor, cool it naturally to room temperature, open the reactor, take out the black reaction product, and obtain a solid product after standing and centrifugation. Dry it at 110°C under vacuum conditions for 1 hour to obtain a highly dispersed NiMoSx catalyst.

2. The method according to claim 1, characterized in that The concentrated acid A described in step (1) is concentrated sulfuric acid or sulfurous acid.

3. The method according to claim 1, characterized in that The concentrated acid B described in step (1) is concentrated hydrochloric acid or concentrated phosphoric acid.

4. The method according to claim 1, characterized in that The mass ratio of the composite acid in step (1) is concentrated acid A: concentrated acid B = 1:1-1:5.