Process for catalyzing coal liquefaction by direct loading reaction of composite molybdenum-based metal salt

Abstract

The invention discloses a process for catalyzing coal liquefaction through a composite molybdenum-based metal salt direct load reaction, and the key point of the technical scheme is that the process comprises the following steps: S1, preparing a catalyst: obtaining a composite molybdenum-based metal salt catalyst precursor solution; s2, coal liquefaction or coal / oil co-liquefaction: generating a liquid product, tailings and a gas product; s3, treatment of tailings: extracting the tailings through a solvent to recover organic matters, carrying out high-temperature oxidation treatment on the tailings, and recovering and sublimating molybdenum salt for recycling; s4, gas product treatment: hydrogen in the gas product is separated through an adsorption method and circularly applied, and the gas product is used as a residue heat treatment fuel after desorption; the composite molybdenum-based metal salt catalyst is adopted, the coal liquefaction conversion rate and the liquid phase yield are remarkably improved, the residue rate is reduced, efficient coal liquefaction is achieved under the low reaction pressure, molybdenum salt is recycled through the sublimation characteristic of the molybdenum compound and the ammonia water solution, cyclic utilization of the catalyst is achieved, and the cost is reduced; meanwhile, molybdenum salt in the tailings is recycled through high-temperature oxidation, and waste discharge is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of coal liquefaction, and in particular to a process for catalyzing coal liquefaction by direct-supported reaction of a composite molybdenum-based metal salt. Background Art

[0002] During the coal liquefaction and coal / oil co-liquefaction reaction processes, the catalysts involved in the reaction usually form solid slag together with the unconverted coal after solid-liquid separation and are discharged from the reaction system. The utilization of coal liquefaction and coal / oil co-liquefaction residues is mainly concentrated in the field of carbon material preparation, and there is little research on the separation and recovery of organic and metal components in the residues. Therefore, in-depth research on the characteristics of coal liquefaction and coal / oil co-liquefaction residues is of great fundamental significance for the further development and utilization of the products.

[0003] At present, in the process of coal liquefaction and coal / oil co-liquefaction, the catalyst is fed into the reactor together with the coal slurry for reaction, and is discharged from the system together with the residue after the reaction. Since the catalyst is not recycled, the lower-cost Fe-based catalyst is usually used. However, although the Fe-based catalyst is low-cost, its reaction activity is poor and it has a greater impact on the enrichment of the reaction products.

[0004] In comparison, the reaction activity of Mo-based catalysts is significantly better than that of Fe-based catalysts, and the enrichment of reaction products is higher. However, the high cost of Mo-based catalysts restricts their widespread application. Therefore, based on the sublimation characteristics of molybdenum oxide (MoO3) under high temperature conditions, a process for catalyzing coal liquefaction by direct reaction of composite molybdenum-based metal salts has been developed. The purpose is to achieve the recycling of highly active Mo-based catalysts in the coal liquefaction process through this process, thereby significantly reducing the use cost of Mo-based catalysts and improving the overall efficiency and economy of the coal liquefaction process. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a process for catalyzing coal liquefaction by direct reaction of a composite molybdenum-based metal salt, which solves the problems raised in the background technology.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions:

[0007] A process for catalyzing coal liquefaction by direct reaction of a composite molybdenum-based metal salt, the process comprising the following steps:

[0008] S1. Catalyst preparation: molybdenum compounds and other metal compounds are obtained by high temperature roasting of molybdenum-containing ore, and reacted with alkaline solution and sulfide to obtain a composite molybdenum-based metal salt catalyst precursor solution;

[0009] S2. Coal liquefaction or coal / oil co-liquefaction: a composite molybdenum-based metal salt catalyst precursor solution is mixed with coal powder and hydrogenated in a suspended bed reactor to generate a liquid product, tailings, and a gas product;

[0010] S3. Tailings treatment: Recover organic matter from tailings by solvent extraction and subject the tailings to high-temperature oxidation and sublimation treatment to recover sublimated molybdenum salts for recycling;

[0011] S4. Gas product processing: Hydrogen in the product is extracted by adsorption and used as fuel for thermal conversion of residues after desorption.

[0012] Preferably, the molybdenum-containing ore in step S1 is one of molybdenite, molybdenum concentrate, nickel-molybdenum ore, tungsten-molybdenum ore, calcium molybdate ore, iron molybdate ore, wulfen-lead ore, etc., or a mixture thereof.

[0013] Preferably, in the step S1, the calcination temperature is 400° C. to 650° C., the calcination time is 30 minutes to 70 minutes, and the molybdenum compound is mainly molybdenum disulfide and molybdenum oxide.

[0014] Preferably, the alkaline solution in step S1 is one of ammonia water, sodium sulfide, ammonium sulfide, sodium hydroxide, etc. or a mixture thereof, and the molar ratio of the alkaline solution to the molybdenum compound is 3:1 to 1.5:1, and the concentration of the added alkaline solution is 5% to 20%.

[0015] Preferably, the sulfide in the step S1 is one of sodium sulfide, ammonium sulfide, sodium hydrosulfate, etc., and the molar ratio of the sulfide to the molybdenum compound is 0.4:1 to 4:1.

[0016] Preferably, the metal salt or metal source in the S2 step includes one of ferrous sulfate, nickel sulfate, nickel nitrate, cobalt chloride, cobalt sulfate, sodium tungstate, calcium tungstate, etc. or a mixture thereof, and the amount of the metal salt added is a mass ratio of 0.1:100 to 1:100 to the coal powder based on the mass of iron, nickel, cobalt and tungsten, wherein the amount of the iron additive added is 0.5:100 to 1:100, the amount of the nickel additive added is 0.05:100 to 0.5:100, the amount of the cobalt additive added is 0.01:100 to 0.1:100, and the amount of the tungsten additive added is 0.01:100 to 0.1:100.

[0017] Preferably, in the step S2, the mass ratio of the coal powder to the composite molybdenum-based metal salt catalyst precursor solution is 100:0.1 to 100:1, and the particle size of the coal powder is 50 to 200 meshes.

[0018] Preferably, the hydrogenation reaction in the suspended bed reactor in the S2 step is carried out at a temperature of 350°C to 450°C and a pressure of 5 to 15 MPa, the reaction time is 1 to 6 hours, and the supply amount of hydrogen is 2 to 5 times the mass of the coal powder.

[0019] Preferably, the organic matter in the tailings in the S3 step is separated after being recovered by a solvent, and the solvent is recycled and reused to extract and separate the organic matter in the tailings, the solvent is one of tetrahydrofuran, toluene, and xylene, the mass ratio of the solvent to the residue is 15 to 30:1, the mixing and stirring temperature is 70°C to 110°C, the stirring time is 1 to 6 hours, the solvent extract recovery temperature is 70 to 130 degrees Celsius, and the solvent recovery rate is 80%-95%.

[0020] Preferably, the high-temperature oxidation treatment temperature of the tailings in the S3 step is 550°C to 950°C, and the treatment time is 30 minutes to 80 minutes. The molybdenum salt is sublimated and condensed and recovered during the oxidation process. The molybdenum salt is absorbed by an alkaline solution (such as ammonia water, sodium hydroxide, etc.) and converted into molybdate, which is then used for the recycling of the catalyst. During the oxidation treatment process, the recovery rate of the molybdenum element in the residue is 60% to 85%.

[0021] In summary, the present invention mainly has the following beneficial effects:

[0022] 1. The present invention adopts a composite molybdenum-based metal salt catalyst to greatly improve the conversion rate and liquid phase yield in the coal liquefaction process, while significantly reducing the residue rate. Experimental results show that the process can achieve a higher coal conversion rate and liquid phase product yield at a lower reaction pressure, thereby improving the overall efficiency of coal liquefaction.

[0023] 2. Through the high-temperature sublimation characteristics of molybdenum compounds, the present invention can efficiently recover molybdenum catalysts and recover molybdenum salts through oxidation treatment and ammonia solution, thereby realizing the recycling of molybdenum-based catalysts, significantly reducing the cost of catalyst use and improving economic efficiency.

[0024] 3. The present invention recovers molybdenum salts in tailings through high-temperature oxidation treatment, thereby reducing waste emissions. At the same time, the reuse of the recovered molybdenum salts helps to fully utilize resources, reduce environmental pollution, and has strong environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a process flow chart of the present invention;

[0026] Figure 2 It is a process flow chart of tailings treatment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0028] The following examples are used to illustrate the present invention, but they cannot be used to limit the scope of protection of the present invention. The conditions in the examples can be further adjusted according to specific conditions. Simple improvements to the method of the present invention under the premise of the concept of the present invention belong to the scope of protection claimed in the present invention.

[0029] refer to Figure 1 and Figure 2 , a process for catalyzing coal liquefaction by direct reaction of a composite molybdenum-based metal salt, the process comprising the following steps:

[0030] S1. Catalyst preparation: molybdenum compounds and other metal compounds are obtained by high temperature roasting of molybdenum-containing ore, and reacted with alkaline solution and sulfide to obtain a composite molybdenum-based metal salt catalyst precursor solution;

[0031] S2. Coal liquefaction or coal / oil co-liquefaction: a composite molybdenum-based metal salt catalyst precursor solution is mixed with coal powder and hydrogenated in a suspended bed reactor to generate a liquid product, tailings, and a gas product;

[0032] S3. Tailings treatment: Recover organic matter from tailings by solvent extraction and subject the tailings to high-temperature oxidation and sublimation treatment to recover sublimated molybdenum salts for recycling;

[0033] S4. Gas product processing: Hydrogen in the product is extracted by adsorption and used as fuel for thermal conversion of residues after desorption.

[0034] Example 1

[0035] 0.15 g of molybdenite was placed in a muffle furnace and roasted at 600° C. for 1 hour to ensure that the molybdenite was completely reacted and a molybdenum compound was generated. During the roasting process, attention should be paid to the control of temperature and time to avoid excessive oxidation leading to decomposition of the molybdenum compound. After the roasting was completed, the molybdenite sample was taken out and naturally cooled to room temperature. The cooled molybdenite sample was dissolved in 20 ml of ammonia solution, and the pH of the solution was adjusted to 5 to 9 to ensure that the molybdenum compound could fully react with ammonia water to generate a stable molybdenum salt solution. On this basis, 9 g of coal powder was added and stirred at room temperature for 1 hour to ensure that the molybdenum compound could be evenly adsorbed on the surface of the coal powder. During the stirring process, the stirring speed could be appropriately adjusted to ensure good contact between the coal powder and the molybdenum compound.

[0036] The stirred mixture was transferred to a vacuum drying oven at 100° C. for drying for 6 to 8 hours. Drying under vacuum conditions can better remove moisture in the solvent and avoid loss caused by evaporation of moisture at high temperature. The dried product is a uniform powdery material. The dried material, residual oil, and tetralin were added to a suspended bed reactor in a mass ratio of 1:1:1 to carry out a hydrogenation reaction. The reaction conditions are: temperature 400° C., initial pressure 7 MPa, reaction time 1 hour, and sulfur source 0.047 g (Mo / S=0.5 in terms of sulfur element). Under these conditions, the catalyst in the reactor is fully in contact with the coal powder, and a hydrocracking reaction is carried out in a hydrogen environment.

[0037] After the reaction is completed, liquid products and solid residues are obtained through liquid-solid separation. The liquid products are extracted with n-hexane and tetrahydrofuran to further extract organic substances in the coal / oil co-liquefaction residue. Through solvent recovery technology, the recovery rate of organic solvents is as high as more than 90%, ensuring efficient utilization of resources.

[0038] After drying and crushing, the liquefied residue is placed in a tubular furnace and subjected to high-temperature oxidation in an oxygen atmosphere at a temperature of 900°C and an oxidation time of 1 hour. During the process, the molybdenum salt will sublime and be recovered through gas condensation. An ammonia solution absorption system is provided at the gas outlet, which can effectively recover the sublimated molybdenum salt and convert it into molybdate to facilitate the recycling of the catalyst. The conversion rate of molybdenum element in the residue sample after oxidation treatment is relatively high, reaching more than 80%, further enhancing the overall efficiency of the coal liquefaction process. Through this process, the molybdenum-based catalyst can not only significantly improve the coal liquefaction efficiency, but also realize the recovery and reuse of the catalyst, reduce the production cost, and have good economic and environmental benefits.

[0039] Example 2

[0040] After accurately weighing 0.105g of molybdenum oxide, dissolve it in 20ml of ammonia solution, adjust the pH value of the solution to 5 to 9, and make it evenly dissolved. Then, slowly add 1.2g of ammonium sulfide solution at a water bath temperature of 60°C, and continue to react for 30 minutes to ensure that ammonium sulfide and molybdenum oxide react completely to form a molybdenum-based metal salt. The temperature and pH control in this process are very important, which helps to ensure the effective formation of the composite molybdenum-based metal salt. Then, add 9g of coal powder and mix it with the molybdenum-based metal salt solution. At this time, continue to stir in a 60°C water bath for 1 hour to ensure that the coal powder is in complete contact with the catalyst solution, promote the adsorption of the catalyst and the reaction of the coal powder. After the reaction is completed, transfer all products to a vacuum drying oven at 100°C for drying for 6 to 8 hours until the product is completely dry.

[0041] The dried catalyst, vacuum residue oil and tetralin are mixed in a mass ratio of 1:1:1 and sent to a suspended bed reactor for hydrogenation reaction. The hydrogenation reaction conditions are: reaction temperature 400°C, initial pressure 7MPa, reaction time 1 hour, and hydrogen flow rate is adjusted according to 2 to 5 times the mass of coal powder. Under this reaction condition, coal powder is converted into liquid product by reaction with residue oil and tetralin to generate coal / oil co-liquefaction residue.

[0042] After the reaction is completed, the liquid-solid product is extracted with n-hexane and tetrahydrofuran solvents to obtain a coal / oil co-liquefaction residue. The liquefied residue is dried and crushed, and then placed in a tubular furnace for high-temperature oxidation. The oxidation process is carried out at a temperature of 800° C. in an oxygen atmosphere for 30 to 60 minutes to ensure that the molybdenum element in the residue is completely converted, and the molybdenum salt is sublimated. The sublimated molybdenum salt is collected through a condenser and converted into molybdate. The molybdenum recovery rate in this process is high, and closed-loop recycling of molybdenum can be achieved, and it can be put into the preparation and use of the catalyst again;

[0043] The implementation of this process not only improves the efficiency of coal liquefaction, but also realizes the recycling of molybdenum catalyst, greatly reduces the cost of catalyst use, and also promotes the environmental friendliness of the coal liquefaction process.

[0044] Example 3

[0045] 0.105g of molybdenum oxide was accurately weighed and dissolved in 20ml of ammonia solution. The pH value of the solution was adjusted to 5 to 9 to fully dissolve the molybdenum oxide. Next, 0.250g of ferric sulfate was added and stirred evenly to form a composite molybdenum-based metal salt. The ferric sulfate in this step was used as a co-catalyst to further enhance the catalytic effect and reaction efficiency. After the molybdenum-based metal salt in the solution was formed, 9g of coal powder was added and continued to be stirred at room temperature for 1 hour to ensure that the coal powder and the catalyst were evenly mixed to promote the reaction. After all reactants were mixed, they were transferred to a vacuum drying oven at 100°C for drying for 6 to 8 hours until all solvents were completely volatilized to ensure the stability of the dried product.

[0046] The dried coal powder, vacuum residue oil and tetralin are mixed in a mass ratio of 1:1:1 and sent to a suspended bed reactor for hydrogenation reaction. The hydrogenation reaction conditions are: reaction temperature 400°C, initial pressure 7MPa, reaction time 1 hour, and 0.047g sulfur is also added to the reaction system to further promote the conversion of the coal powder. Under this condition, the coal powder generates coal / oil co-liquefaction residue through hydrogenation reaction. After the reaction, the liquid and solid products are extracted by n-hexane and tetrahydrofuran solvents to obtain coal / oil co-liquefaction residue. After the residue is dried and crushed, it is placed in a tubular furnace for high-temperature oxidation treatment. The oxidation conditions are temperature 750°C, oxygen atmosphere, and treatment time of 30 to 60 minutes to ensure that the molybdenum element in the residue is completely oxidized and the molybdenum salt is sublimated. The sublimated molybdenum salt is absorbed by an ammonia solution and converted into molybdate, which is finally recovered and recycled.

[0047] Through this series of steps, the efficient recycling of molybdenum catalysts in the coal liquefaction process was successfully achieved, which not only improved the coal conversion efficiency, but also realized the recovery and reuse of molybdenum, reduced molybdenum waste, and reduced the cost of catalyst use. In addition, the oxidation process also helps to reduce harmful emissions in the reaction and improve the environmental friendliness of the process.

[0048] Example 4

[0049] According to the reaction results of Example 1, Example 2 and Example 3, the data of liquid phase yield, coal conversion rate, asphaltene yield, residue rate and reaction end pressure in the coal liquefaction process are sorted out, as shown in the following table:

[0050] parameter Example 1 Example 2 Example 3 Coal conversion rate (wt%) 96.03％ 96.98％ 99.33％ Liquid product yield (wt%) 68.53％ 81.70％ 89.33％ Asphaltene yield (wt%) 22.33％ 10.17％ 9.37％ Residue rate (wt%) 3.97％ 3.02％ 0.67％ Reaction end pressure (MPa) 9.9 9.0 8.8

[0051] Liquid phase yield and conversion rate table

[0052] According to the comparative analysis of the embodiments, the use of catalysts containing molybdenum compounds and iron compounds can significantly improve the conversion rate of coal liquefaction and the yield of liquid products, reduce the formation of residues, and lower the reaction pressure, showing a relatively ideal catalytic effect. This indicates that the application of the catalyst of the present invention in coal liquefaction and coal / oil co-liquefaction processes has good prospects.

[0053] Although the embodiments of the present invention have been shown and described, it is understood by those skilled in the art that, unless otherwise defined, the technical terms or scientific terms used in the present invention should have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs, and the words "include" or "comprise" and the like used in the present invention mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents.

[0054] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A process for catalyzing coal liquefaction by direct reaction of a composite molybdenum-based metal salt, characterized in that: The process includes the following steps: S1. Catalyst preparation: molybdenum compounds and other metal compounds are obtained by high temperature roasting of molybdenum-containing ore, and reacted with alkaline solution and sulfide to obtain a composite molybdenum-based metal salt catalyst precursor solution; S2. Coal liquefaction or coal / oil co-liquefaction: a composite molybdenum-based metal salt catalyst precursor solution is mixed with coal powder and hydrogenated in a suspended bed reactor to generate liquid products, tailings, and gas products; S3. Tailings treatment: Recover organic matter from tailings by solvent extraction and subject the tailings to high-temperature oxidation and sublimation treatment to recover sublimated molybdenum salts for recycling; S4. Gas product processing: Hydrogen in the product is extracted by adsorption and used as fuel for thermal conversion of residues after desorption.

2. The process for catalyzing coal liquefaction by direct reaction of a composite molybdenum-based metal salt according to claim 1, characterized in that: The molybdenum-containing ore in step S1 is one of molybdenite, molybdenum concentrate, nickel-molybdenum ore, tungsten-molybdenum ore, calcium molybdate ore, iron molybdate ore, wulfen-lead ore, etc., or a mixture thereof.

3. The process for catalyzing coal liquefaction by direct reaction of a composite molybdenum-based metal salt according to claim 1, characterized in that: In the step S1, the calcination temperature is 400° C. to 650° C., and the calcination time is 30 minutes to 70 minutes, wherein the molybdenum compound is mainly molybdenum disulfide and molybdenum oxide.

4. The process for catalyzing coal liquefaction by direct reaction of a composite molybdenum-based metal salt according to claim 1, characterized in that: In the step S1, the alkaline solution is one of ammonia water, sodium sulfide, ammonium sulfide, sodium hydroxide, etc. or a mixture thereof, and the molar ratio of the alkaline solution to the molybdenum compound is 3:1 to 1.5:1, and the concentration of the added alkaline solution is 5% to 20%.

5. The process for catalyzing coal liquefaction by direct reaction of a composite molybdenum-based metal salt according to claim 1, characterized in that: In the step S1, the sulfide is one of sodium sulfide, ammonium sulfide, sodium hydrogen sulfate, etc., and the molar ratio of the sulfide to the molybdenum compound is 0.4:1 to 4:

1.

6. The process for catalyzing coal liquefaction by direct reaction of a composite molybdenum-based metal salt according to claim 1, characterized in that: In the S2 step, the metal salt or metal source includes one of ferrous sulfate, nickel sulfate, nickel nitrate, cobalt chloride, cobalt sulfate, sodium tungstate, calcium tungstate, etc. or a mixture thereof, and the added amount of the metal salt is 0.1:100 to 1:100 in terms of the mass ratio of iron, nickel, cobalt and tungsten to the coal powder, wherein the added amount of the iron additive is 0.5:100 to 1:100, the added amount of the nickel additive is 0.05:100 to 0.5:100, the added amount of the cobalt additive is 0.01:100 to 0.1:100, and the added amount of the tungsten additive is 0.01:100 to 0.1:

100.

7. The process for catalyzing coal liquefaction by direct reaction of a composite molybdenum-based metal salt according to claim 1, characterized in that: In the step S2, the mass ratio of the coal powder to the composite molybdenum-based metal salt catalyst precursor solution is 100:0.1 to 100:1, and the particle size of the coal powder is 50 to 200 meshes.

8. The process for catalyzing coal liquefaction by direct reaction of a composite molybdenum-based metal salt according to claim 1, characterized in that: The hydrogenation reaction in the suspended bed reactor in step S2 is carried out at a temperature of 350°C to 450°C and a pressure of 5 to 15 MPa. The reaction time is 1 to 6 hours, and the supply amount of hydrogen is 2 to 5 times the mass of the coal powder.

9. The process for catalyzing coal liquefaction by direct reaction of a composite molybdenum-based metal salt according to claim 1, characterized in that: In the S3 step, the organic matter in the tailings is separated after being recovered by the solvent, and the solvent is recycled and reused to extract and separate the organic matter in the tailings. The solvent is one of tetrahydrofuran, toluene, and xylene. The mass ratio of the solvent to the residue is 15 to 30:1, the mixing and stirring temperature is 70°C to 110°C, the stirring time is 1 to 6 hours, the solvent extract recovery temperature is 70 to 130 degrees Celsius, and the solvent recovery rate is 80%-95%.

10. The process for catalyzing coal liquefaction by direct reaction of a composite molybdenum-based metal salt according to claim 1, characterized in that: In the step S3, the high-temperature oxidation treatment temperature of the tailings is 550°C to 950°C, and the treatment time is 30 minutes to 80 minutes. The molybdenum salt is sublimated and condensed and recovered during the oxidation process. The molybdenum salt is absorbed by an alkaline solution (such as ammonia water, sodium hydroxide, etc.) and converted into molybdate, which is then used for the recycling of the catalyst. During the oxidation treatment process, the conversion rate of the molybdenum element in the residue is 60% to 85%.

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