Method for preparing oil product by oxidation-hydrogenation two-step mild catalytic cracking of low-rank coal

Abstract

The invention discloses a method for preparing an oil product by oxidation-hydrogenation two-step mild catalytic cracking of low-rank coal, which comprises the following steps of: firstly, carrying out oxidative depolymerization reaction on the low-rank coal by using hydrogen peroxide, decomposing residual hydrogen peroxide in a liquid product of the reaction, and drying by distillation to obtain an oxidative depolymerization product solid; carrying out hydrocracking reaction on the oxidative depolymerization product solid in a hydrogen-donating solvent by using 20wt% of SiW12 and 1wt% of Pd / SiO2 catalyst, and rectifying and recovering the solvent to prepare a target oil product. The method provided by the invention can realize direct conversion of coal under mild process conditions, has a high coal conversion rate, is helpful for realizing clean and efficient utilization of coal resources, assists green and sustainable development of the coal chemical industry, and has a good application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of direct coal conversion, and relates to a method for direct coal liquefaction, and in particular to a method for preparing oil products by performing two-step mild catalytic cracking of low-rank coal by oxidation-hydrogenation. Background Art

[0002] Coal direct liquefaction technology mainly involves destroying the macromolecular structure of coal under high temperature and high pressure, and then further converting it into small molecular liquid fuel through hydrogenation reaction. In 1913, German chemist Bergius first studied the technology of producing liquid fuel by hydrogenation of coal under high temperature and high pressure and obtained a patent, thus laying the foundation for direct coal hydrogenation liquefaction technology.

[0003] To date, there are many mature industrial coal direct liquefaction processes, such as Germany's IGOR process, Japan's NEDOL process, the United States' CTSL process and HTI process, and China's Shenhua process. However, traditional coal direct liquefaction technology always has harsh high-temperature and high-pressure reaction conditions. Taking Shenhua Group's coal direct liquefaction technology (CN 1587351A) as an example, it requires 430-465°C and 15-19MPa hydrogen pressure, which not only brings higher energy consumption and operating costs, but also its high temperature and high-pressure environment will accelerate the corrosion and wear of reactors, pipelines and other equipment, resulting in high equipment investment and maintenance costs.

[0004] Developing technologies related to the preparation of high-end fine chemicals by directional cracking of coal under mild conditions can give full play to the natural aromatic ring structure characteristics of coal, increase the added value of coal-based products, and avoid the homogenization of coal chemical and petrochemical product chains. Direct liquefaction of coal under mild conditions can not only reduce the hydrogen consumption and energy consumption in the liquefaction process and improve the utilization rate of hydrogen, but also reduce equipment investment and maintenance costs, which is conducive to the green and sustainable development of the coal chemical industry. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing oil products by mild catalytic cracking of low-rank coal in two steps of oxidation-hydrogenation, so as to reduce the temperature and pressure conditions of the direct conversion process of coal and provide new ideas for the clean, low-carbon and high value-added utilization of coal resources.

[0006] To achieve the above-mentioned purpose of the invention, the method for preparing oil products by two-step mild catalytic cracking of low-rank coal by oxidation-hydrogenation specifically includes the following technical solutions:

[0007] 1) Using low-rank coal as a catalytic cracking raw material, and subjecting the low-rank coal to an oxidative depolymerization reaction using hydrogen peroxide;

[0008] 2) Separating the liquid product of the oxidative depolymerization reaction, decomposing the remaining hydrogen peroxide therein, and evaporating to dryness to obtain a solid oxidative depolymerization product;

[0009] 3) dispersing the oxidative depolymerization product solid in a solution containing 20 wt% SiW 12 -1wt%Pd / SiO 2 The hydrogen supply solvent of the catalyst is charged with hydrogen to carry out a hydrocracking reaction;

[0010] 4) Separate the hydrocracking reaction products, recover the hydrogen supply solvent by distillation, and prepare the target oil product.

[0011] Among them, the present invention preferably crushes the raw material low-rank coal into a fineness of less than 75μm for use.

[0012] Specifically, the preferred process conditions for the oxidative depolymerization reaction of the present invention are reaction at 30-70° C. for 2-10 hours.

[0013] More specifically, the concentration of hydrogen peroxide used in the oxidative depolymerization reaction is preferably 5 to 30 wt %.

[0014] Furthermore, the remaining hydrogen peroxide in the liquid product of the oxidative depolymerization reaction of the present invention is 2 Decomposed and removed in the presence of a catalyst.

[0015] The present invention provides the Pd / SiO 2 There is no special requirement for the source of the catalyst, and it can be Pd / SiO prepared by various conventional methods. 2 Catalyst. Preferably, the Pd / SiO 2 The catalyst is prepared by impregnating palladium chloride onto fumed silica using an equal volume impregnation method, drying and grinding, calcining at 400° C. in an air atmosphere for 4 hours, and then reducing with hydrogen at 200° C. for 2 hours to obtain the catalyst.

[0016] Furthermore, the present invention preferably uses 5wt% Pd / SiO 2 Catalyst; more preferably, the particle size of the catalyst is 380 to 830 μm.

[0017] Specifically, the hydrogen supply solvent for the hydrocracking reaction of the present invention may include, but is not limited to, any one of cyclohexane, tetralin, decalin, isopropanol, methanol or ethanol.

[0018] More specifically, the preferred process conditions for the hydrocracking reaction of the present invention are reaction at 280-380° C. for 2-6 hours under an initial hydrogen pressure of 1-3 MPa.

[0019] Similarly, the present invention is for the 20wt%SiW 12 -1wt%Pd / SiO 2There is no special requirement for the source of the catalyst, and it can be prepared by various conventional methods. Preferably, the catalyst of the present invention is a 20wt% SiW catalyst obtained by impregnating palladium chloride onto fumed silica by an equal volume impregnation method, drying and grinding, calcining at 400°C in air atmosphere for 4h, impregnating silicotungstic acid, and reducing with hydrogen at 200°C for 2h. 12 -1wt%Pd / SiO 2 catalyst.

[0020] The target oil product prepared by the above method of the present invention can be further processed through existing mature related cascade separation processes to obtain high-purity chemicals with higher added value.

[0021] The present invention uses hydrogen peroxide to oxidize low-rank coal, which can cause the complex low-rank coal to undergo preliminary depolymerization under relatively mild conditions to obtain macromolecular fragment oxidation products. Hydrogen peroxide oxidation is a relatively mild oxidation method. During the oxidation of low-rank coal, the weak covalent bonds (such as COC) in the coal are first broken, and the -CH 2 -and-CH 2 CH 2 -bridge bonds are also easily oxidized by hydrogen peroxide. The water-soluble substances after oxidation are rich in aromatic ring structures, and the solid oxidative depolymerization product obtained by evaporation is used as the next step of hydrocracking raw material, which can achieve hydrogenation liquefaction under lower temperature and pressure conditions.

[0022] The coalification degree of low-rank coal is low, and the cross-linking association between macromolecular organic matter is relatively weak. Therefore, hydrogen peroxide oxidation is more suitable for the depolymerization of low-rank coal due to its mild characteristics. For coal with a higher degree of metamorphism, in addition to hydrogen peroxide oxidation, more intense oxidation methods can be used to break its more stable association, such as ozone oxidation, sodium hypochlorite oxidation, ruthenium ion oxidation and other oxidation methods, so as to achieve better oxidative depolymerization of organic macromolecules in coal. For example, ozone oxidation has a strong oxidizing ability, and can quickly react with various chemical bonds in coal under mild conditions, effectively destroying the macromolecular structure of coal and achieving deep oxidative depolymerization.

[0023] Compared with the existing industrial coal direct liquefaction process technology, the method of preparing oil products by two-step mild catalytic cracking of low-rank coal by oxidation-hydrogenation of the present invention has the following advantages:

[0024] 1. The present invention introduces an oxidative depolymerization process, so that the direct conversion temperature and pressure conditions of coal are milder, and the hydrocracking process can be carried out within the range of 280-380°C and 1-3MPa hydrogen pressure;

[0025] 2. The hydrocracking catalyst used in the present invention contains silicotungstic acid as a heteropolyacid, which synergizes with metal palladium to promote hydrogen heterolysis, reduce reaction pressure, and reduce hydrogen loss, thereby reducing reaction energy consumption and realizing resource conservation and utilization.

[0026] 3. The method of the present invention can achieve a good direct coal conversion effect. Based on the data balance of the dry ash-free basis of low-rank coal, residue and oxidative depolymerization product solids, the conversion rate of the oxidative depolymerization process can reach more than 70%, the yield of the depolymerization product can reach more than 30%, and the conversion rate of the hydrocracking process can reach more than 50%, which has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a process flow chart of the present invention.

[0028] 10-oxidation unit: 11-oxidation reactor; 12-automatic pressure regulating valve; 13-first solid-liquid separation device; 14-first liquid conveying device; 15-hydrogen peroxide decomposition device; 16-second solid-liquid separation device; 17-second liquid conveying device; 18-first distillation device; 19-drying box;

[0029] 20-hydrogenation unit: 21-pulverizer; 22-hydrogenation reactor; 23-third solid-liquid separation device; 24-third liquid conveying device; 25-second distillation device; 26-condenser; 27-fourth liquid conveying device; 28-oil storage device. Implementation

[0030] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solution of the present invention so that those skilled in the art can well understand and utilize the present invention, rather than limiting the scope of protection of the present invention.

[0031] The production processes, experimental methods or detection methods involved in the embodiments of the present invention, unless otherwise specified, are all conventional methods in the prior art, and their names and / or abbreviations are all conventional names in the field, and are very clear and unambiguous in the relevant application fields. Technical personnel in the field can understand the conventional process steps based on the names and apply the corresponding equipment, and implement them according to conventional conditions or the conditions recommended by the manufacturer.

[0032] The various instruments, equipment, raw materials or reagents used in the embodiments of the present invention are not particularly limited in terms of their sources, and are all conventional products that can be purchased through regular commercial channels, or can be prepared according to conventional methods well known to those skilled in the art.

[0033] The method for preparing oil products by two-step mild catalytic cracking of low-rank coal by oxidation-hydrogenation can be carried out by Figure 1The device and process flow shown in the figure are carried out, wherein the device includes an oxidation unit (10) and a hydrogenation unit (20), wherein the oxidation unit (10) is used to oxidatively depolymerize low-rank coal under mild conditions into oxidative depolymerization products of large molecular fragments, and the hydrogenation unit (20) is used to catalytically hydrocracking the above-mentioned oxidative depolymerization products under mild conditions into small molecular oil products.

[0034] The oxidation unit (10) comprises:

[0035] The oxidation reactor (11) is used to add low-rank coal and hydrogen peroxide to carry out oxidation depolymerization reaction. The reactor is connected to an automatic pressure regulating valve (12) for releasing the gas generated by the oxidation depolymerization reaction to keep the pressure of the reactor constant. After the reaction, the mixture of water-soluble macromolecular oxidation depolymerization products and residues in the reactor is separated by a first solid-liquid separation device (13), and the liquid product enters an open hydrogen peroxide decomposition device (15) through a first liquid conveying device (14). The excess hydrogen peroxide therein is quickly and completely decomposed using a circulating catalyst 1, and the catalyst is separated and recycled by a second solid-liquid separation device (16). Due to the wear and tear of the catalyst particles, it is necessary to regularly replace and replenish a portion of the fresh catalyst 1. The liquid obtained after separation enters a first distillation device (18) through a second liquid conveying device (17), evaporates the water, and is dried in a drying oven (19) to obtain a solid oxidation depolymerization product.

[0036] Catalyst 1 is 5wt% Pd / SiO with a particle size of 380-830μm. 2 The catalyst is prepared specifically according to the following method:

[0037] Add 1 g of PdCl into 200 mL of ultrapure water. 2 , 1 mL of 35 wt% concentrated hydrochloric acid, ultrasonically dispersed for 0.5 h, accurately diluted to 250 mL with ultrapure water, and ultrasonically dispersed for 0.5 h to obtain PdCl with a Pd concentration of 2.4 mg / mL 4 Solution.

[0038] After drying the fumed silica at 120 °C for 12 h, 8 g was weighed as a catalyst carrier and 175.44 mL of the prepared PdCl 4 The solution was stirred at room temperature until solid, placed in an oven and dried at 120°C for 12 hours, ground into uniform powder, and calcined at 400°C for 4 hours in a muffle furnace under air atmosphere. After grinding again, it was placed in a tube furnace and reduced in a hydrogen atmosphere at 200°C for 2 hours to prepare 5wt% Pd / SiO 2 The catalyst powder is finally granulated into 380-830 μm.

[0039] In a specific embodiment, it is preferred to use low-rank coal crushed to a fineness of less than 75 μm.

[0040] In a specific embodiment, the oxidative depolymerization reaction is preferably carried out at 30-70° C., and more preferably, the oxidative depolymerization reaction time is generally 2-10 hours.

[0041] The hydrogenation unit (20) comprises:

[0042] The hydrogenation reactor (22) is used for catalytic hydrogenation cracking reaction of the oxidative depolymerization product. The solid oxidative depolymerization product from the oxidation unit (10) is crushed into a powder product by a pulverizer (21), and used as a hydrogenation raw material. It is catalytically hydrogenated and cracked in the hydrogenation reactor (22) together with the catalyst 2, hydrogen, and a hydrogen supply solvent to obtain a mixture of hydrogenated liquid products, hydrogen supply solvents, gaseous byproducts, catalysts, and residues. The gas is discharged through the tail gas pipeline, and the remaining mixture is separated by the third solid-liquid separation device (23). The resulting liquid enters the second distillation device (25) through the third liquid conveying device (24) for solvent evaporation, and then is condensed and recovered by the condenser (26) for recycling. The concentrated liquid remaining after distillation is the target oil product, which enters the oil product storage device (28) for storage through the fourth liquid conveying device (27).

[0043] Catalyst 2 is 20wt% SiW 12 -1wt%Pd / SiO 2 The catalyst is prepared specifically according to the following method:

[0044] After drying the fumed silica at 120 °C for 12 h, 10 g was weighed as a catalyst carrier and 42.09 mL of the prepared PdCl 4 The solution and 57.91 mL of ultrapure water were stirred at room temperature until solid, placed in an oven at 120 ° C for 12 hours, ground into uniform powder, and calcined at 400 ° C for 4 hours in a muffle furnace under air atmosphere. 1.25 g of silicotungstic acid and 22.5 mL of ultrapure water were added to the calcined product, stirred at room temperature until solid, placed in an oven at 120 ° C for 12 hours, ground into uniform powder, and reduced in a tubular furnace at 200 ° C in a hydrogen atmosphere for 2 hours to prepare 20wt% SiW 12 -1wt%Pd / SiO 2 catalyst.

[0045] In a specific embodiment, it is preferred to control the initial hydrogen pressure to be 1 to 3 MPa and perform the hydrocracking at 280 to 380° C. More preferably, the hydrocracking reaction time is generally 2 to 6 hours.

[0046] In a specific embodiment, the hydrogen-donating solvent may be any one of cyclohexane, tetralin, decalin, isopropanol, methanol or ethanol.

[0047] The above-mentioned 20wt% SiW was tested using diphenyl ether. 12 -1wt%Pd / SiO 2 The hydrogenation catalytic activity of the catalyst was compared with that of 1wt%Pd / SiO 2 The catalytic effects of the catalysts were compared.

[0048] After drying the fumed silica at 120 °C for 12 h, 10 g was weighed as a catalyst carrier and 42.09 mL of the prepared PdCl 4 The solution was mixed with 57.91 mL of ultrapure water and stirred at room temperature until solid, dried in an oven at 120 °C for 12 h, ground into uniform powder, and calcined in a muffle furnace at 400 °C for 4 h in an air atmosphere. After grinding again, it was placed in a tube furnace and reduced in a hydrogen atmosphere at 200 °C for 2 h to prepare 1 wt% Pd / SiO 2 Catalyst powder.

[0049] In a 50mL electromagnetic stirring catalytic reactor, 100mg of diphenyl ether and 20mL of isopropanol were added, and 50mg of catalyst 20% SiW 12 -1%Pd / SiO 2 and 1%Pd / SiO 2 , fill with 1MPa hydrogen, set the reaction speed to 700r / min, temperature to 160℃, and reaction time to 2h.

[0050] After the reaction, GC / MS was used to detect and analyze the reaction products, and the composition of the products was calculated based on the internal standard method.

[0051] Using catalyst 1% Pd / SiO 2 The conversion rate of diphenyl ether hydrogenation process was 52.17%, and the reaction products mainly included cyclohexane, cyclohexanol, cyclohexanone, phenol, dicyclohexyl ether and cyclohexyl phenyl ether, and the yields of each were 19.50%, 2.34%, 3.69%, 0.45%, 1.29% and 24.89%. The carbon balance of the reaction process was calculated to be 99.71%. The above results show that in the absence of silicotungstic acid, the catalyst 1%Pd / SiO 2 The hydrogenation catalytic activity is poor.

[0052] Under the same hydrogenation conditions, using a catalyst with 20wt% SiW 12 -1wt%Pd / SiO 2The conversion rate of diphenyl ether hydrogenation process was 83.15%, and the reaction product composition also mainly included cyclohexane, cyclohexanol, cyclohexanone, phenol, dicyclohexyl ether and cyclohexyl phenyl ether, with respective yields of 10.37%, 12.17%, 29.88%, 1.61%, 3.03% and 26.08%. The carbon balance of the reaction process was calculated and the result was 99.02%.

[0053] The above calculation results show that 20%SiW 12 -1%Pd / SiO 2 The catalyst has a good hydrogenation effect, and the silicotungstic acid and metal palladium work synergistically to promote the activation of hydrogen.

[0054] In a specific embodiment of the present invention, the raw coal used, including Naomaohu coal, Zaozhuang coal, Xiaolongtan coal and Shenhua lump coal, are all low-rank coal. Example

[0055] Example 1

[0056] Take Naomaohu coal as raw material, crush it with a coal mill, sieve it to below 75μm, and dry it at 120℃ for later use.

[0057] Weigh 5 g of Naomaohu coal powder and add it into a 1L three-necked round-bottom flask, then add 200 mL of 30 wt% hydrogen peroxide solution, connect a condenser to the top of the flask for cooling, heat to 60°C and stir to carry out oxidation reaction for 150 minutes.

[0058] After the reaction is completed, the reaction mixture is filtered using a polytetrafluoroethylene water filter membrane in a sand core funnel to obtain an oxidation residue solid and an oxidation depolymerization product aqueous solution. The oxidation residue solid is dried at 120° C. and then weighed.

[0059] Add 1-2 g of 5 wt% Pd / SiO granulated to 380-830 μm into the aqueous solution of the oxidative depolymerization product. 2 The catalyst was reacted at room temperature for 24 hours, and after the remaining hydrogen peroxide was decomposed, it was filtered and the catalyst was recovered for recycling.

[0060] The filtrate obtained by filtration was evaporated to remove the solvent water, dried at 120° C., and ground to obtain a solid oxidative depolymerization product, which was weighed and used as a raw material for the catalytic hydrogenation process.

[0061] Based on the mass balance of the above raw material Naomaohu coal powder, the obtained oxidation residue solid and the oxidative depolymerization product solid on a dry ash-free basis, the conversion rate of the above oxidative depolymerization process was 71.78%, and the yield of the solid oxidative depolymerization product was 36.84%.

[0062] Add 50 mg of catalyst 20% SiW into a 50 mL high temperature and high pressure reactor. 12 -1%Pd / SiO2 , 100 mg of oxidative depolymerization product solid, 20 mL of cyclohexane, filled with 3 MPa of hydrogen, set the stirring speed to 400 r / min, the reaction temperature to 330°C, and the reaction time to 6 h.

[0063] After the reaction, the composition and content of the reaction product were detected by GC / MS, and the conversion rate was determined by the mass change of the solid matter before and after the reaction.

[0064] The hydrogenation conversion rate of the above hydrocracking process is 60.89%. More than 64 substances were detected by GC / MS. The relative content of various products was calculated by peak area normalization method, among which the content of aromatic compounds was 22.17%, including condensed aromatic compounds with 1 to 3 rings. Specifically, the content of methylnaphthalene in aromatic compounds was 4.46%, the content of toluene was 5.98%, the content of mesitylene was 0.79%, the content of biphenyl was 1.59%, the content of 4-methylphenanthrene was 0.274%, and the rest included hydrocarbon compounds and a small amount of oxygen-containing and nitrogen-containing compounds.

[0065] Example 2

[0066] Weigh 5 g of the Naomaohu coal powder of Example 1 and add it into a 1 L three-necked round-bottom flask. Then, weigh 200 mL of 5 wt % hydrogen peroxide and add it. Connect a condenser to the top of the flask for cooling, heat to 70° C., stir and carry out oxidation reaction for 600 min.

[0067] After the reaction is completed, the reaction mixture is filtered using a polytetrafluoroethylene water filter membrane in a sand core funnel to obtain an oxidation residue solid and an oxidation depolymerization product aqueous solution. The oxidation residue solid is dried at 120° C. and then weighed.

[0068] Add 1-2 g of 5 wt% Pd / SiO granulated to 380-830 μm into the aqueous solution of the oxidative depolymerization product. 2 The catalyst was reacted at room temperature for 24 hours, and after the remaining hydrogen peroxide was decomposed, it was filtered and the catalyst was recovered for recycling.

[0069] The filtrate obtained by filtration was evaporated to remove the solvent water, dried at 120° C., and ground to obtain a solid oxidative depolymerization product, which was weighed and used as a raw material for the catalytic hydrogenation process.

[0070] Based on the mass balance of the above raw material Naomaohu coal powder, the obtained oxidation residue solid and the oxidative depolymerization product solid on a dry ash-free basis, the conversion rate of the above oxidative depolymerization process was 89.65%, and the yield of the solid oxidative depolymerization product was 33.47%.

[0071] Add 50 mg of catalyst 20% SiW into a 50 mL high temperature and high pressure reactor. 12 -1%Pd / SiO 2, 100 mg of oxidative depolymerization product solid, 20 mL of cyclohexane, filled with 3 MPa of hydrogen, set the stirring speed to 400 r / min, the reaction temperature to 380°C, and the reaction time to 3 h.

[0072] After the reaction was completed, the hydrogenation conversion rate of the reaction was calculated to be 89.80%.

[0073] Example 3

[0074] Weigh 5 g of the Naomaohu coal powder of Example 1 and add it into a 1 L three-necked round-bottom flask. Then, weigh 200 mL of 30 wt % hydrogen peroxide and add it. Connect a condenser to the top of the flask for cooling, heat to 30° C., stir and carry out oxidation reaction for 600 min.

[0075] After the reaction is completed, the reaction mixture is filtered using a polytetrafluoroethylene water filter membrane in a sand core funnel to obtain an oxidation residue solid and an oxidation depolymerization product aqueous solution. The oxidation residue solid is dried at 120° C. and then weighed.

[0076] Add 1-2 g of 5 wt% Pd / SiO granulated to 380-830 μm into the aqueous solution of the oxidative depolymerization product. 2 The catalyst was reacted at room temperature for 24 hours, and after the remaining hydrogen peroxide was decomposed, it was filtered and the catalyst was recovered for recycling.

[0077] The filtrate obtained by filtration was evaporated to remove the solvent water, dried at 120° C., and ground to obtain a solid oxidative depolymerization product, which was weighed and used as a raw material for the catalytic hydrogenation process.

[0078] Based on the mass balance of the above raw material Naomaohu coal powder, the obtained oxidation residue solid and the oxidative depolymerization product solid on a dry ash-free basis, the conversion rate of the above oxidative depolymerization process was 83.76%, and the yield of the solid oxidative depolymerization product was 30.63%.

[0079] Add 50 mg of catalyst 20% SiW into a 50 mL high temperature and high pressure reactor. 12 -1%Pd / SiO 2 , 100 mg of oxidative depolymerization product solid, 20 mL of isopropanol, filled with 1 MPa of hydrogen, set the stirring speed to 400 r / min, the reaction temperature to 350°C, and the reaction time to 6 h.

[0080] After the reaction was completed, the hydrogenation conversion rate of the reaction was calculated to be 65.17%.

[0081] Example 4

[0082] Weigh 5 g of the Naomaohu coal powder of Example 1 and add it into a 1 L three-necked round-bottom flask. Then, weigh 200 mL of 30 wt % hydrogen peroxide and add it. Connect a condenser to the top of the flask for cooling, heat to 70° C., stir and perform oxidation reaction for 120 min.

[0083] After the reaction is completed, the reaction mixture is filtered using a polytetrafluoroethylene water filter membrane in a sand core funnel to obtain an oxidation residue solid and an oxidation depolymerization product aqueous solution. The oxidation residue solid is dried at 120° C. and then weighed.

[0084] Add 1-2 g of 5 wt% Pd / SiO granulated to 380-830 μm into the aqueous solution of the oxidative depolymerization product. 2 The catalyst was reacted at room temperature for 24 hours, and after the remaining hydrogen peroxide was decomposed, it was filtered and the catalyst was recovered for recycling.

[0085] The filtrate obtained by filtration was evaporated to remove the solvent water, dried at 120° C., and ground to obtain a solid oxidative depolymerization product, which was weighed and used as a raw material for the catalytic hydrogenation process.

[0086] Based on the mass balance of the above raw material Naomaohu coal powder, the obtained oxidation residue solid and the oxidative depolymerization product solid on a dry ash-free basis, the conversion rate of the above oxidative depolymerization process was 84.17%, and the yield of the solid oxidative depolymerization product was 37.66%.

[0087] Add 50 mg of catalyst 20% SiW into a 50 mL high temperature and high pressure reactor. 12 -1%Pd / SiO 2 , 100 mg of oxidative depolymerization product solid, 20 mL of cyclohexane, filled with 2 MPa of hydrogen, set the stirring speed to 400 r / min, the reaction temperature to 280°C, and the reaction time to 2 h.

[0088] After the reaction was completed, the hydrogenation conversion rate of the reaction was calculated to be 52.07%.

[0089] Example 5

[0090] Weigh 5 g of the Naomaohu coal powder of Example 1 and add it into a 1 L three-necked round-bottom flask. Then, weigh 200 mL of 30 wt % hydrogen peroxide and add it. Connect a condenser to the top of the flask for cooling, heat it to 60° C., stir and carry out oxidation reaction for 150 min.

[0091] After the reaction is completed, the reaction mixture is filtered using a polytetrafluoroethylene water filter membrane in a sand core funnel to obtain an oxidation residue solid and an oxidation depolymerization product aqueous solution. The oxidation residue solid is dried at 120° C. and then weighed.

[0092] Add 1-2 g of 5 wt% Pd / SiO granulated to 380-830 μm into the aqueous solution of the oxidative depolymerization product. 2 The catalyst was reacted at room temperature for 24 hours, and after the remaining hydrogen peroxide was decomposed, it was filtered and the catalyst was recovered for recycling.

[0093] The filtrate obtained by filtration was evaporated to remove the solvent water, dried at 120° C., and ground to obtain a solid oxidative depolymerization product, which was weighed and used as a raw material for the catalytic hydrogenation process.

[0094] Based on the mass balance of the above raw material Naomaohu coal powder, the obtained oxidation residue solid and the oxidative depolymerization product solid on a dry ash-free basis, the conversion rate of the above oxidative depolymerization process was 71.78%, and the yield of the solid oxidative depolymerization product was 36.84%.

[0095] Add 50 mg of catalyst 20% SiW into a 50 mL high temperature and high pressure reactor. 12 -1%Pd / SiO 2 , 100 mg of oxidative depolymerization product solid, 20 mL of methanol, filled with 3 MPa of hydrogen, set the stirring speed to 400 r / min, the reaction temperature to 300°C, and the reaction time to 2 h.

[0096] After the reaction was completed, the hydrogenation conversion rate of the reaction was calculated to be 75.93%.

[0097] Example 6

[0098] Take Zaozhuang coal as raw material, crush it with a coal mill, sieve it to below 75μm, and dry it at 120℃ for later use.

[0099] Weigh 5 g of Zaozhuang coal powder and add it into a 1 L three-necked round-bottom flask, then measure 200 mL of 20 wt % hydrogen peroxide and add it. Connect a condenser to the top of the flask for cooling, heat to 50 °C and stir to carry out oxidation reaction for 180 min.

[0100] After the reaction is completed, the reaction mixture is filtered using a polytetrafluoroethylene water filter membrane in a sand core funnel to obtain an oxidation residue solid and an oxidation depolymerization product aqueous solution. The oxidation residue solid is dried at 120° C. and then weighed.

[0101] Add 1-2 g of 5 wt% Pd / SiO granulated to 380-830 μm into the aqueous solution of the oxidative depolymerization product. 2 The catalyst was reacted at room temperature for 24 hours, and after the remaining hydrogen peroxide was decomposed, it was filtered and the catalyst was recovered for recycling.

[0102] The filtrate obtained by filtration was evaporated to remove the solvent water, dried at 120° C., and ground to obtain a solid oxidative depolymerization product, which was weighed and used as a raw material for the catalytic hydrogenation process.

[0103] Based on the mass balance of the dry ash-free basis of the above-mentioned raw material Zaozhuang coal, the obtained oxidation residue solid and the oxidative depolymerization product solid, the conversion rate of the above-mentioned oxidative depolymerization process was 79.61%, and the yield of the solid oxidative depolymerization product was 37.55%.

[0104] Add 50 mg of catalyst 20% SiW into a 50 mL high temperature and high pressure reactor. 12 -1%Pd / SiO 2 , 100 mg of oxidative depolymerization product solid, 20 mL of cyclohexane, filled with 3 MPa of hydrogen, set the stirring speed to 400 r / min, the reaction temperature to 350°C, and the reaction time to 6 h.

[0105] After the reaction was completed, the hydrogenation conversion rate of the reaction was calculated to be 64.10%.

[0106] Example 7

[0107] Take Xiaolongtan coal as raw material, crush it with a coal mill, sieve it to below 75μm, and dry it at 120℃ for later use.

[0108] Weigh 5 g of Xiaolongtan coal powder and add it into a 1 L three-necked round-bottom flask, then add 200 mL of 10 wt % hydrogen peroxide, connect a condenser to the top of the flask for cooling, heat to 40 °C and stir to carry out oxidation reaction for 300 min.

[0109] After the reaction is completed, the reaction mixture is filtered using a polytetrafluoroethylene water filter membrane in a sand core funnel to obtain an oxidation residue solid and an oxidation depolymerization product aqueous solution. The oxidation residue solid is dried at 120° C. and then weighed.

[0110] Add 1-2 g of 5 wt% Pd / SiO granulated to 380-830 μm into the aqueous solution of the oxidative depolymerization product. 2 The catalyst was reacted at room temperature for 24 hours, and after the remaining hydrogen peroxide was decomposed, it was filtered and the catalyst was recovered for recycling.

[0111] The filtrate obtained by filtration was evaporated to remove the solvent water, dried at 120° C., and ground to obtain a solid oxidative depolymerization product, which was weighed and used as a raw material for the catalytic hydrogenation process.

[0112] Based on the mass balance of the dry ash-free basis of the above-mentioned raw material Xiaolongtan coal, the obtained oxidation residue solid and the oxidative depolymerization product solid, the conversion rate of the above-mentioned oxidative depolymerization process was 83.12%, and the yield of the solid oxidative depolymerization product was 38.01%.

[0113] Add 50 mg of catalyst 20% SiW into a 50 mL high temperature and high pressure reactor. 12 -1%Pd / SiO 2 , 100 mg of oxidative depolymerization product solid, 20 mL of methanol, filled with 1 MPa of hydrogen, set the stirring speed to 400 r / min, the reaction temperature to 350°C, and the reaction time to 6 h.

[0114] After the reaction was completed, the hydrogenation conversion rate of the reaction was calculated to be 83.97%.

[0115] Example 8

[0116] Use Shenhua lump coal as raw material, crush it with a coal mill, sieve it to below 75μm, and dry it at 120℃ for later use.

[0117] Weigh 5 g of Shenhua lump coal powder and add it into a 1 L three-necked round-bottom flask, then add 200 mL of 30 wt % hydrogen peroxide, connect a condenser to the top of the flask for cooling, heat to 70 °C and stir to carry out oxidation reaction for 600 min.

[0118] After the reaction is completed, the reaction mixture is filtered using a polytetrafluoroethylene water filter membrane in a sand core funnel to obtain an oxidation residue solid and an oxidation depolymerization product aqueous solution. The oxidation residue solid is dried at 120° C. and then weighed.

[0119] Add 1-2 g of 5 wt% Pd / SiO granulated to 380-830 μm into the aqueous solution of the oxidative depolymerization product. 2 The catalyst was reacted at room temperature for 24 hours, and after the remaining hydrogen peroxide was decomposed, it was filtered and the catalyst was recovered for recycling.

[0120] The filtrate obtained by filtration was evaporated to remove the solvent water, dried at 120° C., and ground to obtain a solid oxidative depolymerization product, which was weighed and used as a raw material for the catalytic hydrogenation process.

[0121] Based on the mass balance of the above raw material Shenhua lump coal powder, the obtained oxidation residue solid and the oxidative depolymerization product solid on a dry ash-free basis, the conversion rate of the above oxidative depolymerization process was 70.91%, and the yield of the solid oxidative depolymerization product was 34.91%.

[0122] Add 50 mg of catalyst 20% SiW into a 50 mL high temperature and high pressure reactor. 12 -1%Pd / SiO 2 , 100 mg of oxidative depolymerization product solid, 20 mL of ethanol, 3 MPa of hydrogen gas was charged, the stirring speed was set to 400 r / min, the reaction temperature was 350°C, and the reaction time was 6 h.

[0123] After the reaction was completed, the hydrogenation conversion rate of the reaction was calculated to be 59.20%.

[0124] Example 9

[0125] 1 kg of Naomaohu coal crushed to 75 μm and dried was weighed and added to the oxidation reactor, and then 20 L of 30 wt% hydrogen peroxide was added. The mixture was heated to 60° C. under normal pressure and stirred for oxidation reaction for 150 min.

[0126] The oxidative depolymerization product aqueous solution was filtered to a solution containing 5 wt% Pd / SiO 2The catalyst was placed in a hydrogen peroxide decomposition device, reacted at room temperature for 24 hours, and then filtered into a first distillation device. After evaporating the solvent, the solid oxidative depolymerization product was dried and crushed.

[0127] The above-mentioned oxidative depolymerization conversion rate is 70.36%, and the yield of solid oxidative depolymerization product is 35.66%.

[0128] The hydrogenation reactor was set to a reaction temperature of 350 °C, a reaction time of 6 h, a hydrogen pressure of 3 MPa, a solvent of cyclohexane, and a catalyst of 20% SiW 12 -1%Pd / SiO 2 The solid product of Naomaohu coal oxidation depolymerization obtained above was used as a reactant for catalytic hydrogenation reaction, and the reaction conversion rate could reach 65.87%.

[0129] After the reaction, the solvent is distilled and recovered by a second distillation device for cyclic use.

[0130] Example 10

[0131] 1 kg of Naomaohu coal crushed to 75 μm and dried was weighed and added to an oxidation reactor, and then 20 L of 30 wt% hydrogen peroxide was added. The mixture was heated to 60° C. under normal pressure and stirred for oxidation reaction for 300 min.

[0132] The oxidative depolymerization product aqueous solution was filtered to a solution containing 5 wt% Pd / SiO 2 The catalyst was placed in a hydrogen peroxide decomposition device, reacted at room temperature for 24 hours, and then filtered into a first distillation device. After evaporating the solvent, the solid oxidative depolymerization product was dried and crushed.

[0133] The above-mentioned oxidative depolymerization conversion rate was 73.54%, and the yield of solid oxidative depolymerization product was 36.01%.

[0134] The hydrogenation reactor was set to a reaction temperature of 300 °C, a reaction time of 6 h, a hydrogen pressure of 3 MPa, a solvent of cyclohexane, and a catalyst of 20% SiW 12 -1%Pd / SiO 2 The solid product of Naomaohu coal oxidation depolymerization obtained above was used as a reactant for catalytic hydrogenation reaction, and the reaction conversion rate could reach 55.21%.

[0135] After the reaction, the solvent is distilled and recovered by a second distillation device for cyclic use.

[0136] Embodiment 11

[0137] 1 kg of Xiaolongtan coal crushed to 75 μm and dried was weighed and added to an oxidation reactor, and then 20 L of 30 wt% hydrogen peroxide was added. The mixture was heated to 50° C. under normal pressure and stirred for oxidation reaction for 150 min.

[0138] The oxidative depolymerization product aqueous solution was filtered to a solution containing 5 wt% Pd / SiO2 The catalyst was placed in a hydrogen peroxide decomposition device, reacted at room temperature for 24 hours, and then filtered into a first distillation device. After evaporating the solvent, the solid oxidative depolymerization product was dried and crushed.

[0139] The above-mentioned oxidative depolymerization conversion rate is 78.17%, and the yield of solid oxidative depolymerization product is 41.96%.

[0140] The hydrogenation reactor was set to a reaction temperature of 350 °C, a reaction time of 6 h, a hydrogen pressure of 3 MPa, a solvent of cyclohexane, and a catalyst of 20% SiW 12 -1%Pd / SiO 2 The solid product of Xiaolongtan coal oxidation depolymerization obtained above was used as a reactant for catalytic hydrogenation reaction, and the reaction conversion rate could reach 70.79%.

[0141] After the reaction, the solvent is distilled and recovered by a second distillation device for cyclic use.

[0142] Comparative Example 1

[0143] The Naomaohu coal powder with a size of less than 75 μm in Example 1 was used as raw material, and the oxidative depolymerization process was not performed, but the hydrocracking reaction was directly performed.

[0144] Add 50 mg of catalyst 20% SiW into a 50 mL high temperature and high pressure reactor. 12 -1%Pd / SiO 2 , 100 mg of the Naomaohu coal powder of Example 1, 20 mL of cyclohexane, 3 MPa of hydrogen gas were charged, the stirring speed was set to 400 r / min, the reaction temperature was 330°C, and the reaction time was 6 h.

[0145] After the reaction, it was calculated that the hydrogenation conversion rate of Naomaohu coal was only 33.36%.

[0146] Compared with Example 1, in which the Naomaohu coal is first oxidized with hydrogen peroxide to obtain an oxidative depolymerization solid product and then catalytically hydrogenated, the Naomaohu coal powder has not undergone preliminary depolymerization by hydrogen peroxide oxidation, and the cross-linking and association between its macromolecular organic matter is still relatively stable, so its hydrogenation conversion rate is greatly reduced compared with Example 1, indicating that the oxidative depolymerization process makes the structure of low-rank coal tend to be loose, and the method of first oxidation and then hydrogenation is easier to carry out than direct hydrogenation liquefaction of raw coal.

[0147] The above embodiments of the present invention do not describe all the details in detail, nor limit the present invention to the above embodiments. Various changes, modifications, substitutions and variations made by ordinary technicians in this field without departing from the principles and purpose of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing oil products by two-step mild catalytic cracking of low-rank coal by oxidation-hydrogenation, comprising: 1) Using low-rank coal as a catalytic cracking raw material, and subjecting the low-rank coal to an oxidative depolymerization reaction using hydrogen peroxide; 2) Separating the liquid product of the oxidative depolymerization reaction, decomposing the remaining hydrogen peroxide therein, and evaporating to dryness to obtain a solid oxidative depolymerization product; 3) dispersing the oxidative depolymerization product solid in a solution containing 20 wt% SiW 12 -1wt% Pd / SiO2 catalyst in a hydrogen supply solvent, and hydrogen is charged to carry out a hydrocracking reaction; 4) Separate the hydrocracking reaction products, recover the hydrogen supply solvent by distillation, and prepare the target oil product.

2. The method for preparing oil products by two-step mild catalytic cracking of low-rank coal by oxidation-hydrogenation according to claim 1 is characterized in that The fineness of the low-rank coal is below 75 μm.

3. The method for preparing oil products by two-step mild catalytic cracking of low-rank coal by oxidation-hydrogenation according to claim 1 is characterized in that The oxidative depolymerization reaction is carried out at 30-70°C for 2-10 hours.

4. The method for preparing oil products by two-step mild catalytic cracking of low-rank coal by oxidation-hydrogenation according to claim 1 is characterized in that The concentration of hydrogen peroxide is 5 to 30 wt%.

5. The method for preparing oil products by two-step mild catalytic cracking of low-rank coal by oxidation-hydrogenation according to claim 1, characterized in that The residual hydrogen peroxide in the liquid product of the oxidative depolymerization reaction is decomposed and removed in the presence of a Pd / SiO2 catalyst.

6. The method for preparing oil products by two-step mild catalytic cracking of low-rank coal by oxidation-hydrogenation according to claim 5, characterized in that The Pd / SiO2 catalyst is obtained by impregnating palladium chloride onto fumed silica by an impregnation method, drying and grinding, calcining in an air atmosphere at 400° C. for 4 hours, and then reducing in hydrogen at 200° C. for 2 hours.

7. The method for preparing oil products by two-step mild catalytic cracking of low-rank coal by oxidation-hydrogenation according to claim 5, characterized in that A 5wt% Pd / SiO2 catalyst with a particle size of 380-830 μm was used.

8. The method for preparing oil products by two-step mild catalytic cracking of low-rank coal by oxidation-hydrogenation according to claim 1 is characterized in that The hydrogen-donating solvent is any one of cyclohexane, tetralin, decalin, isopropanol, methanol or ethanol.

9. The method for preparing oil products by two-step mild catalytic cracking of low-rank coal by oxidation-hydrogenation according to claim 1, characterized in that The hydrocracking reaction is carried out at an initial hydrogen pressure of 1 to 3 MPa and at 280 to 380° C. for 2 to 6 hours.

10. The method for preparing oil products by two-step mild catalytic cracking of low-rank coal by oxidation-hydrogenation according to claim 1, characterized in that The 20wt%SiW 12 -1wt% Pd / SiO2 catalyst is obtained by impregnating palladium chloride onto fumed silica by impregnation method, drying and grinding, calcining at 400°C in air atmosphere for 4 hours, impregnating silicotungstic acid, and reducing with hydrogen at 200°C for 2 hours.

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