A solid catalyst for coal-to-synthesis gas, and its preparation method and application

Abstract

The present invention belongs to the technical field of catalyst preparation and coal chemical industry, and discloses a coal-to-syngas solid catalyst and its preparation method and application. The preparation method is as follows: after drying, grinding and screening pulverized coal, an organic solvent is added to swell it, and then rare earth metal salt and transition metal salt are added, acid is added to adjust the pH, and after mixing evenly, the mixture is heated to 200-300°C for reaction; the solid powder after the reaction is washed and dried to obtain an atomic-level dispersed supported coal-to-syngas solid catalyst. The present invention uses pulverized coal with low utilization rate to prepare a coal-to-syngas catalyst, and the waste acid and organic solvent generated in the preparation process can be repeatedly recycled to reduce the emission of pollutants. The preparation method is simple, the energy consumption is low, and the dual benefits of economy and environment are achieved. The prepared catalyst is applied to a fixed bed reactor for coal catalytic gasification to produce natural gas, which can effectively improve the utilization rate of coal and the conversion rate of coal into gas phase products.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation and coal chemical industry, and specifically relates to a solid catalyst for synthesizing coal-to-gas, a preparation method and application thereof. Background Art

[0002] Coal-to-syngas is a key technology for achieving clean, efficient and comprehensive utilization of coal in coal chemical industry. It is an important way to convert coal and one of the key technologies for synthetic chemicals, combined cycle power generation and coal-to-substitute natural gas. The method for preparing coal-to-syngas in the prior art is to gasify low-rank coal to prepare CO and H2. Specifically, low-rank coal is pyrolyzed to obtain upgraded coal, and synthesis gas or coal gas is prepared using upgraded coal, H2O and O2. This technology has a low coal conversion rate, which greatly wastes coal resources in low-rank coal, causes environmental pollution, and the output of the prepared synthesis gas is low.

[0003] Patent CN 111253979A discloses a method for producing syngas from coal, which is to make a mixed gas from dried low-rank coal under oxygen-free or low-oxygen conditions, and fully utilize hydrocarbons including CH4 in the mixed gas to prepare syngas mainly containing CO and H2. The syngas has a high calorific value and fully and effectively utilizes the volatile matter in the low-rank coal. Unfortunately, this method is costly and the process is cumbersome.

[0004] Patent CN 110862840A discloses a method for producing synthesis gas using wastewater and upgraded coal. The method comprises: gasifying and reducing dried low-rank coal under anaerobic or micro-aerobic conditions to remove most of the volatile matter to obtain upgraded coal. The upgraded coal is reacted with water vapor under anaerobic or micro-aerobic conditions to prepare synthesis gas containing H2 and CO. The coal substances in the low-rank coal are fully and effectively utilized. However, the process has high requirements for the process equipment, many process steps, and complex operation.

[0005] Pulverized coal is a solid waste produced by coal chemical process such as water-coal slurry gasification. It has a very low utilization rate and most of it is dumped as waste, resulting in a huge waste of resources.

[0006] Highly dispersed metal-based catalysts have advantages such as high reactive sites and large specific surface area, and many studies have been reported. However, due to the small particle size of the material, metal atoms are easy to aggregate to form metal particles or metal oxides, thereby reducing the activity and stability of the catalyst. On the other hand, the high cost of the catalyst precursor also limits its application in actual industry. Summary of the invention

[0007] In view of the shortcomings and deficiencies of the above prior art, the primary purpose of the present invention is to provide a method for preparing a solid catalyst for coal-to-syngas. The solid catalyst is prepared by using pulverized coal produced by a water-coal slurry gasification process, has high catalytic efficiency, and the organic solvent and hydrochloric acid produced during the preparation process can be recycled, which has significant economic and environmental benefits.

[0008] Another object of the present invention is to provide a coal-to-syngas solid catalyst prepared by the above method.

[0009] Another object of the present invention is to provide application of the above solid catalyst in catalysis of coal-to-syngas.

[0010] The purpose of the present invention is achieved through the following technical solutions:

[0011] A method for preparing a solid catalyst for coal-to-syngas comprises the following steps:

[0012] (1) Dry, grind and sieve the pulverized coal, add an organic solvent to swell it, then add rare earth metal salt and transition metal salt, add acid to adjust the pH, mix well and heat to 200-300°C for reaction;

[0013] (2) Washing and drying the solid powder after the reaction in step (1) to obtain an atomic-level dispersed supported coal-to-syngas solid catalyst.

[0014] Furthermore, the coal powder in step (1) is coal powder produced by a water-coal slurry gasification process.

[0015] Furthermore, the drying temperature in step (1) is preferably 80-105° C., and the grinding and screening refers to grinding through a 100-200 mesh sieve.

[0016] Furthermore, the organic solvent in step (1) is one or a mixed solvent of two or more selected from tetralin, N,N-dimethylformamide (DMF), toluene, pyridine and cyclohexanone.

[0017] Furthermore, in step (1), the volume mass ratio of the amount of the organic solvent added to the pulverized coal is 2 to 5:1 (L / kg).

[0018] Furthermore, the rare earth metal salt in step (1) is one or more of scandium salt, yttrium salt, lanthanum salt and cerium salt.

[0019] Furthermore, the transition metal salt in step (1) is one or more of an iron salt, a cobalt salt and a nickel salt, preferably an iron salt.

[0020] Furthermore, in step (1), the mass ratio of the pulverized coal to the rare earth metal salt and the transition metal salt is 1:0.2-0.5:0.2-0.5; preferably 1:0.3-0.4:0.3-0.4.

[0021] Furthermore, in step (1), the acid addition to adjust the pH is preferably carried out by using 1-3 mol / L hydrochloric acid to adjust the pH to 1-3.

[0022] Furthermore, the reaction in step (1) is carried out under pressurized or normal pressure reflux conditions, and the reaction time is 2 to 5 hours.

[0023] Furthermore, the volatilized gas (containing hydrochloric acid and organic solvent) in the reaction in step (1) is condensed and refluxed at 70-100° C. and then collected and reused.

[0024] Furthermore, the washing in step (2) refers to washing with hydrochloric acid first and then washing with water; and the drying refers to drying at 100°C.

[0025] The preparation process flow chart of the above-mentioned coal-to-syngas solid catalyst is as follows: Figure 1 shown.

[0026] A coal-to-synthesis gas solid catalyst is prepared by the above method.

[0027] The application of the above solid catalyst in coal-to-syngas catalysis.

[0028] Furthermore, the application step is: uniformly mixing the solid catalyst with coal powder or coal blocks, and applying it to a fixed bed reactor for catalytic coal gasification to produce natural gas, so as to improve the utilization rate of coal and the conversion rate of coal into gas products.

[0029] Further preferably, the mixing amount of the solid catalyst is 1% to 4% of the mass of the coal powder or coal block.

[0030] The technical principle of the present invention is as follows: first, in order to reduce costs, we use pulverized coal after the reaction of the water-coal slurry gasification process as raw material. In order to improve the reaction activity of coal powder, an organic solvent is added to perform swelling pretreatment at a certain temperature. The organic solvent includes tetralin, N,N-dimethylformamide (DMF), toluene, pyridine or cyclohexanone. Secondly, in order to prevent the agglomeration of metal atoms, we use an acid such as hydrochloric acid to acidify and provide a certain acidic environment so that rare earth metals and transition metals are uniformly doped in the catalyst. The waste acid and organic solvent generated during the preparation of this catalyst can be recycled, and the obtained solid catalyst can be flexibly proportioned with coal powder or coal blocks according to actual needs during use, which is convenient and efficient, effectively improving the utilization rate of coal and the conversion rate of coal into gas phase products.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The preparation method of the present invention uses pulverized coal after the water-coal slurry gasification process reaction as raw material, has low cost, simple preparation method, low energy consumption, high economic benefit, and can realize the resource utilization of solid waste; and the effective metal components of the obtained catalyst are dispersed at the atomic level, have high catalytic activity for coal-to-syngas, and achieve dual economic and environmental benefits.

[0033] (2) The preparation method of the present invention can effectively avoid the agglomeration of metal atoms by adjusting the pH of the solution, thereby improving the catalytic activity.

[0034] (3) The coal-to-syngas solid catalyst of the present invention can be directly mixed with coal powder and coal blocks in any proportion, and after being evenly mixed, it can be applied to a fixed bed reactor for catalytic gasification of coal to produce natural gas, effectively improving the utilization rate of coal and the conversion rate of coal into gas products. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The present invention is a process flow chart for preparing the solid catalyst for coal-to-syngas.

[0036] Figure 2 This is the XRD diagram of the coal-to-syngas solid catalyst obtained in Example 2 of the present invention.

[0037] Figure 3 This is a SEM image of the coal-to-syngas solid catalyst obtained in Example 2 of the present invention.

[0038] Figure 4 This is a TEM image of the coal-to-syngas solid catalyst obtained in Example 2 of the present invention. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0040] Example 1

[0041] The method for preparing a solid catalyst for coal-to-syngas of this embodiment comprises the following specific steps:

[0042] (1) Powdered coal was dried at 105°C and ground to pass through a 200-mesh sieve. 60 kg of sieved coal powder and 180 L of tetralin were mixed and swollen at 80°C. After swelling, 12 kg of cerium sulfate and 12 kg of ferric chloride were added. 1M hydrochloric acid was added to adjust the pH of the solution to 2. After mixing, the mixture was heated to 200-300°C and reacted for 4 hours. The volatilized gas (containing hydrochloric acid and tetralin) during the reaction was condensed and refluxed at 80°C and then reused.

[0043] (2) The solid powder after the reaction in step (1) was washed with 3M HCl for 12 hours, then washed with water, and dried at 100° C. to obtain an atomically dispersed supported coal-to-syngas solid catalyst.

[0044] Example 2

[0045] The method for preparing a solid catalyst for coal-to-syngas of this embodiment comprises the following specific steps:

[0046] (1) Powdered coal was dried at 105°C and ground to pass through a 200-mesh sieve. 60 kg of sieved coal powder and 180 L of tetralin were mixed and swollen at 80°C. After swelling, 18 kg of cerium sulfate and 18 kg of ferric chloride were added. 1 M hydrochloric acid was added to adjust the pH of the solution to 2. After mixing, the mixture was heated to 200-300°C and reacted for 4 hours. The volatilized gas (containing hydrochloric acid and tetralin) during the reaction was condensed and refluxed at 80°C and then reused.

[0047] (2) The solid powder after the reaction in step (1) was washed with 3M HCl for 12 hours, then washed with water, and dried at 100° C. to obtain an atomically dispersed supported coal-to-syngas solid catalyst.

[0048] The XRD pattern, SEM pattern and TEM pattern of the solid catalyst obtained in this example are shown as follows: Figures 2 to 4 As shown. Figure 2 It can be seen that there are two broad diffraction peaks at about 24° and 43°, which belong to the (002) and (100) crystal planes of amorphous carbon materials. In addition, no diffraction peaks of iron and cerium compounds were detected in different samples, indicating that the crystallinity of iron and cerium compounds in the materials is poor. Excluding the existence of large particles and agglomerates, only a small amount of iron and cerium elements are doped in the carbon materials. Figure 3 It can be seen that the catalyst particles are irregular block structures with a size of 100 to 200 nm. Figure 4 A in the middle is the TEM dark field image of the catalyst, from which it can be seen that the metal elements are evenly dispersed. Figure 4 B in the figure shows irregular lattice fringes, indicating that the catalyst has an amorphous structure, and the circled part is the metal element. Figure 4 C is the HAADF-STEM image of the catalyst and the corresponding Fe-Ce element mapping in the selected area ( Figure 4 D), indicating that ferrocerium was successfully doped into the carbon skeleton and was evenly dispersed in the catalyst.

[0049] Example 3

[0050] The method for preparing a solid catalyst for coal-to-syngas of this embodiment comprises the following specific steps:

[0051] (1) Powdered coal was dried at 105°C and ground to pass through a 200-mesh sieve. 60 kg of sieved coal powder and 180 L of tetralin were mixed and swollen at 80°C. After swelling, 24 kg of cerium sulfate and 24 kg of ferric chloride were added. 1 M hydrochloric acid was added to adjust the pH of the solution to 2. After mixing, the mixture was heated to 200-300°C and reacted for 4 hours. The volatilized gas (containing hydrochloric acid and tetralin) during the reaction was condensed and refluxed at 80°C and then reused.

[0052] (2) The solid powder after the reaction in step (1) was washed with 3M HCl for 12 hours, then washed with water, and dried at 100° C. to obtain an atomically dispersed supported coal-to-syngas solid catalyst.

[0053] Example 4

[0054] The method for preparing a solid catalyst for coal-to-syngas of this embodiment comprises the following specific steps:

[0055] (1) Powdered coal was dried at 105°C and ground to pass through a 200-mesh sieve. 60 kg of sieved coal powder and 180 L of tetralin were mixed and swollen at 80°C. After swelling, 30 kg of cerium sulfate and 30 kg of ferric chloride were added. 1 M hydrochloric acid was added to adjust the pH of the solution to 2. After mixing, the mixture was heated to 200-300°C and reacted for 4 hours. The volatilized gas (containing hydrochloric acid and tetralin) during the reaction was condensed and refluxed at 80°C and then reused.

[0056] (2) The solid powder after the reaction in step (1) was washed with 3M HCl for 12 hours, then washed with water, and dried at 100° C. to obtain an atomically dispersed supported coal-to-syngas solid catalyst.

[0057] Example 5

[0058] The products prepared in Examples 1 to 4 above are used as catalysts to carry out coal catalytic gasification reaction, and the steps are as follows:

[0059] The solid catalyst was mixed with coal powder at a mass ratio of 100:2 and then used in a fixed bed reactor for catalytic coal gasification to produce natural gas. The coal catalytic gasification reaction conditions were: in a stainless steel fixed bed reactor with an inner diameter of 32 cm and a height of 800 cm, the pressure of the reaction system was adjusted by argon. Coal catalytic gasification conditions: deionized water flow rate of 1.0 ml / min, reaction temperature of 937 K, and reaction system pressure of 3.4 MPa. The change in the conversion rate of catalytic coal into gas phase products over time and the amount of CH4 accumulated and precipitated are shown in Table 1.

[0060] Table 1 Conversion rate of coal into gas phase products and methane production

[0061]

[0062] From the results in Table 1, it can be seen that as the ratio of rare earth metal salt to transition metal salt increases, the catalyst performance first increases and then decreases. The best catalyst is the catalyst prepared in Example 2. When the reaction is carried out for 50 minutes, the conversion rate of coal into gas phase products reaches 19.3%, and the methane generation amount is 1.45mmolg -1 After 250 minutes of reaction, the conversion rate of coal into gas products reached 76.26%, and the methane production was 5.27 mmol g -1 , which are greater than those of the catalysts in other embodiments.

[0063] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing a solid catalyst for coal-to-syngas, characterized in that: The method comprises the following preparation steps: (1) After drying, grinding and screening pulverized coal, an organic solvent is added to swell the pulverized coal, and then rare earth metal salt and transition metal salt are added, acid is added to adjust the pH, and after mixing evenly, the mixture is heated to 200-300° C. for reaction; the rare earth metal salt is one or more of scandium salt, yttrium salt, lanthanum salt and cerium salt; the transition metal salt is one or more of iron salt, cobalt salt and nickel salt; the mass ratio of pulverized coal to rare earth metal salt and transition metal salt is 1:0.2-0.5:0.2-0.5; the acid addition to adjust the pH refers to using 1-3 mol / L hydrochloric acid to adjust the pH to 1-3; (2) washing and drying the solid powder after the reaction in step (1) to obtain an atomic-level dispersed supported coal-to-syngas solid catalyst; the effective metal components of the obtained catalyst are dispersed at the atomic level.

2. The method for preparing a solid catalyst for coal-to-synthesis gas according to claim 1, characterized in that: The coal powder in step (1) is the coal powder produced by the water-coal slurry gasification process; the drying temperature is 80-105° C., and the grinding and screening refers to grinding through a 100-200 mesh sieve.

3. The method for preparing a solid catalyst for coal-to-syngas according to claim 1, characterized in that: The organic solvent in step (1) is one or a mixed solvent of two or more selected from tetralin, N,N-dimethylformamide, toluene, pyridine and cyclohexanone, and the volume mass ratio of the added amount of the organic solvent to the pulverized coal is 2 to 5:1 in liters: kilograms.

4. The method for preparing a solid catalyst for coal-to-synthesis gas according to claim 1, characterized in that: The mass ratio of the pulverized coal to the rare earth metal salt and the transition metal salt is 1:0.3-0.4:0.3-0.

4.

5. The method for preparing a solid catalyst for coal-to-synthesis gas according to claim 1, characterized in that: The reaction in step (1) is carried out under pressurized or atmospheric reflux conditions, and the reaction time is 2 to 5 hours; the volatilized gas from the reaction is collected and recycled after condensation reflux at 70 to 100°C; the washing in step (2) refers to washing with hydrochloric acid first and then with water; the drying refers to drying at 100°C.

6. A solid catalyst for producing synthesis gas from coal, characterized in that: It is prepared by the method according to any one of claims 1 to 5.

7. Use of the solid catalyst according to claim 6 in catalysis of coal-to-syngas, characterized in that: The application steps are: uniformly mixing the solid catalyst with coal powder or coal blocks, and applying the solid catalyst to a fixed bed reactor for catalytic gasification of coal to produce natural gas, thereby improving the utilization rate of coal and the conversion rate of coal into gas phase products.

8. The use of the solid catalyst according to claim 7 in catalysis of coal-to-syngas, characterized in that: The mixing amount of the solid catalyst is 1% to 4% of the mass of the coal powder or coal block.

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