A high-temperature anti-sintering biochar-based tar reforming catalyst and its preparation method

Abstract

This invention provides a high-temperature anti-sintering biochar-based tar reforming catalyst and its preparation method, belonging to the field of catalyst technology. The invention involves mixing biochar and porous mullite, then subjecting the mixture to ultrasonic treatment in a nickel nitrate solution. After filtration and drying, a composite catalyst precursor is obtained; this precursor is then calcined to obtain the high-temperature anti-sintering biochar-based tar reforming catalyst. The catalyst prepared by this invention maintains structural stability even in a high-temperature medium environment of 800℃, thereby significantly improving the service life of tar reforming catalysts.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a high-temperature anti-sintering biochar-based tar reforming catalyst and its preparation method. Background Technology

[0002] Biomass waste is the world's largest renewable resource. Converting it into clean fuel gas through pyrolysis and gasification technology is a crucial means of replacing traditional fossil fuels. This gas can then be used to produce chemicals, fuels, or for power generation and heating. However, the purification of tar byproducts is a bottleneck in the development of biomass waste pyrolysis and gasification technology. The key lies in developing various supported nano-metal catalysts to catalytically reform tar into small-molecule combustible gases. Biochar-supported nano-metal catalysts, in particular, have attracted widespread attention due to their low cost, wide availability of raw materials, and high activity. However, in the high-temperature reaction medium of tar reforming, biochar-supported nano-metal catalysts are prone to rapid deactivation due to the high-temperature sintering of nano-metals, resulting in a short lifespan and severely limiting their potential for industrial application.

[0003] Mullite (3Al₂O₃·2SiO₂) belongs to the orthorhombic crystal system and is a sillimanite structure with oxygen vacancy defects. Porous mullite has an ordered pore structure, high pore specific surface area, and characteristics such as low high-temperature creep rate, high load softening temperature, and good resistance to chemical corrosion. Therefore, porous mullite has great potential as a rigid framework for tar reforming catalysts. Summary of the Invention

[0004] In view of this, the present invention provides a high-temperature anti-sintering biochar-based tar reforming catalyst and its preparation method. The present invention involves mixing biochar and porous mullite, then subjecting the mixture to ultrasonic treatment in a nickel nitrate solution, followed by filtration and drying to obtain a composite catalyst precursor; this precursor is then calcined to obtain the high-temperature anti-sintering biochar-based tar reforming catalyst. The catalyst prepared by the present invention can maintain structural stability even in a high-temperature medium environment of 800℃, thereby significantly improving the service life of the tar reforming catalyst.

[0005] This invention is achieved using the following technical solution:

[0006] A method for preparing a high-temperature resistant sintering biochar-based tar reforming catalyst includes the following steps:

[0007] S1. Preparation of composite catalyst precursor:

[0008] The biochar was dried, ground, and sieved to obtain biochar powder.

[0009] The porous mullite was ground and sieved to obtain porous mullite powder;

[0010] The biochar powder and the porous mullite powder were mixed at a mass ratio of 4.5:1, and then ball-milled to obtain a mixture.

[0011] The mixture is mixed with nickel nitrate solution and then ultrasonically treated for 2 to 4 hours.

[0012] After filtration and drying, the composite catalyst precursor was obtained.

[0013] S2, calcination treatment:

[0014] The composite catalyst precursor was placed in a quartz tube furnace and calcined at 700℃~900℃ for 1~5h under an inert atmosphere to obtain a high-temperature anti-sintering biochar-based tar reforming catalyst.

[0015] Preferably, the biochar is wood chips.

[0016] Preferably, the biochar powder has a particle size of 100-200 mesh.

[0017] Preferably, the porous mullite powder has a particle size of 100-200 mesh.

[0018] Preferably, the concentration of the nickel nitrate solution is 2.0 mol / L, and the mass-to-volume ratio of the mixture to the nickel nitrate solution is 1:9 g / ml.

[0019] Preferably, the ball mill rotates at 5000 rpm and the milling time is 3 hours.

[0020] Preferably, the inert atmosphere is nitrogen.

[0021] Compared with the prior art, the beneficial effects of this invention are:

[0022] This invention provides a method for preparing a high-temperature anti-sintering biochar-based tar reforming catalyst. The method uses biochar as an anchoring support for nano-metals. The pore structure of biochar influences the anchoring position of the nano-metals, which is crucial for inhibiting the sintering growth of nano-metals in high-temperature media. Using mechanical ball milling pretreatment, wood biochar is uniformly dispersed on the inner surface of porous mullite channels, serving as adsorption sites for metal ions. After calcination, nanoparticles are uniformly distributed on the surface of the biochar support within the porous mullite. This invention fully utilizes the high-temperature stable porous structure of mullite as a framework, effectively suppressing the tendency for excessive growth of metal nanoparticles induced by structural collapse of conventional biochar supports in high-temperature media due to the Oswald ripening effect, thereby improving the catalyst's anti-sintering deactivation performance during high-temperature tar reforming. Attached Figure Description

[0023] Figure 1 The surface morphology of the catalyst described in Example 1 after the catalytic reforming reaction of tar is shown. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0025] This invention provides a method for preparing a high-temperature anti-sintering biochar-based tar reforming catalyst, comprising the following steps:

[0026] S1. Preparation of composite catalyst precursor:

[0027] The biochar was dried, ground, and sieved to obtain biochar powder.

[0028] The porous mullite was ground and sieved to obtain porous mullite powder;

[0029] The biochar powder and the porous mullite powder were mixed at a mass ratio of 4.5:1, and then ball-milled to obtain a mixture.

[0030] The mixture is mixed with nickel nitrate solution and then ultrasonically treated for 2 to 4 hours.

[0031] After filtration and drying, the composite catalyst precursor was obtained.

[0032] S2, calcination treatment:

[0033] The composite catalyst precursor was placed in a quartz tube furnace and calcined at 700℃~900℃ for 1~5h under an inert atmosphere to obtain a high-temperature anti-sintering biochar-based tar reforming catalyst.

[0034] In some embodiments, the biochar is wood chips.

[0035] In some embodiments, the particle size of the biochar powder is 100-200 mesh.

[0036] In some embodiments, the porous mullite powder has a particle size of 100-200 mesh.

[0037] In some embodiments, the concentration of the nickel nitrate solution is 2.0 mol / L, and the mass-to-volume ratio of the mixture to the nickel nitrate solution is 1:9 g / ml.

[0038] In some embodiments, the ball mill rotates at 5000 rpm and the milling time is 3 hours.

[0039] In some embodiments, the inert atmosphere is nitrogen.

[0040] It should be noted that, unless otherwise specified, the raw materials used in the following embodiments can be obtained by commercial purchase or conventional methods, and the experimental methods without specific conditions are all conventional methods and conditions well known in the art.

[0041] Example 1

[0042] A method for preparing a high-temperature anti-sintering biochar-based tar reforming catalyst, comprising the following steps:

[0043] S1. Preparation of composite catalyst precursor:

[0044] The wood chips were dried, ground, and passed through a 150-mesh sieve to obtain biochar powder.

[0045] Porous mullite was ground and passed through a 150-mesh sieve to obtain porous mullite powder;

[0046] The biochar powder and the porous mullite powder were mixed at a mass ratio of 4.5:1, and then ball-milled to obtain a mixture. The ball milling speed was 5000 rpm and the ball milling time was 3 hours.

[0047] The mixture was mixed with a 2.0 mol / L nickel nitrate solution at a mass-to-volume ratio of 1:9 g / mL and then ultrasonicated for 2 hours.

[0048] After filtration and drying, the composite catalyst precursor was obtained.

[0049] S2, calcination treatment:

[0050] The composite catalyst precursor was placed in a quartz tube furnace and calcined at 800°C for 1 hour under a nitrogen atmosphere to obtain a high-temperature anti-sintering biochar-based tar reforming catalyst.

[0051] Example 2

[0052] A method for preparing a high-temperature anti-sintering biochar-based tar reforming catalyst, comprising the following steps:

[0053] S1. Preparation of composite catalyst precursor:

[0054] The wood chips were dried, ground, and passed through a 150-mesh sieve to obtain biochar powder.

[0055] Porous mullite was ground and passed through a 150-mesh sieve to obtain porous mullite powder;

[0056] The biochar powder and the porous mullite powder were mixed at a mass ratio of 4.5:1, and then ball-milled to obtain a mixture. The ball milling speed was 5000 rpm and the ball milling time was 3 hours.

[0057] The mixture was mixed with a 2.0 mol / L nickel nitrate solution at a mass-to-volume ratio of 1:9 g / mL and then sonicated for 4 hours.

[0058] After filtration and drying, the composite catalyst precursor was obtained.

[0059] S2, calcination treatment:

[0060] The composite catalyst precursor was placed in a quartz tube furnace and calcined at 800°C for 1 hour under a nitrogen atmosphere to obtain a high-temperature anti-sintering biochar-based tar reforming catalyst.

[0061] Example 3

[0062] A method for preparing a high-temperature resistant sintering biochar-based tar reforming catalyst includes the following steps:

[0063] S1. Preparation of composite catalyst precursor:

[0064] The wood chips were dried, ground, and passed through a 150-mesh sieve to obtain biochar powder.

[0065] Porous mullite was ground and passed through a 150-mesh sieve to obtain porous mullite powder;

[0066] The biochar powder and the porous mullite powder were mixed at a mass ratio of 4.5:1, and then ball-milled to obtain a mixture. The ball milling speed was 5000 rpm and the ball milling time was 3 hours.

[0067] The mixture was mixed with a 2.0 mol / L nickel nitrate solution at a mass-to-volume ratio of 1:9 g / mL and then ultrasonicated for 2 hours.

[0068] After filtration and drying, the composite catalyst precursor was obtained.

[0069] S2, calcination treatment:

[0070] The composite catalyst precursor was placed in a quartz tube furnace and calcined at 800°C for 5 hours under a nitrogen atmosphere to obtain a high-temperature anti-sintering biochar-based tar reforming catalyst.

[0071] The high-temperature anti-sintering biochar-based tar reforming catalysts prepared in Examples 1-3 were used in low-temperature catalytic reforming experiments of tar, with the following procedures:

[0072] The polycyclic aromatic hydrocarbons phenanthrene and pyrene were selected as model compounds of typical tar recalcitrant components. High-temperature steam (190℃) prepared by a steam generator was used as the catalytic reaction medium to carry out low-temperature reforming of tar with nickel-based catalysts. The reforming reaction temperature was set to 800℃.

[0073] Among them, the analysis of tar low-temperature catalytic reforming products: the gaseous products after the tar catalytic reforming reaction were collected using a gas collection bag, and the components of the gaseous products were quantitatively analyzed according to the national standard GB / T10410-2008 (gas chromatography analysis of the constant components of manufactured gas and liquefied petroleum gas). The test results are shown in Table 1.

[0074] The surface morphology of the catalyst after the reaction was studied using scanning electron microscopy (SEM). The results showed that the nanoparticles remained uniformly distributed and did not exhibit sintering growth. (See attached figures.) Figure 1 .

[0075] Table 1. Experimental results of low-temperature reforming conversion efficiency and cracking small molecule gas components of tar.

[0076] project Example 1 Example 2 Example 3 Fibonacci conversion rate (%) 95.2 96.8 93.4 <![CDATA[Phi-H2 (%)]]> 63.5 68.2 64.5 Fiber-CO (%) 20.1 15.4 21.5 <![CDATA[Phe - CH4(%)]]> 5.1 3.2 6.1 <![CDATA[Fe - CO2 (%)]]> 11.3 13.2 7.9 Pyrene conversion rate (%) 91.7 94.3 93.5 <![CDATA[Pyrene - H2 (%)]]> 62.6 61.2 60.8 Pyrene-CO (%) 23.4 26.3 25.7 <![CDATA[Pyrene - CH4 (%)]]> 1.9 3.6 4.3 <![CDATA[Pyrene - CO2 (%)]]> 12.1 8.9 9.2

[0077] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a high-temperature anti-sintering biochar-based tar reforming catalyst, characterized in that, Includes the following steps: S1. Preparation of composite catalyst precursor: The biochar was dried, ground, and sieved to obtain biochar powder. The porous mullite was ground and sieved to obtain porous mullite powder; The biochar powder and the porous mullite powder were mixed at a mass ratio of 4.5:1, and then ball-milled to obtain a mixture. The mixture is mixed with nickel nitrate solution and then ultrasonically treated for 2 to 4 hours. After filtration and drying, the composite catalyst precursor was obtained. S2, calcination treatment: The composite catalyst precursor was placed in a quartz tube furnace and calcined at 700℃~900℃ for 1~5h under an inert atmosphere to obtain a high-temperature anti-sintering biochar-based tar reforming catalyst.

2. The preparation method according to claim 1, characterized in that, The biochar is wood chips.

3. The preparation method according to claim 1, characterized in that, The biochar powder has a particle size of 100-200 mesh.

4. The preparation method according to claim 1, characterized in that, The porous mullite powder has a particle size of 100-200 mesh.

5. The preparation method according to claim 1, characterized in that, The concentration of the nickel nitrate solution is 2.0 mol / L, and the mass-to-volume ratio of the mixture to the nickel nitrate solution is 1:9 g / ml.

6. The preparation method according to claim 1, characterized in that, The ball mill rotates at 5000 rpm and the milling time is 3 hours.

7. The preparation method according to claim 1, characterized in that, The inert atmosphere is nitrogen.

8. A high-temperature resistant, sintering-resistant biochar-based tar reforming catalyst, characterized in that, It is prepared using any one of the methods described in claims 1 to 7.

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