Monolithic catalyst for upgrading of biomass gas and preparation, catalytic method

Abstract

This invention discloses a monolithic catalyst for biomass gas upgrading, its preparation, and a catalytic method. The monolithic catalyst employs an impregnation method to load active components onto a honeycomb ceramic support, followed by drying and calcination to obtain the finished product. This catalyst has the function of catalytically converting biomass gas, effectively increasing its calorific value. While improving the utilization value of biomass gas, it also expands the application field of monolithic catalysts, providing conditions for large-scale industrial production of catalysts and possessing broad application prospects. This invention uses honeycomb ceramics as the catalyst support, providing excellent structural support for the loading and dispersion of active components, broadening the sources and application fields of catalyst supports, and simplifying the catalyst preparation process. The Ni-Co bimetallic catalyst for biomass gas upgrading catalyzes CO and H2 in biomass gas to generate methane and other low-carbon hydrocarbons with higher calorific value, increasing the yield of low-carbon hydrocarbons (C1-C3).

Description

Technical Field

[0001] This invention belongs to the field of biomass gas upgrading, specifically relating to an integral catalyst for biomass gas upgrading and its preparation and catalytic method. Background Technology

[0002] Biomass gasification technology is one of the effective technological pathways for the clean utilization of biomass energy. Its gasification product, biomass gas, can enable large-scale urban gas supply, partially replacing fossil fuel natural gas, and playing an important role in the future adjustment of my country's energy structure.

[0003] However, there are still some factors restricting the development potential of biomass gas, one of which is its low calorific value, only about one-quarter that of standard natural gas. Therefore, catalytic conversion of the combustible components of biomass gas to increase its lower heating value and meet the supply requirements of urban gas in my country is a major issue to be considered after the realization of biomass gasification. Summary of the Invention

[0004] The purpose of this invention is to provide an integral catalyst for upgrading biomass gas, which can solve the above-mentioned problems and improve the calorific value of biomass gas, as well as its preparation and catalytic method.

[0005] This invention discloses a monolithic catalyst for upgrading biomass gas. The catalyst support is a cylindrical monolithic honeycomb ceramic support; the active components are nickel and cobalt, accounting for 2-4% of the catalyst mass by metal weight.

[0006] Furthermore, the monolithic catalyst is a Ni-Co / honeycomb ceramic catalyst containing 2.0 wt.% nickel and 4.0 wt.% cobalt.

[0007] Furthermore, the honeycomb ceramic carrier has a size of Φ45×45mm, a particle size of 400 mesh, and its main chemical component is cordierite.

[0008] This invention also discloses a method for preparing an integral catalyst for upgrading biomass gas, comprising the following steps:

[0009] S1. The honeycomb ceramic support is immersed in a mixed solution composed of soluble salts of nickel and soluble salts of cobalt, and then dried to obtain the catalyst precursor;

[0010] S2. The catalyst precursor obtained in step S1 is placed in a muffle furnace and calcined to obtain the finished catalyst.

[0011] Furthermore, the soluble salt of nickel is nickel nitrate, and the soluble salt of cobalt is cobalt hydrochloride.

[0012] Furthermore, in step S1, the immersion temperature is 40-60℃; the immersion time is 12h.

[0013] Furthermore, in step S2, the roasting atmosphere is air; the roasting temperature is 400-500℃; and the roasting time is 4-6 hours.

[0014] This invention also discloses a catalytic method for an integral catalyst for upgrading biomass gas, comprising the following steps:

[0015] SA1. The monolithic catalyst described above or the monolithic catalyst prepared by the above method is placed in a fixed-bed reactor;

[0016] SA2. Under a nitrogen atmosphere, the temperature of the catalyst bed containing the monolithic catalyst is slowly raised to 450°C at a heating rate of 3-5°C / min. The gas is then switched to a reducing atmosphere of nitrogen and hydrogen, with hydrogen accounting for 15-30% of the total gas volume. The reduction is carried out at a constant temperature for 2-4 hours.

[0017] SA3. After the reduction is completed, switch to a nitrogen atmosphere and reduce the temperature inside the fixed bed reactor to 300°C. Then, introduce biomass fuel gas into the reactor. The feed dry gas composition is CO2 accounting for 20% of the total volume, N2 accounting for 12% of the total volume, and the remaining volume is H2 and CO, accounting for 68% of the total volume.

[0018] Furthermore, in step SA1, the pressure inside the fixed-bed reactor is 0.1-0.3 MPa, the temperature is 300-380℃, and the gas hourly space velocity is 750-1500 h⁻¹. -1 The H2 / CO ratio is 0.5-2.0, where H2 / CO represents the volume ratio of H2 to CO.

[0019] The combustible components CO and H2 in biomass gas pass through an integral catalyst from top to bottom along the axial direction in a fixed-bed reactor. They come into full contact with active metals Ni and Co on the catalyst surface and undergo dissociation, experiencing three processes: chain initiation, chain growth, and chain termination, ultimately generating low-carbon hydrocarbons such as CH4 and C2H6.

[0020] The beneficial effects of this invention are:

[0021] 1. This invention uses honeycomb ceramics as a catalyst support, which provides good structural support for the loading and dispersion of active components, broadens the sources and application fields of catalyst supports, and simplifies the catalyst preparation process; the Ni-Co bimetallic catalyst for biomass gas upgrading catalyzes CO and H2 in biomass gas to generate methane and other low-carbon hydrocarbons with higher calorific value. Compared with traditional single-metal catalysts, it can combine the advantages of the active components of two catalysts and increase the yield of low-carbon hydrocarbons (C1-C3).

[0022] 2. The catalyst of this invention is suitable for the process of upgrading biomass gas to meet the gas supply requirements of urban areas. It can effectively increase the calorific value of biomass gas, broaden the application scope of biomass gas, expand the application scale of biomass gas, and transform this renewable energy into a more usable and easy-to-use clean energy. Attached Figure Description

[0023] Figure 1 This is a system diagram of the catalyst preparation and catalytic method in this invention.

[0024] Figure reference numerals: 1-Metal salt solution, 2-Cellular ceramic carrier, 3-Constant temperature water bath, 4-Electric heating drying oven, 5-Muffle furnace, 6-Catalyst performance evaluation system, 7-CO, 8-H2, 9-N2, 10-CO2, 11-Mass flow meter, 12-Fixed bed reactor, 13-Back pressure valve, 14-Cold trap, 15-Color-changing silica gel. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings: Specific Implementation

[0027] I. Source of Raw Materials

[0028] The honeycomb ceramic carrier, reagents, and other materials used in this invention were all purchased from the market.

[0029] II. Catalyst Sample Preparation

[0030] Example 1: 21.11g of Ni(NO3)2·6H2O metal salt solution 1 was placed in a 100ml beaker, and 80ml of deionized water was added to dissolve it with ultrasonic assistance. The honeycomb ceramic carrier 2 was placed in the metal salt solution 1 and impregnated at a constant temperature of 60℃ for 12h. After impregnation, it was placed in an electric heating drying oven 3 and dried at 110℃ for 12h. Then it was transferred to a muffle furnace 5 and calcined at 450℃ for 5h in air atmosphere to obtain a Ni / honeycomb ceramic catalyst containing 2.0wt.% nickel.

[0031] Example 2: 21.11g of Ni(NO3)2·6H2O and 17.20g of CoCl2·6H2O metal salt solution 1 were placed in a 100ml beaker and 80ml of deionized water were added to dissolve the solution with ultrasonic assistance. A mixed solution was prepared, and the honeycomb ceramic carrier 2 was immersed in the mixed solution. The immersion was carried out at a constant temperature of 60℃ for 12h. After the immersion was completed, the carrier was placed in an electric heating drying oven 3 and dried at 110℃ for 12h. Then, the carrier was transferred to a muffle furnace 5 and calcined at 450℃ for 5h in an air atmosphere to obtain a Ni-Co / honeycomb ceramic catalyst containing 2.0wt.% nickel and 2.0wt.% cobalt.

[0032] Example 3: 21.11g of Ni(NO3)2·6H2O and 38.70g of CoCl2·6H2O metal salt solution 1 were placed in a 150ml beaker and 100ml of deionized water were added for ultrasonic-assisted dissolution to prepare a solution. The honeycomb ceramic carrier 2 was immersed in the mixed solution and immersed at a constant temperature of 60℃ for 12h. After immersion, it was placed in an electric heating drying oven 3 and dried at 110℃ for 12h. Then it was transferred to a muffle furnace 5 and calcined at 450℃ for 5h in air atmosphere to obtain a Ni-Co / honeycomb ceramic catalyst containing 2.0wt.% nickel and 4.0wt.% cobalt.

[0033] Example 4: 47.49g of Ni(NO3)2·6H2O and 17.20g of CoCl2·6H2O metal salt solution 1 were placed in a 150ml beaker and 100ml of deionized water were added for ultrasonic-assisted dissolution to prepare a solution. A honeycomb ceramic carrier 2 was immersed in the mixed solution and immersed at a constant temperature of 60℃ for 12h. After immersion, it was placed in an electric heating drying oven 3 and dried at 110℃ for 12h. Then it was transferred to a muffle furnace 5 and calcined at 450℃ for 5h in air atmosphere to obtain a Ni-Co / honeycomb ceramic catalyst containing 4.0wt.% nickel and 2.0wt.% cobalt.

[0034] The catalysts prepared in Examples 1-4 were loaded into Figure 1 In the fixed-bed reactor 12 shown, the catalyst bed temperature is slowly raised to 450°C at a heating rate of 3-5°C / min under a nitrogen atmosphere. The gas is then switched to a reducing atmosphere of nitrogen and hydrogen, with hydrogen accounting for 15-30% of the total gas volume. The reduction is carried out at a constant temperature for 2-4 hours.

[0035] Under the control of mass flow meter 11, after the catalyst reduction is completed, the atmosphere is switched to nitrogen to reduce the temperature in the fixed bed reactor 12 to 300℃. Then, biomass fuel gas is introduced into the fixed bed reactor 12. The composition of the feed dry gas is CO2 accounting for 20% of the total volume, N2 accounting for 12% of the total volume, and the remaining volume is H2 and CO, accounting for 68% of the total volume.

[0036] The specific reaction conditions are: pressure 0.1-0.3 MPa, temperature 300-380℃, and gas hourly space velocity 750-1500 h⁻¹. -1 The H2 / CO ratio is 0.5-2.0, where H2 / CO represents the volume ratio of H2 to CO.

[0037] The combustible components CO and H2 in biomass gas pass through an integral catalyst from top to bottom along the axial direction in a fixed-bed reactor. They come into full contact with active metals Ni and Co on the catalyst surface and undergo dissociation, experiencing three processes: chain initiation, chain growth, and chain termination, ultimately generating low-carbon hydrocarbons such as CH4 and C2H6.

[0038] The specific chemical reactions involved in the experiment are shown in Table 1.

[0039] Table 1. Experimental Reaction Principle of Biomass Gas Upgrading

[0040]

[0041] The catalyst performance evaluation system 6 is equipped with a cold trap at the end to remove moisture from the product. A gas collection bag is used at the end outlet to collect the dry gas after the reaction, and a gas chromatograph is used to analyze the gas product components of the biomass gas upgrading experiment.

[0042] CO, H2, CH4, and N2 are detected by a TCD detector, while C2-C3 are detected by an FID detector.

[0043] CO conversion rate (X) CO (%,%) and product selectivity (S) CO2 ,S Ci ,%) are calculated by formulas (1), (2), and (3) respectively, where F CO,in (mol / min) and F CO,out (mol / min) represents the molar flow rate of CO entering and exiting the reactor, F CO2,in (mol / min) and F CO2,out (mol / min) is the molar flow rate of CO2 entering and exiting the reactor, F Ci,out (mol / min) represents the molar flow rate of the hydrocarbon component with carbon atom number i at the reactor outlet; the lower heating value of the produced gas (LHV, MJ / Nm³) 3 The gas is calculated using formula (4), where V is the volume fraction of each component in the gas produced.

[0044]

[0045]

[0046]

[0047] LHV = 10.79 × V H2 +12.64×V CO +35.88×V CH4 +59.44×V C2H4 +64.35×V C2H6 +93.18×V C3H8 (4)

[0048] The experimental results showed that the optimal reaction conditions were: pressure 0.3 MPa, temperature 360 ​​°C, and space velocity 1000 h⁻¹. -1The catalyst works best when H2 / CO = 2. The performance evaluation results under this reaction condition are shown in Tables 2 and 3.

[0049] Table 2 Performance evaluation results of different catalysts

[0050]

[0051] Table 3. Effects of different catalysts on improving calorific value

[0052] Sample number <![CDATA[Intake air calorific value (MJ / Nm 3 )]]> <![CDATA[Calorific value of gas production (MJ / Nm 3 )]]> Calorific value growth rate (%) Example 1 7.76 8.92 14.97 Example 2 7.76 9.14 17.89 Example 3 7.76 9.84 26.82 Example 4 7.76 9.34 20.43

[0053] As shown in Table 2, a comparison of Examples 1-3 shows that the addition of the second metal cobalt can improve the catalytic effect of the catalyst, increase the conversion rate of CO, reduce the selectivity of CO2 and CH4, and at the same time, the selectivity of low-carbon hydrocarbons of C2-C3 also increases.

[0054] Based on the data shown in Table 2, and comparing the catalytic results of Examples 1-4, it can be seen that there are significant differences in the calorific value improvement effect of catalysts with different metal loadings. The lower heating value of the outlet gas in Example 3 is higher, and the improvement effect is more obvious.

[0055] A comparison of Examples 2 and 4 reveals that increasing the nickel loading leads to an increase in the selectivity of CH4 and a slight decrease in the selectivity of C2-C3.

[0056] Based on the calorific value improvement data in Table 3 and the performance evaluation results in Table 2, it can be seen that the Ni-Co / honeycomb ceramic catalyst containing 2.0 wt.% nickel and 4.0 wt.% cobalt has the best reaction effect, the highest C2-C3 selectivity, and its lower heating value growth rate reaches the highest value of 26.82%.

[0057] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A catalytic method for upgrading biomass gas using an integral catalyst, characterized in that, The monolithic catalyst described above is used to catalyze CO and H2 in biomass fuel gas to produce methane and other low-carbon hydrocarbons with higher calorific value. The monolithic catalyst support is a cylindrical monolithic honeycomb ceramic support; the active components are nickel and cobalt, by metal mass. The monolithic catalyst is a Ni-Co / honeycomb ceramic catalyst containing 2.0 wt.% nickel and 4.0 wt.% cobalt; The honeycomb ceramic carrier has a size of Φ45×45mm, a particle size of 400 mesh, and its main chemical component is cordierite; The catalyst was prepared by the following steps: a cordierite honeycomb ceramic support was impregnated in a mixed solution of Ni(NO3)2·6H2O and CoCl2·6H2O for 12 h at 60°C, dried at 110°C for 12 h after impregnation, and then calcined at 450°C for 5 h in air atmosphere to obtain the finished catalyst. The catalytic method includes the following steps: SA1. Place the monolithic catalyst in a fixed-bed reactor; SA2. Under a nitrogen atmosphere, the temperature of the catalyst bed containing the monolithic catalyst is slowly raised to 450°C at a heating rate of 3-5°C / min. The gas is then switched to a reducing atmosphere of nitrogen and hydrogen, with hydrogen accounting for 15-30% of the total gas volume. The reduction is carried out at a constant temperature for 2-4 hours. SA3. After the reduction is completed, switch to a nitrogen atmosphere and reduce the temperature inside the fixed bed reactor to 300°C. Then, introduce biomass fuel gas into the reactor. The dry gas composition of the feed is CO2 accounting for 20% of the total volume, N2 accounting for 12% of the total volume, and the remainder is H2 and CO accounting for 68% of the total volume.

2. The catalytic method for the integral catalyst for biomass gas upgrading according to claim 1, characterized in that: In step SA1, the pressure inside the fixed-bed reactor is 0.1-0.3 MPa, the temperature is 300-380°C, and the gas hourly space velocity is 750-1500 h⁻¹. -1 The H2 / CO ratio is 0.5-2.0, where H2 / CO represents the volume ratio of H2 to CO. In a fixed-bed reactor, the combustible components CO and H2 in biomass gas pass through an integral catalyst from top to bottom along the axial direction. On the catalyst surface, they come into full contact with active metals Ni and Co and dissociate, undergoing three processes: chain initiation, chain growth, and chain termination, ultimately generating CH4 and other low-carbon hydrocarbons.

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