Biomass waste fractional pyrolysis catalytic gasification hydrogen production process system

Abstract

The present application relates to the technical field of biomass gasification hydrogen production, and particularly relates to a biomass waste segmented pyrolysis catalytic gasification hydrogen production process system. The hydrogen production rate of the biomass gasification hydrogen production technology is low, and it is difficult to reach more than 700 mL / g of biomass. In view of the above technical problems, the present application provides a biomass waste segmented pyrolysis catalytic gasification hydrogen production process system. Through hierarchical and step-by-step thermochemical conversion, cheap aluminum smelting waste residue, pyrolysis semi-coke and carbon molecular sieve are used as catalysts to pyrolyze the residual coke tar steam, which significantly reduces the coke yield in the pyrolysis process and improves the hydrogen production rate. The aluminum smelting waste residue is coupled with the molecular sieve to catalyze the coke cracking, which improves the effect of the cheap nickel-based catalyst in the coke cracking hydrogen production. The carbon molecular sieve is loaded with nickel to catalyze the reforming of hydrocarbon gas, so that the hydrogen proportion reaches more than 70%, and the purpose of energy utilization, reduction, harmless and resource utilization of the biomass waste, the aluminum smelting waste residue and the pyrolysis residue is achieved.

Description

Technical Field

[0001] This invention relates to the field of biomass gasification hydrogen production technology, specifically to a staged pyrolysis catalytic gasification hydrogen production process system for biomass waste. Background Technology

[0002] In recent years, hydrogen energy has received much attention as a clean energy carrier, and its large-scale production technologies mainly focus on fossil fuel cracking and reforming, water electrolysis, and purification of industrial by-product gases. Currently, about 96% of global hydrogen production capacity comes from gray hydrogen (direct cracking of fossil fuels) and blue hydrogen (fossil reforming coupled with carbon capture), but producing 1 kg of hydrogen is accompanied by more than 10 kg of CO2 emissions, which is significantly contradictory to the goal of low-carbon development. Although water electrolysis to produce green hydrogen can achieve zero carbon emissions, it accounts for only 4% of the total, and is constrained by the high cost of precious metal catalysts, the efficiency bottleneck of electrolyzers, and the volatility of renewable energy power, making it difficult to achieve rapid large-scale application.

[0003] Biomass gasification for hydrogen production exhibits unique advantages due to the renewable nature of its feedstock and its carbon cycle characteristics: theoretically, it can achieve full life-cycle carbon balance by gasifying and converting biomass resources such as agricultural and forestry waste; if integrated with carbon capture and storage (CCUS) technology, it can even generate a negative carbon effect, significantly enhancing green carbon sequestration capacity. However, this technology faces the following core bottlenecks:

[0004] Hydrogen-to-carbon ratio imbalance and selectivity defects

[0005] Biomass feedstocks inherently have low hydrogen content (typical H / C atomic ratio of 0.1-0.3). During pyrolysis, hydrogen preferentially participates in moisture removal and the formation of oxygen-containing volatiles (such as CO and CH4), resulting in insufficient hydrogen selectivity in the gasification products. Experiments show that the hydrogen yield of conventional fluidized bed gasification is generally below 60 g / kg biomass, and the H2 volume concentration in the syngas is mostly below 40%, which is insufficient to meet the requirements for efficient hydrogen production.

[0006] Tar byproducts limit system efficiency

[0007] The gasification process is accompanied by the generation of a large amount of polycyclic aromatic hydrocarbon tar (content can reach 20-100 g / Nm). 3 This not only causes energy loss (accounting for 15-30% of the raw material energy), but also easily clogs pipelines and poisons the catalyst. Existing purification technologies (such as cyclone dust removal and catalytic cracking) have problems such as high energy consumption and easy catalyst deactivation, which significantly increases the operating cost of the system.

[0008] Process Coupling and Energy Optimization Challenges

[0009] Biomass gasification requires coordination of multiple reaction stages, including pyrolysis, reforming, and water-gas shift reaction. However, traditional fixed-bed / fluidized-bed processes lack sufficient control over temperature fields and gas-solid residence time, resulting in low gasification efficiency (cold gas efficiency is typically below 70%). Furthermore, the lack of integrated optimization of tar treatment and waste heat recovery systems further restricts overall energy efficiency improvement.

[0010] Existing improvement schemes mostly focus on catalyst modification (such as doping rare earth elements into nickel-based catalysts) or reactor structure optimization (such as dual-bed gasification). While these can improve local reaction efficiency, they do not fundamentally solve the systemic problems of low hydrogen selectivity and tar co-control. Therefore, it is urgent to develop new gasification processes and reaction systems to achieve a breakthrough in both efficiency and economy of biomass hydrogen production by controlling the gasification medium, enhancing in-situ catalysis, and optimizing heat and mass transfer. Summary of the Invention

[0011] A problem with existing technologies is that the hydrogen production rate of biomass gasification hydrogen production technology is relatively low, rarely exceeding 700 mL / g. To address this issue, this invention provides a staged pyrolysis catalytic gasification hydrogen production process system for biomass waste, comprising the following steps:

[0012] (1) Dry and crush the biomass waste to less than 3mm;

[0013] (2) The crushed biomass waste obtained in step (1) is continuously added to the cascade pyrolysis device. Under the action of gravity, the material is processed in sequence through the baking section, the thermal premixing section, the pyrolysis gasification section and the catalytic reforming section to obtain semi-coke and volatile matter. The obtained semi-coke is discharged from the bottom of the cascade pyrolysis device at regular intervals. The volatile matter is filtered by the semi-coke accumulated in the catalytic conversion section to remove fly ash and obtain high-temperature pyrolysis gas.

[0014] (3) The high-temperature pyrolysis gas is continuously fed into the atmospheric pressure catalytic converter I, so that the tar in the high-temperature cracking gas undergoes catalytic cracking to obtain high-hydrogen fuel gas.

[0015] (4) The high-hydrogen gas obtained in atmospheric pressure catalytic converter I is continuously fed into atmospheric pressure catalytic converter II, so that the alkane gas in the high-hydrogen gas undergoes catalytic cracking to produce hydrogen gas, and hydrogen-rich gas is generated at the bottom of atmospheric pressure catalytic converter II.

[0016] Preferably, the crushed biomass waste obtained in step (1) is added to the cascade pyrolysis device through a screw feeder at a feeding rate of 0.5-5 kg / h.

[0017] Preferably, the temperature ranges of the baking section, the hot premixing section, the pyrolysis gasification section and the catalytic reforming section in step (2) are 250-300℃, 500-600℃, 750-800℃ and 900-1000℃, respectively.

[0018] Preferably, a mixture of pure oxygen and water vapor is continuously introduced into the catalytic reforming section. The inlet is located in the middle of the catalytic reforming section, and the inlet direction is parallel to the ground. The flow rate of O2 is 100-200 mL / min, and the flow rate of water vapor is 0.5-2 g / min.

[0019] Preferably, coke discharge begins when the height of the semi-coke in the cascade pyrolysis unit exceeds the lower edge of the catalytic reforming section inlet, and stops when the height of the semi-coke in the cascade pyrolysis unit is lower than the middle of the catalytic reforming section.

[0020] Preferably, the catalyst packed in the atmospheric pressure catalytic converter I is a nickel-iron based catalyst supported on a mixture of ZSM-5 molecular sieve and aluminum smelting waste.

[0021] Preferably, the preparation method of the nickel-iron-based catalyst includes the following steps:

[0022] (1) After acidification pretreatment and high-temperature roasting, porous aluminum smelting waste residue is obtained;

[0023] (2) The porous aluminum smelting waste residue and ZSM-5 molecular sieve were mixed evenly at a mass ratio of 4:6 to obtain a composite carrier;

[0024] (3) Add the composite carrier to deionized water. The mass ratio of the composite carrier to deionized water is 1-2:10. Then add nickel nitrate and ferric chloride. Sonicate and stir at 60-80℃ until the water is completely evaporated. Then place the solid mixture in air at 500-600℃ for 1.5-2h to obtain the nickel-iron-based catalyst. The mass ratio between nickel nitrate, ferric chloride and composite carrier is 8:4:100.

[0025] Preferably, the packing and compaction density of the catalyst in the atmospheric pressure catalytic converter I is 0.8-1.2 g / cm³. 3 .

[0026] Preferably, the catalyst packed in the atmospheric pressure catalytic converter II is a nickel-based catalyst supported on a carbon molecular sieve.

[0027] Preferably, the preparation method of the nickel-based catalyst includes the following steps:

[0028] (1) Biochar and KOH are mixed evenly at a mass ratio of 1:2 and activated at 500-600℃ under nitrogen protection for 1-2 hours. Then the temperature is raised to 900℃ and CO2 is introduced while nitrogen is being introduced for 2-4 hours to finally obtain activated carbon. The flow rate of CO2 is 50 mL / min.

[0029] (2) The macropores of activated carbon are filled and carbonized by benzene deposition to form a multi-level porous carbon molecular sieve.

[0030] (3) Add the multi-level porous carbon molecular sieve to deionized water, wherein the mass ratio of the multi-level porous carbon molecular sieve to deionized water is 1-2:10. Then add nickel nitrate, and sonicate and stir at 60-80℃ until the water is completely evaporated. Then calcine at 500-600℃ for 1.5-2h under nitrogen or inert gas protection to obtain a nickel-based catalyst.

[0031] Preferably, the biomass waste includes one or more of pine sawdust, corn stalks, and poplar wood.

[0032] The present invention has the following beneficial effects:

[0033] (1) Biomass feedstock is fed into the cascade pyrolysis unit via a screw feeder. After roasting, the carbon content and calorific value of the biomass feedstock increase. Under the action of gravity, the feedstock continuously enters the thermal premixing section, the pyrolysis gasification section, and the catalytic reforming section. The temperature in the pyrolysis section is 600-800℃. The semi-coke obtained from pyrolysis is deposited at the bottom under the action of gravity. With the accumulation of semi-coke, it can act as a catalyst for tar conversion, converting part of the tar. In the catalytic reforming section, O2 / H2O is introduced to reform the tar and hydrocarbon gases, releasing heat to achieve self-sufficiency in heating and filtering the fly ash from pyrolysis.

[0034] (2) In the segmented pyrolysis device for wood waste, 30-50% of the tar can be converted, but 50-70% of the tar is still unconverted. The high-temperature pyrolysis gas containing tar is introduced into the atmospheric pressure catalytic conversion furnace I. The nickel-iron-based catalyst in the conversion furnace is carried by a mixture of ZSM-5 molecular sieve and aluminum smelting waste, which further catalytically converts the tar into high-hydrogen fuel gas. The conversion temperature is 800-1000℃, and the tar conversion rate can reach more than 99%.

[0035] (3) The high-hydrogen fuel gas still contains a certain amount of hydrocarbon gases such as CH4, and the proportion of CO2 is slightly higher. It needs to undergo catalytic reforming in atmospheric pressure catalytic converter II to finally obtain hydrogen-rich fuel gas, in which the hydrogen content reaches more than 70%.

[0036] (4) This invention utilizes inexpensive aluminum smelting waste, pyrolysis semi-coke, and carbon molecular sieves as catalysts through graded and stepwise thermochemical conversion. The pyrolysis residue catalyzes tar vapor, significantly reducing the tar yield and increasing the hydrogen yield during pyrolysis. The aluminum smelting waste coupled with molecular sieve catalyzes tar cracking, enhancing the effect of inexpensive nickel-based catalysts in catalyzing tar cracking to produce hydrogen. By loading nickel onto carbon molecular sieves to catalyze the reforming of hydrocarbon gases, the hydrogen ratio reaches more than 70%, achieving the energy conversion and volume reduction of biomass waste and the harmless and resource-based utilization of aluminum smelting waste and pyrolysis residue. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of a staged pyrolysis catalytic gasification hydrogen production process system for biomass waste provided by the present invention.

[0038] In the diagram: 101. Baking section, 102. Hot premixing section, 103. Pyrolysis gasification section, 104. Catalytic reforming section. Detailed implementation method:

[0039] The present invention will be described in detail below with reference to embodiments. However, it should be understood that the following embodiments are merely illustrative examples of implementation of the present invention and are not intended to limit the scope of the present invention.

[0040] The cascade pyrolysis device used in Embodiment 1 of this invention adopts the segmented pyrolysis catalytic gasification hydrogen production device for wood waste in Chinese invention patent CN114907869 A. The baking section, thermal premixing section, pyrolysis gasification section and catalytic reforming section mentioned in this invention correspond to the baking section 101, thermal premixing section 102, pyrolysis gasification section 103 and catalytic reforming section 104 in the structure of the segmented pyrolysis catalytic gasification hydrogen production device for wood waste previously applied for by the research team of this invention.

[0041] In Example 1 of this invention, both atmospheric pressure catalytic converter I and atmospheric pressure catalytic converter II are atmospheric pressure fixed-bed reactors, purchased from Suzhou Furande Experimental Equipment Co., Ltd., model FD-BC. During the reaction, the catalyst is loaded into the catalyst loading zone within the atmospheric pressure fixed-bed reactor, with a compacted density of 0.8 g / cm³. 3 .

[0042] The aluminum smelting waste slag (Huzhou Senge New Materials Co., Ltd.) used in Example 1 of this invention has the following composition as shown in Table 1:

[0043] Table 1

[0044]

[0045] In Example 1 of this invention, the catalyst packed in the atmospheric pressure catalytic converter I is a nickel-iron based catalyst with a mixture of ZSM-5 molecular sieve and aluminum smelting waste as a support. The preparation method is as follows:

[0046] (1) Immerse aluminum smelting waste in 30% dilute sulfuric acid and stir for 4 hours for acidification pretreatment;

[0047] (2) The aluminum smelting waste slag after acidification pretreatment was placed in air at 600℃ and roasted for 3 hours to obtain porous aluminum smelting waste slag.

[0048] (3) The porous aluminum smelting waste residue and ZSM-5 molecular sieve were mixed evenly at a mass ratio of 4:6 to obtain a composite carrier;

[0049] (4) Add the composite carrier to deionized water at a mass ratio of 1:10. Then add nickel nitrate and ferric chloride. Sonicate and stir at 60°C until the water is completely evaporated. Then calcine the solid mixture in air at 550°C for 2 hours to obtain the nickel-iron-based catalyst. The mass ratio between nickel nitrate, ferric chloride and composite carrier is 8:4:100.

[0050] The ZSM-5 molecular sieve used in the following embodiments of the present invention is of model ZSM-5, with a silicon-to-aluminum ratio of 25, and was purchased from the catalyst factory of Nankai University.

[0051] In Example 1 of this invention, the catalyst packed in the atmospheric pressure catalytic converter II is a nickel-based catalyst supported on a carbon molecular sieve. The preparation method of the nickel-based catalyst is as follows:

[0052] (1) Biochar and KOH were mixed evenly at a mass ratio of 1:2 and activated at 550℃ under nitrogen protection for 2 hours. Then the temperature was raised to 900℃ and CO2 was introduced while nitrogen was being introduced for 2 hours to finally obtain activated carbon. The flow rate of CO2 was 50 mL / min and the volume flow ratio of CO2 to nitrogen was 1:1.

[0053] (2) By benzene deposition, 75g of activated carbon was placed in a fixed bed under normal pressure, and toluene vapor was introduced at a flow rate of 0.5g / min. The reaction was carried out at 900℃ for 0.5h to obtain a multi-level porous carbon molecular sieve.

[0054] (3) Add the multi-level porous carbon molecular sieve to deionized water, wherein the mass ratio of the multi-level porous carbon molecular sieve to deionized water is 1:10. Then add nickel nitrate, sonicate and stir at 60°C until the water is completely evaporated, and then calcine at 550°C for 2 hours under nitrogen protection to obtain a nickel-based catalyst.

[0055] The biochar used in the preparation of nickel-based catalysts is pyrolytic char obtained by pyrolyzing pine wood chips at 800℃ for 0.5h under nitrogen protection.

[0056] In this invention, tar yield = tar quantity / biomass waste × 100%.

[0057] In the following embodiments of the present invention, the hydrogen content is expressed in mL / g, which refers to the volume of hydrogen obtained from each gram of biomass after staged pyrolysis catalytic gasification.

[0058] Example 1

[0059] A staged pyrolysis catalytic gasification hydrogen production process system for biomass waste (process unit structural diagram is attached to the instruction manual) Figure 1 (As shown), the steps are as follows:

[0060] (1) Dry the pine wood chips until the moisture content is below 10% and break them to 3mm;

[0061] (2) The crushed biomass waste obtained in step (1) is continuously fed into the cascade pyrolysis device via a screw feeder at a feeding rate of 5 kg / h. Under the action of gravity and the premixing and stirring components in the cascade pyrolysis device, the material is processed sequentially through the baking section, the hot premixing section, the pyrolysis gasification section, and the catalytic reforming section to obtain semi-coke and volatile matter. The temperatures of the baking section, the hot premixing section, the pyrolysis gasification section, and the catalytic reforming section are 250℃, 500℃, 750℃, and 900℃, respectively. A mixture of pure oxygen and water vapor is continuously introduced into the catalytic reforming section, with the inlet located in the middle of the catalytic reforming section. The air intake direction is parallel to the ground, the O2 flow rate is 100 mL / min, and the water vapor flow rate is 0.5 g / min. When the height of the semi-coke in the cascade pyrolysis unit exceeds the lower edge of the air inlet of the catalytic reforming section, coke discharge begins. When the height of the semi-coke in the cascade pyrolysis unit is lower than the middle of the catalytic reforming section, coke discharge stops. The volatiles are filtered through the semi-coke accumulated in the catalytic conversion section to remove fly ash and obtain high-temperature pyrolysis gas. The high-temperature pyrolysis gas contains 450 mL / g hydrogen, 55 mL / g methane, 100 mL / g carbon dioxide, and 175 mL / g carbon monoxide, and the tar yield is 8%.

[0062] (3) High-temperature pyrolysis gas is continuously fed into atmospheric pressure catalytic converter I through a pipeline. The tar in the high-temperature pyrolysis gas undergoes catalytic cracking in atmospheric pressure catalytic converter I at a reaction temperature of 1000℃ to obtain high-hydrogen fuel gas. The high-hydrogen fuel gas contains 579 ml / g hydrogen, 33 ml / g methane, 125 ml / g carbon dioxide, and 223 ml / g carbon monoxide, and the tar yield is reduced to 0.1%.

[0063] (4) The high-hydrogen gas obtained in atmospheric pressure catalytic converter I is continuously fed into atmospheric pressure catalytic converter II. The alkane gas in the high-hydrogen gas undergoes catalytic cracking in atmospheric pressure catalytic converter II to produce hydrogen gas. The reaction temperature is 800℃. The gas at the bottom of atmospheric pressure catalytic converter II is collected to obtain hydrogen-rich gas. The hydrogen-rich gas contains 725 ml / g of hydrogen, 10 ml / g of methane, 55 ml / g of carbon dioxide, and 253 ml / g of carbon monoxide.

[0064] Example 2 is the same as Example 1, except that the temperatures in the baking section, hot premixing section, pyrolysis gasification section and catalytic reforming section in Example 2 are 200℃, 300℃, 600℃ and 800℃, respectively.

[0065] The high-temperature pyrolysis gas obtained in Example 2 contained 320 mL / g hydrogen, 105 mL / g methane, 120 mL / g carbon dioxide, and 160 mL / g carbon monoxide.

[0066] In Example 2, the high-hydrogen fuel gas contained 490 mL / g of hydrogen, 65 mL / g of methane, 135 mL / g of carbon dioxide, and 180 mL / g of carbon monoxide, with the tar yield reduced to 1%.

[0067] The hydrogen-rich gas obtained in Example 2 contained 579 mL / g of hydrogen, 35 mL / g of methane, 95 mL / g of carbon dioxide, and 235 mL / g of carbon monoxide.

[0068] Example 3 is the same as Example 1, except that the temperatures in the baking section, hot premixing section, pyrolysis gasification section and catalytic reforming section in Example 3 are 300℃, 600℃, 800℃ and 1000℃, respectively.

[0069] The high-temperature pyrolysis gas obtained in Example 3 contained 420 mL / g hydrogen, 75 mL / g methane, 65 mL / g carbon dioxide, and 185 mL / g carbon monoxide.

[0070] In Example 3, the high-hydrogen fuel gas contained 510 mL / g hydrogen, 40 mL / g methane, 120 mL / g carbon dioxide, and 220 mL / g carbon monoxide, with the tar yield reduced to 0.5%.

[0071] The hydrogen-rich gas obtained in Example 3 contained 710 mL / g of hydrogen, 18 mL / g of methane, 56 mL / g of carbon dioxide, and 265 mL / g of carbon monoxide.

[0072] Example 4 is the same as Example 1, except that the catalyst used in the atmospheric pressure catalytic converter I of Example 4 is prepared by the following method:

[0073] (1) Immerse aluminum smelting waste in 30% dilute sulfuric acid and stir for 4 hours for acidification pretreatment;

[0074] (2) The aluminum smelting waste slag after acidification pretreatment was placed in air at 600℃ and roasted for 3 hours to obtain porous aluminum smelting waste slag.

[0075] (3) The porous aluminum smelting waste residue and ZSM-5 molecular sieve were mixed evenly at a mass ratio of 4:6 to obtain a composite carrier;

[0076] (4) Add the composite carrier to deionized water. The mass ratio of the composite carrier to deionized water is 1:10. Then add nickel nitrate and ferric chloride. Sonicate and stir at 60°C until the water is completely evaporated. Then place the solid mixture at 550°C and calcine it in air for 2 hours to obtain the nickel-iron-based catalyst. The mass ratio between nickel nitrate, ferric chloride and composite carrier is 4:1:100.

[0077] The high-temperature pyrolysis gas obtained in Example 4 contained 450 mL / g hydrogen, 55 mL / g methane, 100 mL / g carbon dioxide, and 175 mL / g carbon monoxide.

[0078] In Example 4, the high-hydrogen fuel gas contained 490 mL / g of hydrogen, 50 mL / g of methane, 115 mL / g of carbon dioxide, and 180 mL / g of carbon monoxide, with the tar yield reduced to 0.4%.

[0079] The hydrogen-rich gas obtained in Example 4 contained 662 mL / g of hydrogen, 20 mL / g of methane, 85 mL / g of carbon dioxide, and 260 mL / g of carbon monoxide.

[0080] Example 5 is the same as Example 1, except that the catalyst used in the atmospheric pressure catalytic converter I of Example 5 is prepared by the following method:

[0081] (1) Immerse aluminum smelting waste in 30% dilute sulfuric acid and stir for 4 hours for acidification pretreatment;

[0082] (2) The aluminum smelting waste slag after acidification pretreatment was placed in air at 600℃ and roasted for 3 hours to obtain porous aluminum smelting waste slag.

[0083] (3) The porous aluminum smelting waste residue and ZSM-5 molecular sieve were mixed evenly at a mass ratio of 4:6 to obtain a composite carrier;

[0084] (4) Add the composite carrier to deionized water at a mass ratio of 1:10. Then add nickel nitrate and ferric chloride. Sonicate and stir at 60°C until the water is completely evaporated. Then calcine the solid mixture in air at 550°C for 2 hours to obtain the nickel-iron-based catalyst. The mass ratio of nickel nitrate, ferric chloride and composite carrier is 6:2:100.

[0085] The high-temperature pyrolysis gas obtained in Example 5 contained 450 mL / g hydrogen, 55 mL / g methane, 100 mL / g carbon dioxide, and 175 mL / g carbon monoxide.

[0086] In Example 5, the high-hydrogen fuel gas contained 510 mL / g of hydrogen, 35 mL / g of methane, 115 mL / g of carbon dioxide, and 186 mL / g of carbon monoxide, with the tar yield reduced to 0.4%.

[0087] The hydrogen-rich gas obtained in Example 5 contained 685 mL / g of hydrogen, 12 mL / g of methane, 80 mL / g of carbon dioxide, and 255 mL / g of carbon monoxide.

[0088] Comparative Example 1 is the same as Example 1, except that the catalyst packed in the atmospheric pressure catalytic converter I in Comparative Example 1 is a nickel-iron based catalyst with ZSM-5 molecular sieve as the support. The preparation method is as follows:

[0089] ZSM-5 molecular sieve was added to deionized water at a mass ratio of 1:10. Then, nickel nitrate and ferric chloride were added, and the mixture was ultrasonically stirred at 60°C until the water was completely evaporated. The solid mixture was then calcined in air at 550°C for 2 hours to obtain the nickel-iron-based catalyst. The mass ratio of nickel nitrate, ferric chloride and ZSM-5 molecular sieve was 8:4:100.

[0090] The high-temperature pyrolysis gas obtained in Comparative Example 1 contained 450 mL / g of hydrogen, 55 mL / g of methane, 100 mL / g of carbon dioxide, and 175 mL / g of carbon monoxide.

[0091] The hydrogen-rich fuel gas obtained in Comparative Example 1 contained 520 mL / g hydrogen, 45 mL / g methane, 125 mL / g carbon dioxide, and 196 mL / g carbon monoxide, with the tar yield reduced to 0.4%.

[0092] The hydrogen-rich gas obtained in Comparative Example 1 contained 679 mL / g of hydrogen, 15 mL / g of methane, 75 mL / g of carbon dioxide, and 265 mL / g of carbon monoxide.

[0093] Comparative Example 2 is the same as Example 1, except that the catalyst used in the atmospheric pressure catalytic converter I of Comparative Example 2 is a nickel-iron based catalyst with aluminum smelting waste slag as a carrier. The preparation method is as follows:

[0094] (1) Immerse aluminum smelting waste in 30% dilute sulfuric acid and stir for 4 hours for acidification pretreatment;

[0095] (2) The aluminum smelting waste slag after acidification pretreatment was placed in air at 600℃ and roasted for 3 hours to obtain porous aluminum smelting waste slag.

[0096] (3) Add porous aluminum smelting waste to deionized water. The mass ratio of porous aluminum smelting waste to deionized water is 1:10. Then add nickel nitrate and ferric chloride. Ultrasonically stir at 60°C until the water is completely evaporated. Then place the solid mixture at 550°C and calcine in air for 2 hours to obtain the nickel-iron-based catalyst. The mass ratio between nickel nitrate, ferric chloride and porous aluminum smelting waste is 8:4:100.

[0097] The high-temperature pyrolysis gas obtained in Comparative Example 2 contained 450 mL / g of hydrogen, 55 mL / g of methane, 100 mL / g of carbon dioxide, and 175 mL / g of carbon monoxide.

[0098] The hydrogen-rich fuel gas obtained in Comparative Example 2 contained 500 mL / g hydrogen, 50 mL / g methane, 145 mL / g carbon dioxide, and 210 mL / g carbon monoxide, with the tar yield reduced to 1%.

[0099] The hydrogen-rich gas obtained in Comparative Example 2 contained 628 mL / g of hydrogen, 25 mL / g of methane, 120 mL / g of carbon dioxide, and 290 mL / g of carbon monoxide.

[0100] Comparative Example 3 is the same as Example 1, except that when preparing the nickel-iron based catalyst with the mixture of ZSM-5 molecular sieve and aluminum smelting waste as the carrier, step (3) is to mix the porous aluminum smelting waste and ZSM-5 molecular sieve at a mass ratio of 7:3 to obtain the composite carrier.

[0101] The high-temperature pyrolysis gas obtained in Comparative Example 3 contained 450 mL / g of hydrogen, 55 mL / g of methane, 100 mL / g of carbon dioxide, and 175 mL / g of carbon monoxide.

[0102] The hydrogen-rich fuel gas obtained in Comparative Example 3 contained 510 mL / g hydrogen, 45 mL / g methane, 135 mL / g carbon dioxide, and 200 mL / g carbon monoxide, with the tar yield reduced to 0.6%.

[0103] The hydrogen-rich gas obtained in Comparative Example 3 contained 682 mL / g of hydrogen, 20 mL / g of methane, 115 mL / g of carbon dioxide, and 265 mL / g of carbon monoxide.

[0104] Comparative Example 4 is the same as Example 1, except that when preparing the nickel-iron based catalyst with the mixture of ZSM-5 molecular sieve and aluminum smelting waste as the carrier, step (3) is to mix the porous aluminum smelting waste and ZSM-5 molecular sieve at a mass ratio of 1:9 to obtain the composite carrier.

[0105] The high-temperature pyrolysis gas obtained in Comparative Example 4 contained 450 mL / g of hydrogen, 55 mL / g of methane, 100 mL / g of carbon dioxide, and 175 mL / g of carbon monoxide.

[0106] In Comparative Example 4, the high-hydrogen fuel gas contained 505 mL / g of hydrogen, 45 mL / g of methane, 130 mL / g of carbon dioxide, and 205 mL / g of carbon monoxide, with the tar yield reduced to 0.8%.

[0107] The hydrogen-rich gas obtained in Comparative Example 4 contained 665 mL / g of hydrogen, 22 mL / g of methane, 125 mL / g of carbon dioxide, and 280 mL / g of carbon monoxide.

[0108] Comparative Example 5 is the same as Example 1, except that the baking temperature of the biomass waste in Comparative Example 5 is 150°C.

[0109] The high-temperature pyrolysis gas obtained in Comparative Example 5 contained 420 mL / g of hydrogen, 75 mL / g of methane, 110 mL / g of carbon dioxide, and 180 mL / g of carbon monoxide.

[0110] In Comparative Example 5, the high-hydrogen fuel gas contained 520 mL / g of hydrogen, 55 mL / g of methane, 135 mL / g of carbon dioxide, and 200 mL / g of carbon monoxide, with the tar yield reduced to 0.2%.

[0111] The hydrogen-rich gas obtained in Comparative Example 5 contained 679 mL / g of hydrogen, 20 mL / g of methane, 95 mL / g of carbon dioxide, and 260 mL / g of carbon monoxide.

[0112] Comparative Example 6 is the same as Example 1, except that the catalyst packed in the atmospheric pressure catalytic converter I of Comparative Example 6 is a nickel-based catalyst with a mixture of ZSM-5 molecular sieve and aluminum smelting waste as a support. The preparation method is as follows:

[0113] (1) Immerse aluminum smelting waste in 30% dilute sulfuric acid and stir for 4 hours for acidification pretreatment;

[0114] (2) The aluminum smelting waste slag after acidification pretreatment was placed in air at 600℃ and roasted for 3 hours to obtain porous aluminum smelting waste slag.

[0115] (3) The porous aluminum smelting waste residue and ZSM-5 molecular sieve were mixed evenly at a mass ratio of 4:6 to obtain a composite carrier;

[0116] (4) Add the composite carrier to deionized water at a mass ratio of 1:10. Then add nickel nitrate and sonicate and stir at 60°C until the water is completely evaporated. Then place the solid mixture in air at 550°C for 2 hours to obtain the nickel-based catalyst. The mass ratio of nickel nitrate to the composite carrier is 12:100.

[0117] The high-temperature pyrolysis gas obtained in Comparative Example 6 contained 450 mL / g of hydrogen, 55 mL / g of methane, 100 mL / g of carbon dioxide, and 175 mL / g of carbon monoxide.

[0118] The hydrogen-rich fuel gas obtained in Comparative Example 6 contained 493 mL / g of hydrogen, 41 mL / g of methane, 120 mL / g of carbon dioxide, and 213 mL / g of carbon monoxide, with the tar yield reduced to 1%.

[0119] The hydrogen-rich gas obtained in Comparative Example 6 contained 690 mL / g of hydrogen, 18 mL / g of methane, 85 mL / g of carbon dioxide, and 253 mL / g of carbon monoxide.

[0120] Comparative Example 7 is the same as Example 1, except that the catalyst packed in the atmospheric pressure catalytic converter I of Comparative Example 7 is an iron-based catalyst with a mixture of ZSM-5 molecular sieve and aluminum smelting waste as a support. The preparation method is as follows:

[0121] (1) Immerse aluminum smelting waste in 30% dilute sulfuric acid and stir for 4 hours for acidification pretreatment;

[0122] (2) The aluminum smelting waste slag after acidification pretreatment was placed in air at 600℃ and roasted for 3 hours to obtain porous aluminum smelting waste slag.

[0123] (3) The porous aluminum smelting waste residue and ZSM-5 molecular sieve were mixed evenly at a mass ratio of 4:6 to obtain a composite carrier;

[0124] (4) Add the composite carrier to deionized water at a mass ratio of 1:10, then add ferric chloride, and sonicate and stir at 60°C until the water is completely evaporated. Then place the solid mixture at 550°C and calcine it in air for 2 hours to obtain the nickel-iron-based catalyst. The mass ratio between ferric chloride and the composite carrier is 12:100.

[0125] The high-temperature pyrolysis gas obtained in Comparative Example 7 contained 450 mL / g of hydrogen, 55 mL / g of methane, 100 mL / g of carbon dioxide, and 175 mL / g of carbon monoxide.

[0126] The hydrogen-rich fuel gas obtained in Comparative Example 7 contained 460 mL / g of hydrogen, 56 mL / g of methane, 160 mL / g of carbon dioxide, and 166 mL / g of carbon monoxide, with the tar yield reduced to 2%.

[0127] The hydrogen-rich gas obtained in Comparative Example 7 contained 623 mL / g of hydrogen, 28 mL / g of methane, 105 mL / g of carbon dioxide, and 215 mL / g of carbon monoxide.

[0128] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A staged pyrolysis catalytic gasification process for hydrogen production from biomass waste, characterized in that, The preparation steps include the following: (1) Dry the pine wood chips until the moisture content is below 10% and break them into 3mm pieces; (2) The crushed biomass waste obtained in step (1) is continuously fed into the cascade pyrolysis device via a screw feeder at a feeding rate of 5 kg / h. Under the action of gravity and the premixing and stirring components in the cascade pyrolysis device, the material is processed sequentially through the baking section, the hot premixing section, the pyrolysis gasification section, and the catalytic reforming section to obtain semi-coke and volatile matter. The temperatures of the baking section, the hot premixing section, the pyrolysis gasification section, and the catalytic reforming section are 250℃, 500℃, 750℃, 900℃ or 300℃, 600℃, 800℃, 1000℃, respectively. A mixture of pure oxygen and water vapor is continuously introduced into the catalytic reforming section. Located in the middle of the catalytic reforming section, with the air inlet direction parallel to the ground, the O2 flow rate is 100 mL / min and the water vapor flow rate is 0.5 g / min. When the height of the semi-coke in the cascade pyrolysis unit exceeds the lower edge of the air inlet of the catalytic reforming section, coke discharge begins. When the height of the semi-coke in the cascade pyrolysis unit is lower than the middle of the catalytic reforming section, coke discharge stops. The volatiles are filtered through the semi-coke accumulated in the catalytic reforming section to remove fly ash, resulting in high-temperature pyrolysis gas. The high-temperature pyrolysis gas contains 450 mL / g hydrogen, 55 mL / g methane, 100 mL / g carbon dioxide, and 175 mL / g carbon monoxide, with a tar yield of 8%. (3) The high-temperature pyrolysis gas is continuously fed into the atmospheric pressure catalytic converter I through a pipeline. The tar in the high-temperature pyrolysis gas undergoes catalytic cracking in the atmospheric pressure catalytic converter I at a reaction temperature of 1000℃ to obtain high-hydrogen fuel gas. The high-hydrogen fuel gas contains 579 mL / g of hydrogen, 33 mL / g of methane, 125 mL / g of carbon dioxide, and 223 mL / g of carbon monoxide. The tar yield is reduced to 0.1%. (4) The high-hydrogen fuel obtained in atmospheric pressure catalytic converter I is continuously fed into atmospheric pressure catalytic converter II. The alkane gas in the high-hydrogen fuel undergoes catalytic cracking in atmospheric pressure catalytic converter II to produce hydrogen. The reaction temperature is 800℃. The gas at the bottom of atmospheric pressure catalytic converter II is collected to obtain hydrogen-rich fuel. Atmospheric pressure catalytic converter I and atmospheric pressure catalytic converter II are atmospheric pressure fixed-bed reactors. During the reaction, the catalyst is loaded in the catalyst loading zone of the atmospheric pressure fixed-bed reactor, and the loading compaction density is 0.8 g / cm³. The catalyst packed in atmospheric pressure catalytic converter I is a nickel-iron based catalyst supported on a mixture of ZSM-5 molecular sieve and aluminum smelting waste. The preparation method is as follows: (a) The aluminum smelting waste residue was soaked in dilute sulfuric acid with a mass concentration of 30% and stirred for 4 hours for acidification pretreatment; (b) The aluminum smelting waste slag after acidification pretreatment was placed in air at 600°C for 3 hours to obtain porous aluminum smelting waste slag. (c) The porous aluminum smelting waste residue and ZSM-5 molecular sieve were mixed evenly at a mass ratio of 4:6 to obtain a composite carrier; (d) The composite support was added to deionized water at a mass ratio of 1:

10. Then nickel nitrate and ferric chloride were added. The mixture was ultrasonicated and stirred at 60°C until the water was completely evaporated. The solid mixture was then calcined in air at 550°C for 2 hours to obtain the nickel-iron-based catalyst. The mass ratio of nickel nitrate, ferric chloride and composite support was 8:4:

100. Aluminum smelting waste, by mass percentage, includes the following components: Al2O3 78.80%; MgO 6.43%; SiO2 3.43%; CaO 3.35%; Fe2O3 1.41%; TiO2 0.49%; ZnO 0.44%; BaO 0.54%; CuO 0.36%; Na2O 1.72%; ZSM-5 molecular sieve, silica-alumina ratio 25; The catalyst packed in atmospheric pressure catalytic converter II is a nickel-based catalyst supported on carbon molecular sieves. The preparation method of the nickel-based catalyst is as follows: (e) Biochar and KOH were mixed evenly at a mass ratio of 1:2 and activated at 550°C under nitrogen protection for 2 hours. Then the temperature was raised to 900°C and CO2 was introduced while nitrogen was being introduced for 2 hours to finally obtain activated carbon. The flow rate of CO2 was 50 mL / min and the volume flow ratio of CO2 to nitrogen was 1:

1. (f) By benzene deposition, 75g of activated carbon was placed in a fixed bed under normal pressure, and toluene vapor was introduced at a flow rate of 0.5g / min. The reaction was carried out at 900℃ for 0.5h to obtain a multi-level porous carbon molecular sieve. (g) Add the multi-level porous carbon molecular sieve to deionized water, wherein the mass ratio of the multi-level porous carbon molecular sieve to deionized water is 1:10, then add nickel nitrate, sonicate and stir at 60°C until the water is completely evaporated, and then calcine at 550°C for 2 hours under nitrogen protection to obtain a nickel-based catalyst. The biochar used in the preparation of nickel-based catalysts is pyrolytic char obtained by pyrolyzing pine wood chips at 800℃ for 0.5h under nitrogen protection.

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