Method for carbon-hydrogen co-production and quality-divided utilization of tar generated by pyrolysis and gasification of organic solid waste

Abstract

The invention belongs to the technical field of carbon neutralization, and discloses an organic solid waste pyrolysis gasification tar hydrocarbon co-production quality-divided utilization method, which comprises the following steps of: firstly, dividing tar generated in an organic solid waste pyrolysis gasification process into light tar, medium tar and heavy tar according to boiling range difference through in-situ thermal-state quality division; the light tar is subjected to catalytic steam reforming to obtain hydrogen-rich synthesis gas, the medium tar is subjected to steam reforming to obtain synthesis gas and semicoke generated by condensation polymerization, and the semicoke and the heavy tar are subjected to steam activation to obtain synthesis gas and porous carbon; and carrying out water-gas shift, CO2 capture and pressure swing adsorption purification treatment on the obtained synthesis gas to obtain battery-grade hydrogen. According to the method, the tar is converted into high-value porous carbon and high-purity hydrogen step by step through stage treatment and quality-divided utilization of the tar, so that the problems of rapid deactivation of a catalyst, waste of high-temperature energy and the like in the tar treatment process are effectively solved, and resource utilization of the tar is realized.

Description

Technical Field

[0001] The present invention belongs to the field of carbon neutrality technology and relates to organic solid waste treatment, and in particular to a method for the co-production and quality-differentiated utilization of tar carbon and hydrogen from pyrolysis and gasification of organic solid waste. Background Art

[0002] Organic solid waste includes biomass waste, rubber and plastic waste, etc., which is an important part of the resources of "urban mines". Organic solid waste is processed into fossil fuel substitutes such as RDF, bio-oil, and synthesis gas through carbonization, pyrolysis, gasification, etc., which is an important way to alleviate the energy crisis and reduce carbon emissions in the energy field. However, due to the high volatile content and low fixed carbon content of biomass and rubber and plastic wastes, a large amount of tar is inevitably produced during the thermal conversion process, which reduces the thermal conversion efficiency and carbon utilization rate of organic matter, and causes corrosion and blockage of downstream equipment, seriously affecting the thermal conversion and utilization of organic solid waste. In addition, since most organic solid waste raw materials are poor conductors of heat, it is very easy to cause uneven mass transfer and heat transfer during the thermal conversion process, which further increases the yield of tar in the process of expanding the production scale, limiting the industrial application of organic solid waste thermochemical conversion technology. How to efficiently treat the tar generated during the thermal conversion of organic solid waste and realize the efficient conversion and resource utilization of tar is a technical problem that needs to be solved before the industrial utilization of organic solid waste thermal conversion technology can be realized.

[0003] The tar components produced during the pyrolysis and gasification of organic solid waste are complex and varied, mainly monocyclic or polycyclic aromatic compounds, generally with high acidity and viscosity, strong corrosiveness, and easy to condense into solid semi-coke in high-temperature pipelines, causing pipeline blockage. For this reason, physical and chemical methods are often used in the prior art to remove or transform tar. Among them, physical removal mainly includes water washing, cooling, filtering and other methods to convert it from the high-temperature gas phase to the liquid phase component and then separate it from the gas phase product. Although the cost is relatively low, the reaction process is difficult to continue, and the resource utilization of hydrocarbon elements in the tar component cannot be achieved. At the same time, the tar separated by physical methods is a hazardous waste and still needs to be disposed of harmlessly. Chemical conversion mainly includes combustion, catalytic cracking or reforming methods to convert it into greenhouse gases such as CO2 or combustible gas products such as CO and H2, or by preparing it into biochar-based materials to achieve high-value utilization of tar. Compared with direct removal by physical methods, chemical conversion realizes the resource utilization of tar while completing tar conversion, which is more in line with the requirements of green chemical thinking and atomic economy. However, due to the complex composition of tar, the conversion process often requires relatively harsh reaction conditions such as high temperature and catalysts. In addition, large molecular weight tar components are easily condensed into solid semi-coke during the conversion process. Tar components with larger molecular weight can easily lead to catalyst deactivation during catalytic reforming, which increases the difficulty and cost of tar chemical conversion.

[0004] To this end, Chinese invention patent CN113025383B discloses a pyrolysis gasification tar conversion and utilization device and method, which uses Brownian gas to assist the combustion of tar to remove tar, improves the combustion efficiency of tar by external oxygen supply, and removes solid particles mixed in the tar from the bottom of the device, thereby achieving efficient removal of tar and energy recovery. However, this patent only realizes the energy utilization in tar, and the utilization efficiency of tar is limited by the thermal conversion of combustion. Chinese invention patent application CN115181589A discloses a device for hydrogen-rich catalytic pyrolysis of organic solid waste and volatile reforming in series, which maximizes the generation of low-molecular gaseous hydrocarbons such as methane while removing tar, but during the conversion process, the conversion efficiency of tar can only be improved by adjusting the reforming temperature or extending the residence time. There are great differences in the chemical properties and reactivity of tars with different boiling ranges. The chemical properties of low-molecular-weight light tars are relatively stable, and they need to be decomposed into harmless small-molecule compounds through catalytic reforming. Medium-weight tars are very likely to cause carbon deposition or deactivation of the catalyst during the catalytic reforming process, which seriously affects the working life of the catalyst, and are easily condensed into large-molecule polycyclic aromatic hydrocarbon heavy tars or solid semi-cokes during the reforming process. Large-molecule heavy tars or solid semi-cokes are subject to mass transfer and heat transfer restrictions, and ordinary reforming reaction conditions make it difficult to improve the carbon conversion rate during the reforming process. It can be seen that the single-method treatment mode of thermal conversion of organic solid waste to tar is difficult to achieve its efficient conversion and high-value utilization.

[0005] Therefore, in the process of disposing of organic solid waste tar, it is necessary to combine appropriate harmless treatment and resource utilization methods according to the component characteristics of tar, improve the conversion efficiency of tar through the qualitative transformation of each component in tar, and convert it into products with higher utilization value such as porous carbon or high-purity hydrogen, so as to reduce the pollution of tar to the thermal conversion products of organic solid waste, as well as the corrosion and damage to downstream equipment. Summary of the invention

[0006] In view of the deficiencies in the treatment or conversion process of tar produced by thermal conversion of organic solid waste in the prior art described in the background technology, the present invention designs a method for the co-production and fractional utilization of carbon and hydrogen from tar by pyrolysis and gasification of organic solid waste, which divides the tar into light, medium and heavy tar according to the boiling range, and converts the tar components in each boiling range into synthesis gas or porous carbon based on the physical and chemical properties of the tar components, thereby realizing the fractional conversion and utilization of tar.

[0007] The method for co-production and quality-separation of tar carbon and hydrogen from pyrolysis and gasification of organic solid waste provided by the present invention is as follows: Figure 1 As shown, the following steps are included:

[0008] S1: The tar generated in the process of thermal conversion of organic solid waste is separated by in-situ thermal separation, and is divided into light tar with a boiling range of 100-200°C, medium tar with a boiling range of 200-400°C, and heavy tar with a boiling point above 400°C or / and solid semi-coke formed by condensation of tar according to the boiling range;

[0009] S2: catalytically steam reforming the light tar in step S1 to obtain synthesis gas containing H2 and CO;

[0010] S3: steam reforming the medium tar in step S1 to obtain synthesis gas containing H2 and CO, and solid semi-coke obtained by polycondensation of the medium tar;

[0011] S4: mixing the heavy tar and / or solid semi-coke obtained in step S1 with the solid semi-coke obtained in step S3, and performing steam activation to obtain porous carbon and synthesis gas containing H2 and CO;

[0012] S5: performing water-gas shift and CO2 capture on the synthesis gas obtained in any one of steps S2 to S4 to obtain hydrogen with a purity higher than 90%;

[0013] Alternatively, the synthesis gases obtained in steps S2 to S4 are mixed and then subjected to water-gas shift and CO2 capture to obtain hydrogen with a purity higher than 90%.

[0014] In step S1, the organic solid waste refers to lignocellulose waste such as abandoned garden waste, synthetic polymer waste such as abandoned rubber and plastic, and mixed organic solid waste composed of lignocellulose and synthetic polymer such as domestic waste.

[0015] In addition, the tar described in step S1 refers to monocyclic or polycyclic aromatic hydrocarbon organic matter generated during pyrolysis, gasification or combustion of organic solid waste. In step S1, the tar is divided into light tar, medium tar and heavy tar according to the boiling range; the tar is reformed by steam to: C+H2O=CO+H2. The carbon content in the tar can be obtained by elemental analyzer testing.

[0016] The light tar is mainly monocyclic aromatic compounds such as toluene and xylene, with relatively small molecular weight, relatively stable structure, and difficult to polycondense. It is mainly converted and removed by catalytic steam reforming. The medium tar is mainly phenolic substances (such as guaiacol, quinone, etc.), benzoic acid, naphthalene and other monocyclic easily polycondensed or polycyclic aromatic organic compounds, which are easily polycondensed into heavy tar or semi-coke during heating, and easily cause catalyst carbon deposition and deactivation during catalytic reforming conversion, etc., suitable for catalyst-free steam reforming conversion, and the heavy tar and semi-coke formed by polycondensation during the conversion process are separated from the gas phase product and disposed separately. The heavy tar refers to aromatic macromolecular compounds with three rings and more than three rings, such as anthracene, phenanthrene, etc.; these are mainly high-viscosity liquid or semi-solid substances, which are easily polycondensed into solid semi-coke and other substances with large mass transfer and heat transfer resistance and strong chemical inertness, with relatively high ignition point, and also have a relatively stable state under high temperature, suitable for water vapor or CO2 activation treatment, and converted into porous carbon and gas phase products.

[0017] Furthermore, the in-situ thermal separation in step S1 refers to the gradient segmented cooling of the high-temperature oil-gas mixture produced after the pyrolysis and gasification of organic solid waste, and the natural decrease of the temperature gradient to separate heavy tar and / or solid semi-coke, medium tar, and light tar in sequence.

[0018] In step S2, the catalytic steam reforming of the light tar refers to the use of Ni / Al2O3 catalyst or Ni / LaFeO3 catalyst (the catalyst is purchased from outside) under the condition of 650-750°C steam, based on the catalytic activity of metal Ni in breaking CC and CH, to promote the ring-opening oxidation of monocyclic aromatic hydrocarbons in the light tar, and promote the dissociation of water vapor through the catalyst carrier, so as to quickly and efficiently convert the light tar into synthesis gas mainly composed of CO and H2 at a temperature of 650-750°C. During the catalytic steam reforming of light tar, the reaction raw material space velocity is controlled to be 10000-14000h -1 The reaction raw materials include water vapor and light tar; the molar ratio of the water vapor to the carbon in the light tar is 3 to 3.5:1.

[0019] In step S3, the steam reforming of the medium tar refers to controlling the reaction temperature to 800-900°C and the reaction time to 1-5 minutes under the reaction conditions without a catalyst. The cracking or polycondensation reaction of the medium tar is promoted by prolonging the reaction time under the high temperature reaction environment, so that it is cracked and converted into a synthesis gas mainly composed of CO and H2, and a partial polycondensation reaction occurs during the cracking to generate a solid semi-coke product. In the steam reforming process of the medium tar, the reaction raw materials include water vapor and medium tar; the molar ratio of the water vapor to the carbon in the medium tar is 3-3.5:1.

[0020] In addition, the reaction temperature in step S3 is slightly higher than that in step S2, and the reaction time is also longer than that in step S2, but since no catalyst is used in the reaction process, the rapid deactivation of the catalyst due to carbon deposition, etc., of the medium-quality tar, which is very prone to polycondensation and carbon deposition, during the steam reforming process is avoided. At the same time, the solid semi-coke product generated by the medium-quality tar during the steam reforming process can be synergistically disposed with the heavy tar separated in step S1, thereby realizing the graded and quality-based disposal of the tar generated during the thermal conversion of organic solid waste.

[0021] In step S4, the solid semi-coke or the mixture of heavy tar and solid semi-coke is activated under high temperature conditions of 900-1100°C and pressure conditions of 0.06-0.12MPa, and the activation reaction time is 1-5min; CO2 enriched in the CO2 capture process in step S5 can also be further introduced for activation; the CO2 activation reaction is: C+CO2=2CO. On the one hand, the decomposition of heavy tar and solid semi-coke with large molecular weight can be promoted by increasing the reaction temperature, and on the other hand, pressurization can reduce the volume of the reactor, reduce the energy consumption cost required for heating, and prolong the residence time of the gaseous reactants, facilitate the control of the reaction process, and contribute to the formation of the pore structure of the solid semi-coke, thereby converting the heavy tar and solid semi-coke into high-value porous carbon. In the activation process of the mixture of solid semi-coke or heavy tar and solid semi-coke, the reaction raw materials include water vapor and a mixture of solid semi-coke or heavy tar and solid semi-coke; the molar ratio of carbon in the water vapor and the mixture of solid semi-coke or heavy tar and solid semi-coke is 3-3.5:1.

[0022] Furthermore, the activation method in step S4 is: introducing water vapor into a closed container containing solid semi-coke or a mixture of heavy tar and solid semi-coke for activation reaction, and water vapor or CO2 enriched in the CO2 capture process can also be continuously introduced into the reactor for activation to increase the system reaction pressure, thereby reducing the volume of the reactor, prolonging the reaction time, reducing the heating cost, and promoting the formation of a porous structure of the residual carbonaceous material.

[0023] In step S5, the synthesis gas containing CO and H2 obtained in each step is subjected to a water-gas shift reaction, CO is converted into H2 by the water-gas shift reaction CO+H2O=CO2+H2, and CO2 is captured by in-situ adsorption of CaO or adsorption of methanol at 0-5°C, thereby increasing the concentration of hydrogen in the product and obtaining hydrogen with a purity higher than 90%. The conditions for the water-gas shift reaction are: using Ni&Pt / CeO2, Ni / Fe2O3 or Ni / Fe2O3&CeO2 as a catalyst (the catalyst is purchased externally), CO and water vapor react for 5-10 minutes under water vapor conditions at 400-600°C to generate CO2 and H2; the generated CO2 is captured.

[0024] Furthermore, the above-mentioned method for the co-production and quality-differentiated utilization of tar from pyrolysis and gasification of organic solid waste also includes:

[0025] S6: Purify the hydrogen obtained in step S5 by pressure swing adsorption to obtain a battery-grade hydrogen product with a purity higher than 99.99%.

[0026] The hydrogen with a purity higher than 90% obtained in step S5 is purified by pressure swing adsorption in step S6, thereby increasing the purity of the hydrogen product to more than 99.99% to obtain a high-purity hydrogen product. Pressure swing adsorption can adopt conventional means disclosed in the art.

[0027] The beneficial effects of the method for co-production and quality-differentiated utilization of tar hydrocarbons provided by the present invention are as follows:

[0028] The present invention achieves a qualitative transformation of tar from the thermal conversion of organic solid waste, and respectively performs catalytic steam reforming, steam reforming and carbon activation on light, medium and heavy tars and solid semi-coke, ultimately obtaining high-purity hydrogen and porous carbon high-value products, thereby effectively avoiding technical defects such as low resource utilization rate in the tar treatment process, high operating costs caused by catalyst carbon deposition and deactivation or excessively high reaction temperature, and can efficiently and cost-effectively solve the tar problem that is inevitably generated in the thermal conversion of organic solid waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention is a flowchart of the steps of the method for thermally converting tar from organic solid waste to separate substances and utilizing the tar. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions of various embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] In the following examples, the steam reforming of light tar uses a fixed bed reactor with a catalyst; the steam reforming of medium tar uses a fixed bed reactor without a catalyst; and the activation of heavy tar and solid semi-coke uses a closed container.

[0032] Example 1

[0033] This embodiment provides a method for the co-production and separation of tar carbon and hydrogen from pyrolysis and gasification of organic solid waste, using waste straw gasification tar as raw material, and completing the separation and utilization of tar carbon and hydrogen under relatively low temperature reaction conditions through the steps of the present invention, as follows:

[0034] S1: The tar produced during the thermal conversion of organic solid waste is naturally cooled and divided into light tar with a boiling range of 100-200°C, medium tar with a boiling point of 200-400°C, and heavy tar with a boiling point above 400°C according to the boiling range. In the separation process, 25wt% of light tar, 35wt% of medium tar, and 40wt% of heavy tar are obtained. The mass percentage "wt%" here refers to the mass ratio relative to the tar raw material for thermal conversion of organic solid waste, and the same expression method is used in the following steps.

[0035] S2: The light tar in step S1 is heated on a Ni / Al2O3 catalyst at a reaction temperature of 700±50°C, and then steam is introduced (the reaction raw material space velocity is controlled to be 12000h -1 The reaction raw materials include water vapor and light tar; the molar ratio of water vapor to carbon in light tar is 3:1), and catalytic steam reforming is carried out. After the reaction is completed, a synthesis gas with H2 and CO as the main components is obtained.

[0036] S3: Steam reforming the medium-quality tar in step S1 by introducing water vapor at a reaction temperature of 850±50°C (the molar ratio of water vapor to carbon in the medium-quality tar is 3:1) for 5 minutes to obtain synthesis gas containing H2 and CO, and solid semi-coke obtained by condensation of the medium-quality tar, wherein the yield of the solid semi-coke is 11wt%.

[0037] S4: After mixing the heavy tar separated in step S1 with the solid semi-coke obtained in step S3, water vapor is introduced into a closed container at a reaction temperature of 900±50°C (the molar ratio of water vapor to carbon in the mixture of heavy tar and solid semi-coke is 3:1), the reaction pressure is controlled to 0.07±0.01MPa, and an activation reaction is carried out. The activation reaction time is 5min, and porous carbon with 0.18kg / kg tar and synthesis gas containing H2 and CO are obtained.

[0038] S5: The synthesis gas containing H2 and CO obtained in steps S2 to S4 is mixed and then subjected to water-gas shift treatment. The catalyst used in the water-gas shift reaction is Ni / Fe2O3&CeO2, the reaction temperature is 500°C, and the reaction time is 10 min. The water-gas shift converts the CO therein into CO2 and H2, and the 5°C methanol adsorption method is used to complete the adsorption of CO2 to obtain hydrogen with a purity higher than 90%, and the hydrogen yield obtained is 1.05Nm 3 / kg tar.

[0039] S6: Purify the hydrogen obtained in step S5 by pressure swing adsorption to obtain a battery-grade hydrogen product of 0.72 Nm 3 / kg tar.

[0040] The main feature of this embodiment is that a relatively low reaction temperature is selected for tar conversion in each reaction step. The hydrogen yield and porous carbon yield are shown in Table 1.

[0041] Example 2

[0042] This embodiment provides a method for producing hydrogen and porous carbon by utilizing tar from pyrolysis and gasification of organic solid waste, using waste straw gasification tar as raw material, and improving the gasification conversion rate of heavy tar and semi-coke under high temperature and pressure activation reaction conditions through the tar carbon-hydrogen cogeneration and utilization steps of the present invention, as follows:

[0043] S1: The tar produced during the thermal conversion of organic solid waste is naturally cooled and divided into light tar with a boiling range of 100-200°C, medium tar with a boiling point of 200-400°C, and heavy tar with a boiling point above 400°C according to the boiling range. In the separation process, 25wt% of light tar, 35wt% of medium tar, and 40wt% of heavy tar are obtained. The mass percentage "wt%" here refers to the mass ratio relative to the tar raw material for thermal conversion of organic solid waste, and the same expression method is used in the following steps.

[0044] S2: The light tar in step S1 is heated on a Ni / Al2O3 catalyst at a reaction temperature of 700±50°C, and then steam is introduced (the reaction raw material space velocity is controlled to be 12000h -1 The reaction raw materials include water vapor and light tar; the molar ratio of water vapor to carbon in light tar is 3:1), and catalytic steam reforming is carried out. After the reaction is completed, a synthesis gas with H2 and CO as the main components is obtained.

[0045] S3: steam reforming the medium tar in step S1 at a reaction temperature of 900±50°C (the molar ratio of water vapor to carbon in the medium tar is 3:1) for 5 minutes to obtain synthesis gas containing H2 and CO, and solid semi-coke obtained by polycondensation of the medium tar, wherein the semi-coke yield is 6wt%;

[0046] S4: After mixing the heavy tar separated in step S1 with the solid semi-coke obtained in step S3, water vapor is introduced into a closed container at a reaction temperature of 1050±50°C (the molar ratio of water vapor to carbon in the mixture of heavy tar and solid semi-coke is 3:1), the reaction pressure is controlled to 0.10±0.02MPa, and an activation reaction is carried out. The activation reaction time is 5min, and porous carbon with 0.12kg / kg tar and synthesis gas containing H2 and CO are obtained.

[0047] S5: The synthesis gas containing H2 and CO obtained in steps S2 to S4 is mixed and then subjected to water-gas shift treatment. The catalyst used in the water-gas shift reaction is Ni / Fe2O3&CeO2, the reaction temperature is 500°C, and the reaction time is 10 min. The water-gas shift converts the CO therein into CO2 and H2, and the 5°C methanol adsorption method is used to complete the adsorption of CO2 to obtain hydrogen with a purity higher than 90%, and the hydrogen yield obtained is 1.21Nm 3 / kg tar.

[0048] S6: Purify the hydrogen obtained in step S5 by pressure swing adsorption to obtain a battery-grade hydrogen product 0.83Nm 3 / kg tar.

[0049] The difference between this embodiment and embodiment 1 is that in step S4, a reaction temperature of 1050±50°C and a pressure of 0.10±0.02MPa are used to carry out the activation conversion reaction of heavy tar and solid semi-coke. The hydrogen yield and porous carbon yield are shown in Table 1.

[0050] Example 3

[0051] This embodiment provides a method for producing hydrogen and porous carbon by utilizing tar from pyrolysis and gasification of organic solid waste, using waste straw gasification tar as raw material, and improving the hydrogen yield by using the tar carbon-hydrogen co-production and utilization step described in the present invention, and preferably using a catalyst for catalytic steam reforming, as follows:

[0052] S1: The tar produced during the thermal conversion of organic solid waste is naturally cooled and divided into light tar with a boiling range of 100-200°C, medium tar with a boiling point of 200-400°C, and heavy tar with a boiling point above 400°C according to the boiling range. In the separation process, 25wt% of light tar, 35wt% of medium tar, and 40wt% of heavy tar are obtained. The mass percentage "wt%" here refers to the mass ratio relative to the tar raw material for thermal conversion of organic solid waste, and the same expression method is used in the following steps.

[0053] S2: The light tar in step S1 is heated on a Ni / LaFeO3 catalyst at a reaction temperature of 700±50°C, and then steam is introduced (the reaction raw material space velocity is controlled to be 12000h -1 The reaction raw materials include water vapor and light tar; the molar ratio of water vapor to carbon in light tar is 3:1), and catalytic steam reforming is carried out. After the reaction is completed, a synthesis gas with H2 and CO as the main components is obtained.

[0054] S3: steam reforming the medium tar in step S1 at a reaction temperature of 850±50°C (the molar ratio of steam to carbon in the medium tar is 3:1) for 5 minutes to obtain synthesis gas containing H2 and CO, and solid semi-coke obtained by polycondensation of the medium tar, wherein the semi-coke yield is 10wt%;

[0055] S4: After mixing the heavy tar separated in step S1 with the solid semi-coke obtained in step S3, water vapor is introduced into a closed container at a reaction temperature of 900±50°C (the molar ratio of water vapor to carbon in the mixture of heavy tar and solid semi-coke is 3:1), the reaction pressure is controlled to 0.07±0.01MPa, and an activation reaction is carried out. The activation reaction time is 5min, and porous carbon with 0.17kg / kg tar and synthesis gas containing H2 and CO are obtained.

[0056] S5: The synthesis gas containing H2 and CO obtained in steps S2 to S4 is mixed and then subjected to water-gas shift treatment. The catalyst used in the water-gas shift reaction is Ni / Fe2O3&CeO2, the reaction temperature is 500°C, and the reaction time is 10 min. The water-gas shift converts the CO therein into CO2 and H2, and uses CaO to complete the in-situ adsorption of CO2 to obtain hydrogen with a purity higher than 90%. The hydrogen yield obtained is 1.12Nm 3 / kg tar.

[0057] S6: Purify the hydrogen obtained in step S5 by pressure swing adsorption to obtain a battery-grade hydrogen product 0.74Nm 3 / kg tar.

[0058] The difference between this embodiment and embodiment 1 is that Ni / LaFeO3 catalyst is selected in step S2, and its hydrogen yield and porous carbon yield are shown in Table 1.

[0059] Table 1 The yield of tar fractionation and utilization at each stage under different operating conditions

[0060]

[0061]

[0062] As can be seen from Table 1, the method for fractionation and utilization of tar from pyrolysis and gasification of organic solid waste provided by the present invention is to separate the tar into light tar, medium tar and heavy tar according to the boiling range of the tar, and then convert the above tar components into synthesis gas by catalytic steam reforming, steam reforming and activation, and purify the tar by water-gas shift reaction and pressure swing adsorption to obtain high-purity hydrogen, with a maximum of 0.83Nm 3 / kg of battery-grade hydrogen yield can achieve a porous carbon yield of 0.12-0.18kg / kg. Under the same circumstances, the use of highly reactive and highly selective catalytic steam reforming catalysts, or increasing the reaction temperature of the activation treatment, can increase the hydrogen yield, but will lead to a decrease in the porous carbon yield. Therefore, in the actual operation process, the operating parameters can be adjusted according to product requirements, and the tar can be converted and utilized at the optimal reaction temperature to achieve harmless disposal of tar and co-production of high-purity hydrogen and porous carbon.

[0063] Example 4

[0064] This embodiment provides a method for the fractionation and utilization of pyrolysis tar from different organic solid waste raw materials, using tar from waste straw, bamboo waste, domestic garbage, brewing waste and waste fan blades as raw materials respectively. First, the above organic solid waste raw materials are placed in a 600°C fluidized bed rapid pyrolysis device to obtain tar, and then the tar is fractionated and utilized through the tar carbon-hydrogen cogeneration fractionation and utilization step of the present invention, as follows:

[0065] S1: The tar produced during the thermal conversion of organic solid waste is naturally cooled and divided into light tar with a boiling range of 100-200°C, medium tar with a boiling point of 200-400°C, and heavy tar with a boiling point above 400°C according to the boiling range. The mass ratios of the three types of tar obtained by pyrolysis of different raw materials are shown in Table 2 (the mass percentage "wt%" here refers to the mass ratio relative to the tar raw material for thermal conversion of organic solid waste, and the same expression method is used in the following steps).

[0066] S2: The light tar in step S1 is heated on a Ni / Al2O3 catalyst at a reaction temperature of 700±50°C, and then steam is introduced (the reaction raw material space velocity is controlled to be 12000h -1 The reaction raw materials include water vapor and light tar; the molar ratio of water vapor to carbon in light tar is 3:1), and catalytic steam reforming is carried out. After the reaction is completed, a synthesis gas with H2 and CO as the main components is obtained.

[0067] S3: Steam reforming the medium-weight tar in step S1 by introducing water vapor at a reaction temperature of 850±50°C (the molar ratio of water vapor to carbon in the medium-weight tar is 3:1) for 5 minutes to obtain synthesis gas containing H2 and CO, and solid semi-coke obtained by condensation of the medium-weight tar. The yields of the medium-weight tar by pyrolysis of different raw materials are shown in Table 2.

[0068] S4: After mixing the heavy tar separated in step S1 with the solid semi-coke obtained in step S3, water vapor is introduced into a closed container at a reaction temperature of 900±50°C (the molar ratio of water vapor to carbon in the mixture of heavy tar and solid semi-coke is 3:1), the reaction pressure is controlled to be 0.07±0.01MPa, and an activation reaction is carried out. The activation reaction time is 5min to obtain porous carbon and synthesis gas containing H2 and CO. The porous carbon yield is shown in Table 2.

[0069] S5: The synthesis gas containing H2 and CO obtained in steps S2 to S4 is mixed and subjected to water gas shift treatment. The catalyst used in the water gas shift reaction is Ni / Fe2O3&CeO2, the reaction temperature is 500°C, and the reaction time is 10 min. The water gas shift converts the CO therein into CO2 and H2, and uses CaO to complete the in-situ adsorption of CO2 to obtain hydrogen with a purity higher than 90%. The hydrogen yield is shown in Table 2.

[0070] S6: The hydrogen obtained in step S5 is purified by pressure swing adsorption to obtain a battery-grade hydrogen product. The yield is shown in Table 2.

[0071] Table 2 Yields of different raw material pyrolysis tar at different stages of quality utilization

[0072] raw material Waste straw Bamboo waste Household waste Brewing waste Waste fan blades Light tar (wt%) 25 31 39 36 17 Medium tar (wt%) 35 34 35 29 38 Heavy tar (wt%) 40 35 26 35 45 Medium tar gasification semi-coke yield (wt%) 11 15 7 8 18 Porous carbon yield (kg / kg tar) 0.18 0.17 0.12 0.13 0.22 <![CDATA[90% hydrogen production rate (Nm 3 / kg tar)]]> 1.05 1.08 1.10 0.98 0.85 <![CDATA[Battery-grade hydrogen production rate (Nm 3 / kg tar)]]> 0.72 0.73 0.78 0.61 0.49

[0073] As can be seen from Table 2, the tars obtained from the pyrolysis of different organic solid waste raw materials, after being separated according to their boiling range, have slightly different mass ratios of light tar, medium tar and heavy tar, and the obtained battery-grade hydrogen and porous carbon yields are not exactly the same. The tars obtained from the pyrolysis of lignocellulosic raw materials such as waste straw and bamboo waste have a high aromatic ring component, and the proportion of heavy tar can reach up to 40wt%, while the light tar yield of rubber and plastic raw materials mainly composed of synthetic polymers such as domestic garbage is relatively high. In addition, under the same conversion steps, the porous carbon yield is also highly correlated with the source of tar. The tars obtained from the pyrolysis of waste straw, waste bamboo materials, and brewing waste, which are mainly lignocellulosic raw materials, have a porous carbon yield of 0.12kg / kg tar higher than that of domestic garbage tar, and the tar produced by the pyrolysis of domestic garbage can obtain a higher battery-grade hydrogen yield during the conversion process. Therefore, in the actual operation process, the yield of the target product can be predicted according to the property characteristics of the organic solid waste raw materials, so as to obtain the target product with higher yield in a targeted manner during the tar fractionation and utilization process.

[0074] Those skilled in the art will appreciate that the embodiments herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A method for the co-production and quality-differentiation of tar from pyrolysis and gasification of organic solid waste, characterized in that: The following steps are involved: S1: The tar generated in the process of thermal conversion of organic solid waste is separated by in-situ thermal separation, and is divided into light tar with a boiling range of 100-200°C, medium tar with a boiling range of 200-400°C, and heavy tar with a boiling point above 400°C or / and solid semi-coke formed by condensation of tar according to the boiling range; S2: catalytically steam reforming the light tar in step S1 to obtain synthesis gas containing H2 and CO; S3: steam reforming the medium tar in step S1 to obtain synthesis gas containing H2 and CO, and solid semi-coke obtained by polycondensation of the medium tar; S4: mixing the heavy tar and / or solid semi-coke obtained in step S1 with the solid semi-coke obtained in step S3, and performing steam activation to obtain porous carbon and synthesis gas containing H2 and CO; S5: performing water-gas shift and CO2 capture on the synthesis gas obtained in any one of steps S2 to S4 to obtain hydrogen with a purity higher than 90%; Alternatively, the synthesis gases obtained in steps S2 to S4 are mixed and then subjected to water-gas shift and CO2 capture to obtain hydrogen with a purity higher than 90%.

2. The method for co-production and quality-differentiation of tar from pyrolysis and gasification of organic solid waste according to claim 1 is characterized in that: The in-situ thermal separation refers to the gradient segmented cooling of the oil-gas mixture produced after the pyrolysis and gasification of organic solid waste, and the separation of heavy tar and / or solid semi-coke, medium tar, and light tar in sequence according to the temperature gradient reduction.

3. The method for co-production and quality-differentiation of tar from pyrolysis and gasification of organic solid waste according to claim 1 or 2, characterized in that: In step S2, the light tar catalytic steam reforming uses a Ni / Al2O3 catalyst or a Ni / LaFeO3 catalyst, and the steam reforming temperature is controlled at 650-750°C.

4. The method for co-production and quality-differentiation of tar from pyrolysis and gasification of organic solid waste according to claim 3 is characterized in that: During the catalytic steam reforming of light tar, the reaction raw material space velocity is controlled to be 10000-14000h -1 .

5. The method for co-production and quality-differentiation of tar from pyrolysis and gasification of organic solid waste according to claim 1 or 2, characterized in that: In step S3, the medium tar steam reforming uses a steam reforming reaction at 800-900°C.

6. The method for co-production and quality-differentiation of tar from pyrolysis and gasification of organic solid waste according to claim 1 or 2, characterized in that: In step S4, the water vapor activation temperature is 900-1100° C., and the reaction pressure is 0.06-0.12 MPa.

7. The method for co-production and quality-differentiation of tar from pyrolysis and gasification of organic solid waste according to claim 6 is characterized in that: The method for activating the solid semi-coke or the mixture of heavy tar and solid semi-coke is: introducing water vapor into a closed container containing the solid semi-coke or the mixture of heavy tar and solid semi-coke to carry out an activation reaction.

8. The method for co-production and quality-differentiation of tar from pyrolysis and gasification of organic solid waste according to claim 7 is characterized in that: The CO2 enriched in the CO2 capture process in step S5 is also introduced into the closed container for activation.

9. The method for co-production and quality-differentiation of tar from pyrolysis and gasification of organic solid waste according to claim 1, characterized in that: The method further comprises S6: purifying the hydrogen obtained in step S5 by pressure swing adsorption to obtain a battery-grade hydrogen product with a purity higher than 99.99%.

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