Isothermal differential evaluation device and method for catalytic reaction activity in tar reforming process

Abstract

The invention discloses an isothermal differential evaluation device and method for catalytic reaction activity in a tar reforming process. The device comprises: a gas supply unit for providing a carrier gas and an isotope-labeled reformed gas; the tar quantitative conveying unit is used for continuously conveying liquid tar; the tar and gas mixing unit is provided with a combined reactor with a throat structure and a conical flow guide part, so that gaseous tar and reformed gas are fully mixed and then flow in a plug flow manner; the isothermal differential catalytic reaction unit is provided with an infrared or microwave heating device and is internally provided with a porous catalyst sheet; the unreacted tar recovery unit is used for collecting unconverted tar in batches through parallel adsorption devices; the gas product testing unit is used for detecting non-condensable small molecule gas components in real time; and the condensable volatile component on-line detection unit is used for analyzing products in real time through a time-of-flight mass spectrum. The isothermal differential reaction characteristics of the catalyst can be accurately evaluated, kinetic data of tar catalytic conversion can be calculated, and the detection result is accurate.

Description

Technical Field

[0001] The invention relates to an isothermal differential evaluation device and method for catalytic reaction activity in a tar reforming process, belonging to the technical field of chemical reaction testing and analysis. Background Art

[0002] Tar is both a target product of high-temperature pyrolysis of hydrocarbon fuels such as coal, biomass, and waste tires, and an inevitable liquid byproduct and pollutant during medium- and low-temperature gasification and incomplete combustion. As a target product of pyrolysis, tar can be catalytically reformed to extract high-value chemicals and catalytically converted into fuel oils such as gasoline and diesel. However, as a byproduct and pollutant of gasification and combustion, tar has a significant impact on gasification and combustion technologies and processes, increasing purification costs, causing secondary pollution, and endangering operator health. Research is urgently needed on catalytic reforming technologies for removing tar from gasification and combustion processes.

[0003] Catalytic reforming of tar is a process in which tar comes into contact with reforming gas under certain temperature conditions and is converted into small non-condensable gas molecules (H2, CO, CO2, CH4, C2H4, C2H6, C3H6, C3H8, N2, etc.) and condensable volatile components (benzene, toluene, xylene, naphthalene, etc.) under the action of a catalyst. This process is a complex gas-solid heterogeneous catalytic reaction system involving numerous reaction products. Common catalysts for catalytic reforming of tar include: natural ore catalysts, synthetic catalysts such as nickel-based / iron-based catalysts, alkali metal oxides, ash-containing solid residues remaining after the pyrolysis / gasification / combustion of hydrocarbon solid fuels (such as biochar, coal coke, etc.), activated carbon, etc. Studying the catalytic reforming reaction of tar helps to gain a deeper understanding of the catalytic conversion characteristics of tar, reveal the catalytic reaction mechanism, evaluate the catalytic activity of catalysts, and guide catalyst design and catalytic reforming process development.

[0004] Research on the reaction characteristics of tar catalytic reforming has always been a key and difficult issue. This is related to both the complex tar components and products and the testing equipment and methods for catalytic reaction activity. Chinese patent CN105675794 A discloses a device and method for testing the activity of catalysts in the catalytic cracking process of garbage tar. The device and method mainly consist of a gasifier, a catalytic reactor, and a detector for the concentration of non-condensable small molecule gases such as CO / CO2 / H2 / CH4 / C2H4, and adopt an intermittent feeding method. The catalyst is loaded in a thin and high type (the ratio of the filling length to the equivalent diameter of the catalyst particles is ≥100; the ratio of the catalytic bed diameter in the catalytic reactor to the equivalent diameter of the catalyst particles is ≥8), which is essentially an integrating reactor. The device and method are used to calculate the overall first-order kinetic data of individual gas components and total gas products of tar conversion to non-condensable small molecule gas products. The tar conversion rate refers specifically to the yield of tar converted to non-condensable small molecule gas components, excluding volatile condensable product components. Chinese Patent CN103558323A discloses a microfluidized bed cracking reaction analysis device and a method for analyzing coal tar cracking reactions using the same. This device and method uses a quantitative loop to intermittently inject coal tar into a fluidized bed reactor for cracking. The amount of gas product generated is used to infer the tar conversion rate and calculate the tar cracking reaction kinetics. Chinese Patent CN103364521A discloses a gas-solid reaction isothermal differential analysis method and isothermal differential analyzer. A trace amount of sample is injected into a microfluidized bed via a transient pulse injection system for reaction. Gas products are detected online using rapid process mass spectrometry to obtain the temporal evolution of the conversion rate and calculate the reaction characteristics of the gas product generation. In theory, Chinese Patent CN103558323A and Chinese Patent CN103364521A can also be used to evaluate the catalytic reaction activity of catalyst particles. However, due to the fluidized bed reactor structure, the particles are in a fully mixed flow state within the reactor, making it difficult to evaluate the isothermal differential catalytic reaction activity of the catalyst. The above three patents all use intermittent feeding measures to test the conversion behavior of trace samples; however, the actual production process is mostly a steady-state process with stable reaction temperature and continuous material addition and discharge. In addition, the tar conversion process is complicated. The substances at the outlet of the reactor include not only non-condensable small molecular gases but also products such as condensable volatile components and unreacted and converted tar. It is not accurate to use gas components to calculate the tar conversion rate and the tar conversion kinetics. It more reflects the gas generation behavior. In addition, the reaction atmosphere is mostly inert atmosphere. When using atmospheres such as CO2, H2 and water vapor, since the reaction products also include the above atmospheres, it is very difficult to accurately calculate the yield of CO2, H2 and water vapor generated. It is also unclear how much of the above products comes from the atmosphere and how much comes from C, H, O in the tar, which brings great difficulties to the analysis of the catalytic mechanism.

[0005] In actual tar catalytic conversion processes, the catalyst is often loaded at a high height, and the conversion process reflects the lumped reaction characteristics of the entire catalyst bed, rather than the conversion process of a single-layer catalyst. However, in catalyst design and performance research, there is a strong desire to understand the intrinsic reaction characteristics of the catalyst, which requires differentiating the catalytic bed, that is, examining the conversion characteristics of a single-layer catalyst. Therefore, the determination and kinetic calculation of the differential catalytic reaction activity of the interaction between liquid hydrocarbon fuels and catalysts under specified temperature conditions is crucial, but has always been a difficult and challenging issue. Currently, there are no devices and methods for evaluating the catalytic reaction activity of differential catalytic beds during the catalytic conversion of hydrocarbon fuels using microconverters. The present invention is proposed to address this issue. Summary of the Invention

[0006] The purpose of the present invention is to provide an isothermal differential evaluation device and method for the catalytic reaction activity of the tar reforming process, which can accurately evaluate the isothermal differential reaction characteristics of the catalyst, calculate the kinetic data of the catalytic conversion of tar, and obtain accurate detection results.

[0007] The present invention is based on the following principles: the catalyst is pretreated to form a porous catalyst sheet, which is used to simulate the differential catalytic unit in the stacked catalyst bed. Accurately quantified liquid samples are continuously transported to the mixing unit and contacted with the isotope-labeled reformed gas; they are evenly mixed under the action of the throat and porous plate of the mixing unit, and flow in the micro-mixing unit as a plug flow under the action of the conical guide component. In the micro-converter, the tar-reformed gas reacts under the action of the porous catalyst sheet, and the generated products and unreacted tar are quickly released. The unreacted tar is collected and quantified by the timed switching adsorption device to obtain the relationship between the tar conversion rate and time; the generation characteristics and kinetics of non-condensable small molecule gas components are obtained through rapid process mass spectrometry and chromatography; the real-time generation of condensable volatile components is tested by time-of-flight mass spectrometry, and the kinetics of key components are calculated.

[0008] The isothermal differential evaluation device for catalytic reaction activity in a tar reforming process provided by the present invention comprises:

[0009] Gas supply unit, providing carrier gas and isotope-labeled reforming gas;

[0010] Tar quantitative delivery unit, continuously delivering liquid tar;

[0011] The tar and gas mixing unit is a combined reactor with a throat structure and a conical guide piece, which enables the gaseous tar and reformed gas to be fully mixed and flow in a plug flow;

[0012] Isothermal differential catalytic reaction unit, equipped with infrared or microwave heating device and built-in porous catalyst sheet;

[0013] Unreacted tar recovery unit, which collects unconverted tar in batches through parallel adsorption devices;

[0014] Gas product testing unit, real-time detection of non-condensable small molecule gas components;

[0015] The online detection unit for condensable volatile components analyzes the products in real time by time-of-flight mass spectrometry.

[0016] Preferably, the structure of the tar and gas mixing unit is as follows:

[0017] The frustum section is provided with ≥3 groups of equilateral triangle throat arrays, the number of equilateral triangles on a single edge line is ≥3, and the edge lines of the frustum are provided with ≥2 throats, evenly distributed on the side of the frustum;

[0018] The cylindrical section has a built-in conical guide, and the ratio of the cone bottom diameter to the cylinder diameter is 1:3-1:4

[0019] A porous baffle with an opening rate of 10-50% is set on the top of the frustum;

[0020] The throat and porous baffle structure allow the tar vapor, carrier gas and reformed gas to be mixed evenly, and the cylindrical part and the set cone further destroy the gas turbulence, so that the tar, carrier gas and reformed gas flow in a plug flow pattern.

[0021] Preferably, the structure of the isothermal differential catalytic reaction unit is as follows:

[0022] The cylindrical reaction zone at the bottom has a height of 20-50 mm and is equipped with a gas distribution plate suitable for catalyst sheets with a diameter of ≤30 mm;

[0023] The cone exhaust zone at the top is 1 / 4-1 / 3 of the height of the cylindrical zone, which facilitates the rapid departure of the product and unreacted tar from the reaction zone.

[0024] The tar and gas mixing unit is connected in series with the isothermal differential catalytic reaction unit or the reactors are directly connected together.

[0025] Preferably, the tar quantitative delivery unit adopts a peristaltic pump or a horizontal flow pump, and the tar is continuously supplied and accurately quantified during the experiment, with an error of ≤5%.

[0026] Preferably, the unreacted tar recovery unit includes ≥3 parallel adsorption devices, including an eight-way valve, a tar cooling and adsorption device, a gas flow meter, a gas sampling pump, and supporting pipelines and valves. The eight-way valve is followed by ≥3 tar cooling and adsorption devices, which are arranged in parallel and have equal operating times for each device. The mass of unconverted tar measured by the gas flow meter is obtained by measuring the mass of the adsorption material in the adsorption device before and after use at a specified temperature.

[0027] The gas product testing unit includes a gas chromatograph, a rapid process mass spectrometer or a time-of-flight mass spectrometer;

[0028] Specifically, the online detection device for condensable and volatile components in the catalytic reforming process products utilizes an analytical device, such as a time-of-flight mass spectrometer, capable of real-time detection of macromolecular components. The average composition of the non-condensable small-molecule gas products in the catalytic reforming process products is determined by collecting the gas products and detecting them using a chromatograph. The main equipment includes a tar cooling and adsorption device, a gas flowmeter, a gas sampling pump, a gas bag, and a chromatograph, through which the gas flows in sequence. The real-time evolution of each gas component is monitored online using analytical devices, such as rapid process mass spectrometry and infrared, with the detection interface located in the pipeline between the gas sampling pump and the gas bag. The chromatograph and online detection device are connected in parallel.

[0029] The condensable volatile component detection unit is connected in parallel with the unreacted tar recovery unit and the gas product testing unit.

[0030] Based on the isothermal differential evaluation device, the present invention also provides an isothermal differential evaluation method for catalytic reaction activity in a tar reforming process, comprising the following steps:

[0031] The steps of catalyst pretreatment and isothermal differential catalytic conversion and isothermal differential catalytic reaction activity testing are carried out in the isothermal differential evaluation device.

[0032] Specifically, the catalyst pretreatment includes the steps of mixing catalyst powder with a pore-forming agent, pressing the mixture, and then calcining the mixture to form porous catalyst flakes;

[0033] The thickness of the porous catalyst sheet is ≤1 mm, the diameter is ≤30 mm, and the inner diameter of the isothermal differential catalytic reaction conversion unit is ≤2 mm, ensuring that the catalyst sheet can be placed on the porous sieve plate of the isothermal differential catalytic reaction converter; the catalyst sheet needs to be calcined in the isothermal differential catalytic reaction conversion unit to form a porous catalyst sheet for simulating the differential unit of the traditional catalyst material layer;

[0034] The catalyst is selected from natural ores, nickel-based / iron-based synthetic catalysts, alkali metal oxides, ash-containing solid residues remaining after pyrolysis / gasification / combustion of hydrocarbon solid fuels (such as biochar, coal coke, etc.) and activated carbon;

[0035] The pore-forming agent is polypropylene, polyethylene or polyacrylamide, and the mass ratio of the pore-forming agent to the catalyst is ≤1:1.

[0036] Preferably, the isothermal differential catalytic conversion comprises the following steps:

[0037] The gas supply unit is used to deliver carrier gas and reformed gas to the tar and gas mixing unit, and the tar quantitative delivery unit is used to continuously deliver liquid tar to the tar and gas mixing unit;

[0038] After being fully mixed, the tar, carrier gas, and reformed gas enter the isothermal differential catalytic reaction unit, where they come into contact with the porous catalyst sheet and initiate the catalytic reaction. By controlling the thickness of the catalyst sheet and the height and diameter of the catalytic reaction zone, the residence time of the gaseous reactants in the porous catalyst sheet is very short, and the generated reactants, unconverted tar, and reformed gas quickly leave the reaction zone while still flowing in a plug flow state.

[0039] The non-condensable small molecule gas products in the generated products are detected in real time to determine the sources of C, H, and O in the above-mentioned gas products, as well as the proportions of tar and reformed gas. The real-time generation of condensable volatile components is detected in real time using time-of-flight mass spectrometry to determine the sources of C, H, and O in the above-mentioned condensable volatile components, as well as the proportions of tar and reformed gas.

[0040] Preferably, the reformed gas is isotope-labeled CO2, H2O, H2 or a mixture thereof, and the labeling element is at least one of C, H, and O. Isotope labeling facilitates tracing the C, H, and O elements in the generated gas products and condensable volatiles, and clarifies the proportion of them coming from tar and reformed gas.

[0041] The carrier gas is an inert gas such as N2 or Ar;

[0042] The tar includes coal tar, biomass tar, bio-oil, shale oil or petroleum high-temperature decomposable liquid. The tar is kept at a constant temperature of 25-35° C. during transportation to ensure fluidity during the tar transportation process.

[0043] The isothermal differential evaluation method of the present invention comprises the following evaluation steps based on the results obtained from the isothermal differential catalytic reaction activity test:

[0044] Evaluation of tar conversion rate; evaluation of tar catalytic conversion into non-condensable gas products; evaluation of tar catalytic conversion into condensable volatile components.

[0045] The specific calculation method is as follows:

[0046] 1) Using inert gas as the tracer gas, the total volume of non-condensable gas products generated during the catalytic conversion process containing the tracer gas can be calculated based on the total flow rate of the tracer gas during the reaction time and the average concentration of the tracer gas in the gas products;

[0047] 2) The unreacted tar recovery unit and the unit for monitoring the non-condensable small molecular gas products in the catalytic reforming process products are each equipped with a gas flow meter. Based on the gas flow rate passing through the test process, the ratio of the gas flow passing through the above two units to the total gas flow can be calculated. The gas volume passing through the online detection device for volatile components under isothermal conditions and its ratio to the total gas flow can also be calculated;

[0048] 3) Based on the unconverted tar recovered in the unreacted tar recovery unit within a specified test time and the ratio of the gas flow rate passing through during this time to the total generated gas flow rate, the total amount of unconverted tar within this time period can be calculated; combined with the amount of tar introduced during this time period, the tar conversion rate and unconversion rate within this time period can be calculated; based on the order in which the tar cooling and adsorption devices connected in sequence by the eight-way valve are used to treat the unreacted tar, the relationship between the tar conversion rate and reaction time, and the relationship between the tar reaction rate and reaction time can be calculated; and based on the Arrhenius equation, the tar conversion kinetics data of the reaction can be calculated.

[0049] 4) Based on the average concentration and real-time generation of non-condensable small molecule gas products in the catalytic reforming process products and the ratio of the gas flow rate passing through the test device to the total gas flow rate, the total gas volume of each gas component and the temporal trend of the gas volume per unit time can be calculated. Furthermore, the time-varying curve of the conversion rate and the time-varying curve of the generation rate of tar to the specified gas component can be calculated; based on the Arrhenius equation, the reaction kinetic data of the generation of a single gas component during the catalytic conversion of tar can be calculated.

[0050] 5) Based on the key component content tested by the online volatile component detection device and the ratio of the gas volume passing through the detection device to the total gas flow, the time-varying curve of the conversion rate and the time-varying curve of the generation rate of a key component during the catalytic conversion of tar can be calculated; based on the Arrhenius equation, the reaction kinetic data of the generation of individual gas components during the catalytic conversion of tar can be calculated.

[0051] 6) Based on the above calculations, the dynamic relationship between the tar conversion rate, the conversion of tar to non-condensable small molecular gas components, and the conversion of tar to condensable volatile components over time during the tar conversion process under the action of the differential catalyst bed during the catalytic reforming of tar can be evaluated.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] The present invention can provide testing and evaluation of the differential conversion characteristics of the catalyst bed under isothermal conditions and steady-state supply conditions of tar and reformed gas. It is very easy to obtain the dynamic relationship and corresponding kinetic parameters of the tar conversion rate, the conversion of tar into non-condensable small molecular gas components, and the conversion of tar into condensable volatile components over time, thereby providing a testing and evaluation device and method for actual catalytic conversion processes and catalyst development.

[0054] The present invention has broad applicability to catalytic conversion feedstocks and catalysts. It is suitable not only for the catalytic conversion of tar, but also for the catalytic conversion of high-temperature decomposable liquid components such as bio-oil, shale oil, and petroleum. Suitable catalysts include natural mineral catalysts, alkali metal oxides, ash-containing solid residues remaining after pyrolysis / gasification / combustion of hydrocarbon solid fuels, activated carbon, and synthetic catalysts.

[0055] The present invention provides accurate and comprehensive test results. Accurately controlled tracer gas volume flow rates and the gas volume flow rates on each detection channel for generated gas products make it easy to calculate the total gas volume generated. Combined with the average concentration and real-time generation of non-condensable small molecule gas products, this accurately translates into the temporal evolution of gas component generation yields. Isotope labeling of the reformed gas facilitates traceability of the C, H, and O elements in the products. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a schematic diagram of the isothermal differential evaluation device for catalytic reaction activity in the tar reforming process of the present invention.

[0057] Figure 2 It is a schematic structural diagram of the mixing unit reactor and the catalytic reforming reactor in the isothermal differential evaluation device of the present invention.

[0058] Figure 3 This is a real-time generation curve of the non-condensable small molecule gas product detected by mass spectrometry in Example 1 of the present invention.

[0059] Figure 4 This is a curve of the yield and time of the non-condensable small molecule gas product in Example 1 of the present invention.

[0060] Figure 5 This is a real-time generation curve of condensable volatile components in the product generated in Example 1 of the present invention.

[0061] Figure 6 It is a schematic diagram of the direct connection between the mixing unit reactor and the catalytic reforming reactor in the isothermal differential evaluation device of the present invention.

[0062] The marks in the figure are as follows:

[0063] 1. Inert tracer gas; 2. One-way valve; 3. Mass flowmeter; 4. Isotope-labeled water; 5. Metering water pump; 6. Steam generator; 7. Isotope-labeled CO2; 8. Tar sample; 9. Metering oil pump; 10. Tar-carrier gas-reformed gas mixing unit; 11. Electric heating furnace; 12. Ball valve; 13. Tar-carrier gas-reformed gas exhaust port; 14. Heating device; 15. Isothermal differential catalytic reaction device; 16. Porous catalyst sheet; 17. Non-condensable small molecule gas product; 18. Vacuum sampling pump; 19. Volume flowmeter; 20. Unconverted tar cooling and absorption device; 21. Pass valve; 22 exhaust port for catalytic conversion products of tar + unconverted tar; 23 gas bag; 24 micro gas chromatography; 25 rapid process mass spectrometry; 26 time-of-flight mass spectrometry; 27 exhaust port for condensable volatile components; 28 inlet for tar-carrier gas-reforming gas mixed gas; 29 cone part of mixing unit reactor; 30 throat; 31 gas distribution plate; 32 conical component; 33 gas distribution plate; 34 cylindrical part of mixing unit reactor; 35 cylindrical part of catalytic reforming reactor; 36 conical part of catalytic reforming reactor; 37 outlet for catalytic conversion products + unconverted tar. DETAILED DESCRIPTION

[0064] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0065] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0066] The schematic diagram of the isothermal differential evaluation device for catalytic reaction activity in the tar reforming process of the present invention is shown in FIG. Figure 1As shown, the system comprises a gas supply unit, a tar quantitative delivery unit, a tar and gas mixing unit, an isothermal differential catalytic reaction conversion unit, an unreacted tar recovery unit, a gas product testing unit, and an online detection unit for condensable volatile components in the tar reforming product. The operation process is as follows: tar is precisely quantitatively delivered to the mixing unit and converted into a gaseous state. The gaseous tar is thoroughly mixed with the carrier gas and reforming reaction gas, and moves axially in a plug flow pattern. The continuously supplied tar, carrier gas, and reforming reaction gas pass over the thin porous catalyst in the isothermal differential reforming reaction unit, initiating a catalytic reforming reaction. Unconverted tar and generated products are rapidly discharged from the reforming reaction unit. A portion of the unconverted tar and generated products are collected and quantified by a quenching and adsorption device. A portion of the unconverted tar and generated products are separated by quenching and adsorption devices. The gas components are analyzed by a rapid real-time monitoring device to determine the real-time generation of condensable small molecular gas components. The remaining gas components are collected and their average composition is analyzed by chromatography. The remaining unconverted tar and generated products, while in a heat-insulated state, enter a real-time monitoring device to analyze the real-time formation of condensable volatile components. After the reaction is completed, the device and method can determine the overall conversion characteristics and kinetics of the tar, the conversion characteristics and formation kinetics of non-condensable gas components, and the conversion characteristics and formation kinetics of condensable volatiles.

[0067] The catalysts involved in the present invention include but are not limited to: natural ore catalysts, nickel-based / iron-based and other artificial synthetic catalysts, alkali metal oxides, ash-containing solid residues remaining after pyrolysis / gasification / combustion of hydrocarbon solid fuels, activated carbon, etc.

[0068] Before catalytic conversion, the evenly mixed catalyst powder and pore-forming agent powder are pressed into thin sheets, which are calcined in an isothermal differential catalytic reaction conversion unit at a temperature consistent with the catalytic conversion reaction temperature. After calcination, the pore-forming agent decomposes to form porous catalyst sheets.

[0069] After the catalyst and pore-forming agent are crushed and sieved, powders with a particle size of ≤0.1 mm are selected and mixed evenly, and then pressed into catalyst flakes with a diameter of ≤30 mm and a thickness of ≤1 mm by a tablet press, wherein the addition ratio of the pore-forming agent to the catalyst is ≤1; the catalyst flakes are calcined in an isothermal differential catalytic reaction conversion unit to form porous catalyst flakes with a thickness of ≤1 mm.

[0070] The tar reformed gas involved in the present invention includes isotope-labeled CO2, H2O, H2 and a mixture of the above reformed gases, and the labeled elements are one or more of C, H and O.

[0071] like Figure 2As shown, the structure of the tar and gas mixing unit is as follows: the frustum section is provided with ≥3 groups of equilateral triangle throat arrays, the number of equilateral triangles on a single edge line is ≥3, and the side of the frustum is provided with ≥2 edges of the throat, which are evenly distributed on the side of the frustum; the cylindrical section has a built-in conical guide, and the ratio of the cone bottom diameter to the cylinder diameter is 1:3-1:4; a porous baffle with an opening rate of 10-50% is provided on the top of the frustum; the throat and porous baffle structure make the tar vapor, carrier gas and reformed gas mix evenly, and the cylindrical part and the set cone further destroy the gas turbulence, so that the tar, carrier gas and reformed gas flow in a plug flow pattern.

[0072] like Figure 2 As shown in the figure, the structure of the isothermal differential catalytic reaction unit is as follows: the cylindrical reaction zone at the bottom has a height of 20-50 mm, and is equipped with a gas distribution plate to adapt to catalyst sheets with a diameter of ≤30 mm; the conical exhaust zone at the top has a height of 1 / 4-1 / 3 of the cylindrical zone, which facilitates the rapid departure of products and unreacted tar from the reaction zone.

[0073] The tar and gas mixing unit is connected in series with the isothermal differential catalytic reaction unit.

[0074] like Figure 6 As shown, the reactors of the tar and gas thorough mixing unit and the isothermal differential catalytic reaction conversion unit can also be directly connected together without a valve 12 in between.

[0075] like Figure 1 As shown, the tar quantitative delivery unit adopts a peristaltic pump or a horizontal flow pump. During the experiment, the tar is continuously supplied and accurately quantified with an error of ≤5%.

[0076] like Figure 1 As shown, the branch for measuring the overall conversion characteristics and kinetics of tar after catalytic conversion includes an eight-way valve, a tar cooling and adsorption device, a gas flowmeter, a gas sampling pump, supporting pipelines, and valves. The eight-way valve is connected to at least three tar cooling and adsorption devices, arranged in parallel, with each device operating for an equal amount of time. The mass of unconverted tar, measured by the gas flowmeter, is obtained by measuring the mass change of the adsorption material in the adsorption device before and after use at a specified temperature.

[0077] In the present invention, the gas product testing unit includes a gas chromatograph, a rapid process mass spectrometer or a time-of-flight mass spectrometer;

[0078] Specifically, the online detection device for condensable and volatile components in the catalytic reforming process products utilizes an analytical device, such as a time-of-flight mass spectrometer, capable of real-time detection of macromolecular components. The average composition of the non-condensable small-molecule gas products in the catalytic reforming process products is determined by collecting the gas products and detecting them using a chromatograph. The main equipment includes a tar cooling and adsorption device, a gas flowmeter, a gas sampling pump, a gas bag, and a chromatograph, through which the gas flows in sequence. The real-time evolution of each gas component is monitored online using analytical devices, such as rapid process mass spectrometry and infrared, with the detection interface located in the pipeline between the gas sampling pump and the gas bag. The chromatograph and online detection device are connected in parallel.

[0079] The condensable volatile component detection unit is connected in parallel with the unreacted tar recovery unit and the gas product testing unit.

[0080] Based on the isothermal differential evaluation device, the present invention also provides an isothermal differential evaluation method for the catalytic reaction activity of the tar reforming process, which includes the following steps: a catalyst pretreatment method, an isothermal differential catalytic conversion method, and an isothermal differential catalytic reaction activity testing method.

[0081] Catalyst pretreatment involves thoroughly mixing tar catalyst powder and pore-forming agent powder, with the pore-forming agent to catalyst ratio ≤ 1. The mixed catalyst powder and pore-forming agent powder are then pressed into catalyst flakes ≤ 1mm thick. The diameter of the catalyst flakes is ≤ 30mm and ≤ 2mm of the inner diameter of the isothermal differential catalytic reaction converter unit to ensure they can be placed on the porous sieve plate of the isothermal differential catalytic reaction converter. The catalyst flakes are then calcined in the isothermal differential catalytic reaction converter unit to form porous catalyst flakes ≤ 1mm thick, which are used to simulate the differential unit of a traditional catalyst layer.

[0082] Among them, the isothermal differential catalytic conversion mainly includes the following steps:

[0083] 1) The tar sample is supplied continuously, rather than a one-time instantaneous addition of a trace amount of tar sample, so that the tar vapor is in a steady state during the catalyst activity evaluation process;

[0084] 2) The tar reformed gas used is a mixture of CO2, H2O, H2, and the aforementioned reformed gases, with the C, H, and O in the reformed gas labeled. The non-condensable small molecule gas products in the generated products are detected in real time to determine the sources of the C, H, and O in the gas products, as well as the proportion of tar and reformed gas sources. Time-of-flight mass spectrometry is used to detect the real-time generation of condensable volatile components in real time to determine the sources of the C, H, and O in the condensable volatile components, as well as the proportion of tar and reformed gas sources.

[0085] 3) Before the catalytic reaction activity test, the tar vapor, carrier gas, and reformed gas were fully mixed in the mixing unit, and the flow pattern of the mixed gas was adjusted to plug flow by controlling the diameter of the mixing device and the conical component installed inside;

[0086] 4) During the catalytic reaction activity test, tar vapor, carrier gas, and reformed gas are heated to the specified reaction temperature using a rapid heating device, such as an infrared device. The heated gas then contacts a pre-placed porous catalyst sheet, initiating the catalytic reaction. By controlling the thickness of the catalyst sheet and the height and diameter of the catalytic reaction zone, the gaseous reactants maintain a very short residence time within the porous catalyst sheet, allowing the generated reactants, unconverted tar, and reformed gas to rapidly exit the reaction zone while maintaining a plug flow.

[0087] The isothermal differential catalytic reaction activity evaluation includes the evaluation method of tar conversion rate, the evaluation method of tar catalytic conversion into non-condensable gas products, and the evaluation method of tar catalytic conversion into condensable volatile components. The calculation process is as follows:

[0088] A) During the experiment, an inert gas was used as the tracer gas. Based on the total flow rate of the tracer gas during the reaction time and the average concentration of the tracer gas in the gaseous products, the total volume of the non-condensable gas products generated during the catalytic conversion process containing the tracer gas can be calculated.

[0089] B) The unreacted tar recovery unit and the unit for monitoring the non-condensable small molecular gas products in the catalytic reforming process products are each provided with a gas flow meter. Based on the gas flow rate passing through the unit during the test, the ratio of the gas flow rate passing through the two units to the total gas flow rate can be calculated. The volume of gas passing through the online detection device for volatile components under isothermal conditions and its ratio to the total gas flow rate can also be calculated.

[0090] C) The total amount of unconverted tar recovered in the unreacted tar recovery unit within a specified test time and the ratio of the gas flow rate passing through during that time to the total generated gas flow rate can be calculated; the tar conversion rate and unconversion rate within that time period can be calculated based on the amount of tar introduced during that time period; the relationship between the tar conversion rate and reaction time, and the relationship between the tar reaction rate and reaction time can be calculated based on the order in which the tar cooling and adsorption devices connected in sequence to the eight-way valve are used to treat the unreacted tar; and the tar conversion kinetics data of the reaction can be calculated based on the Arrhenius equation.

[0091] D) Based on the average concentration and real-time generation of non-condensable small molecule gas products in the catalytic reforming process products and the ratio of the gas flow rate passing through the test device to the total gas flow rate, the total gas volume of each gas component and the temporal trend of the gas volume per unit time can be calculated. Furthermore, the time-varying curve of the conversion rate and the time-varying curve of the generation rate of tar to a specified gas component can be calculated. The reaction kinetic data for the generation of a single gas component during the catalytic conversion of tar can be calculated based on the Arrhenius equation.

[0092] E) Based on the key component content tested by the volatile component online detection device and the ratio of the gas volume passing through the detection device to the total gas flow, the time-varying curve of the conversion rate and the time-varying curve of the generation rate of the key component during the catalytic conversion of tar can be calculated; based on the Arrhenius equation, the reaction kinetic data of the generation of individual gas components during the catalytic conversion of tar can be calculated.

[0093] F) Based on the above calculations, the dynamic relationship between the tar conversion rate, the conversion of tar to non-condensable small molecular gas components, and the conversion of tar to condensable volatile components over time during the tar conversion process under the action of the differential catalyst bed during the catalytic reforming of tar can be evaluated.

[0094] Example 1

[0095] exist Figure 1 The isothermal differential evaluation device shown is used to perform isothermal differential evaluation of the catalytic reaction activity of the tar reforming process.

[0096] The catalyst requires pretreatment before use. Alkali metal-containing biochar catalyst powder and polypropylene pore-forming agent powder are thoroughly mixed in a mass ratio of 2:1. The mixture is then pressed into catalyst flakes 0.5 mm thick and 25 mm in diameter using a tablet press. The catalyst flakes are then calcined in an isothermal differential catalytic reaction conversion unit. The calcination temperature is 800°C at a heating rate of 10°C / min, and the temperature is maintained at 800°C for 1 hour. The calcination atmosphere is nitrogen. After calcination, a porous catalyst flake approximately 0.5 mm thick is obtained.

[0097] The tar-carrier gas-reformed gas mixing unit is heated to 250°C. The reactor structure is as follows Figure 2As shown. Ar (tracer gas) carrier gas was introduced into the mixing unit at a rate of 0.5 L / min. The metering water pump connected to the steam generator was turned on, and H isotope-labeled water (D2O) was introduced into the steam generator at a flow rate of 0.02 mL / min. After the carrier gas and steam stabilized, tar was introduced into the mixing unit at a feed rate of 0.01 mL / min. The tar, steam, and carrier gas were uniformly mixed through the throat and gas distribution plate. The mixed gas was controlled to exhibit plug flow by providing a conical component and controlling the inner diameter of the cylindrical portion of the mixing unit.

[0098] When the mixing unit is running stably, the tar-carrier gas-water vapor mixture is introduced into the isothermal differential catalytic reaction conversion unit loaded with porous catalyst sheets. The reactor structure is as follows: Figure 2 As shown in the figure, the reaction temperature was set to 800°C, and the catalytic reaction was initiated. All catalytic reforming products and unreacted tar were rapidly discharged from the micro-catalytic reaction unit. The gas sampling pump and pipeline valve of the unreacted tar recovery unit were opened, and the gas was collected using a cooling and adsorption device. The collection time for each device was set to 2 minutes. After drying the cooling and adsorption devices used in sequence, the amount of unconverted tar during the collection time was determined.

[0099] At the same time, the pump of the gas product test unit is turned on, and after the unconverted tar is processed using the cooling and absorption device, the generation of non-condensable small molecular gas components (H2, CO, CO2, CH4, etc.) is monitored in real time using a rapid process mass spectrometer. Figure 3 As shown in the figure, the evolution trend of the generation signals of gas components such as H2, CO, CO2, and CH4 over time can be seen. Gas is collected in a gas bag and chromatographically analyzed to analyze the average concentration of the gas components in the gas bag. Based on the average concentration, the real-time generation of gas components, and the ratio of the non-condensable small molecule gas flowing through the pipeline to the total non-condensable small molecule gas generated, the relationship between the yield of non-condensable small molecule gas in the tar differential catalytic process and time is obtained, as shown in Figure 1. Figure 4 As shown, it can be seen that the generation rate of gas components such as H2, CO, CO2, and CH4 (i.e., the conversion rate of tar catalytically converted into each gas component) has evolved over time;

[0100] At the same time, the condensable volatile components in the tar reforming products are detected online using time-of-flight mass spectrometry, and the real-time generation of the main products is as follows: Figure 5 As shown in the figure, the temporal evolution of the generation intensity of the main condensable components during the conversion process can be seen. Based on this analysis, the catalytic reaction activity of the differential catalyst bed during the catalytic conversion of tar can be determined, and the relationship between the tar conversion rate and the generation of non-condensable small molecular gas products and condensable volatile components during the catalytic conversion process can be understood.

Claims

1. An isothermal differential evaluation device for catalytic reaction activity in a tar reforming process, comprising: Gas supply unit, providing carrier gas and isotope-labeled reforming gas; Tar quantitative delivery unit, continuously delivering liquid tar; The tar and gas mixing unit is a combined reactor with a throat structure and a conical guide piece, which enables the gaseous tar and reformed gas to be fully mixed and flow in a plug flow; Isothermal differential catalytic reaction unit, equipped with infrared or microwave heating device and built-in porous catalyst sheet; Unreacted tar recovery unit, which collects unconverted tar in batches through parallel adsorption devices; Gas product testing unit, real-time detection of non-condensable small molecule gas components; The online detection unit for condensable volatile components analyzes the products in real time by time-of-flight mass spectrometry.

2. The isothermal differential evaluation device according to claim 1, characterized in that: The structure of the tar and gas mixing unit is as follows: The frustum section is provided with ≥3 groups of equilateral triangle throat arrays; The cylindrical section has a built-in conical guide, and the ratio of the cone bottom diameter to the cylinder diameter is 1:3-1:4 A porous baffle with an opening rate of 10-50% is arranged on the top of the frustum.

3. The isothermal differential evaluation device according to claim 1 or 2, characterized in that: The structure of the isothermal differential catalytic reaction unit is as follows: The cylindrical reaction zone at the bottom has a height of 20-50 mm and is equipped with a gas distribution plate suitable for catalyst sheets with a diameter of ≤30 mm; The upper conical exhaust area has a height of 1 / 4-1 / 3 of the cylindrical area.

4. The isothermal differential evaluation device according to claim 1 or 2, characterized in that: The tar quantitative delivery unit adopts a peristaltic pump or a horizontal flow pump.

5. The isothermal differential evaluation device according to claim 1 or 2, characterized in that: The unreacted tar recovery unit comprises ≥3 parallel adsorption devices; The gas product testing unit includes a gas chromatograph, a rapid process mass spectrometer or a time-of-flight mass spectrometer. The condensable volatile component detection unit is connected in parallel with the unreacted tar recovery unit and the gas product testing unit.

6. An isothermal differential evaluation method for catalytic reaction activity in a tar reforming process, comprising the following steps: The steps of catalyst pretreatment and isothermal differential catalytic conversion and isothermal differential catalytic reaction activity testing are carried out in the isothermal differential evaluation device according to any one of claims 1 to 5.

7. The isothermal differential evaluation method according to claim 6, wherein: The catalyst pretreatment includes the steps of mixing catalyst powder with a pore-forming agent, pressing the mixture, and then calcining the mixture to form porous catalyst flakes; The thickness of the catalyst sheet is ≤1mm and the diameter is ≤30mm; The catalyst is selected from natural ores, nickel-based / iron-based synthetic catalysts, alkali metal oxides, and ash-containing solid residues remaining after pyrolysis / gasification / combustion of hydrocarbon solid fuels; The pore-forming agent is polypropylene, polyethylene or polyacrylamide, and the mass ratio of the pore-forming agent to the catalyst is ≤1:

1.

8. The isothermal differential evaluation method according to claim 6 or 7, characterized in that: The isothermal differential catalytic conversion comprises the following steps: The gas supply unit is used to deliver carrier gas and reformed gas to the tar and gas mixing unit, and the tar quantitative delivery unit is used to continuously deliver liquid tar to the tar and gas mixing unit; After being fully mixed, the tar, carrier gas and reformed gas enter the isothermal differential catalytic reaction unit, contact with the porous catalyst sheet, and start the catalytic reaction.

9. The isothermal differential evaluation method according to claim 6 or 7, characterized in that: The reformed gas is isotope-labeled CO2, H2O, H2 or a mixture thereof, and the labeling element is at least one of C, H, and O; The tar includes coal tar, biomass tar, bio-oil, shale oil or petroleum high-temperature decomposable liquid, and the tar is kept at a constant temperature of 25-35° C. during transportation.

10. The isothermal differential evaluation method according to claim 6 or 7, characterized in that: The isothermal differential evaluation method includes the following evaluation steps based on the results obtained from the isothermal differential catalytic reaction activity test: Evaluation of tar conversion rate; evaluation of tar catalytic conversion into non-condensable gas products; evaluation of tar catalytic conversion into condensable volatile components.

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