A catalyst for sludge drying coupled with methanol steam reforming to produce hydrogen, a preparation method, application and system thereof

Abstract

The present application relates to waste heat recycling, biomass resource utilization and hydrogen production technical field, especially to a kind of sludge drying coupling methanol steam reforming hydrogen production catalyst and its preparation method, application and system.It comprises composite carrier and active component particles, composite carrier comprises V2O3, V8C7 and V2O3-V8C7, the V2O3 and V8C7 contact and form the V2O3-V8C7 heterojunction structure of close interface;Active component Ni is dispersed in the form of nanoparticle on the surface of the composite carrier.The present application provides a kind of methanol steam reforming hydrogen production catalyst, with V2O3-V8C7 two components as heterojunction composite carrier, the catalyst activity of Ni as active metal is high, the hydrogen production of methanol steam reforming hydrogen production is as high as 0.3924 mol / h·g ‑1 , and methanol conversion rate is as high as 93.3%.

Description

Technical Field

[0001] This invention relates to the fields of waste heat recovery and utilization, biomass resource utilization and hydrogen production technology, and in particular to a catalyst for hydrogen production by sludge drying coupled with methanol steam reforming, as well as its preparation method, application and system. Background Technology

[0002] Sludge is a byproduct of urban wastewater treatment, rich in various organic matter, heavy metals, and pathogens. Early methods involved direct landfilling or incineration, but the high water content of landfilling leads to large land occupation and heavy metal or toxic component contamination of land and groundwater. Incineration requires large amounts of auxiliary fuel and has excessive energy consumption. Therefore, drying pretreatment is necessary to reduce volume and weight, and stabilize sludge properties. Although there are many methods for treating sludge, sludge drying is the most mature, effective, rapid, and simple method. Sludge drying is a key technology for resource recovery, recycling, and volume reduction of sludge. Large-scale sludge drying can be used more efficiently for incineration power generation, as building materials, and as organic fertilizer, and can also eliminate pathogens, thus transforming waste into resources. This is of great significance for environmental protection, resource conservation, and turning waste into treasure. However, the sludge drying process requires a large amount of heat to remove the large amount of water contained in the sludge, and organic matter is also volatilized and released during the drying process. Current sludge drying processes do not fully utilize this water and organic matter.

[0003] Methanol steam reforming for hydrogen production is a technology that converts methanol and other organic compounds, along with water, into hydrogen through a chemical reaction. Its core technology involves a catalyst that, at a specific temperature, allows methanol and other organic compounds to undergo a reforming reaction with water vapor to produce hydrogen. Methanol has a high carbon-to-hydrogen ratio, is liquid at room temperature, and is easy to transport and store, making it an excellent feedstock for hydrogen production. Furthermore, methanol is widely available, produced from biomass, eliminating reliance on non-renewable energy sources, making it a green and environmentally friendly energy source. Compared to traditional hydrogen production technologies (such as methane steam reforming), methanol steam reforming for hydrogen production has a lower reaction temperature and lower energy consumption, demonstrating great potential for the development of hydrogen energy.

[0004] Coupled sludge drying and methanol steam reforming hydrogen production technologies can greatly improve hydrogen production efficiency while eliminating pollutant gases generated during sludge drying, which is of positive significance for achieving dual carbon targets and environmental protection. Summary of the Invention

[0005] This invention provides a catalyst for sludge drying coupled with methanol steam reforming to produce hydrogen, as well as its preparation method, application, and system. The purpose is to utilize the tail gas and waste heat from sludge drying to participate in the methanol steam reforming hydrogen production reaction, thereby increasing hydrogen production. The waste heat from the tail gas after the reaction is used to participate in sludge drying, thereby improving energy utilization.

[0006] To achieve the above objectives, the present invention provides a sludge drying coupled with methanol steam reforming for hydrogen production. The catalyst comprises a composite support and active component particles. The composite support comprises V2O3, V8C7, and V2O3-V8C7. The V2O3 and V8C7 are in contact to form a V2O3-V8C7 heterojunction structure with a tight interface. The mass ratio of carbon to vanadium in the composite support is 2-3:1. The active component Ni is dispersed on the surface of the composite support in the form of nanoparticles with an average particle size of 5-15 nm.

[0007] The catalyst support in this application is V2O3, V8C7, and a V2O3-V8C7 composite support. The V2O3-V8C7 composite support is prepared by varying the vanadium-to-carbon mass ratio. This support is not a simple physical mixture of V2O3 and V8C7, but rather a heterojunction structure with a tight interface. In this heterojunction, the V2O3 and V8C7 phases are interwoven in nanoscale particles, forming numerous stable phase interfaces. Within these interfaces, V2O3 and V8C7 form a strong interaction, which alters their electronic structure, strengthens the anchoring of Ni metal particles, promotes Ni dispersion, inhibits Ni sintering at high temperatures, and maintains the structural stability of the active sites. As a component of the catalyst support, V2O3 provides an oxidizing environment, which is beneficial for CO oxidation and the water-gas shift reaction; V8C7 provides a reducing environment, which is beneficial for methanol decomposition and hydrogen generation. The active component Ni is highly dispersed in nanoparticle form on the surface of this composite support. This specific structure synergistically promotes methanol decomposition and the water-gas shift reaction, significantly improving hydrogen selectivity and yield.

[0008] Preferably, the loading of the active component Ni in the catalyst is 10wt%-20wt% in the overall catalyst.

[0009] Under the same technical concept, the present invention also provides a method for preparing the sludge drying coupled with methanol steam reforming hydrogen production catalyst, specifically including the following steps:

[0010] S1. Mix and dissolve vanadium salt with carbon-containing organic matter to obtain solution A. Dry solution A to obtain a dry solid.

[0011] S2. Grind the dry solid into particles, place it in a Joule furnace and calcine it under a vacuum atmosphere, grind and sieve the calcined solid to obtain the catalyst composite support.

[0012] S3. Dissolve the nickel salt in a solvent to obtain solution B, and add solution B to the catalyst composite support prepared in S2 for impregnation;

[0013] S4. The impregnated catalyst composite support is dried and then placed in a tube furnace for calcination under a nitrogen atmosphere; after calcination, it is placed in a reduction furnace for reduction under a hydrogen atmosphere to obtain a methanol steam reforming hydrogen production catalyst.

[0014] The catalyst composite support of this application is formed in situ by Joule heating ultra-fast heating technology. Joule heating technology can bring the precursor to ultra-high temperature within seconds. Its extremely high heating rate can instantly break the VO bond in the precursor and promote the rapid formation of VC bond, thereby simultaneously generating V2O3 and V8C7 phases and maximizing their heterogeneous interface area.

[0015] Preferably, the vanadium salt in step S1 is at least one of ammonium metavanadate or vanadium oxalate; the carbon-containing organic matter includes at least one of glucose or sucrose; the mass ratio of the vanadium salt to the carbon-containing organic matter is 1:1-4; the mixing and dissolving process is accompanied by stirring and water bath heating at 60℃-80℃, and the drying is specifically drying in an oven at 75℃-85℃ for 24h-48h.

[0016] Preferably, in step S2, the Joule heating is performed at a heating rate of 85℃ / s-95℃ / s to 800℃-1100℃ and held for 40s-60s. The particle size of the solid after calcination is less than 200 mesh after grinding and sieving.

[0017] Preferably, in step S3, the amount of nickel added to the nickel salt is 10wt%-20wt% of the total catalyst, and the nickel salt is nickel nitrate; the solvent is at least one of water or anhydrous ethanol.

[0018] Preferably, in step S4, the heating rate of the tubular furnace is 5℃ / min-10℃ / min, the calcination temperature is 400℃-450℃ and held for 3h-4h, and the reduction temperature of the reduction furnace is raised to 400℃-450℃ at a heating rate of 5℃ / min-10℃ / min, the hydrogen flow rate is 40ml / min-50ml / min, and the reduction time is 2h-3h.

[0019] Under the same technical concept, the present invention also provides an application of the sludge drying coupled methanol steam reforming hydrogen production catalyst or the sludge drying coupled methanol steam reforming hydrogen production catalyst prepared by the preparation method, wherein the catalyst is used for methanol steam reforming hydrogen production reaction; the catalyst is placed in a methanol steam reforming hydrogen production system, and the tail gas after sludge drying is introduced into the methanol steam reforming hydrogen production system, wherein the tail gas after sludge drying contains water vapor, methanol and small molecule organic alcohols, and a reforming reaction occurs in the sludge drying coupled methanol steam reforming hydrogen production system to obtain hydrogen.

[0020] Coupled sludge drying and methanol steam reforming for hydrogen production significantly improves hydrogen production efficiency. Sludge drying generates a large amount of high-temperature steam, while methanol steam reforming for hydrogen production requires steam as a feedstock. By coupling the two, no additional steam is needed. The sludge drying tail gas also contains small-molecule alcohols, small-molecule furans, and other organic molecules. These organic molecules can enter the reforming hydrogen production system along with the drying tail gas, participating in the hydrogen production reaction along with methanol. This effectively provides an additional hydrogen source for the hydrogen production reaction, greatly increasing hydrogen yield.

[0021] Preferably, the sludge drying device is connected to a methanol steam reforming hydrogen production system, and the waste heat from the methanol steam reforming hydrogen production reaction is used to reheat and dry the sludge, with the drying temperature being 100℃-220℃.

[0022] At a drying temperature of 100℃, sludge mainly precipitates organic compounds such as methanol, ethanol, formic acid, and acetic acid. At drying temperatures above 140℃, it mainly precipitates organic compounds such as propionic acid, butyric acid, and esters.

[0023] The waste heat from the sludge drying exhaust gas can be supplied to the methanol steam reforming hydrogen production reaction. The waste heat from the reaction exhaust gas is then fed back into the dried sludge, forming an energy closed loop and significantly reducing the system's total energy consumption. Through the cascade utilization of energy and materials, the overall system's energy consumption is reduced, and the hydrogen yield is increased.

[0024] Under the same technical concept, the present invention also provides a sludge drying coupled with methanol steam reforming hydrogen production system, characterized in that the sludge drying coupled with methanol steam reforming hydrogen production system includes the methanol steam reforming hydrogen production catalyst or the methanol steam reforming hydrogen production catalyst prepared by the preparation method.

[0025] The methanol steam reforming hydrogen production system includes a sludge drying device, an input device, a methanol steam reforming hydrogen production device, a hydrogen purification device, and a tail gas treatment device.

[0026] The sludge drying device includes a drying box, a sludge inlet, a sludge outlet, a steam outlet, a first temperature controller, and a gas-solid separator. The sludge inlet and the first temperature controller are installed on the drying box. The sludge outlet and the steam outlet are connected to the drying box in a low-to-high sequence. One end of the gas-solid separator is connected to the drying box through the steam outlet, and the other end is connected to the drying box through the sludge outlet.

[0027] The input device includes an input channel, a mixer, and a methanol injection pump. The input channel is connected to a gas-solid separator, the mixer is installed on the input channel, and the methanol injection pump is connected to the mixer and injects methanol into the mixer.

[0028] The methanol vapor reforming hydrogen production unit includes a heating and holding furnace, a catalyst, a filter device, and a second temperature controller. The catalyst and the filter device are installed in the heating and holding furnace, and the second temperature controller controls the temperature in the heating and holding furnace.

[0029] The hydrogen purification device is connected to the methanol steam reforming hydrogen production device, the tail gas treatment device, and the sludge drying device. The hydrogen purification device includes a discharge port, which outputs hydrogen. The waste heat tail gas output by the hydrogen purification device is input into the sludge drying device to reheat and dry the sludge.

[0030] The exhaust gas treatment device receives other exhaust gases output from the hydrogen purification device, processes them, and then discharges them outside the methanol vapor reforming hydrogen production system.

[0031] The above-described solution of the present invention has the following beneficial effects:

[0032] 1) The steam generated from sludge drying is used for methanol reforming to produce hydrogen, replacing the traditional external steam preparation and supply, thus reducing the total energy consumption of the system; small molecule alcohols, small molecule furans and other organic compounds in the sludge drying tail gas can participate in the reforming reaction as reactants, greatly increasing hydrogen production.

[0033] 2) This invention provides a sludge drying coupled with methanol steam reforming for hydrogen production. Using a V₂O₃-V₈C₇ dual-component heterojunction composite support, and with Ni as the active metal, the catalyst exhibits high activity, achieving a hydrogen yield of up to 0.3924 mol / h·g during methanol steam reforming. -1 The methanol conversion rate is as high as 93.3%.

[0034] 3) This invention is the first to employ Joule heating ultrafast sintering technology to prepare a V₂O₃-V₈C₇ heterojunction support. Unlike the slow heating of traditional tube furnaces, Joule heating technology can bring the precursor to ultra-high temperatures within seconds. Its extremely high heating rate can instantly break the VO bonds in the precursor and promote the rapid formation of VC bonds, thereby simultaneously generating the V₂O₃ and V₈C₇ phases and maximizing their heterojunction interface area. Simultaneously, the rapid cooling process can lock in this highly active metastable interface structure. The heterojunction structure prepared by this method exhibits an interface density and catalytic synergistic effect that are difficult to achieve using traditional methods.

[0035] 4) This coupling system, through a unique process design, utilizes the waste heat from sludge drying exhaust gas for preheating and vaporizing methanol solution, achieving in-situ energy recovery and utilization. The waste heat from the exhaust gas can stabilize reaction temperature fluctuations, ensuring an optimal reaction environment. In the process of this invention, combining the volatile organic compounds from sludge drying with methanol can increase hydrogen production. However, the composition of the volatile organic compounds is complex. The catalyst prepared in this invention possesses high dispersibility and anti-carbon deposition capabilities, enabling it to cope with complex reaction environments and achieve high reactant conversion rates. Furthermore, through the coordinated control of drying temperature and reforming reaction temperature, it achieves cascaded energy utilization and stable hydrogen production efficiency. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the sludge drying and methanol steam reforming hydrogen production coupling system of the present invention;

[0037] Figure 2 This is an electron microscope image of the Ni / V2O3-V8C7 catalyst prepared in Example 1 of this invention;

[0038] Figure 3 The images show the XRD patterns of V2O3, V2O3-V8C7, and V8C7 of the methanol steam reforming hydrogen production catalyst composite supports prepared in Example 1 and Comparative Examples 1 and 2 of this invention.

[0039] Figure 4 This is an electron microscope image of the heterojunction structure in the Ni / V2O3-V8C7 catalyst of Example 1 of the present invention;

[0040] The components include: 1. Drying box; 2. Sludge inlet; 3. Sludge outlet; 4. Steam outlet; 5. First temperature controller; 6. Gas-solid separator; 7. Sludge; 8. Input channel; 9. Mixer; 10. Methanol injection pump; 11. Heating and insulation furnace; 12. Catalyst; 13. Filter device; 14. Second temperature controller; 15. Hydrogen purification device; 16. Outlet; and 17. Tail gas treatment device. Detailed Implementation

[0041] To make the technical problems, solutions, and advantages of this invention clearer, a detailed description will be provided below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0042] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0043] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a locking connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0045] A schematic diagram of the sludge drying coupled with methanol steam reforming hydrogen production system used in the embodiment is shown below. Figure 1 As shown, the sludge drying coupled methanol steam reforming hydrogen production system includes a sludge drying device, an input device, a methanol steam reforming hydrogen production device, a hydrogen purification device 15, and a tail gas treatment device 17.

[0046] The sludge drying device includes a drying chamber 1, a sludge inlet 2, a sludge outlet 3, a steam outlet 4, a first temperature controller 5, and a gas-solid separator 6. The sludge inlet 2 and the first temperature controller 5 are installed on the drying chamber 1. The sludge outlet 3 and the steam outlet 4 are connected to the drying chamber 1 in a low-to-high sequence. One end of the gas-solid separator 6 is connected to the drying chamber 1 through the steam outlet 4, and the other end is connected to the drying chamber 1 through the sludge outlet 3. Sludge 7 is installed inside the drying chamber 1. There is also an N2 input device to inject nitrogen into the drying chamber 1.

[0047] The input device includes an input channel 8, a mixer 9, and a methanol injection pump 10. The input channel 8 is connected to the gas-solid separator 6. The mixer 9 is installed on the input channel 8. The methanol injection pump 10 is connected to the mixer 9 and injects methanol into the mixer 9.

[0048] The methanol steam reforming hydrogen production unit includes a heating and holding furnace 11, a catalyst 12, a filter device 13, and a second temperature controller 14. The catalyst 12 and the filter device 13 are arranged in the heating and holding furnace 11, and the second temperature controller 14 controls the temperature in the heating and holding furnace 11. The catalyst 12 is the catalyst prepared in each embodiment, and the filter device 13 is quartz wool.

[0049] The hydrogen purification device 15 is connected to the methanol steam reforming hydrogen production device, the tail gas treatment device 17 and the sludge drying device respectively. The hydrogen purification device 15 includes an outlet 16, which outputs hydrogen. The waste heat tail gas output by the hydrogen purification device 15 is input into the sludge drying device to reheat and dry the sludge.

[0050] The exhaust gas treatment device 17 receives other exhaust gases output from the hydrogen purification device 15, processes them, and then discharges them outside the methanol vapor reforming hydrogen production system.

[0051] Figure 1 The middle arrow indicates the direction of gas flow. During the circulation process, the high-temperature water vapor generated by the sludge drying device drives the methanol or other organic matter to volatilize through the residual heat of the steam, forming methanol-containing vapor. This vapor enters the mixer 9 through the input channel 8 and mixes with the methanol injected by the methanol injection pump 10. The hydrogen purification device 15 collects and discharges the output hydrogen separately. Other tail gas enters the tail gas treatment device 17 and is treated before being discharged. The N2 tail gas containing residual heat is input into the sludge drying device to provide energy.

[0052] Example 1: Preparation of 10Ni / V2O3-V8C7 catalyst

[0053] A method for preparing a Ni / V₂O₃-V₈C₇ catalyst using ammonium metavanadate as the vanadium source, glucose as the carbon source, and nickel nitrate as the nickel salt includes the following steps:

[0054] (1) Weigh ammonium metavanadate and glucose in a mass ratio of 1:2, add 100ml of deionized water, and heat in a water bath at 60℃ to dissolve. Pour the solution into a crucible and dry in an oven at 85℃ for 48h.

[0055] (2) The dried solid is ground and then the particles are placed in a Joule furnace and heated to 950°C at a heating rate of 95°C / s and kept at that temperature for 60s. After cooling, the particles are taken out, ground and sieved. The powder is less than 200 mesh, and a V2O3-V8C7 heterojunction carrier with a carbon to vanadium mass ratio of 1.2:1 is obtained.

[0056] (3) Weigh 1g of V2O3-V8C7 heterojunction carrier, and then dissolve 0.526g of Ni(NO3)3·6H2O (equivalent to 10wt%Ni) in 2ml of anhydrous ethanol. Add the solution to the V2O3-V8C7 heterojunction carrier and impregnate for 12h.

[0057] (4) After impregnation, the sample is placed in an 85°C drying oven for 8 hours, then placed in a tube furnace and heated to 400°C at a heating rate of 5°C / min and held for 3 hours. The sample is then placed in a reduction furnace and heated to 450°C at a heating rate of 5°C / min with a hydrogen flow rate of 50 ml / min for 2 hours to obtain the Ni / V2O3-V8C7 catalyst.

[0058] (5) 0.5g Ni / V2O3-V8C7 catalyst was added to a solid packed bed as a catalyst for sludge drying coupled with methanol steam reforming to produce hydrogen. The methanol injection pump had an injection rate of 0.15ml / min.

[0059] (6) The temperature of the sludge drying device was set to 180℃. The raw sludge (85% moisture content) was sent into the drying box and dried at 180℃ for 3 hours to obtain dry sludge with a moisture content of 14%. The vapor phase composition of the steam after sludge drying was H2O (77wt%), methanol (8wt%), ethanol (6wt%), and other organic matter (7wt%). The steam after sludge drying and the tail gas were introduced into the methanol steam reforming reaction. The input rate of the steam after sludge drying was 0.125m. 3 / min, the residual heat of the steam causes methanol to evaporate, forming methanol-containing vapor, which then enters the reaction device;

[0060] Figure 2 This is an electron microscope image of the Ni / V2O3-V8C7 catalyst prepared in Example 1 of this invention;

[0061] Figure 3 The images show the XRD patterns of V2O3, V2O3-V8C7, and V8C7 of the methanol steam reforming hydrogen production catalyst composite supports prepared in Example 1 and Comparative Examples 1 and 2 of this invention.

[0062] Figure 4 This is an electron microscope image of the heterojunction structure in the Ni / V2O3-V8C7 catalyst of Example 1 of the present invention;

[0063] As can be seen from the figure, the Ni / V2O3-V8C7 catalyst prepared in Example 1 has V2O3 crystals adjacent to V8C7 crystals on the same support, exhibiting a distinct heterojunction structure.

[0064] Example 2 Preparation of 10Ni / V2O3-V8C7-2 catalyst

[0065] A method for preparing a Ni / V₂O₃-V₈C₇₂ catalyst using vanadium oxalate as the vanadium source, sucrose as the carbon source, and nickel nitrate as the nickel source includes the following steps:

[0066] (1) Weigh vanadium oxalate and sucrose in a mass ratio of 1:2, add 100ml of deionized water, and heat in a water bath at 60℃ to dissolve. Pour the solution into a crucible and dry in an oven at 85℃ for 48h.

[0067] (2) The dried solid was ground and then the particles were placed in a Joule furnace and heated to 850°C at a heating rate of 95°C / s and kept at that temperature for 60s. After cooling, the particles were taken out, ground and sieved. The powder was less than 200 mesh, and a V2O3-V8C7 dual carrier with a carbon to vanadium mass ratio of 1.5:1 was obtained.

[0068] (3) Weigh 1g of V2O3-V8C7 heterojunction carrier, and then dissolve 0.526g of Ni(NO3)3·6H2O (equivalent to 10wt%Ni) in 2ml of anhydrous ethanol and add it to the V2O3-V8C7 heterojunction carrier for impregnation for 12h.

[0069] (4) After impregnation, the sample is placed in an 85°C drying oven for 8 hours, then placed in a tube furnace and heated to 400°C at a heating rate of 5°C / min and held for 3 hours. The sample is then placed in a reduction furnace and heated to 450°C at a heating rate of 5°C / min with a hydrogen flow rate of 50 ml / min for 2 hours to obtain the Ni / V2O3-V8C7 catalyst.

[0070] (5) Add 0.5g Ni / V2O3-V8C7 catalyst to a solid packed bed reactor for methanol steam reforming reaction; the methanol steam injection rate is 0.15ml / min.

[0071] (6) The temperature of the sludge drying device was set to 180℃. The raw sludge (85% moisture content) was sent into the drying box and dried at 180℃ for 3 hours to obtain dry sludge with a moisture content of 13%. The gas phase components were H2O (78wt%), methanol (8wt%), ethanol (6wt%), and other organic matter (6wt%). The steam and tail gas after sludge drying were introduced into the methanol steam reforming reaction. The input rate of the steam after sludge drying was 0.125m. 3 The methanol evaporates at a rate of 0.000 m / min, driven by the residual heat of the steam, forming methanol-containing vapor that then enters the reaction apparatus.

[0072] Example 3 Preparation of 10Ni / V2O3-V8C7 catalyst

[0073] The preparation method is the same as in Example 1, except that the methanol reforming reaction temperature is 500℃. The original sludge (85% moisture content) was then dried in a drying oven at 180℃ for 3 hours to obtain dry sludge with a moisture content of 14%. The gas phase components consisted of H2O (77wt%), methanol (9wt%), ethanol (8wt%), and other organic matter (6wt%).

[0074] Example 4: Application of a coupling system based on 10Ni / V2O3-V8C7 at a drying temperature of 220°C.

[0075] (1) Using the sludge drying and methanol steam reforming hydrogen production system of the present invention, the original sludge (moisture content 85%) is sent into the drying box and dried at 220°C for 3 hours to obtain dry sludge with a moisture content of 8%.

[0076] (2) At the same time, the gaseous components generated during the sludge drying process are collected and introduced into the methanol reforming hydrogen production unit. The gaseous components are H2O (78wt%), methanol (9wt%), ethanol (6wt%) and other organic matter (7wt%).

[0077] Example 5 Preparation of 20Ni / V2O3-V8C7 catalyst

[0078] The preparation method is the same as in Example 1, except that 1.052 g of Ni(NO3)3·6H2O (equivalent to 20 wt% Ni) was weighed and impregnated with a V2O3-V8C7 heterojunction carrier. The original sludge (85% moisture content) was then placed in a drying oven and dried at 180°C for 3 hours to obtain dry sludge with a moisture content of 14%. The gas phase components were H2O (79 wt%), methanol (8 wt%), ethanol (7 wt%), and other organic matter (6 wt%).

[0079] Comparative Example 1: Preparation of 10Ni / V8C7 catalyst

[0080] A method for preparing a Ni / V8C7 catalyst using ammonium metavanadate as the vanadium source, glucose as the carbon source, and nickel nitrate as the nickel source includes the following steps:

[0081] (1) Weigh out ammonium metavanadate and glucose in a mass ratio of 1:5, add 100ml of deionized water, and heat in a water bath at 60℃ to dissolve.

[0082] (2) Pour the solution into a crucible and dry it in an 85°C oven for 48 hours. Grind the dried solid and then put the particles into a Joule furnace and heat them to 1100°C at a heating rate of 95°C / s. Keep them at that temperature for 60 seconds. After cooling, take them out, grind them, and sieve them. The powder is less than 200 mesh to obtain the V8C7 carrier.

[0083] (3) Weigh 1g of V8C7 carrier, and then dissolve 0.526g of Ni(NO3)3·6H2O (equivalent to 10wt%Ni) in 2ml of anhydrous ethanol and add it to the V8C7 carrier for 12h of soaking.

[0084] (4) After impregnation, the sample is placed in an 85°C drying oven for 8 hours, then placed in a tube furnace and heated to 400°C at a heating rate of 5°C / min and held for 3 hours. The sample is then placed in a reduction furnace and heated to 450°C at a heating rate of 5°C / min with a hydrogen flow rate of 50 ml / min for 2 hours to obtain the Ni / V8C7 catalyst.

[0085] (5) Add 0.5g of catalyst to a solid packed bed as a catalyst for methanol steam reforming reaction coupled with sludge drying. The injection rate of the methanol injection pump is 0.15ml / min.

[0086] (6) The temperature of the sludge drying device is set to 180℃. The steam and tail gas after sludge drying are introduced into the methanol steam reforming reaction. The input rate of the steam after sludge drying is 0.125m. 3 The methanol evaporates at a rate of 0.000 m / min, driven by the residual heat of the steam, forming methanol-containing vapor that then enters the reaction apparatus.

[0087] Comparative Example 2: Preparation of 10Ni / V2O3 catalyst

[0088] A method for preparing a Ni / V₂O₃ catalyst using ammonium metavanadate as the vanadium source, glucose as the carbon source, and nickel nitrate as the nickel source includes the following steps:

[0089] (1) Weigh ammonium metavanadate and glucose in a mass ratio of 1:0.5, add 100ml of deionized water, and heat in a water bath at 60℃ to dissolve.

[0090] (2) Pour the solution into a crucible and dry it in an 85°C oven for 48 hours. Grind the dried solid and then put the particles into a Joule furnace and heat them to 800°C at a heating rate of 95°C / s. Keep them at that temperature for 60 seconds. After cooling, take them out, grind them, and sieve them. The powder is less than 200 mesh to obtain the V2O3 carrier.

[0091] (3) Weigh 1g of V2O3 carrier, and then dissolve 0.526g of Ni(NO3)3·6H2O (equivalent to 10wt% Ni) in 2ml of anhydrous ethanol and add it to the V2O3 carrier for impregnation for 12h.

[0092] (4) After impregnation, the sample is placed in an 85°C drying oven for 8 hours, then placed in a tube furnace and heated to 400°C at a heating rate of 5°C / min and held for 3 hours. The sample is then placed in a reduction furnace and heated to 450°C at a heating rate of 5°C / min with a hydrogen flow rate of 50 ml / min for 2 hours to obtain the Ni / V2O3 catalyst.

[0093] (5) Add 0.5% catalyst to a solid packed bed reactor for methanol steam reforming reaction. The methanol injection rate is 0.15 ml / min.

[0094] (6) The temperature of the sludge drying device is set to 180°C, and the dried steam and tail gas are introduced into the methanol steam reforming hydrogen production unit.

[0095] Comparative Example 3: Preparation of 10Ni / V2O3-V8C7 catalyst

[0096] The preparation method is the same as in Example 1, except that steam and tail gas from the sludge drying device are not introduced. Instead, a mixed solution of methanol and water is injected to carry out a methanol steam reforming hydrogen production reaction, wherein the molar ratio of methanol to water is 1:1.5 and the solution injection rate is 0.15 ml / min.

[0097] Comparative Example 4: Preparation of 10Ni / V2O3 catalyst

[0098] The preparation method is the same as that of Comparative Example 2, except that deionized water is used as the nickel salt impregnation solvent.

[0099] Comparative Example 5: Application of a 10Ni / V2O3-V8C7-based coupling system at a drying temperature of 140°C.

[0100] The operation method is the same as in Example 4, but the drying temperature is 140°C, which is different from Example 5. The resulting sludge has a moisture content of 20% and the gas phase components are H2O (76wt%), methanol (14wt%), ethanol (8wt%) and other organic matter (4wt%).

[0101] Comparative Example 6: Application of a 10Ni / V2O3-V8C7-based coupling system at a drying temperature of 100°C.

[0102] The operation method is the same as in Example 4, but the drying temperature is 100°C, which is different from Example 5. The resulting sludge has a moisture content of 28% and the gas phase components are H2O (74wt%), methanol (15wt%), ethanol (9wt%) and other organic matter (2wt%).

[0103] Catalyst hydrogen production performance

[0104] The reaction temperature, hydrogen yield, and methanol conversion data of the methanol steam reforming hydrogen production catalysts in the examples and comparative examples are shown in Table 1.

[0105] As shown in Table 1, the additional water vapor and small molecule alcohol organic matter provided by the sludge drying system in Example 1 resulted in a hydrogen production of 0.3248 mol / h·g at 400°C. -1The conversion rate of methanol was 81.29%, and the hydrogen production increased significantly compared with Comparative Example 3. Although the conversion rate was not as high as that of Comparative Example 3, it is speculated that excessive water vapor, methanol or small molecule alcohols will affect the performance of the catalyst. This is because the contact between the reactants and the catalyst is insufficient or the reaction rate of the catalyst cannot keep up with the replenishment of the reactants, resulting in a decrease in the conversion rate.

[0106] Compared with Comparative Examples 1 and 2, Example 4 clearly shows that the hydrogen production of Example 4 is higher than that of the latter two, reaching 0.924 mol / h·g. -1 It can be inferred that the synergistic effect of the V2O3-V8C7 heterojunction support can promote the methanol reforming reaction. Furthermore, the high performance of Example 4 is attributed to the synergistic activation effect of the V2O3-V8C7 heterojunction support on reactant molecules. Strong electron transfer exists at the heterojunction interface, and the strong metal-support interaction of the heterojunction anchors Ni particles, inhibiting Ni sintering at high temperatures and maintaining the structural stability of active sites. The highly dispersed Ni nanoparticles provide ample active sites, structurally different from the single-support catalysts of Comparative Examples 1 and 2. V2O3 provides an oxidizing environment, which is beneficial for CO oxidation and the water-gas shift reaction; V8C7 provides a reducing environment, which is beneficial for methanol decomposition and hydrogen generation. The combination of the two achieves functional complementarity, improving the overall catalytic performance.

[0107] Comparing Comparative Example 2 with Comparative Example 4, it can be seen that the catalytic performance of the catalyst can also be affected by changing the impregnation solution. Due to the non-polarity of anhydrous ethanol, the dissolved nickel nitrate is more dispersed on the support, while deionized water is a polar molecule, which can easily cause Ni to cluster when loaded, thus reducing the catalytic activity.

[0108] Comparing Examples 2 and 3, it is evident that the choice of the support precursor affects the catalytic performance. The conversion rate of Example 3 is lower than that of Example 2, but the hydrogen production is higher, demonstrating that Example 3 has higher selectivity for hydrogen and higher hydrogen purity in the reforming reaction tail gas. This is advantageous in industrial production, as it can reduce the cost of gas separation. Example 2, on the other hand, generated more byproducts other than hydrogen.

[0109] Comparing Example 3 and Example 5, it can be seen that increasing the Ni loading can improve the hydrogen yield. However, excessive Ni loading leads to Ni metal particle agglomeration, reducing the effective active sites and thus decreasing the activation capacity for methanol. The results show that the hydrogen yield of the 10wt% Ni catalyst is 0.3924 mol / h·g. -1 The hydrogen production of the 20wt% Ni catalyst increased by only 0.0096 mol / h·g compared to the 10wt% Ni catalyst. -1 It can be seen that the 10wt% Ni added to the load is deactivated.

[0110] Comparing Example 3 with Example 1, it can be seen that increasing the reaction temperature to 500°C can promote the methanol steam reforming reaction and significantly increase hydrogen production. The hydrogen production from the additional small-molecule alcohols and water vapor produced by sludge drying in Example 1 at 400°C is close to the hydrogen production in Example 3 at 500°C without additional small-molecule alcohols and water vapor. Therefore, it can be inferred that when Example 1 reaches a reaction temperature of 500°C, it can exceed that of Example 3, proving that the small-molecule alcohols and furan-like organic compounds in the sludge drying steam can serve as an additional hydrogen source, thereby increasing hydrogen production.

[0111] Comparing Example 4 with Example 3, and Comparative Examples 5 and 6, it can be seen that: Example 4 had the highest drying temperature of 220°C, which could quickly dry the moisture and small-molecule alcohols in the sludge. However, the hydrogen yield was higher than that of Example 3. The main reason was the different drying temperatures. In Example 4, the sludge moisture evaporated rapidly, resulting in excessive steam entering the methanol steam reforming system. This led to dilution of the methanol concentration, incomplete reaction, and reduced hydrogen production. In contrast, Comparative Examples 5 and 6 had lower drying temperatures, resulting in slow moisture evaporation. A small amount of low-temperature steam entered the methanol steam reforming system. Insufficient additional heat transfer and insufficient steam supply led to excessively high methanol concentration in the system, resulting in incomplete reaction and reduced hydrogen production.

[0112] In summary, this invention provides a method for hydrogen production through sludge drying coupled with methanol steam reforming. Furthermore, it utilizes vanadium salts and carbonaceous organic matter to prepare a V₂O₃-V₈C₇ heterojunction support in a one-step process, supporting metallic Ni to prepare a Ni / V₂O₃-V₈C₇ catalyst. By utilizing the additional hydrogen source and steam provided by sludge drying, along with waste heat from the steam, the hydrogen yield from methanol steam reforming is increased while reducing overall system energy consumption. This solves the problems of wasted steam heat and water vapor caused by sludge drying, as well as tail gas pollution.

[0113] Table 1. Temperature, hydrogen production, and methanol conversion data for various catalysts.

[0114] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A sludge drying coupled with methanol steam reforming catalyst for hydrogen production, characterized in that, The catalyst comprises a composite support and active component particles. The composite support comprises V2O3, V8C7, and V2O3-V8C7. The V2O3 and V8C7 are in contact to form a V2O3-V8C7 heterojunction structure with a tight interface. The mass ratio of carbon to vanadium in the composite support is 2-3:

1. The active component Ni is dispersed on the surface of the composite support in the form of nanoparticles with an average particle size of 5-15 nm. The preparation method of the sludge drying coupled methanol steam reforming hydrogen production catalyst specifically includes the following steps: S1. Mix and dissolve vanadium salt with carbon-containing organic matter to obtain solution A. Dry solution A to obtain a dry solid. S2. Grind the dry solid into particles and place it in a Joule furnace for Joule calcination in a vacuum atmosphere. Heat it to 800℃-1100℃ at a heating rate of 85℃ / s-95℃ / s and hold for 40s-60s. Grind the calcined solid and sieve it to obtain the catalyst composite support. S3. Dissolve the nickel salt in a solvent to obtain solution B, and add solution B to the catalyst composite support prepared in S2 for impregnation; S4. The impregnated catalyst composite support is dried and then placed in a tube furnace for calcination under a nitrogen atmosphere. After calcination, it is placed in a reduction furnace for reduction under a hydrogen atmosphere to obtain a sludge drying coupled with methanol steam reforming hydrogen production catalyst.

2. The catalyst according to claim 1, characterized in that, The loading of the active component Ni in the catalyst is 10wt%-20wt%.

3. The catalyst according to claim 1, characterized in that, The vanadium salt mentioned in step S1 is at least one of ammonium metavanadate or vanadium oxalate; the carbon-containing organic matter includes at least one of glucose or sucrose; the mass ratio of the vanadium salt to the carbon-containing organic matter is 1:1-4; the mixing and dissolving process is accompanied by stirring and water bath heating at 60℃-80℃; the drying process specifically involves drying in an oven at 75℃-85℃ for 24h-48h.

4. The catalyst according to claim 1, characterized in that, In step S2, the particle size of the calcined solid after grinding and sieving is less than 200 mesh.

5. The catalyst according to claim 1, characterized in that, In step S3, the amount of nickel added to the nickel salt is 10wt%-20wt% of the total catalyst, and the nickel salt is nickel nitrate; the solvent is at least one of water or anhydrous ethanol.

6. The catalyst according to claim 1, characterized in that, In step S4, the heating rate of the tubular furnace is 5℃ / min-10℃ / min, the calcination temperature is 400℃-450℃ and the holding time is 3h-4h, and the reduction temperature of the reduction furnace is increased to 400℃-450℃ at a heating rate of 5℃ / min-10℃ / min, the hydrogen flow rate is 40ml / min-50ml / min, and the reduction time is 2h-3h.

7. An application of the sludge drying coupled with methanol steam reforming hydrogen production catalyst as described in any one of claims 1-6, characterized in that, The catalyst is used for methanol steam reforming to produce hydrogen. The catalyst is placed in the methanol steam reforming to produce hydrogen system, and the tail gas after sludge drying is introduced into the methanol steam reforming to produce hydrogen system. The drying temperature is between 140℃ and 220℃. The tail gas after sludge drying contains water vapor, methanol and small molecule organic alcohols. A reforming reaction occurs in the sludge drying coupled methanol steam reforming to produce hydrogen.

8. The application as described in claim 7, characterized in that, The sludge drying device is connected to the methanol steam reforming hydrogen production system, and the waste heat from the methanol steam reforming hydrogen production reaction is used to reheat and dry the sludge.

9. A sludge drying coupled with methanol steam reforming hydrogen production system, characterized in that, The sludge drying coupled methanol steam reforming hydrogen production system includes the sludge drying coupled methanol steam reforming hydrogen production catalyst as described in any one of claims 1-6. The methanol steam reforming hydrogen production system includes a sludge drying device, an input device, a methanol steam reforming hydrogen production device, a hydrogen purification device (15), and a tail gas treatment device (17). The sludge drying device includes a drying box (1), a sludge inlet (2), a sludge outlet (3), a steam outlet (4), a first temperature controller (5), and a gas-solid separator (6). The sludge inlet (2) and the first temperature controller (5) are installed on the drying box (1). The sludge outlet (3) and the steam outlet (4) are connected to the drying box (1) in a low-high order. One end of the gas-solid separator (6) is connected to the drying box (1) through the steam outlet (4), and the other end is connected to the drying box (1) through the sludge outlet (3). The input device includes an input channel (8), a mixer (9), and a methanol injection pump (10). The input channel (8) is connected to the gas-solid separator (6). The mixer (9) is installed on the input channel (8). The methanol injection pump (10) is connected to the mixer (9) and injects methanol into the mixer (9). The methanol steam reforming hydrogen production unit includes a heating and holding furnace (11), a catalyst (12), a filter (13), and a second temperature controller (14). The catalyst (12) and the filter (13) are installed in the heating and holding furnace (11), and the second temperature controller (14) controls the temperature in the heating and holding furnace (11). The hydrogen purification device (15) is connected to the methanol steam reforming hydrogen production device, the tail gas treatment device (17) and the sludge drying device respectively. The hydrogen purification device (15) includes a discharge port (16) which outputs hydrogen. The waste heat tail gas output by the hydrogen purification device (15) is input into the sludge drying device to reheat and dry the sludge. The tail gas treatment device (17) receives other tail gas output from the hydrogen purification device (15), processes it, and then discharges it outside the methanol vapor reforming hydrogen production system.

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