CN1672788A - Catalyst for autothermal reformation of methanol to prepare hydrogen and its prepn process and application - Google Patents
Catalyst for autothermal reformation of methanol to prepare hydrogen and its prepn process and application Download PDFInfo
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Abstract
The catalyst has metal oxide without copper and noble metal as main active component and the composite oxide of RE and transition metal as transition layer assistant. Its preparation process includes coating transition layer assistant sol onto the carrier, drying and roasting, setting in boiled active component solution, heating the solution in the temperature raise rate of 1-2 deg.c/min to 130-190 deg.c, taking out the catalyst, blowing the catalyst to eliminate the residue in the catalyst passages, drying and roasting to obtain the catalyst. The catalyst needs activation before use, has methanol converting rate maintained in 100 % after use for 1000 hr and is suitable for use in hydrogen source system of fuel cell with unstable operation.
Description
Technical Field
The invention relates to a catalyst for autothermal reforming of methanol to produce hydrogen.
The invention also relates to a preparation method of the catalyst.
The invention also relates to the application of the catalyst.
Background
Since the beginning of research on fuel cells, it has been one of the hot spots in various countries to provide a hydrogen source to a mobile power source such as a vehicle-mounted fuel cell by reforming alcohols or hydrocarbons. At present, automobile manufacturers in the states of the united states, germany, japan, and the like have a plurality of fuel cell vehicles for hydrogen sources for methanol reforming and gasoline reforming, and many large companies in the world demonstrate power generation devices with integrated fuel reforming and fuel cell. In 2002, 9 months, the NECAR 5 methanol reforming fuel cell vehicle of Daimler Chrysler company completes the growth across the continental United states and becomes a milestone in the development process of vehicle-mounted reforming hydrogen production fuel cell electric vehicles.
The preparation of hydrogen from methanol by reforming generally comprises the processes of methanol reforming, CO shift and CO selective oxidation or pressure swing adsorption to remove CO, wherein the methanol reforming process is the most basic and main reaction process, and the following main reactions occur under the action of a catalyst:
wherein, the reaction (1) is a steam reforming process when not existing, and an external heat source is needed for strong endothermic reaction; the presence of reaction (1), referred to as an autothermal reforming or combined reforming hydrogen production process, is a coupling of steam reforming and oxidative reforming processes. In the process of preparing hydrogen by autothermal reforming, a small amount of oxygen (air) is introduced into a methanol and water reaction system to combust part of methanol, the released heat is directly supplied to methanol and water vapor for reforming reaction, and endothermic and exothermic reactions are coupled in situ, so that the requirements of frequent and rapid starting and rapid response when the power is changed of a fuel cell, particularly a vehicle-mounted fuel cell, a boat-used fuel cell or a standby power supply fuel cell, are most probably met.
At present, the research on the vehicle-mounted methanol and gasoline reforming hydrogen production technology is well developed, and the vehicle-mounted methanol and gasoline reforming hydrogen production technology is successfully carried out, but the developed reforming hydrogen production system cannot meet the special requirements of the vehicle-mounted or boat fuel cell hydrogen source in the aspects of miniaturization, integration, frequent and rapid start, rapid response during power change and the like. One of the technical difficulties is the volume and form of the catalyst in the hydrogen production process. The traditional granular catalyst is packed in a stacking way, and the pressure drop is large; the heat capacity is high, and ignition is difficult; easy abrasion and pulverization and low shock resistance; the high particle density, weight and volume make the integration and rapid start-up of the on-board reforming hydrogen production system more difficult. Researchers have therefore sought new ways to develop a new generation of methanol reforming hydrogen production catalysts, and monolithic ceramic honeycomb or metal honeycomb catalysts are one of the important development directions.
Since the GM company and the Ford company applied the monolithic ceramic-supported catalyst to the purification of automobile exhaust in the early 70 s of the last century, the monolithic catalyst and the technology achieved great success in the field of the purification of automobile exhaust, but in general, the application fields of the monolithic catalyst are limited to the purification of automobile exhaust, the catalyst for inhibiting airplane ozone, the filter in the metallurgical industry, the heat exchanger and the like. The monolithic catalyst (carrier) generally has parallel longitudinal channels, the active components of the catalyst are supported on the surfaces of the channels, and the channels are divided by thin partition walls, so that the monolithic catalyst (carrier) has the advantages of longitudinal channels, small pressure drop and small volume, and is suitable for running at high airspeed; the whole structure has good strength and strong shock resistance; the heat capacity is small, and the ignition is easy; the whole assembly is easy to replace; the catalyst has less active component carrying amount and high efficiency. These advantages of monolithic catalysts undoubtedly provide the necessary preconditions for miniaturization, fast response and high efficiency of on-board or mobile fuel cell hydrogen sources.
Foreign researchers have performed some work on the development of monolithic catalysts for on-board methanol reforming hydrogen production and gasoline reforming hydrogen production. Methanol reforming hydrogen production catalysts such as Pt-Zn-MOx catalyst (MOx is mixed metal oxide) in patent EP1312412A2, Pd-Zn/Cu-Zn double-coated catalyst in patent US2001016188A1, Pd-Zn-Ce-Zr catalyst in patent US2001/0021469A1, and the like. The U.S. Argonne national laboratory has developed a study of gasoline reforming monolithic catalysts with Rh, Pt, Ni as active components. The active components in the catalyst mainly comprise Pd, Pt and Zn, noble metals Pd and Pt are supported on composite metal oxides of Zn and the like in advance, are ball-milled to prepare Slurry, and then are coated on a honeycomb ceramic carrier which is generally cordierite to prepare the monolithic catalyst. The loading amount of the active components is more than 200g/L, and the activity and the stability are gradually enhanced along with the increase of the loading amount, and the dosage of the noble metal is correspondingly larger. In addition, such catalysts are generally activated beforehand before use, and the greatest disadvantage is that as the reaction proceeds, the loss of the reforming active component Zn causes a gradual increase in the CO content of the reformed gas.
From the patents and research reports reported in the publications, the research and development of the integral catalyst for hydrogen production by methanol autothermal reforming mainly focuses on the Pd-Zn and Pt-Zn catalysts containing noble metals; research has been carried out by Argonne national laboratory of the United states of America as a non-noble metal monolithic catalyst for hydrogen production by gasoline autothermal reforming; in the research of non-noble metal methanol autothermal reforming monolithic catalysts, l.j.petersson et al, sweden, reported a Cu/Cr/cordierite monolithic catalyst, but only given the hydrogen concentration and CO selectivity after removal of nitrogen from the product gas, and not the methanol conversion under autothermal conditions. Mature non-noble metal monolithic catalysts for methanol autothermal reforming hydrogen production have not been reported yet.
Disclosure of Invention
The invention aims to provide a non-noble metal methanol autothermal reforming monolithic end product catalyst which can be used in a hydrogen source system of a fuel cell. High activity and high stability are basic targets. The invention lays a foundation for the integration, high efficiency, quick start and response of the fuel cell hydrogen source system.
It is another object of the present invention to provide a process for preparing the above catalyst.
The catalyst provided by the invention takes non-copper-based and non-noble metal oxides as main active components, takes a composite oxide of rare earth metal and transition metal as a structure stabilizing auxiliary agent and a thermal stabilizing auxiliary agent, and coats the components on a cordierite honeycomb ceramic carrier. The catalyst does not need to be activated in advance before use; the methanol conversion rate is still 100% after a 1000hr life test; after multiple times of shutdown and start impact, the activity and selectivity of the catalyst are kept unchanged. Thus, the catalyst is well suited for providing a source of hydrogen for fuel cell systems operating in a non-steady state.
The specific content of the invention comprises:
1. the invention provides a formula of a catalyst for autothermal reforming of methanol to produce hydrogen
The catalyst is made of cordierite honeycomb ceramic (2 MgO)2·Al2O3·5SiO2) As a carrier (substrate), a composite oxide of rare earth metal and transition metal is used as a transition layer (support) and an auxiliary agent (promoter), and a non-copper-based and non-noble metal composite oxide is used as a main active component of the catalyst. Wherein, the oxides used as the transition layer, the thermal stabilizing auxiliary agent and the structural stabilizing auxiliary agent are selected from two or more of rare earth metal lanthanides such as lanthanum (La), cerium (Ce) and gadolinium (Gd) and oxides of transition metals such as titanium (Ti), chromium (Cr), zirconium (Zr), vanadium (V), manganese (Mn), nickel (Ni) and the like, the rare earth metals are preferably lanthanum (La) and cerium (Ce), and the transition metals are preferably titanium (Ti) and zirconium (Zr). In the transition layer, zirconium (Zr) oxide (ZrO)2) The percentage by weight of (C) is 5-80%, preferably 15-45%, of the total weight of the transition layer. The weight of the transition layer is cordierite load10-60%, preferably 30-40% by weight. The main active component of the catalyst is selected from elementsMetals 20-30 in the schedule are two or more oxides of zinc (Zn), chromium (Cr), iron (Fe), manganese (Mn), cobalt (Co), nickel (Ni), vanadium (V), preferably zinc (Zn), chromium (Cr), nickel (Ni), manganese (Mn). In the active component, the weight of zinc (Zn) oxide (ZnO) is not less than 40%, preferably 50-80% of the total weight of the active component. The weight of the active component is 30-60%, preferably 40-50% of the weight of the cordierite carrier.
The method for coating the active components and the auxiliary agents in the formula on the honeycomb ceramic carrier comprises the following steps:
the transition layer is coated on the cordierite honeycomb ceramic carrier which is treated in advance in the form of composite oxide sol by adopting an impregnation method. In order to obtain a sufficient specific surface area, an alumina sol or an alumina wet ball-milling sol may be coated on the cordierite carrier in advance by an impregnation method. The operation of the impregnation process is well known to the skilled person. The weight of the coated alumina gel accounts for 5-15%, preferably 8-12% of the weight of the blank honeycomb ceramic. The weight of the transition layer composite oxide sol is 10 to 60%, preferably 30 to 40% of the cordierite carrier weight. The composite oxide sol of the transition layer is prepared by a sol-gel method. And blowing by compressed air, drying and roasting after the impregnation is finished to obtain the catalyst intermediate. Wherein the drying method can be air drying, oven drying, microwave drying or freeze drying, preferably microwave drying or freeze drying. The operation of compressed air purging and firing procedures is also well known to those skilled in the art. The roasting temperature and time are 500-900 ℃ for 1-6 hours, preferably 650-800 ℃ for 2 hours. The process is repeated one or more times until the desired loading of the transition layer component is achieved.
The invention can also prepare the transition layer composite oxide into milky Slurry (Slurry) by a wet ball milling method and coat the milky Slurry on the pretreated cordierite honeycomb ceramic carrier, and the preparation method of the Slurry is well known by researchers in the field. The operations of the subsequent procedures of compressed air blowing, drying, roasting and the like after the impregnation are the same as the above. The process is repeated one or more times until the desired loading of the transition layer component is achieved.
The hot coating method of the catalyst active component of the present invention is specifically described as follows: the soluble salt solution of the active component is mixed according to a specified proportion, and the precursor of the catalytic component can be selected from nitrate, oxalate, carbonate or chloride, and the nitrate and the oxalate are preferred. Transferring the mixed solution into an open container such as a beaker, placing the open container such as the beaker into a temperature programming electric furnace, heating and boiling the mixed solution, placing a catalyst intermediate, controlling the temperature rise rate of the solution to be 1-2 ℃/min, taking out the catalyst when the final temperature of the solution is between 130 ℃ and 190 ℃, preferably 150 ℃ and 170 ℃, quickly blowing and cleaning residues in a catalyst channel by using compressed air, placing the prepared catalyst into an oven, drying the catalyst for 2-10 hours, preferably 4-6 hours at 120 ℃, and then placing the catalyst into a muffle furnace for roasting at 500 ℃ and 900 ℃ for 1-6 hours, preferably 650 ℃ and 800 ℃ for 2 hours to obtain the finished catalyst. The method is repeated once or for a plurality of times until the required active ingredient loading is achieved.
The preparation method of the catalyst can also adopt a one-step thermal coating mode to coat the main catalytic active component and the catalyst auxiliary agent on the pretreated cordierite honeycomb ceramic carrier to prepare the catalyst. Soluble salt solutions of the main active components of the catalyst and the auxiliary agents are mixed in the stoichiometric ratio as described above and applied to the cordierite carrier according to the hot coating method of the present invention. The selection of drying mode and the procedures of channel blowing and roasting are the same as above. The method needs to be repeated for a plurality of times until the required active ingredient and auxiliary agent loading capacity is achieved.
The invention has the following practical range and application prospect:
the monolithic catalyst is used in the process of hydrogen production by autothermal reforming of methanol, forms a hydrogen source system together with a CO water-vapor conversion process and a CO purification process, and provides a suitable hydrogen fuel for a fuel cell, particularly a Proton Exchange Membrane Fuel Cell (PEMFC) system. Because the catalyst adopts an integral structure, the strength is good, and the shock resistance is strong; the heat capacity is small, and the starting is rapid; the whole assembly is easy to replace; the reactor has small volume and compact structure. The advantages enable the miniaturization, integration and quick start of the whole fuel cell hydrogen source system, quick response to the power change of the fuel cell and the like, so the methanol autothermal reforming hydrogen production monolithic catalyst is particularly suitable for the fuel cell hydrogen source system which supplies hydrogen in a mobile and on-site hydrogen production mode, such as a vehicle-mounted fuel cell hydrogen source system, a small and medium-sized on-site hydrogen production hydrogen filling station and the like. The fuel cell can be used in places with inconvenient traffic as a power supply and as a dispersed military power supply, such as villas, small residential areas, rural areas, launching devices, tanks, armed stations, tunnels and the like.
As is well known, fuel cell technology has become a hot research and development focus in the energy and traffic fields of the world today as the best solution and new technology platform for hydrogen energy utilization. At the stage when PEMFC technology has been gradually commercialized, the supply of fuel hydrogen has become a prominent and imminent problem, and the problem of hydrogen source has become one of the bottlenecks in the overall technological development of fuel cells. The factors such as cost, performance, national conditions and the like are comprehensively considered, and on the premise that matched infrastructures such as hydrogen storage, transportation and filling are not available at present, hydrogen is produced on site by using hydrocarbons such as natural gas, methanol, gasoline and the like to supply the fuel cell for power generation, so that the demand of the fuel cell on fuel in the near term and even the middle term can be met. Therefore, the development of the fossil fuel reforming hydrogen production technology with advanced performance and the related catalyst has important practical significance and wide development prospect. The catalyst of the invention adopts an integral structure, does not need to be activated in advance before use, is quick to start, is suitable for temperature shock change and oxidation reduction atmosphere change caused by different working conditions such as start-up, load change, shutdown and the like of the fuel cell, has high activity, good stability and long service life, is suitable for being applied to a hydrogen source system of the fuel cell, and fills the blank of related research fields in China.
The novelty and inventive step of the present invention resides in,
(1) the catalyst has high activity, good stability and long service life, does not need to be activated in advance before use, is started quickly, can quickly respond to different working conditions of fuel cell start-up, load change, shutdown and the like, overcomes many limitations of the conventional copper-based catalyst and noble metal catalyst, and is a new generation of methanol autothermal reforming hydrogen production monolithic catalyst.
(2) In the invention point (1), the catalyst adopts a honeycomb ceramic integral structure, the heat capacity is small, and the ignition and the starting are rapid; the strength is good, and the shock resistanceis strong; the whole assembly is easy to replace; the reactor has small volume and compact structure, thus being more suitable for being applied to a fuel cell hydrogen source system for producing hydrogen on site or in a mobile way.
(3) In the invention (1), the catalyst adopts non-copper-based and non-noble metal composite oxides as main active components, so that the limitations of conventional copper-based catalysts and noble metal catalysts in the aspects of reaction activity, stability, pre-activation before use and the like are overcome; meanwhile, the composite oxide of rare earth metal and transition metal is introduced as a structure stabilizing auxiliary agent and a thermal stabilizing auxiliary agent, so that the stability of the catalyst is further improved, and the novel methanol self-heating reforming catalyst with high activity, good stability and long service life is prepared.
(4) In the invention point (1), the coating method of the active component of the catalyst is originally created by the research room, which not only well solves the problem of loading the active component of the catalyst, improves the activity and the stability of the catalyst, but also better embodies the idea of non-uniform distribution of the active component in the catalyst engineering design in the preparation of the honeycomb ceramic monolithic catalyst.
Drawings
FIG. 1 shows a life test of a catalyst according to the invention;
FIG. 2 shows a pressure experiment of the catalyst of the present invention;
FIG. 3 shows a pure oxygen experiment of the catalyst of the present invention;
FIG. 4 shows a 5kW class system experiment for the catalyst of the present invention;
FIG. 5 shows a start-stop impact test of a catalyst of the present invention;
FIG. 6 shows an electron microscope-chromatogram spectrum of the catalyst of the present invention
Detailed Description
Example 1: preparation of Zn-Cr/Ce-Zr/cordierite catalyst
a) Taking a 400cpsi (400 holes per square inch) cordierite honeycomb ceramic 1 block with a diameter of 15 multiplied by 25mmWith 3% HNO3Pretreating for 12 hours, drying for 12 hours at 120 ℃, and roasting for 2 hours at 900 ℃ for later use.
b) Weighing technical grade Ce (NO)3)3·6H2And adding deionized water into the mixture for stirring and dissolving, wherein the mass is 630 g. Weighing technical grade Zr (OH)457.8g, putting into a beaker, adding 110 plus or minus 2ml of 65-68% concentrated nitric acid, heating for reaction until no visible particles exist and the solution is transparent, and adding 200 plus or minus 10ml of deionized water to clarify the solution. Dissolving Zr (NO)3)4Pouring the solution into Ce (NO)3)3Filtering, stirring and mixing evenly in the solution to obtain Ce (NO)3)3With Zr (NO)3)4The solution was mixed. With 13% NH4OH as gelling agent and 35% HNO3Preparing CeO by sol-gel method as dispergator2-ZrO2The composite oxide sol is ready for use. The pH of the sol was found to be 1.16.
c) Weighing 1.8008g of the honeycomb ceramic carrier and using CeO2-ZrO2Dipping the composite oxide sol for 3 minutes, taking out the sol, blowing a channel by using compressed air, drying the sol for 3 minutes by using microwaves, and roasting the sol for 2 hours at 800 ℃ in a muffle furnace. This process was repeated 2 times to obtain 2.3942g of catalyst intermediate.
d) Weighing analytically pure Zn (NO)3)2·6H2O 89.4664g，(NH4)2Cr2O725.3603g, 30ml deionized water is added, the mixture is put on an electric furnace for slight heating dissolution, and the volume is determined to be 100ml after cooling.
e) Measuring 70ml of the mixed solution, transferring the mixed solution into a beaker, placing the beaker on a temperature programming electric furnace, heating and boiling, placing the catalyst intermediate prepared in the step c), controlling the temperature rising rate of the solution to be 2 ℃/min, taking out the catalyst when the final temperature of the solution is 170 ℃, quickly and cleanly blowing residues in a catalyst channel by using compressed air, placing the prepared catalyst into an oven, drying the catalyst for 4 hours at 120 ℃, and then placing the catalyst into a muffle furnace, and roasting the catalyst for 2 hours at 800 ℃ to obtain the Zn-Cr/Ce-Zr/cordierite finished catalyst (A), wherein the weight of the catalyst is 3.3935 g.
Example 2: preparation of Zn-Cr/Ti-Zr/cordierite catalyst
a) Cordierite honeycomb ceramic substrates were pretreated as in example 1.
b) Weighing analytically pure TiO242.7535g of powder, analytically pure ZrO242.5780g of powder, 40ml of deionized water and 4g of pseudo-boehmite (Al) were added2O3·H2O), ball milling for 18 hours. The ball-milled slurry is adjusted to a pH value of 3.0 by using 10% dilute nitric acid solution for later use.
c) Weighing 2.2191g of the honeycomb ceramic carrier and TiO2-ZrO2And soaking the composite oxide latex for 3 minutes, taking out the composite oxide latex, purging a channel by using compressed air, drying the composite oxide latex for 3 minutes by using microwaves, and roasting the composite oxide latex for 2 hours at 500 ℃ in a muffle furnace to obtain 2.6634g of catalyst intermediate.
d) Measuring 70ml of Zn-Cr mixed solution in example 1, transferring the Zn-Cr mixed solution into a beaker, placing the beaker on a temperature programming electric furnace, heating and boiling, placing the catalyst intermediate prepared in the step c), controlling the temperature rising rate of the solution to be 2 ℃/min, taking out the catalyst when the final temperature of the solution is 150 ℃, quickly and cleanly blowing residues in a catalyst channel by using compressed air, placing the prepared catalyst into an oven, drying the catalyst for 4 hours at 120 ℃, and then placing the catalyst into a muffle furnace for roasting for 2 hours at 500 ℃. This procedure was repeated 2 times to obtain a Zn-Cr/Ti-Zr/cordierite finished catalyst (B) having a weight of 3.6093 g.
Example 3: Zn-Cr/Ce-Zr/Al2O3Preparation of cordierite catalyst
a) Cordierite honeycomb ceramic substrates were pretreated as in example 1.
b) Weighing pseudo-boehmite (Al)2O3·H2O)9.5g, gibbsite (Al (OH)3)12.4g of aluminum oxide (. gamma. -Al)2O3)14.3g, aluminum nitrate Al (NO)3)3·9H2O6.7g, mixed and then added with 250ml deionized water, 5ml 65-68% nitric acid, ball milled for 12 hours to get aluminum latex (slurry) with average particle size of 1 μm, viscosity was 1300 centipoise (cp) and pH was 3.60.
c) And (3) taking 1 block of the pretreated carrier, weighing 1.4834g, soaking in aluminum latex for 3 minutes, taking out, purging a channel by using compressed air, drying for 3 minutes by using microwaves, and roasting at 650 ℃ in a muffle furnace for 2 hours to obtain 1.5385g of catalyst intermediate.
d)CeO2-ZrO2Preparation of composite oxide Sol and coating same as example 1, CeO coating2-ZrO2The intermediate weight of the catalyst after sol was 1.8034 g.
e) Measuring 70ml of Zn-Cr mixed solution in example 1, transferring the Zn-Cr mixed solution into a beaker, placing the beaker on a temperature programming electric furnace, heating and boiling, placing the prepared catalyst intermediate, controlling the temperature rising rate of the solution to be 2 ℃/min, taking out the catalyst when the final temperature of the solution is 170 ℃, quickly and cleanly blowing residues in a catalyst channel by using compressed air, placing the prepared catalyst into an oven, drying the catalyst for 4 hours at 120 ℃, and then placing the catalyst into a muffle furnace for roasting for 2 hours at 650 ℃. Obtaining Zn-Cr/Ce-Zr/Al2O3The weight of the cordierite finished catalyst (C) was 2.8635 g.
Example 4: preparation of Zn-Cr-Ce-Zr/cordierite catalyst
a) Cordierite honeycomb ceramic substrates were pretreated as in example 1.
b) Weighing technical grade Ce (NO)3)3·6H2O85.0779 g, weighing analytically pure Zr (NO)3)4·5H2O21.1574g, analytically pure Zn (NO)3)2·6H2O 22.5617g，(NH4)2Cr2O76.3106g, placing into a beaker, adding a small amount of deionized water, placing on an electric furnace for slight heating dissolution, cooling and then setting the volume to 100 ml.
c) Measuring 70ml of the Zn-Cr-Ce-Zr mixed solution, taking 1 block of the pretreated carrier, weighing 2.0884g, transferring the carrier into a beaker, placing the beaker on a temperature-programmed electric furnace, heating and boiling, placing the obtained catalyst intermediate, controlling the temperature rise rate of the solution to be 2 ℃/min, taking out the catalyst when the final temperature of the solution is 170 ℃, quickly blowing and cleaning residues in a catalyst channel by using compressed air, placing the prepared catalyst into a drying oven, drying for 4 hours at 120 ℃, and then placing the catalyst into a muffle furnace, and roasting for 2 hours at 800 ℃. Thus obtaining the Zn-Cr-Ce-Zr/cordierite finished catalyst (D) with the weight of 2.8109 g.
Example 5: preparation of Zn-Mn/Ce-Zr/cordierite catalyst
a) Cordierite honeycomb ceramic carrier pretreatment, CeO2-ZrO2Preparation of composite oxide Sol and coating same as example 1, cordierite Carrier weight 2.2081g, CeO coating2-ZrO2The intermediate weight of the catalyst after sol was 2.9372 g.
b) Weighing analytically pure Zn (NO)3)2·6H2O 16.5617g，50％Mn(NO3)215ml of solution, mixing the two solutions, adding a small amount of deionized water to dissolve the mixture, and setting the volume to be 20 ml.
c) Taking the Zn-Mn mixed solution, dip-coating the catalyst intermediate obtained in the step a) for 3 minutes by an immersion method, taking out the catalyst, quickly and cleanly blowing residues in a catalyst channel by using compressed air, putting the prepared catalyst into a drying oven, drying the catalyst for 4 hours at 120 ℃, and then putting the catalyst into a muffle furnace to bake the catalyst for 2 hours at 800 ℃. This procedure was repeated 4 times to obtain a Zn-Mn/Ce-Zr/cordierite catalyst (E) having a weight of 3.8475 g.
Example 6: catalyst evaluation
Loading the catalyst into a quartz tube microreactor with an inner diameter of 17mm, wherein the space velocity GHSV of methanol is 4000hr-1The methanol conversion rate and the reforming tail gas composition were measured at a water-alcohol molar ratio of 1.2, an oxygen-alcohol molar ratio of 0.30, a raw material inlet temperature of 120 ℃, a reaction temperature of 550 ℃, and a reaction pressure of normal pressure.
The performance evaluations of the above 5 catalysts are shown in Table 1.
Comparative example:
example 7: Zn-Cr/cordierite catalyst preparation
a) The cordierite honeycomb ceramic carrier pretreatment, Zn-Cr active component solution preparation and coating were the same as in example 1.
b) Weighing 70ml of Zn-Cr mixed solution in example 1, taking 1 block of pretreated carrier, weighing 2.0773g, transferring the carrier into a beaker, placing the beaker on a temperature-programmed electric furnace, heating and boiling, placing the prepared catalyst intermediate, controlling the temperature rise rate of the solution to be 2 ℃/min, taking out the catalyst when the final temperature of the solution is 160 ℃, quickly blowing and cleaning residues in a catalyst channel by using compressed air, placing the prepared catalyst into an oven, drying at 120 ℃ for 4 hours, and then placing the oven for roasting at 800 ℃ for 2 hours. This procedure was repeated 2 times to obtain comparative Zn-Cr/cordierite catalyst example (F) having a weight of 4.5305 g.
Example 8: preparation of Zn-Pt-Ru/Ce-Zr/cordierite catalyst
a) The cordierite honeycomb ceramic carrier pretreatment, the Ce-Zr composite oxide sol preparation and the coating were the same as in example 1. The weight of the pretreated carrier is 1.4635g, and the weight of the catalyst intermediate body after the Ce-Zr composite oxide sol is coated is 1.6213 g.
b) Weighing analytically pure Zn (NO)3)2·6H2O90.25 g, taking 33ml of a prepared solution containing 0.05986gPt/ml and 55ml of a prepared solution containing 0.03587gRu/ml, mixing the above substances, slightly heating to dissolve, cooling, and determining the volume of 100 ml.
c) Taking 30ml of the mixed solution, coating the catalyst intermediate obtained in the step a) for 3 minutes by adopting an immersion method, taking out the catalyst, quickly and cleanly blowing residues in a catalyst channel by using compressed air, putting the prepared catalyst into a drying oven, drying the catalyst for 4 hours at 120 ℃, and then putting the catalyst into a muffle furnace to bake for 2 hours at 800 ℃. Comparative Zn-Pt-Ru/Ce-Zr/cordierite catalyst (G) was obtained in a weight of 1.7286G.
Example 9: preparation of Zn-Cr/Ti-Zr/cordierite catalyst
a) Cordierite honeycomb ceramic support pretreatment was the same as in example 1, and Ti-Zr colloids were prepared and coated as in example 2. The pretreated carrier weighed 2.2301g, and the catalyst intermediate weighed 2.5761g after coating the Ti-Zr composite oxide latex.
b) 30ml of the Zn-Cr mixed solution of example 1 was measured, the catalyst intermediate of step a) was dip-coated by dipping for 3 minutes, the catalyst was taken out, the residue in the catalyst channel was rapidly purged with compressed air, the prepared catalyst was put into an oven, dried at 120 ℃ for 4 hours, and then put into a muffle furnace and calcined at 500 ℃ for 2 hours. This procedure was repeated 4 times to obtain comparative Zn-Cr/Ti-Zr/cordierite catalyst (H) having a weight of 3.2192 g.
Example 10: preparation of Zn/Ce-Zr/cordierite catalyst
a) Cordierite honeycomb ceramic support pretreatment was the same as in example 1, and Ce — Zr colloid was prepared and coated as in example 2. The pretreated carrier weighed 1.4445g, and the catalyst intermediate weighed 1.5930g after the Ce-Zr composite oxide latex was coated.
b) Weighing analytically pure Zn (NO)3)2·6H290.25g of O, adding a small amount of deionized water to dissolve, and setting the volume to 100 ml. Taking 30ml of the solution, dip-coating the catalyst intermediate obtained in the step a) for 3 minutes by an immersion method, taking out the catalyst, quickly blowing and cleaning residues in a catalyst channel by using compressed air, putting the prepared catalyst into an oven, drying the catalyst for 4 hours at 120 ℃, and then putting the catalyst into a muffle furnace and roasting the catalyst for 2 hours at 500 ℃. This procedure was repeated 2 times to obtain comparative Zn/Ce-Zr/cordierite catalyst (I) having a weight of 1.7628 g.
The properties of the catalyst in the comparative examples are also shown in Table 1.
TABLE 1 evaluation of catalyst Performance
| Sample (I) | Reformed gas composition,% | Initial activity ％ | Life time, hr | |||
| H2 | CO | CO2 | CH4 | |||
| Example 1 | 51.0 | 2.5-4.0 | 18.5-20.0 | - | 100 | Over 300hr |
| Example 2 | 51.0 | 3.0-4.2 | 18.3-20.1 | - | 100 | Over 300hr |
| Example 3 | 49.2 | 3.5 | 18.9 | 580ppm | 93.5 | Over 300hr |
| Example 4 | 51.3-47.8 | 4.1-7.4 | 17.3-18.7 |
| 100 | Over 300hr |
| Example 5 | 49.8 | 3.6 | 19.1 | 300ppm | 97.2 | - |
| Example 7 | 50.8 | 4.3 | 19.5 | - | 100 | 100hr |
| Example 8 | 48.6-44.5 | 9.6-16.7 | 8.8-14.03 | 89.1 | 8 | |
| Example 9 | 48.0 | 1.30 | 21.0 | - | 82.0 | 4 |
| Example 10 | The reaction temperature fluctuates sharply under the evaluation condition, and the experiment can not run stably | |||||
The effects of the present invention can be seen from the above examples and comparative examples:
1) the catalyst of the invention is used for the reaction of hydrogen production by methanol autothermal reforming, and the methanol space velocity GHSV is 4000hr-1The methanol conversion rate of the reforming reaction is 100% when the molar ratio of water to alcohol is 1.2, the molar ratio of oxygen to alcohol is 0.3, the reaction temperature is 550 ℃, the inlet temperature is 120 ℃, and the reaction pressure is normal pressure; the reformate gas composition is hydrogen (H)2) 51% of nitrogen (N)2) 26.5%, carbon monoxide (CO) 2.5-4%, methane (CH)4) Trace amount of carbon dioxide (CO)2)18.5 to 20.0 percent; the hydrogen yield is 1.60NM3H2/kgCH3OH; the methanol conversion remained 100% after 1000hr, and the carbon monoxide (CO) content decreased from 4% at the beginning of the reaction to 2.5% (stabilized at 2.5% after 200 hr). See figure 1.
2) The catalyst is used for the autothermal reforming reaction of methanol to prepare hydrogen, and the conversion rate of the reforming reaction methanol is still 100% when the reaction pressure is 0.25MPa (gauge pressure) and other operation conditions are the same as the effect 1; the hydrogen yield is still 1.60NM3H2/kgCH3And (5) OH. Hydrogen (H) in the reformate gas composition as compared to atmospheric reaction2) The concentration is slightly increased and the concentration of carbon monoxide (CO) is slightly decreased, i.e. the selectivity of hydrogen and carbon monoxide in the reformate gas is slightly improved. See figure 2.
3) The catalyst of the invention is used for the reaction of hydrogen production by methanol autothermal reforming, and the methanol space velocity GHSV is 4000hr-1The molar ratio of water to alcohol is 1.2, the molar ratio of oxygen to alcohol is 0.28, the reaction temperature is 550 ℃, the inlet temperature is 120 ℃, and the conversion rate of reforming reaction methanol is still 100% when the oxidant is changed from air to pure oxygen and other operation conditions are the same as the effect 1 when the reaction pressure is normal pressure; reformate gas compositionIs hydrogen (H)2) 70%, carbon monoxide (CO) 1.7-2.0%, methane (CH)4) Trace amount of carbon dioxide (CO)2)28.0 to 28.3 percent; the hydrogen yield is 1.65NM3H2/kgCH3And (5) OH. See figure 3.
4) The catalyst is used for a hydrogen source system of a 5 kW-grade methanol autothermal reforming hydrogen production fuel cell, and the space velocity GHSV of methanol is 4000hr-1The conversion rate of reforming reaction methanol is 100% when the molar ratio of water to alcohol is 1.5, the molar ratio of oxygen to alcohol is 0.215, the reaction temperature is 550 ℃, the inlet temperature is 280 ℃ and the reaction pressure is 0.25MPa (gauge pressure); the reformate gas composition is hydrogen (H)2) 57% of nitrogen (N)2) 19.5%, carbon monoxide (CO) 3.0%, methane (CH)4) Trace amount of carbon dioxide (CO)2)20.5 percent; the hydrogen yield is 1.72NM3H2/kgCH3OH; the conversion rate of the methanol is still maintained to be more than 99.5 percent after the stable operation is carried out for 350 hours. See figure 4.
5) The catalyst of the invention can be directly used for the reaction of hydrogen production by autothermal reforming of methanol without pre-activation, and the activity and the selectivity of the catalyst are kept unchanged after multiple times of start-stop impact. At methanol space velocity GHSV of 4000hr-1The molar ratio of water to alcohol is 1.2, the molar ratio of oxygen to alcohol is 0.30, the reaction temperature is 550 ℃, the inlet temperature is 120 ℃, and the reaction pressure is normal pressure, as shown in figure 5.
6) The SEM-EDS spectrogram of the catalyst shows that the catalytic active components are non-uniformly distributed along the radial direction of the honeycomb ceramic wall, which is unique to the preparation method of the catalyst and is different from the conventional preparation method of the honeycomb ceramic catalyst, namely an impregnation method. See fig. 6, where fig. 6a shows example 1 and fig. 6b shows example 9.
Claims (14)
1. A catalyst for preparing hydrogen by autothermal reforming of methanol is prepared by taking cordierite honeycomb ceramic as a carrier, and coating a transition layer additive and an active component on the carrier; wherein:
the transition layer additive is composed of rare earth metal and transition metal oxide, the weight of the transition layer additive is 10-60% of the weight of the carrier, and the weight of the zirconium oxide accounts for 5-80% of the total weight of the transition layer and the additive;
the active components are two or more oxides of metals selected from 20-30 of the periodic table, the weight of the active components accounts for 30-60% of the weight of the carrier, and the weight of the zinc oxide accounts for 40-95% of the total weight of the active components.
2. The catalyst of claim 1 wherein the transition layer promoter is present in an amount of 30 to 40% by weight of the support and the zirconium oxide is present in an amount of 15 to 45% by weight of the total transition layer promoter.
3. The catalyst of claim 1 wherein the weight of the active component is 40 to 50% of the weight of the support and the weight of the zinc oxide is 50 to 80% of the total weight of the active component.
4. The catalyst of claim 1, wherein the rare earth metal is lanthanum, cerium, gadolinium; the transition metal is titanium, chromium, zirconium, vanadium, manganese or nickel.
5. The catalyst of claim 1 or 4, wherein the rare earth metal is lanthanum, cerium; the transition metal is titanium or zirconium.
6. The catalyst of claim 1 wherein the catalytically active component is selected from two or more of zinc, chromium, iron, manganese, cobalt, nickel, vanadium.
7. The catalyst of claim 1 or 6, wherein the catalytically active component is selected from two or more of zinc,chromium, manganese, nickel.
8. A method for preparing the catalyst of any one of the preceding claims, which mainly comprises the following steps:
mixing the transition layer auxiliary agent and the soluble salt solution of the active component according to a proportion, and heating and boiling the mixed solution; putting the carrier into the boiled mixed solution, controlling the temperature rise rate of the solution to be 1-2 ℃/min, taking out the carrier when the final temperature of the solution is between 130-190 ℃, blowing and cleaning residues in a carrier channel, drying at 110-130 ℃ for 2-10 hours, and roasting at 500-900 ℃ for 1-6 hours to obtain the finished catalyst.
9. A method for preparing the catalyst of any one of the preceding claims, which mainly comprises the following steps:
respectively preparing a soluble salt solution of the transition layer additive and a soluble salt solution of the active component into solutions according to a proportion, and coating the transition layer on a cordierite honeycomb ceramic carrier which is coated with aluminum sol or aluminum wet ball milling gel in advance by adopting an impregnation method; drying and roasting, then placing the solution into a boiled active component solution, controlling the heating rate of the solution to be 1-2 ℃/min, taking out the carrier when the final temperature of the solution is between 130-190 ℃, blowing and cleaning residues in a carrier channel, and roasting for 1-6 hours at 900 ℃ after drying to obtain the finished catalyst.
10. The method according to claim 9, wherein the transition layer assistant is applied to the support in the form of a milky slurry or a composite oxide sol.
11. The method of claim 8 or 9, wherein the soluble salt is a nitrate, oxalate, carbonate or chloride.
12. The method of claim 8 or 9, wherein the active ingredient is repeatedly coated to a desired loading.
13. The method according to claim 8 or 9, wherein the drying is natural drying, oven drying, microwave drying, or freeze drying.
14. Use of a catalyst according to any one of the preceding claims in a fuel cell hydrogen source system.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101612563B (en) * | 2008-06-25 | 2012-07-04 | 中国科学院大连化学物理研究所 | Composite oxide catalyst for producing hydrogen by reforming methanol steam, preparation and application thereof |
| CN107649137A (en) * | 2017-10-30 | 2018-02-02 | 四川蜀泰化工科技有限公司 | A kind of catalyst of methanol steam high temperature reformation hydrogen manufacturing, preparation method and application |
| CN110075859A (en) * | 2019-05-30 | 2019-08-02 | 广西氢朝能源科技有限公司 | A kind of hydrogen from methyl alcohol catalyst of low concentration CO and the preparation method and application thereof |
| CN113318726A (en) * | 2020-02-28 | 2021-08-31 | 广东粤能净环保科技有限公司 | Photocatalyst with negative oxygen ion releasing function and preparation method and application thereof |
| CN113522281A (en) * | 2021-08-19 | 2021-10-22 | 润和科华催化剂(上海)有限公司 | Structured autothermal reforming hydrogen production catalyst and preparation method thereof |
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2004
- 2004-03-25 CN CNB2004100313483A patent/CN1305564C/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101612563B (en) * | 2008-06-25 | 2012-07-04 | 中国科学院大连化学物理研究所 | Composite oxide catalyst for producing hydrogen by reforming methanol steam, preparation and application thereof |
| CN107649137A (en) * | 2017-10-30 | 2018-02-02 | 四川蜀泰化工科技有限公司 | A kind of catalyst of methanol steam high temperature reformation hydrogen manufacturing, preparation method and application |
| CN107649137B (en) * | 2017-10-30 | 2020-07-14 | 四川蜀泰化工科技有限公司 | Catalyst for preparing hydrogen by reforming methanol steam at high temperature, preparation method and application |
| CN110075859A (en) * | 2019-05-30 | 2019-08-02 | 广西氢朝能源科技有限公司 | A kind of hydrogen from methyl alcohol catalyst of low concentration CO and the preparation method and application thereof |
| CN113318726A (en) * | 2020-02-28 | 2021-08-31 | 广东粤能净环保科技有限公司 | Photocatalyst with negative oxygen ion releasing function and preparation method and application thereof |
| CN113318726B (en) * | 2020-02-28 | 2023-08-01 | 中科粤能净(山东)新材料有限公司 | Photocatalyst with function of releasing negative oxygen ions and preparation method and application thereof |
| CN113522281A (en) * | 2021-08-19 | 2021-10-22 | 润和科华催化剂(上海)有限公司 | Structured autothermal reforming hydrogen production catalyst and preparation method thereof |
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