Mechanical Synthesis Of Copper-based Catalyst And Its Performance Of Methanol Reforming For Hydrogen Production

In recent years,fuel cells are considered to be the most promising vehicle energy supply device,but the problem of hydrogen sources is a bottleneck in the development of fuel cells.As a non-polluting and renewable liquid fuel,methanol has been widely recognized for its hydrogen production effect.Among many methods for producing hydrogen from methanol,steam reforming of methanol（SRM）has the advantages of high hydrogen production rate and low CO production,and can provide a hydrogen source for fuel cells.If the SRM reaction is to achieve the best performance,the role of the catalyst cannot be ignored.Cu-based catalysts are the most common catalysts used in SRM reactions,but Cu has poor thermal stability and is prone to carbon deposition and sintering at high temperatures.Taking this problem as a starting point,study the reaction conditions of the catalyst preparation process and SRM The effect of its activity,combined with structural characterization methods,explored the catalyst structure-activity-relationship,and established the kinetic equation of the SRM reaction.The main work of this paper is as follows:1.The Cu/Zn/Al catalyst was prepared by the ball milling method,and with the impregnation method as a comparison,the catalyst was applied to the methanol steam reforming hydrogen production reaction and characterized by BET,XRD,H₂-TPR,SEM and other means.The differences in the overall texture properties of the catalysts under the two preparation methods were investigated.The experimental results found that the Cu/Zn/Al catalyst prepared by the ball milling method formed a relatively regular surface mesoporous structure,had a higher specific surface area,and had better Cu dispersion and stability.In addition,the surface has a richer proportion of Cu⁺species,and the interaction with the carrier is stronger.In the subsequent SRM reaction,the methanol conversion rate is higher and the CO concentration is lower.2.Investigate the influence of the preparation parameters of the catalyst such as ball milling time,calcination conditions and component content on the Cu/Zn/Al catalyst.The study found that appropriately increasing the ball milling time can reduce the particle size of Cu and improve its performance in the catalyst system.The different calcination temperature will cause differences in the specific surface area,reduction performance and crystal form of the components of the catalyst.When the temperature is lower than 650°C,the crystal formation of the components in the catalyst is not complete and the stability is poor,which is not conducive to the progress of the SRM reaction.When the calcination temperature is650°C,the specific surface area of the catalyst is larger,and the interaction between the components is also strong,and the crystal formation is complete.If the temperature reaches800°C,the specific surface area of the catalyst is greatly reduced,a certain degree of sintering and carbon deposition occurs on the surface,and the overall performance of the catalyst is poor.Based on the preparation parameters,the effects of different reaction temperatures,liquid feed rates and water-alcohol ratios on the catalyst in the SRM reaction were explored.The results showed that when the reaction temperature is 300℃,the liquid feed rate is3.5m L/h,and the water-to-alcohol ratio is 1.3,the SRM reaction performance of the catalyst is the best.3.Based on the Cu/Zn/Al catalyst,Ce O₂ and Zr O₂ were introduced to modify the catalyst.Through a series of characterization tests,the effect of Ce O₂ and Zr O₂ on the structure and performance of the catalyst was explored.The experimental data showed that Ce O₂ can reduce CO concentration in the reaction,but its thermal stability is poor,and it will weaken the SRM reaction to some extent.After the introduction of Zr O₂,the dispersibility of Cu in the catalyst was improved.Thermogravimetric analysis found that the Ce_xZr_1-xO₂ solid solution oxide formed after the introduction of Ce O₂ and Zr O₂ at the same time can effectively improve the thermal stability of the catalyst and resist the product occurs Carbon deposits at high temperatures.When the reaction temperature is 300℃,the molar ratio of water to alcohol is 1.3,and the feed rate is 3.5m L/h,the overall performance of the catalyst is the best.The methanol conversion rate can reach 94.79%,while the CO concentration is only0.32%.4.Using a single rate model,a kinetic model of Cu₁Zn₁Ce₁Zr₃Al₄ coated catalyst with the best catalytic performance in SRM was established.Under the premise of eliminating out-diffusion and completing the blank experiment,the reaction was tested in a microreactor,with the help of the MATLAB software,determining the kinetic parameters,which provides a theoretical basis for the research of the SRM reactor.