Preparation Of Cobalt-Based Catalysts And Study On Their Catalytic Performance For Hydrogen Production By Steam Reforming Of Ethanol

With the intensification of the energy crisis,hydrogen energy has been applied to various fields of life as a new type of energy,and its production technology has received more and more attention.Ethanol is widely favored by researchers because of the high hydrogen content,low toxicity,and it is safe to transport and store.As an attractive way,Ethanol Steam Reforming provides a environment-friendly route for renewable source to produce hydrogen.However,this hydrogen production system is complicated and by-products are formed in the process.There are many important factors which influence the process such as the supports,the active component's content and dispersion,the reaction conditions and so on.Therefore,it is necessary to develop a highly efficient and stable catalyst to promote the occurrence of the reaction,increase the hydrogen production,and reduce the formation of by-products.At the same time,carbon deposition is the core problem affecting the stability of the catalyst.In this paper,metal cobalt is selected as the active component to act on the catalyst by its ability to break the C-C bond.and catalysts with different supports were prepared to investigate the effect of support on catalyst performance.The main contents and results of this thesis research are as follows:1.Using Ce?NO₃?₃·6H₂O as a source of ruthenium,CeO₂ support was synthesized by hydrothermal method,and then Co/CeO₂ catalyst was synthesized with different cobalt content by equal volume impregnation method usingCo?NO₃?₂·6H₂Oascobaltsource.XRD,H₂-TPR,N₂adsorption-desorption and others can be used to characterize each sample,the synthesized catalyst was used in the steam reforming of ethanol to produce hydrogen,and the conversion rate of the reactant ethanol and the selectivity of the target product hydrogen were used to evaluate the performance of catalyst.The effects of different catalysts with different active components on the catalytic reaction were investigated at different reaction temperatures.The results show that the synthesized CeO₂ support is a spherical and uniformly dispersed mesoporous material.The original structure was maintained after different amounts of cobalt,the active component,were loaded,and a series of xCo/CeO₂ catalysts are formed for ESR reaction.At different reaction temperatures,the 10Co/CeO₂ catalyst showed good activity,and the reaction was best at 500°C with a high ethanol conversion rate of 90%and H₂selectivity of 73%,Also in the stability test,it showed good stability.2.The mesoporous SBA-15 material with larger specific surface area was prepared as catalyst support prepared.A series of Co-xCeO₂/SBA-15 catalysts were prepared by impregnation of a certain amount of active component cobalt and different contents of cerium.The catalysts were characterized by various characterization methods and acted on the ESR reaction to investigate the effect of CeO₂ on the catalytic reaction.The results show that the synthesized catalyst still has the mesoporous structure of SBA-15,and the metal substance is well dispersed on the support.The Co-4CeO₂/SBA-15 catalyst shows good catalytic performance at the reaction temperature of 500°C.The ethanol conversion rate and hydrogen selectivity of the catalyst reached 92%and 73.8%respectively under the condition of water to alcohol volume ratio of 3:1.3.The modified support SBA-15 was used to synthesize the Ce-SBA-15support with different molar ratios of materials?n?Si/Ce??,and the Co/Ce-SBA-15 catalyst was synthesized by equal volume impregnation method.XRD,UV-Vis,FT-IR,H₂-TPR,N₂ adsorption-desorption were used to characterize each sample,Use the synthesized catalyst in reaction to find which is the best.The results show that in the Ce-SBA-15 support prepared by hydrothermal synthesis,which still retains the unique characteristics of SBA-15.Ce ions enter the SBA-15 molecular sieve framework,and have a highly ordered pore structure and a uniform pore size distribution.Compared with Co/SBA-15 catalyst in the catalytic reaction,the addition of Ce reduces the formation of reaction carbon and improves the stability of the catalyst.The catalyst Co/Ce-SBA-15?Si/Ce=20?has good activity and stability,the ethanol conversion rate is 96.6%,and the H₂ selectivity reaches 75.5%.