Study On Catalysts For Hydrogen Production By Steam Reforming Of Methanol

Hydrogen energy is a flexible secondary energy,and is of great significance for energy saving and emission reduction.In practical applications,hydrogen storage and transportation by carriers is a convenient way.As a liquid,methanol is easy to store and transport,and has relatively high safety,making it an ideal hydrogen storage carrier.The hydrogen production can be realized by combining methanol steam reforming with the palladium membrane reactor to realize the integrated hydrogen production,which can be applied to the scenario of miniaturized in-situ hydrogen production.Copper-based catalysts are widely used in industrial hydrogen production by methanol steam reforming,and the reaction temperature used is in the range of 200-280°C.For higher reaction temperature,the active sites are easy to sinter.However,the separation conditions based on the palladium membrane reactor should be 400°C,and the existing methanol steam reforming catalysts are not suitable.Therefore,it is of great significance to study methanol steam reforming catalysts with high temperature resistance which can be also applied in palladium membrance reactor.In this paper,a series of Zn O-Al₂O₃ catalysts and modified Zn O-Al₂O₃catalysts have been prepared by different synthesis methods for hydrogen production of high temperature methanol steam reforming.Based on the catalyst methanol steam reforming evaluation and screening,an optimized catalyst formula and a suitable process condition range have been obtained,and the catalyst has been analyzed by low-temperature nitrogen adsorption and desorption,XRD,TPR,XRF,etc.The following results have been obtained:（1）The hydrothermally synthesized Zn O-Al₂O₃ catalyst has higher specific surface area,better hydrogen production reaction performance and anti-reverse water-gas shift reaction performance of methanol steam reforming;（2）The optimized Zn O-Al₂O₃catalyst’s atomic ratio of zinc to aluminum is 2:2.The methanol conversion of the catalyst at 400℃is close to 100%,and the by-product carbon monoxide is quite low;（3）The optimized Cu O content of the copper-modified Zn O-Al₂O₃ catalyst is 6.11-13.33 wt%,which significantly improves the low-temperature activity of the catalyst.However,the performance of the reverse water gas shift reaction is significantly increased;（4）The by-product methane of the indium-modified Zn O-Al₂O₃ catalyst increases significantly,and methanation would consume a large amount of hydrogen,indicating that the Zn O-Al₂O₃catalyst was not suitable for indium modification;（5）Different synthesis methods and the modified Zn O-Al₂O₃ catalysts have a relatively stable Zn Al₂O₄ spinel crystal phase structure.The diffraction peaks of the Zn Al₂O₄ spinel after the evaluation of the catalysts are significantly enhanced,and the order of the spinel phase diffraction peak enhancement is:indium modification>copper modification>non-modification.It shows that the optimized Zn O-Al₂O₃ catalyst owns better anti-sintering performance,it is more suitable for the hydrogen production reaction process of high temperature methanol steam reforming.