Studies On Catalytic Reaction For Hydrogen Production From Steam Reforming Of Dimethyl Ether

Because of the energy crisis and the environment at the deterioration, hydrogen, as a clean energy, has been attracting more and more attention. Fuel cells is one of the effective usage of hydrogen energy. Hydrogen production from steam reforming of dimethyl ether(DME) can satisfy the proton exchange membrane fuel cells. Therefore the development of DME steam reforming is of important practical significances.In this paper, thermodynamic calculation of hydrogen production form steam reforming of DME was conduct by HSC Chemistry. The influence of temperature and H₂O/DME ratio was discussed. Then, hydrolysis catalysts was fistly screened. And a series of PdZn based catalysts as reforming catalysts were prepared by deposition precipitation method. When mixed with hydrolysis catalyst, the effects of palladium precursors, metal loadings, Pd/Zn ratios and supports was investigated. Based on the optimized catalyst system, the effects of the reduction temperature, loading pattern, H₂O/DME ratio, reaction temperatures were studied for steam reforming of DME.Thermodynamic calculation results show that better DME conversion, H₂ yield and CO₂ selectivity was obtained when the reaction temperature is below 300℃and H₂O/DME is 3⁶. The study of DME steam reforming indicates that solid acid catalyst with the mass ratio ZSM-5/γ-A1₂O₃ ratio of 2 was good for the hydrolysis of DME. In the DME reforming high activity and selectivity were obtained when 10 wt%PdZn/ZrO2 catalyst, prepared with PdCl2 as precursor and the Pd/Zn mole rate of 1/6 was mixed with ZSM-5/γ-A1₂O₃ =2. The particular mixed catalysts reduced of 400℃is favored to maintain catalyic activity and stability. H₂ yield and CO₂ selectivity can be obtained when H₂O/DME ratio was 3, were higher. High temperature was beneficial to the reaction but increased CO selectivity in products. Therefore, reaction should be carried out at temperature below 300℃.