Production Of Hydrogen By Partial Oxidation Of Methanol Over Au-M/CeO₂ Catalysts

The hydrogen may be produced directly from methanol in fuel cells.If the level of CO exceeds a few ppm,the precious metal-based anode electrocatalyst of the fuel cell will be deactivated.Au catalysts,exhibiting high activity for CO oxidation at low temperature,are used for partial oxidation of methanol(POM)and can reduce the content of CO.The effects of second constituent M(Ag,Ru,Pd and Pt),content of Pd,reduce methods,preparing methods and mixed oxide supports on activities of Au-Pd/CeO₂ catalysts for POM were studied.The prepared samples were characterized by XRD,ICP,nitrogen adsorption-desorption,H₂-TPR and CHaOH(H₂, CO₂)-TPD experiments.1.The performance of Au/CeO₂ is influenced by the addition of second constituent M(Ag,Ru,Pd and Pt).The results indicate that the activity of Au-Pd/CeO₂ bimetallic catalysts for POM was the best.2.A series of the PVP-stabilized Au-Pd/CeO₂ bimetallic catalysts with different Pd content were prepared and the activities of Au-Pd/CeO₂ catalysts for POM were studied.Comparing the Au-Pd/CeO₂ catalysts with other Pd content,catalytic active of Au₆₀Pd₄₀/CeO₂ catalyst is higher, because of it has more AuxPdy and H₂ chemisorption amount,lower reduced temperature.3.Different reduced methods may change the particles size and synergistic effect between Au and Pd.The influence of difference reduced methods on the performance of Au-Pd/CeO₂ catalysts was studied.The results show that Au-Pd/CeO₂(ER)catalyst reduced by ethanol has higher methanol conversion,hydrogen selectivity and lower contentof CO for POM.For Au-Pd/CeO₂(ER)catalyst, it had larger BET surface area,dispersion and CH₃OH adsorption amount,stronger interaction between metal and support,formed more number of Au_xPd_y alloy and smaller particles size.4.The different polyelectrolyte-stabilized Au-Pd/CeO₂ catalysts were prepared by CH₃CH₂OH reductant and the performance of Au-Pd/CeO₂ catalysts is studied.A number of Au_xPd_y alloys are found in Au-Pd/CeO₂(PVP)catalyst.Comparing with the Au-Pd/CeO₂(PEG)and Au-Pd/CeO₂ (PVA)catalysts,Au-Pd/CeO₂(PVP)catalyst has stronger interaction between Au-Pd and support, lower CH3OH adsorption amount,and forms more number of Ce³⁺on the surface of CeO₂ support, all these are advantageous to the catalytic activity enhancement.5.Different approaches to preparing highly dispersed Au-Pd/CeO₂ catalysts may even have excellent resistance to sintering and show high activity.The influence of difference preparation methods on the performance of Au-Pd/CeO₂ catalysts was studied.The results indicated that Au-Pd/CeO₂(DP)catalyst prepared by deposition-precipitation method show higher methanol conversion and hydrogen selectivity,the methanol conversion was 100% and hydrogen selectivity...