Methanol reforming by nanostructured Pd/Sm-doped ceria catalysts

Catalysts of 2 wt% Pd/Sm-doped Ceria (SDC) were prepared and evaluated for hydrogen production by methanol reforming. Three preparation methods were used: a one-step method in which formation of the SDC phase and Pd incorporation took place in a single citrate-complexation process (Method A); impregnation of pre-prepared SDC nanopowder supports using Pd(NO₃)₂ solution (Method B); and impregnation of pre-prepared SDC from H₂PdCl₄ solution (Method C). Both methanol conversion and hydrogen yield increased as: bare supports << Method A < Method C < Method B, the latter achieving values of up to 97.4 % and 236.2 %, respectively. Pd was well dispersed as fine nanoparticles by Methods B and C, but larger particles were resolved for Method A. Method B resulted in a high surface concentration of Pd, further improving catalytic activity. Undesirable Cl was retained in samples of Method C. Method B resulted in catalysts with superior nanostructure, resulting in the best activity and CO₂ selectivity.