SYNTHESIS AND CHARACTERIZATION OF LEAD CHEVREL-PHASE THIN-FILMS FOR HYDRODESULFURIZATION CATALYSIS

Reactive sputtering has been used to prepare the lead Chevrel phase PbMo6S8 on several substrates. The effect of processing parameters such as H2S flow rate, Pb sputtering current, substrate temperature, and annealing temperature were found to be very important in determining sample purity. Formation of PbMo6S8 from an as-deposited material apparently occurred at significantly lower annealing temperatures (400-800-degrees-C), compared to conventional solid-state preparations (1000-degrees-C). The thin films of PbMo6S8 were active thiophene hydrodesulfurization catalysts: the absence of impurities including MoS2 could be confirmed for these materials, before and after reaction. Because the characteristic catalytic properties of the lead Chevrel phases were observed, reactive sputtering may be applicable for the preparation of other Chevrel phases on catalyst supports.