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The deuterodesulfurization of thiophene was investigated using selected MoS2 and reduced molybdenum sulfide (Chevrel phase) catalysts. The extent of deuterium incorporation into thiophene and into specific desulfurization products (hydrogen sulfide, butadiene, and butenes) was determined at 400 °C for thiophene conversions near 4%. Unpromoted MoS2 introduced up to 10 times more deuterium into thiophene than did the promoted catalysts (including the Chevrel phase materials). For all catalysts, H2S was formed almost exclusively (typically 90+%), with only small amounts of HDS and D2S being detected. Except for the unpromoted MoS2 catalyst, the deuterium distributions determined for the cis- and trans-2-butene products were nearly identical; the deuterium distribution found for 1-butene was distinct. A mechanism of thiophene hydrodesulfurization can be proposed in which butadiene is the initial desulfurized reaction product. The hydrogen available for hydrogen sulfide formation is derived via hydrogen exchange with thiophene. |
