SELECTIVITIES IN METHYLCYCLOPENTANE AND NORMAL-HEXANE CONVERSION ON SOME METAL-LOADED SAPO-11 CATALYSTS

The medium pore silicoaluminophosphate molecular sieve SAPO-11 of mild acidity was loaded with platinum or palladium by ion exchange and wet impregnation and investigated as to activity and selectivity in methylcyclopentane (MCP) hydrogenolysis and n-hexane (nHEX) conversion at 1 atm and 673 K. For MCP high selectivities for benzene formation were observed, while for nHEX high selectivities for the formation of iso-hexane isomers were found. In addition an unusually high n-hexane selectivity in the ring opening reaction of MCP and the formation of benzene for a set of NaN3-treated Pd/SAPO-11 and Pt/SAPO-11 catalysts were observed for both the MCP and nHEX reactions. The somewhat peculiar selectivity patterns in this class of molecular sieve catalysts are interpreted in terms of a series of reaction pathways incorporating both confinement effects and shape selectivity factors as being of importance in determination of the observed product distributions.