H/D Exchange and Isomerization of Small Alkanes over Unpromoted and Al2O3-Promoted SO2−4/ZrO2 Catalysts

The H/D exchange reaction between methane and deuterated SZ, SZ/Al2O3, and SZA catalysts was studied. The apparent activation energy on SZ/Al2O3 and SZA catalysts is the same as that on SZ, but substantially smaller than that on HZSM-5 zeolite, indicating that the acid strengths of Al2O3-promoted SZ catalysts are identical to that of SZ, but stronger than that of HZSM-5. The catalytic properties of unpromoted and Al2O3-promoted SZ for the isomerization of n-butane and isobutane at 250°C in the presence of H2 were investigated. These catalysts deactivate more slowly during isobutane isomerization than during n-butane isomerization. The rate of isobutane conversion is lower than that of n-butane isomerization for the same sulfated zirconia-based catalyst. The rates of n-butane and isobutane conversion are all in the sequence of SZA>SZ/Al2O3>SZ, the same as that for the H/D exchange of methane over these catalysts.