Alkane hydroisomerization over novel zeolite based catalysts

The catalytic activity and selectivity of Pt/H-BEA catalyst for pentane hydroisomerization were determined. Isomerization activity increased with decreasing sulfation temperature while the apparent activation energies were constant within the limits of accuracy indicating that changes in acid site strength did not occur during the sulfur treatment. The n-pentane conversion, isopentane yield, and apparent energies of activation for reaction at 300°C were compared over the different catalysts. The main byproducts formed over the untreated catalyst, i.e., C₁-C₄, resulted from C-C bond breaking reactions. The activity and selectivity to isopentane increased with sulfur treatment under 450°C. While the selectivity to isopentane of untreated zeolite decreased with increasing approach to equilibrium, the selectivities of the sulfur samples were close to 100%, independent of the conversion level. The catalytic activity and selectivity were studied in a 20-fold parallel reactor system. An individual digital mass flow and pressure controller controlled each plug flow reactor. The hydrocarbon feed and hydrogen were mixed and controlled by a digital controlled evaporator mixer unit and were diluted with helium as needed. GC analysis was applied to the products. The complete computer control of the reaction system by HPVEE (Hewlett-Packard Visual Engineering Environment) allowed varying the total pressure, flow rate, temperature, and alkane concentration automatically. Recorded data were stored in a relational MS Access database. The discussion covers introduction; experimental (catalyst preparation and characterization by TPD, IR spectroscopy); catalytic activity; results; discussion; and conclusions.