Preparation of Pt-ZSM-5 zeolite membrane catalysts for the isomerization of linear alkane

A ZSM-5 supported membrane was synthesized by secondary growth method. The Pt-ZSM5 membrane was prepared by impregnation method. The membrane was characterized by single gas permeation step at room temperature. The isomerization of n-pentane was chosen as a probe reaction for evaluating the catalytic performance of the membrane. In particular, the effect of the space velocity and the time on stream were considered. After the catalytic tests, the membrane was characterized by SEM, EDX and XRD. N2 permeance for the membrane, after calcination, was equal to 2.9 × 10-7 mol/m2.s.Pa indicating a coverage of the larger support pores by the zeolite crystals. This results was also confirmed by the SEM investigation. In addition, XRD analysis showed as the ZSM-5 was the desired zeolite-type. During the catalytic tests, it was observed a decrease of the nC5 conversion and an increase of the iC5 selectivity with WHSV. The nC5 conversion was decreased from 2.5 to less than 0.5, with an enhancement in weight hourly space velocity (WHSV), while the selectivity increases from 30 to over 70. On the other hand, it's conversion on catalyst enhanced from 10% to approximately 38%, with an increase in the reaction temperature from 250 to 450°C.