Hydroconversion of n-Hexane using Pt/H-MOR and Pt/H-BEA Catalysts with Various Pt Contents and Bimetallic PtPd/H-MOR,PtPd/H-BEA,Ptlr/H-MOR and Ptlr/H-BEA Catalysts with Various Secondary Metal Contents

摘要

Monometallic catalysts containing 0.35 up to 0.50 wt%Pt on H-MOR orH-BEA zeolites,as well as bimetallic catalysts containing Pd or Ir of 0.05 up to 0.20-0.25 wt% combined with a fixed Pt content of 0.35 wt% also supported on H-MOR or H-BEA were prepared and tested for n-hexane hydroconversion in a hydrogen flow using pulsed reactor system.The reaction products were gas chromatographically analysed and the catalysts were characterised for acid sites strength distribution via ammonia temperature programmed desorption(TPD)and for metal(s)dispersion in the support via pulsed hydrogen chemisorption.Increased Pt content in either zeolites decreased its dispersion.The addition of Pd to Pt increased the metals dispersion in both zeolites up to a certain content,whereas Ir addition,principally,decreased dispersion.Maximum isohexanesproduction behaved parallel to the metals dispersion in the PtPd containing catalysts(structure sensitive).Hydrocracking was more active on the H-MOR supported catalysts,compared to those supported on H-BEA due to higher acid sites number and strength in the former zeolite.Benzene production via dehydrocycli-sation of n-hexane was relatively more active on the H-BEA containing catalysts than on those containing H-MOR,due to the less effective diffusion resistance in the BEA channels.