Hydroisomerization of long-chain n-alkanes over Pt/AlSBA-15+zeolite bimodal catalysts

In this study, the Pt (0.5 wt%) catalysts supported on the bimodal composite materials consisting of AISBA-15 and zeolite (BEA or MOR) were used for hydroisomerization of the long-chain n-alkanes. Consideration was given to the method by which the AISBA-15 and zeolite (20 wt% concentration) were combined: (i) by adding the zeolite to AISBA-15 synthesis gel (Method 1) and (ii) by mechanical mixing the zeolite and AISBA-15 powders (Method 2). The experiments of hydroisomerization of n-hexadecane were carried out using a fixed bed flow reactor system (5 MPa; 260-360 degrees C; WSHV, 3.5 h(-1); H-2:CH, 350:1 Nm(3)/m(3)). It was found that the synthesis of the supports according to Method 1 resulted in a formation of new mesopores in the "zeolitic" phase of A1SBA-15 + zeolite, and also in a moderate acidity of these materials. The catalysts supported on the carriers prepared according to Method 1 exhibited higher activity and isomerization selectivity than these supported on the carriers prepared according to Method 2. The Method 1 yielded the Pt/AlSBA-15 + BEA catalyst displaying the highest isomerization selectivity (together with the highest contribution of monobranched isomers) and the lowest cracking selectivity.