Preparation of ZSM-22/ASA composite material for enhancing n-dodecane hydroisomerization performance

The ZSM-22/ASA composite material for efficient hydroisomerization of n-dodecane was successfully prepared via a two-step synthesis method. The structure, pore properties, and acidity of the catalysts were elucidated by the means of XRD , N 2 physical adsorption, TEM, FT-IR, and Py-IR. Compared with the mixture catalyst, ZSM-22/ASA has a higher average pore diameter and formed a uniform and open channel structure, which is favorable to the diffusion of the reactant and the efficiency of the acid sites. The zeolite and the ASA phase in the composite are closely bonded by the interface effect, forming an additional Si–O–Al structure, which significantly affected the acidity of the composite catalyst. ZSM-22/ASA composite material exhibits enhanced n-dodecane hydroisomerization selectivity of total isomers and multi-branched isomers, which is attributed to its proper acid strength and pore structure conducive to diffusion. Finally, the location distribution of branched methyl groups was discussed and enhanced more central branching iso-dodecanes was obtained over the ZSM-22/ASA composite material.