Synthesis and Investigation of Catalysts Supported on Micro–Mesoporous MFI Zeolites in Hydroisodewaxing of Diesel Fuels

A series of micro–mesoporous ZSM-5 zeolites with SiO₂/Al₂O₃ molar ratios ranging from 40 to 280 were synthesized hydrothermally using natural aluminosilicate halloysite nanotubes (HNTs) as a precursor for silica and alumina and as a co-template for the generation of mesopores. The physicochemical properties of the synthesized materials were characterized by energy dispersive X-ray fluorescence, X-ray diffraction, scanning and transmission electron microscopy, low-temperature nitrogen adsorption–desorption, and temperature-programmed ammonia desorption. Using the zeolite sample with an optimal combination of physicochemical properties, a Pt catalyst was prepared and tested in hydroisodewaxing of a hydrotreated diesel fuel (DF) feedstock. The catalyst supported on the HNT-based zeolite exhibited high performance in the isodewaxing of middle distillates, thus producing arctic diesel fuels at lower temperatures than those recorded for the catalyst supported on a commercial zeolite with a similar SiO₂/Al₂O₃ ratio.