The hydroisomerization of linear alkanes represents a cornerstone process in modern petroleum refining, particularly in the catalytic isodewaxing of middle distillate fractions. This transformation is industrially vital for producing premium low-pour-point diesel fuels and high-performance lubricants, where improved cold-flow properties are achieved through selective branching of hydrocarbon chains. In this work, zeolite ZSM-23, silicoaluminophosphates SAPO-11 and SAPO-31 were synthesized, and commercial zeolite ZSM-5 was used. Based on these molecular sieves, supports were prepared (using boehmite as a binder in an amount of 30 wt.%) and platinum catalysts on their basis (Pt content – 0,5 wt.%). At each step of synthesis, the materials, supports, and catalysts were characterized by X-ray diffraction, temperature-programmed desorption of ammonia (NH₃-TPD), low-temperature nitrogen adsorption, transmission and scanning. The catalytic activity was evaluated using a laboratory flow-type unit with a fixed catalyst bed reactor in the isomerization of n-hexadecane under the following conditions: hydrogen pressure of 3,5 MPa, feedstock liquid hourly space velocity of 4 h-1, temperature range of 230–400 °C, and a hydrogen-to-oil ratio of 600 Nm3/m3. The conversion of n-hexadecane and the selectivity toward cracking and isomerization reactions were compared for the synthesized catalysts. It was found that the SAPO-11-based catalyst provided the highest feedstock conversion and the maximum selectivity toward multi-branched isomers.
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