Upgrading the properties of diesel fractions is considered one of the crucial processes in the petrochemical industry; and for this purpose in laboratory-scale researching it is studied on the base of the hydroisomerization of n-hexadecane as a main model reaction. Recently, zeolite-based bifunctional catalysts have proven their efficiency due to their remarkable acidity, shape-selectivity and relative resistance to deactivation. In this review, different topological-type zeolite-based catalysts, the mechanism of their catalytic effect in n-C₁₆ isomerization, and the principles of shape-selectivity are reviewed. A comparison of their structural-operational characteristics is made. The impact of some feedstock impurities on the catalyst’s performance and deactivation due to carbonaceous deposits as well as various modern eco-friendly cost-effective synthesis techniques are also discussed.

Gram-scale Ru-containing catalysts templated on structured mesoporous silica of MCM-41 type reinforced with natural aluminosilicate halloysite nanotubes (HNT), as well as their analogues based on pristine halloysite, were synthesized by wetness impregnation under microwave irradiation. The structural properties and elemental composition of the catalysts were studied by TEM, XRD, TPR-H₂, and XRF. Textural characteristics were determined by low-temperature nitrogen adsorption/desorption. The catalytic properties in hydrogenation of aromatic-rich model feed and gasoline fraction were studied in batch reactors in the temperature range of 60–150 °C, under hydrogen pressure of 3 MPa, and a substrate/Ru molar ratio of 2000 for 3 h. Comparing the results of the catalytic tests, we can conclude that each material has its own advantage for the treatment of aromatic-rich feed under specific operating conditions. The Ru/HNT and Ru/MCM-41/HNT catalysts performed best in the 60–100 °C and 60–80 °C temperature regions, respectively, for the removal of aromatics, e.g. benzene, to meet ecological restrictions while retaining the octane numbers.

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.

This paper describes the preparation of two bifunctional Pt catalysts: one supported on a ZSM-23 zeolite (MTT topology) synthesized via a seed-assisted method, and the other on a commercial ZSM-23. Physicochemical characterization (XRD, XRF, SEM, TEM, N₂ physisorption, NH₃-TPD) revealed that the synthesized ZSM-23 possessed a hierarchical structure and a balanced distribution of weak and strong acid sites. In n-hexadecane hydroisomerization, the catalyst based on the synthesized ZSM-23 exhibited superior stability (500 h). In the hydroisodewaxing of a hydrotreated diesel fraction, both catalysts provided similar levels of product quality, achieving a dramatic improvement in cold filter plugging point (CFPP of –46 and –47°C vs. –5°C in the feedstock) and high diesel fuel yields (93.4 and 93.1 wt %). The resulting diesel fuel met all specifications (including CFPP, closed-cup flash point, fractional composition, and density) for GOST R 55475-2013 A-44 grade.

The hydroisomerization of long-chain paraffins, such as n-C₁₆, is a key process for improving the low-temperature properties of diesel fuels. However, the understanding of how the zeolite pore structure and the balance between acid and metal sites determine the efficiency of this process remains incomplete. This work is dedicated to the synthesis and investigation of Pt/ZSM-23 and Pt/ZSM-48 catalysts in n-hexadecane isomerization and diesel fuel hydroisodewaxing. A kinetic investigation of the model feedstock hydroisomerization was conducted at low conversion levels, with a focus on product distribution and structure–property correlations. A detailed analysis was performed on the yield of mono- and multibranched isomers, cracking products and fuel quality indicators (e.g., CFPP, cetane index). Pt/ZSM-23 demonstrated higher isomer selectivity at lower temperatures and a greater degree of proximity between metal and acid sites, whereas Pt/ZSM-48 exhibited increased cracking at elevated temperatures, consistent with its acidity tending towards the stronger type and distinct pore architecture. The kinetic analysis accounted for competing reaction pathways proceeding via carbenium ion intermediates on acid sites and dehydrogenation/hydrogenation reactions on Pt, emphasizing the role of spatial constraints and acid site strength in governing the rates of elementary steps. The prepared catalysts ensured high yields of isomers in the diesel fuel range with significantly reduced cloud points and acceptable density/cetane index values, confirming the potential of using specially designed Pt/zeolite systems for improving diesel fuel quality. This work deepens the understanding of the hydroisomerization mechanism on one-dimensional zeolites and establishes a foundation for the development of catalysts for diesel fuels hydroisodewaxing.