Studies were conducted on the hydrogen-free processing of model alkanes, straight-run gasoline, and catalytic cracking gasoline using a new synthesized Co-Mo-Ce/ZSM + Al₂O₃ nanocatalyst, which demonstrated high activity in desulfurization. Thus, the mass fraction of sulfur in the resulting gasoline was reduced by almost three times compared to the initial value of 0.0776% to 0.0354% as a result of hydrogen-free processing of straight-run gasoline. The amount of sulfur in the resulting product was reduced by almost an order of magnitude with hydrogen-free processing of catalytic cracked gasoline: from 0.1650 in the original gasoline to 0.0123%. The octane number of the refined straight-run gasoline was 77.9–80.9 according to the research method (RM) and 61.13–65.8 with the motor method (MM). Physical and chemical methods of analysis (BET, TPD-NH₃, TEM, SEM, and XRD) revealed that nano-structured acid sites coexist with nano-dispersed metallic sites on the surface of the Co-Mo-Ce/ZSM + Al₂O₃ catalyst. The functioning of these two types of nano-active sites (metallic and acidic) ensures the polyfunctionality of the catalytic action of the nanoparticles. The following reactions occur simultaneously in the hydrogen-free processing: isomerization, dehydrogenation, dehydrocyclization. Hydrogen-free processing of low-octane gasoline fractions on nanosized zeolite-containing catalysts is one of the most promising methods to obtain high-octane motor gasoline.

The process of hydrogen-free processing of petroleum fractions on zeolite- containing catalysts was implemented at a laboratory catalytic plant under conditions of varying technological parameters. Modification was carried out with metals with variable valence, REM, and phosphorus. It is shown that in the process of refining gas condensates and petroleum fractions (gasoline and diesel) without hydrogen-containing gas, the catalytic properties, activity and selectivity of synthesized catalysts depend on the nature and concentration of the introduced modifiers, the structure and condition of the active centers and the conditions of the process. The directions of hydrocarbon transformations in the process of anhydrous refining on a zeolite catalyst are considered. It has been established that the catalysts have multifunctional properties, and are capable of simultaneously conducting several reactions: cracking, hydrodesulfurization, dehydrogenation, isomerization, dehydrocyclization, alkylation. The physicochemical characteristics of zeolite-containing catalysts have been studied by electron microscopy and thermal desorption of ammonia. It is shown that acidic centers coexist with metallic ones on the surface of the developed catalysts. The composition of acid centers may include metals in various degrees of oxidation, fixed both inside the zeolite cavities and on their outer side.

The growing demand for high-quality motor fuels, combined with increasingly stringent environmental regulations, has stimulated research aimed at developing advanced catalytic methods for upgrading petroleum feedstocks. Conventional technologies for the deep purification and upgrading of petroleum fractions are based on hydrotreating processes that require an external H₂ supply, elevated pressure, and dedicated infrastructure, resulting in high capital and energy costs. In this context, hydrogen-free catalytic upgrading is considered a promising alternative approach. This review analyzes current approaches to the hydrogen-free catalytic upgrading of hydrocarbon feedstocks, with particular emphasis on zeolite-based catalysts. The main reaction pathways, including dehydrogenation, isomerization, dehydrocyclization, and intermolecular hydrogen transfer, are discussed in relation to the structural characteristics of the catalysts and their acidic and redox properties. Particular attention is given to microporous ZSM-5, Y, and BEA zeolites, as well as MCM-41-type mesoporous materials, hierarchical micro–mesoporous composites, and nanocatalysts. The effects of the distribution of Brønsted and Lewis acid sites, pore architecture, and modification with metals (Ni, Co, Zn, Mo, rare-earth elements, etc.) on the catalytic activity, selectivity, and operational performance of catalytic systems are examined in detail. The analysis demonstrates that the efficiency of hydrogen-free upgrading processes is governed by the synergistic interaction between the acidic and metallic functions of the catalyst surface, while also depending on the accessibility of active sites and mass transfer. The development of hierarchical porosity can reduce diffusion limitations; however, excessive formation of secondary porosity may lead to a partial loss of the zeolite crystalline structure and acid sites. Similarly, metal incorporation enhances catalyst activity along key reaction pathways, but its effects on selectivity, coke formation, and stability are determined by the nature, loading, and location of the metal sites. Therefore, the prospects for hydrogen-free upgrading are primarily associated with optimizing these interrelated characteristics. Analysis of pilot- and industrial-scale experience with early hydrogen-free processes indicates that current restrictions on sulfur, benzene, and total aromatic contents determine the target selectivity requirements for such catalytic systems. Overall, hydrogen-free catalytic upgrading represents a promising complement to conventional hydroprocessing technologies, offering potential advantages in terms of improved energy efficiency, reduced dependence on hydrogen, and lower environmental impact. Further advances in this field are expected to rely on the coordinated control of acidic and metallic functions, pore structure, and mass transfer, together with the integration of physics-based modeling, systematic experimental screening, and data-driven analytical methods.