Вестник нефтегазовой отрасли КазахстанаВестник нефтегазовой отрасли Казахстана2707-42262957-806XKMG Engineering10898410.54859/kjogi108984Review ArticleCatalytic isomerization of light alkanes: thermodynamic, kinetic, and technological aspectsOrazbayevNurkhan S.nurkhan7allmight@gmail.comhttps://orcid.org/0009-0000-7097-989XSeitenovaGaini Zh.<p>Cand. Sc. (Chemistry), Professor</p>gainiseitenova@gmail.comhttps://orcid.org/0000-0001-6202-3951Eurasian National University30062026821191320605202625052026Copyright © 2026, Orazbayev N.S., Seitenova G.Z.2026<p>The gradual tightening of environmental standards, combined with growing global demand for environmentally friendly fuels, has significantly increased the importance of advanced technologies in oil refining. In this context, the catalytic isomerization of light alkanes (C₄–C₆ fraction) is one of the most strategic processes for improving gasoline quality without increasing the concentration of aromatic hydrocarbons or adding hazardous additives. From a chemical standpoint, this process promotes the structural rearrangement of linear paraffins into corresponding branched isomers, which possess a higher octane numbers. This results in a significant improvement in the fuel’s combustion characteristics, while reducing the formation of environmentally harmful emissions.</p> <p>This review systematically examines the fundamental principles underlying the isomerization of alkanes. Particular attention is given to the reaction mechanism, which proceeds via carbocationic intermediates at acidic catalytic sites, reflecting the well-established mechanism of acid-catalyzed hydrocarbon transformations. Furthermore, the thermodynamic constraints governing the equilibrium distribution of isomers, as well as the kinetic factors influencingreaction rate, product selectivity, and overall process efficiency, are critically analyzed. Special emphasis is placed on bifunctional catalytic systems combining metal and acid functions, enabling the simultaneous hydrogenation–dehydrogenation and skeletal isomerization steps. The role of competing side reactions, notably hydrocracking and aromatization, is also addressed due to their influence on product yield and catalyst stability.</p> <p>Beyond theoretical considerations, this review examines the complexities inherent in real industrial systems. In practice, the attainment of thermodynamic equilibrium is often limited by kinetic constraints, resistance to mass transfer within particles and between phases, as well as by the gradual deactivation of the catalyst due to coke formation or poisoning. These factors require a more detailed understanding of process behavior under industrial operating condition.</p>catalytic isomerizationlight alkaneshydroisomerizationbifunctional catalystscarbocation mechanismthermodynamic equilibriumreaction kineticszeolite catalystscatalyst deactivationoctane number enhancementкаталитикалық изомеризацияжеңіл алкандаргидроизомеризациябифункционалды катализаторларкарбокация механизмітермодинамикалық тепе-теңдікреакция кинетикасыцеолит катализаторларыкатализаторды залалсыздандыруоктан санын көбейтумеханизмтермодинамическое равновесиекинетика реакциицеолитные катализаторыдезактивация катализатораповышение октанового числаWei Ch., Zhang G., Zhao L., et al. Effect of metal–acid balance and textual modifications on hydroisomerization catalysts for n-alkanes with different chain length: A mini-review // Fuel. 2022. Vol. 315. doi: 10.1016/j.fuel.2021.122809.Tan Ya., Hu W., Du Ya., et al. Species and impacts of metal sites over bifunctional catalyst on long-chain n-alkane hydroisomerization: A review // Applied Catalysis A: General. 2021. Vol. 611. doi: 10.1016/j.apcata.2020.117916.Cheng K., wan der Wal L.I., Yoshida H., et al. Impact of spatial organization of bifunctional metal–zeolite catalysts on hydroisomerization of light alkanes // Angewandte Chemie International Edition. 2020. Vol. 59, Issue 9. P. 3592–3600. doi: 10.1002/anie.201915080.Del Campo P., Martinez C., Corma A. Activation and conversion of alkanes in zeolite-type materials // Chemical Society Reviews. 2021. Vol. 50. P. 8511–8595. doi: 10.1039/D0CS01459A.Potter M.E., Le Brocq J.J.M., Oakley A.E., et al. Butane isomerization as a diagnostic tool in solid acid catalyst design // Catalysts. 2020. Vol. 10, Issue 9. doi: 10.3390/catal10091099.Liu L., Zhang M., Wang L., et al. Construction of ordered mesopores outside MTT zeolite for efficient hydroisomerization // Applied Catalysis A: General. 2020. Vol. 602. doi: 10.1016/j.apcata.2020.117664.Wang X.-M., Wen Ch.-L., Fan Y. Synthesis of hierarchical SAPO-11-based catalysts with Al-based metal-organic framework derivative as mesoporogen to improve n-decane branched isomerization // Petroleum Science. 2022. Vol. 19, Issue 6. P. 3171–3181. doi: 10.1016/j.petsci.2022.06.003.Lyu Yu., Yu Zh., Yang Ye., et al. Metal-acid balance in the in-situ solid synthesized Ni/SAPO-11 catalyst for n-hexane hydroisomerization // Fuel. 2019. Vol. 243. P. 348–405. doi: 10.1016/j.fuel.2019.01.013.Besl H., Crowe T.J., Caracotsios M. Nontraditional optimization for isom unit improves profits // Oil & Gas Journal. 1998 [about 1 p.]. Дата обращения: 12.04.2026. Доступ по ссылке: www.ogj.com/home/article/17225389/nontraditional-optimization-for-isom-unit-improves-profits.Said M.M., Ahmed T.S., Moustafa T.M. Predictive Modeling and Optimization for an Industrial Penex Isomerization Unit: A Case Study // Energy & Fuels. 2014. Vol. 28, Issue 12. P. 7726–7741. doi: 10.1021/ef502332k.Seghir M.Z., Djennad M., Schomäcker R., Ghezzar M.R. Study of n-Butane isomerization on acid catalysts niobium and lanthanum promoted tungstated zirconia: n-Butane isomerization activity // Kemija u Industriji. 2022. Vol. 71(7-8). P. 439–446. doi: 10.15255/KUI.2021.078.Koncsag C., Tutun I.A., Safta C. Study of C₅/C₆ isomerization on Pt / H-zeolite catalyst in industrial conditions // Chemistry. 2011. Vol. 22, N 2. P. 102–106.Wang J, Song K, Xiang HW, et al. Single event kinetic modeling for paraffin hydrocracking over an industrial Ni-W silica-aluminum catalyst // Reaction Chemistry & Engineering. 2023. Vol. 8, Issue 1. P. 95–108. doi: 10.1039/D2RE00286H.Zhong H., Song X., He Sh., et al. Reaction behavior and kinetic model of hydroisomerization and hydroaromatization of fluid catalytic cracking gasoline // Molecules. 2025. Vol. 30, Issue 4. doi: 10.3390/molecules30040783.Batalha N., Pinard L., Bouchy C., et al. n-Hexadecane hydroisomerization over Pt-HBEA catalysts. Quantification and effect of the intimacy between metal and protonic sites // Journal of Catalysis. 2013. Vol. 307. P. 122–131. doi: 10.1016/J.JCAT.2013.07.014.Parsafard N., Shakor Z.M. Advancements in zeolite-based catalysts for the isomerization of n-alkanes: mechanistic insights and future directions // Discover Applied Sciences. 2025. Vol. 7. doi: 10.1007/s42452-025-06842-4.Safaat M., Adilina I., Tursiloadi S. A Review on the Hydroisomerisasion of n-Parafins over Supported Metal Catalysts // Jurnal Rekayasa Proses. 2021. Vol. 15, No. 2. P. 141–153. doi: 10.22146/jrekpros.67587.Чеканцев Н.В., Иванчина Э.Д., Чузлов В.А., Куртуков В.А. Оптимизация состава перерабатываемого сырья на установках каталитического риформинга бензинов и изомеризации пентан-гексановой фракции с использованием комплексной математической модели «HYSYS IZOMER ACTIV» // Фундаментальные исследования. 2013. №8-3. С. 766–772.Дюсова Р.М., Жакманова Е.А., Сейтенова Г.Ж. Сравнительная характеристика технологий каталитического риформинга в Казахстане // Вестник нефтегазовой отрасли Казахстана. 2025. Т. 7, №4. C. 91–100. doi: 10.54859/kjogi108876.Szoboszlai Zs., Hancsók J. Investigation of kinetics of hydroisomerization of C₅/C₆ and C₆/C7 alkenes and their binary mixture // Hungarian Journal of Industrial Chemistry. 2011. Vol. 39, Issue 1. P. 117–120.Hancsók J., Kasza T., Visnyei O. Isomerization of n-C₅/C₆ Bioparaffins to Gasoline Components with High Octane Number // Energies. 2020. Vol. 13, Issue 7. doi: 10.3390/en13071672.Mortezaeikia V., Tavakoli O., Khodaparasti M.S. A review on kinetic study approach for pyrolysis of plastic wastes using thermogravimetric analysis // Journal of Analytical and Applied Pyrolysis. 2021. Vol. 160. doi: 10.1016/j.jaap.2021.105340.Martínez J., Zúñiga-Hinojosa M.A., Ruiz-Martínez R.S. A thermodynamic analysis of naphtha catalytic reforming reactions // Processes. 2022. Vol. 10, No. 2. doi: 10.3390/pr10020313.Шакун Ф.Н., Федорова М.Л., Карпенко Т.В., Демидова Е.В. Развитие процессов изомеризации парафиновых углеводородов // Мир нефтепродуктов. 2020. №6. doi: 10.32758/2071-5951-2020-0-6-6-14.Ling H., Wang Q., Shen B. Hydroisomerization and hydrocracking of hydrocracker bottom for producing lube base oil // Fuel Processing Technology. 2009. Vol. 90, Issue 4. P. 531–535. doi: 10.1016/j.fuproc.2009.01.006.Díaz-Cervantes D.K., Elías-Domínguez A., Castro-Agüero Á., et al. A Comparative Study of Kinetic Reaction Schemes for the Isomerization Process of the C₆ Series // Applied Sciences. 2025. Vol. 15, Issue 8. doi: 10.3390/app15084429.Valavarasu G., Sairam B. Light Naphtha Isomerization Process: A Review // Petroleum Science and Technology. 2013. Vol. 31, Issue 6. P. 580–595. doi: 10.1080/10916466.2010.504931.Naqvi S.R., Bibi A., Naqvi M., et al. New trends in improving gasoline quality and octane through naphtha isomerization: a short review // Applied Petrochemical Research. 2018. Vol. 8. P. 131–139. doi: 10.1007/s13203-018-0204-y.Barbosa E., Menon A.K. Thermodynamic and kinetic characterization of salt hydrates for thermochemical energy storage // MRS Communications. 2022. Vol. 12. P. 678–685. doi: 10.1557/s43579-022-00264-8.