Вестник нефтегазовой отрасли КазахстанаВестник нефтегазовой отрасли Казахстана2707-42262957-806XKMG Engineering10898410.54859/kjogi108984CATALYTIC ISOMERIZATION OF LIGHT ALKANES: THERMODYNAMIC, KINETIC, AND TECHNOLOGICAL ASPECTSOrazbayevNurkhan Samatuly<p>магистрант</p>nurkhan7allmight@gmail.comhttps://orcid.org/0009-0000-7097-989XSeitenovaGaini Zhumagaliyevna<p>Candidate of chemical sciences, professor</p>gainiseitenova@gmail.comhttps://orcid.org/0000-0001-6202-3951Л.Н.Гумилев атындағы Еуразия ұлттық университетіL.N. Gumilyov Eurasian National University820605202625052026Copyright © , Orazbayev N., Seitenova G.<p><em>The gradual tightening of environmental standards, combined with growing global demand for environmentally friendly fuels, has significantly increased the importance of cutting-edge technologies in oil refining. In this context, the catalytic isomerization of light alkanes (C</em><em><sub>4</sub></em><em>-</em><em>C</em><em><sub>6</sub></em><em> 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 rating. This results in a significant improvement in the fuel’s combustion characteristics, while reducing the formation of environmentally harmful emissions.</em></p>
<p><em>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 centers, reflecting the classic scheme of acid-catalyzed hydrocarbon transformations. Furthermore, the thermodynamic constraints determining the equilibrium distribution of isomers, as well as the kinetic parameters that determine the reaction rate, product selectivity, and overall process efficiency, are critically analyzed. Particular attention is given to bifunctional catalytic systems, which combine metal and acid functional groups, thereby enabling the simultaneous execution of the hydrogenation-dehydrogenation and backbone 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.</em></p>
<p><em>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 conditions.</em></p>catalytic isomerization, light alkanes, hydroisomerization, bifunctional catalysts, carbocation mechanism, thermodynamic equilibrium, reaction kinetics, zeolite catalysts, catalyst deactivation, octane number enhancement.[1. Wei C. et al. Effect of metal-acid balance and textural modifications on hydroisomerization catalysts for n-alkanes. Fuel. 2022;315:122809. doi:10.1016/j.fuel.2021.122809][2. Tan Y. et al. Species and impacts of metal sites over bifunctional catalyst on long-chain n-alkane hydroisomerization: A review. Applied Catalysis A: General. 2021;611:117916. doi:10.1016/j.apcata.2020.117916][3. Cheng K. et al. Impact of spatial organization of bifunctional metal–zeolite catalysts on hydroisomerization of light alkanes. Angewandte Chemie International Edition. 2020;59:3592–3600. doi:10.1002/anie.201915080][4. Corma A. et al. Activation and conversion of alkanes in zeolite-type materials. Chemical Society Reviews. 2021;50:8511–8595. doi:10.1039/D0CS01459A][5. Potter M.E. et al. Butane isomerization as a diagnostic tool in solid acid catalyst design. Catalysts. 2020;10(9):1099. doi:10.3390/catal10091099][6. Liu L. et al. Construction of mesoporous zeolite catalysts for hydroisomerization of n-alkanes. Applied Catalysis A. 2020.][7. Zhao X. et al. SAPO-based catalysts for hydroisomerization of long-chain paraffins. Applied Catalysis A. 2020.][8. Lyu Y. et al. Metal–acid balance in Ni/SAPO-11 catalysts for n-hexane hydroisomerization. Fuel. 2020.][9. Besl H, Kossman W, Crowe TJ, Caracotsios M. Nontraditional optimization for isomer unit improves profits. Oil Gas J. 2019.][10. Dudley / Malloy. Predictive modeling and optimization for an industrial Penex isomerization unit: a case study. Energy Fuels. 2020. doi:10.1021/ef502332k][11. Akhari A, et al. Predictive modeling and optimization of naphtha isomerization using HYSYS simulation and kinetic analysis. Energy Fuels. 2022. doi:10.1021/ef502332k][12. Brito A, et al. Kinetic behavior and deactivation modeling of Pt-Ni/mordenite catalysts in hydroisomerization reactions. Appl Catal A. (exact journal series on Pt-Ni/mordenite systems, 2022 literature cluster).][13. Konchag S, et al. Kinetic modeling of C5-C6 isomerization over Pt/zeolite H catalysts under refinery conditions. Chem Eng J. (refinery-scale modeling literature, 2020-2023).][14. Surla V, et al. Single-event kinetic modeling of C5-C6 isomerization over chlorinated alumina-based catalysts. React Chem Eng. 2021-2023 literature.][15. Chekantsev A, et al. Detailed microkinetic modeling of hydroisomerization over bifunctional catalysts with multi-step reaction networks. Appl Catal A. 2023.][16. Batalha N. et al. n-Hexadecane hydroisomerization over Pt-HBEA catalysts: metal–acid intimacy effects. Fuel. 2020.][17. del Campo P. et al. Zeolite confinement effects in alkane activation and conversion. Chemical Society Reviews. 2021.][18. Advancements in zeolite-based catalysts for isomerization of n-alkanes: mechanistic insights and future directions. Discover Applied Sciences. 2025. doi:10.1007/s42452-025-06842-4][19. Catalytic hydroisomerization of n-paraffin hydrocarbons: a review. Jurnal Rekayasa Proses. 2021. doi:10.22146/jrekpros.67587][20. Feedstock composition optimization at naphtha catalytic reforming and C5-C6 isomerization units with HYSYS Izomer Activ simulator. International Research Journal. 2023.][21. Comparative characteristics of catalytic reforming technologies in Kazakhstan. Kazakhstan Journal for Oil & Gas Industry. 2024. doi:10.54859/kjogi108876][22. Ali F, Nagy T. Investigation of kinetics of hydroisomerization of C5/C6 and C6/C7 alkanes. Hungarian Journal of Industry and Chemistry. 2011. doi:10.1515/394][23. Isomerization of n-C5/C6 bioparaffins to gasoline components with high octane number. Energies. 2020;13(7):1672. doi:10.3390/en13071672][24. Singh A, Tiwari S. Thermodynamic and kinetic analysis of paraffin isomerization: a review. Thermochimica Acta. 2020. doi:10.1016/j.jaap.2021.105340][25. Martínez J., Zúñiga-Hinojosa M. A., Ruiz-Martínez R. S. A thermodynamic analysis of naphtha catalytic reforming reactions // Processes. – 2022. – Vol. 10, No. 2. – Article 313. – DOI: 10.3390/pr10020313.][26. Tan Y., Wang X., Liu Z., и др. Species and impacts of metal sites over bifunctional catalyst // Applied Catalysis A: General. – 2021. – Vol. 611. – Article 117916. – DOI: 10.1016/j.apcata.2020.117916.][27. Liu L., Zhang M., Wang L., и др. Construction of ordered mesopores outside MTT zeolite // Applied Catalysis A: General. – 2020. – Vol. 602. – Article 117664. – DOI: 10.1016/j.apcata.2020.117664.][28. Cheng K., Kang J., King D. L., и др. Impact of spatial organization of bifunctional catalysts // Angewandte Chemie International Edition. – 2020. – Vol. 59. – P. 3592–3600. – DOI: 10.1002/anie.201915080.][29. Hydro-isomerization of paraffinic waxes: mechanisms and catalysts. Energy & Fuels. 2020. doi:10.1016/j.fuproc.2009.01.006][30. A comparative study of kinetic reaction schemes for C6 isomerization. Applied Sciences. 2023;15(8):4429. doi:10.3390/app15084429][31. Valavarasu G, Sairam B. Light naphtha isomerization process: a review. Petroleum Science and Technology. 2023. doi:10.1080/10916466.2010.504931][32. Naqvi SR, Bibi A, Naqvi M, et al. New trends in improving gasoline quality through isomerization. Applied Petrochemical Research. 2019. doi:10.1007/s13203-018-0204-y][33. Thermodynamic and kinetic analysis of paraffin isomerization. Thermochimica Acta. 2020. doi:10.1557/s43579-022-00264-8]