08/2014 ~ 01/2020, Department of Energy and Power Engineering, Tsinghua University, Ph.D.
08/2010 ~ 07/2014, Department of Thermal Engineering, Tsinghua University, B.S.,
08/2012 ~ 07/2014, School of Economics and Management, Tsinghua University, B. Econ. (minor)

04/2020 ~10/2023, Department of Chemical and Biomolecular Engineering, North Carolina State University, USA, Postdoctoral researcher
11/2023 ~present, School of Mechanical Engineering, Shanghai Jiao Tong Univerisity, China, Tenure-track associate professor

[1] Fluidization XVII, Edinburgh, Scotland, UK, 2023.
[2] 2022 AIChE Annual Meeting, Pheonix, USA, 2022. (Best poster)
[3] The 27th North America Catalysis Society Meeting, USA, 2022.
[4] The 2nd International Conference on Circulating Fluidized Bed Boilers, China, 2019. (Best paper)
[5] The 9th International Symposium on Coal Combustion, Qingdao, China, 2019. (Best paper)
[6] The 23rd International Conference of Fluidized Bed Conversion, Seoul, Korea, 2018.
[7] The 12th International Conference of Circulating Fluidized Bed Technology, Krakow, Poland, 2017.
[8] The 22nd International Conference of Fluidized Bed Conversion, Turku, Finland, 2015.

Our research group is dedicated to addressing the strategic needs of carbon neutrality and high-efficiency energy conversion. We focus on key multiscale challenges involving energy and mass transfer, reaction, and conversion in gas–solid systems, with an emphasis on both fundamental understanding and the development of enabling technologies. Following a “particulate materials–reactors–process systems” research framework, our work integrates the development of high-performance particulate materials, optimized design of gas–solid reactors, and multiscale numerical simulation. These efforts support engineering applications in areas such as biomass-based hydrogen production, oxygen production via air separation, thermochemical energy storage, CO2 capture and utilization, and clean power generation.

Main Research Directions
1. Development and characterization of high-performance particulate materials
We develop advanced catalyst and sorbent particles with oxygen-carrier or carbon-carrier functionalities. Using state-of-the-art characterization techniques, we investigate their performance optimization, structural evolution, and reaction mechanisms during chemical looping and related gas–solid reaction processes.

2. Optimization and design of gas–solid reaction systems
We conduct experimental studies using multiphase reactor platforms, including fixed beds, bubbling beds, and circulating fluidized beds. Combined with advanced gas–solid flow diagnostics such as fiber-optic probes, these platforms enable us to optimize reactor configurations and operating conditions to improve system performance, reaction efficiency, and operational stability.

3. Reaction kinetics and multiscale numerical simulation of reactors
We carry out multiscale reactor modeling and optimization using commercial software such as Barracuda and Ansys Fluent, together with in-house codes. These simulations help improve system efficiency, stability, and scale-up performance. In parallel, density functional theory calculations and artificial intelligence methods are employed to analyze the thermodynamic properties and reaction mechanisms of particulate materials, providing guidance for rational materials design and optimization.
Prospective undergraduate students, master’s students, PhD students, and postdoctoral researchers are welcome to contact us.

2021~2025, US Dept. of Energy, Renewable Natural Gas from Carbonaceous Wastes via Phase Transition CO2/O2 Sorbent Enhanced Chemical Looping Gasification, Main participant；
2019~2022, US Dept. of Energy, Radically Engineering Modular Air Separation System with Tailored Oxygen Sorbents, Main participant；
2018~2022, RAPID Institute, Modular Conversion of Stranded Ethane to Liquid Fuels, Main participant；
2016~2020, National Key R&D Programmes of China, Key technology of 660MW high-efficiency ultra-supercritical circulating fluidized bed boiler, Main participant
2017~2019, International cooperation with Korea Southern Power Co., Ltd. (KOSPO), Required measures for the improvement of in-situ desulfurization efficiency for Samcheok CFBC boilers through modeling research, Main participant；
2017~2018， Cooperation with Dongfang Boiler Group Co., Ltd.， Experimental and modeling study on the external heat exchangers, Main participant；
2017~2019， Development and engineering demonstration of third-generation ultra-low emission circulating fluidized bed boiler technology, Main participant；

Journal Papers (in English)

[1] R Cai#, M Rukh#, A Jones, et al. Isothermal sorption-enhanced biomass gasification for hydrogen-rich syngas production using SrMnO3 redox-activated CO2 sorbents in a fluidized bed. Particuology, 2026.
[2] R Cai, H Bektas, S Raza, et al. Redox‐active oxide/molten salt composites for hybrid thermal‐chemical energy storage. Advanced Energy and Sustainability Research, 2025: 2500196.
[3] M Rukh, R Cai, S Razavi, et al. Ruddlesden–Popper structured Sr3Fe2O7− δ as redox‐activated CO2 sorbents for green hydrogen production. Advanced Energy and Sustainability Research, 2025: 2500213.
[4] H Bektas, R Cai, S Raza, et al. Redox-active oxide-molten salt composites as a new family of high-capacity thermal energy storage materials. Journal of Materials Chemistry A, 2025, 13(25): 20028-20043.
[5] S Razavi, V Rahmanian, R Cai, et al. Perovskite oxides as a new family of tunable CO 2 sorbents. Journal of Materials Chemistry A, 2025, 13(13): 9211-9221.
[6] M C Garcia-Vallejo, M Rukh, S Wang, R Cai, et al. A new approach to improve the economic and environmental attractiveness of biomethane from biomass gasification with redox-activated CO2 sorbents. Chemical Engineering Journal, 2025: 167510.
[7] X Long, J Li, S Yuan, R Cai, et al. Effect of bed material on agglomeration of bed particles in CFB burning pellets from Arundo Donax. Energy, 2025: 136860.
[8] C Hu, X Yang, X Wang, P Guo, D Li, X Zhu, R Cai, et al. Impacts of agro-biomass ash on ilmenite oxygen carrier performance in chemical looping combustion: Catalytic enhancement and microstructural evolution. Chemical Engineering Science, 2025: 122755.
[9] R Cai#, K Yang#, X Wang#, et al. High-throughput design of complex oxides as isothermal, redox-activated CO2 sorbents for green hydrogen generation. Energy & Environmental Science, 2024, 17 (17), 6279-6290.
[10] R Cai#, E Krzystowczyk#, B Braunberger, et al. Techno-economic analysis of chemical looping air separation using a perovskite oxide sorbent. International Journal of Greenhouse Gas Control. 2024, 132: 104070.
[11] M Rukh#, R Cai#, L Brody, et al. Isothermal CO2 separation enabled by redox-active mixed oxide sorbents. Chemical Engineering Journal, 2024, 501: 157545.
[12] H Bektas, R Cai, L Brody, et al. Structural and thermodynamic assessment of Ba and Ba/Mg substituted SrFeO3−δ for “low-temperature” chemical looping air separation. Energy & Fuels, 2024, 38 (12), 11107-11118.
[13] R Cai, L Brody, Y Tian, et al. Numerical modeling of chemical looping oxidative dehydrogenation of ethane in a packed bed reactor. Chemical Engineering Journal, 2023, 469: 143930.
[14] R Cai#, H Bektas#, X Wang#, et al. Accelerated perovskite oxide development for thermochemical energy storage by a high-throughput combinatorial approach. Advanced Energy Materials, 2023, 2203833.
[15] L Brody, M Rukh, R Cai, et al. Sorption-enhanced steam reforming of toluene using multifunctional perovskite phase transition sorbents in a chemical looping scheme. Journal of Physics: Energy, 2023.
[16] R Cai, J Dou, E Krzystowczyk, et al. Chemical looping air separation with Sr0. 8Ca0. 2Fe0. 9Co0. 1O3-δ perovskite sorbent: Packed bed modeling, verification, and optimization. Chemical Engineering Journal, 2022, 429: 132370.
[17] D Li#, R Cai#, Ahn S#, et al. Hydrodynamics in the transport zone of a large-scale circulating fluidized bed boiler[J]. Powder Technology, 2022: 118099. (Equal contribution)
[18] L Brody#, R Cai#, A Thornton, et al. Perovskite-based phase transition sorbents for sorption-enhanced oxidative steam reforming of glycerol. ACS Sustainable Chemistry & Engineering, 2022, 10, 19, 6434–6445. (Equal contribution)
[19] X Wang, Y Gao, E Krzystowczyk, S Iftikhar, J Dou, R Cai, et al. High-throughput oxygen chemical potential engineering of perovskite oxides for chemical looping applications. Energy & Environmental Science, 2022, 15(4), 1512-1528.
[20] S Chen, R Cai, Zhang Y, et al. A semi-empirical model to estimate the apparent viscosity of dense, bubbling gas-solid suspension. Powder Technology, 2021, 377: 289-296.
[21] I Wang, Y Gao, X Wang, R Cai, et al. Liquid metal shell as an effective iron oxide modifier for redox-based hydrogen production at intermediate temperatures. ACS Catalysis, 2021, 11(16): 10228-10238.
[22] X Ke, M Engblom M, L Cheng, L Chen, R Cai, et al. Modeling and experimental investigation on the fuel particle heat-up and devolatilization behavior in a fluidized bed. Fuel, 2021, 288: 119794.
[23] R Cai, B Deng, X Tao, et al. Effects of horizontal tube arrays on heat transfer in an external heat exchanger. Applied Thermal Engineering, 2020, 181: 115964.
[24] Y Li, R Cai, M Zhang, et al. Characterization of the sulfation reactivity of limestones with different particle size in a large-capacity TGA. Fuel, 2020, 271: 117292.
[25] D Li#, R Cai#, H Yang, et al. Operation characteristics of a bubbling fluidized bed heat exchanger with internal solid circulation for a 550-MWe ultra-supercritical CFB boiler. Energy, 2020, 192: 116503. (Equal contribution)
[26] D Li, M Zhang, M Kim, R Cai, et al. Limestone attrition and product layer development during fluidized bed sulfation. Energy & Fuels, 2020, 34(2): 2117-2125.
[27] R Cai, X Ke, Y Huang, et al. Applications of ultrafine limestone sorbents for the desulfurization process in CFB boilers. Environmental Science & Technology, 2019, 53(22): 13514-13523.
[28] R Cai, Y Huang, Y Li, et al. Effects of the limestone particle size on the sulfation reactivity at low SO2 concentrations using an LC-TGA. Materials, 2019, 12, 1496.
[29] R Cai, M Zhang, R Ge, et al. Experimental study on local heat transfer and hydrodynamics of a single tube and tube bundles in an external heat exchanger. Applied Thermal Engineering, 2019, 149: 924-938.
[30] Y Yao, R Cai, Y Zhang, et al. A method to measure the tube-wall temperature in CFB boilers. Applied Thermal Engineering, 2019, 153: 493-500.
[31] X Ke, D Li, M Zhang, C Jeon, R Cai, et al. Ash formation characteristics of two Indonesian coals and the change of ash properties with particle size. Fuel Processing Technology, 2019, 186: 73-80.
[32] R Cai, M Zhang, X Mo, et al. Experimental research on the unstable performances of parallel external loops in the circulating fluidized bed. Chemical Engineering Research and Design, 2018, 139: 1-11
[33] R Cai, H Zhang, M Zhang, et al. Development and application of the design principle of fluidization state specification in CFB coal combustion, a review. Fuel Processing Technology, 2018, 174: 41-52.
[34] R Cai, M Zhang, X Mo, et al. Operation characteristics of external heat exchangers in the 600MW supercritical CFB boiler. Fuel Processing Technology, 2018, 172: 65-71.
[35] X Ke, R Cai, M Zhang, et al. Application of ultra-low NOx emission control for CFB boilers based on theoretical analysis and industrial practices. Fuel Processing Technology, 2018, 181: 252-258.
[36] R Cai, X Ke, J Lyu, et al. Progress of circulating fluidized bed combustion technology in China: a review. Clean Energy, 2017, 1(1): 36-49.
[37] G Yue, R Cai, J Lu, et al. From a CFB reactor to a CFB boiler–the review of R&D progress of CFB coal combustion technology in China. Powder Technology, 2017, 316: 18-28.
[38] X Mo, R Cai, X Huang, et al. The effects of wall friction and solid acceleration on the mal-distribution of gas–solid flow in double identical parallel cyclones. Powder Technology, 2015, 286: 471-477.

Journal Papers (in Chinese)
[39] R Cai, F Li. Tailoring the thermodynamic properties of complex oxides for thermochemical air separation and beyond. CIESC Journal, 2021, 72(12):6122-6130.
[40] R Cai, J Lyu, M Zhang, et al. Hydrodynamic mechanisms of non-uniform distribution of heat transfer in external heat exchangers of ultra-supercritical CFB boilers. Boiler Technology, 2019, 50(4): 36-42.
[41] R Cai, Y Huang, L Cheng, et al. Attrition of limestone during fluidized bed calcination and sulfation, CIESC Journal, 2019, 70(8): 3086-3093.
[42] R Cai, X Ke, R Ge, et al. The in-situ desulfurization with ultra-fine limestone for circulating fluidized bed boilers. Proceedings of the CSEE, 2018, 38(10): 3042-3048.
[43] R Cai, J Lyu, W Ling, et al. Progress of supercritical and ultra-supercritical circulating fluidized bed boiler technology. China Electric Power, 2016, 49(12): 1-7.
[44] L Nie, R Cai, J Lu, et al. Improvements of non-uniform distribution of tube wall temperatures in circulating fluidized bed boiler’s external heat exchangers. Journal of Zhejiang University (Engineering Science), 2021, 55(3): 578-585.
[45] X Tao, R Cai, L Chen, et al. Experimental study on coal combustion characteristics in sintering flue gas atmosphere by thermogravimetry analysis. Thermal Power Generation, 2020, 49(7): 55-60.
[46] X Ke, R Cai, J Lyu, et al. Research progress of the effects of Ca-based sorbents on the NOx reaction in circulating fluidized bed boilers. Clean Coal Technology, 2019, 25(01): 1-11.
[47] M Zhang, R Cai, X Jiang, et al. Design and development of a 660 high-efficiency ultra-supercritical double-furnace CFB boiler. Journal of Chinese Society of Power Engineering, 2018, 38(05):341-346.
[48] X Ke, R Cai, H Yang, et al. Formation and ultra-low emission of NOx for circulating fluidized bed combustion. Proceedings of the CSEE, 2018, 38(02): 390-396+669.
[49] C Liu, R Cai, J Lyu, et al. Research and application of ultra-low emission technology in large-scale CFB boilers burning low-rank coal. China Electric Power, 2018, 51(8): 1-6.
[50] X Mo, R Cai, J Lyu, et al. Analysis of non-uniform distribution of gas-solid flow in the 600MW(e) CFB boiler based on the non-uniform distribution of returning ash temperature. Proceedings of the CSEE, 2016, 36(08): 2175-2180.
[51] X Mo, R Cai, J Lyu, et al. The performance evaluation of the 600MWe supercritical circulating fluidized bed boiler. Boiler Technology, 2016, 47(04):34-38.
[52] P Wang, R Cai, C Liu, et al. Design and operation of a 300 MWe low energy consumption CFB boiler. Journal of Shenyang Institute of Engineering, 2016, 12(04): 308-313.
[53] R Ge, X Zhang, R Cai, et al. Experimental study on the bottom ash discharging and separating in fluidized beds. Journal of China Coal Society, 2018, 43(04): 1134-1139.
[54] X Zhang, R Ge, R Cai, et al. Simulation of the lateral movement on particles under continuous feeding and discharging in a CFB dense zone, Proceedings of the CSEE, 2018, 38(02): 413-420+672.
[55] H Shi, Q Li, R Cai, et al. Experimental study on adsorption of alkali in high temperature flue gas with bed material. Journal of China Coal Society, 2016, 41(10): 2527-2532.
[56] R Ge, D Wang, X Zhang, R Cai, et al. Numerical simulation and experimental study on the bottom ash discharging of bubbling fluidized bed, Journal of China Coal Society, 2017, 42(S2): 486-493.

[1] Design and Manufacturing I
[2] Academic Writing, Standards, and Ethics (International Student Class)

[1]. R Cai, M Zhang, J Lyu, et al. A desulfurization method in circulating fluidized bed boilers. Beijing: CN107596878A, 2018-01-19. (China Patent)
[2]. R Cai, M Zhang, J Lyu, et al. A type of external heat exchanger in circulating fluidized bed boilers. Beijing: CN206724147U, 2017-12-08. (China Patent)
[3]. X Ke, R Cai, J Lyu, et al. A method of realizing ultra-low NOx emission in circulating fluidized bed boilers. Beijing: CN108105759A, 2018-06-01. (China Patent)
[4]. X Ke, R Cai, H Zhang, et al. A method of reducing NOx emission in the flue gas of boilers. Beijing: CN107570004A, 2018-01-12. (China Patent)
[5]. X Ke, R Cai, H Zhang, et al. A catalytic metal heating surface for reducing NOx content in flue gas and preparation method [P]. Beijing: CN107398283A, 2017-11-28.
[6]. J Lyu, X Ke, R Cai, et al. Adsorption denitrification circulating fluidized bed boiler and its operation method. Shanxi: CN107238093A, 2017-10-10.
[7]. X Zhang, R Ge, R Cai, et al. A sheet-shaped stair-type air distribution device for circulating fluidized bed boilers. Beijing: CN107036085A, 2017-08-11.

1. Guest Editor of the special issue “Modeling and Optimization of Gas-Solid Reaction Vessels” of Processes Journal
2. Co-chair of a Session on Experimental Investigation and Modeling of Fluidization Processes at the 2022 AIChE annual meeting
3. Assistant committee member and session chair of the 5th International Conference on Circulating Fluidized Bed Boilers
4. Invited speech at the Seminar hosted by Energies Journal: Development Status and Application Prospects of Clean Combustion and Energy Storage
5. Co-chair of the Youth Form at the 3rd International Conference on Circulating Fluidized Bed Boilers

2022 1st place poster award of the Catalysis and Reaction Engineering Division at AIChE annual meeting
2022 Energies Journal Travel Award (only one postdoc)
2020 Chinese Society of Particuology First Prize of Science and Technology Progress Award (Rank 5)
2020 China Electricity Council First Prize of Electricity Technology Innovation Award (Rank 10)
2020 Outstanding Graduate of Beijing's Higher Education Institutions
2019 Best Paper Award at the 2nd International Conference on Circulating Fluidized Bed Boilers
2018 Tsinghua University Jiangzhen First-Prize Scholarship
2017 Tsinghua University Student Affairs Scholarship
2016 Tsinghua University Outstanding Volunteer Award
2014 Outstanding Graduate of Beijing's Higher Education Institutions
2012 China National Scholarship