Chemical Looping Reforming in Packed Bed Reactors

  • Panagiotis Alexandros Argyris

Student thesis: Phd


Chemical Looping Reforming with packed bed reactors (CLR-PB) is an autothermal technology where hydrogen/syngas can be produced with high yield and integrated total CO2 capture. An oxygen carrier (OC) is used, usually Ni, Cu, Fe, Mn, Co, to perform cyclic stages of oxidation, reduction and reforming. Heat is accumulated during oxidation as the reaction is highly exothermic with air being the feed, reduction with a low-grade fuel converts the material to reduced state to proceed to the final step, reforming, where heat from oxidation is utilized to perform all the endothermic catalytic reforming reactions by feeding natural gas and H2O/CO2. The main products from the process are, pure N2 during oxidation, CO2 and H2O during reduction where CO2 can be easily captured with condensation and syngas during reforming. The process is dynamic using a set of reactors operating in parallel performing the three steps at different times. A pseudo-steady state is reached in the system ensuring a constant steady output of the products. CLR-PB has been examined experimentally in a laboratory-scale reactor for a set of operating conditions in a temperature range of 400-900 °C and up to 5 bar pressure in a Ni-based OC. Moreover, the effect of different feed compositions has been examined as well as different reducing agents as H2, CO and CH4. Increasing initial bed temperature led to better solid conversion for redox reactions while pressure change had little effect in higher flowrates. A complete cycle is demonstrated reaching steady-state behaviour, where > 99% CH4 conversion is achieved. A one-dimensional and a two-dimensional model have been developed and validated against the experimental results generated. The models have been validated with high accuracy with the 2-D model providing higher accuracy but also significantly higher computational times. The models showed that the temperature profile inside the bed generates temperatures up to 100 °C higher during oxidation than the ones recorded by the thermocouples due to the thermal inertia of the thermowell having a delay to capture swift temperature swings. Moreover, the difference in the simulated bed temperature between the 1-D and the 2-D simulations was limited to 2.5% making the 1-D a suitable candidate for reactor and process design. The low-grade fuel feed during reduction is usually taken from the tail-gas output of a pressure swing adsorption (PSA) unit which is usually part of a CLR-PB H2 plant. The two processes are dynamically operated and they were examined in a small-scale H2 plant where the dynamic character is expected to be enhanced. When the PSA (also a dynamic process) is coupled with a CLR-PB unit the dynamic character is only affecting the reduction outlet producing, with fluctuations up to 20% in the products while with the use of different configurations and blowdown tank the output can reach a state to be considered steady. Most importantly the coupling is not affecting the syngas output of the CLR-PB unit and a steady flow of hydrogen is ensured. Two techno-economic studies on large scale H¬2 and ammonia production compared CLR-PB technology with the state-of-the-art technologies. In both plants the resulting cost of production is lower for the CLR-PB configurations when CO2 capture is considered, as well as the CO2 avoidance costs mostly due to the high capture rate >99%.
Date of Award31 Dec 2022
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorVincenzo Spallina (Supervisor) & Chris Hardacre (Supervisor)


  • simulation
  • reactor modelling
  • chemical looping
  • hydrogen production
  • packed bed reactor
  • CO2 capture

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