Reaction Behavior of a Fixed Bed Reactor for Chemical Looping Hydrogen Production with Iron-Based Oxygen Carriers

Hydrogen is believed to be an ideal future energy source with less combustion emissions. Production of hydrogen by the chemical looping method is considered a clean and energy-efficient method compared with the steam reforming technology. In this paper, we investigate the transient kinetic behavior of an iron-based oxygen carrier during the chemical looping hydrogen production process in a fixed bed reactor. Reduction and oxidation of the oxygen carrier are considered and analyzed for better understanding the performance of the reactor. High temperature and high concentration of reduced gas species are beneficial for the reduction of the oxygen carrier due to the reaction kinetics. The hydrogen production rate can be calculated, and the hydrogen amount can be adjusted by arranging the reduction level. The obvious feature of hydrocarbon fuel with an iron-based oxygen carrier is that the process can be divided into three reduction stages. The platform stage during reduction is the most time-consuming. It is better to adjust the C/H ratio of fuel gas to shorten the reduction time and accelerate hydrogen production. The reduction time and partial oxidation time are in linear relation when the reduction level is over 0.33 for reduction between the oxygen carrier and hydrocarbon fuel. This work aims to provide a rapid prediction and the optimization of operating conditions for the chemical looping hydrogen production process.