Thermodynamic analysis on the parametric optimization of a novel chemical looping methane reforming in the separated productions of H2 and CO

Abstract The large-scale natural gas reforming is currently the lowest cost method for hydrogen (H 2 ) production. However, the mixture of H 2 and CO 2 in the produced gas inevitably includes CO 2 and necessitates the costly CO 2 separation. In this work, a novel chemical looping combustion-assisted chemical looping methane reforming technology (CLC-CLR HC ) was proposed to enhance the separated production of H 2 and CO in high purities in the absence of CO 2 . This novel reforming process not only produces high purity CO, H 2 , and even N 2 without pollutants and/or GHG emissions, but realizes the energy coupling. The aim of this study is to thermodynamically analyze the operational parameters of the proposed new system, involving the optimized utilization of CH 4 , maximization of energy coupling and productivity yields and purity. Studies revealed that the optimal molar ratios for the Fe 3 O 4 /CH 4 , CaO/CH 4 and H 2 O/CH 4 in the chemical looping methane reforming process (CLR HC ) were found to be 1.7, 1.0, 1.9, respectively. The molar ratio of the required additional CO 2 from the chemical looping combustion to oxygen carriers should be 0.29. The heat balance between the CLR HC and the CLC was achieved via temperature settings of the air preheating prior to the air reactor of the CLC above 306 °C. Under the optimal conditions, the H 2 purity, H 2 yield, CO purity, CO yield and CH 4 conversion were 98.55%, 2.26 mol/mol, 96.18%, 1.7 mol/mol and 99.24% respectively. The exergy efficiency of the system is about 70.60% and the CO 2 utilization efficiency up to 94.62%.