Experimental Study and Modeling Analysis of Catalytic Partial Oxidation of Methane with Addition of CO2and H2O Using a Rh-Coated Foam Monolith Reactor

Abstract

The catalyst deactivation of rhodium-coated foam monolith with CO2 and/or H2O addition was investigated both experimentally and numerically to understand the means to improve the durability of the rhodium catalyst applied for catalytic partial oxidation of methane (CPOM). The results showed that the addition of He, CO2, and/or H2O could all improve the catalyst stability mainly due to the reduced hot-spot temperature in the oxidation zone for the reason of either the dilution effect or the simultaneously endothermic reaction of CO2/steam reforming. In particular, the catalyst stability can be greatly enhanced even at a low C/O ratio (i.e., carbon/oxygen ratio in atom of 0.85) with the addition of CO2 or H2O. Under the same conditions, high CH4 conversion (e.g., 0.8−0.85) can be achieved. The H2 yield can be adjusted by the added quantities of CO2 and/or H2O, which would allow the conventional pure CPOM process to be flexible to tune the composition of its product gas. These experimental results improved the understanding of how to modulate the CPOM process to achieve different reactor performances with the corresponding catalyst stability. Furthermore, CFD simulation with detailed chemistry was carried out. The model predictions had good agreement with the experimental results using the modified kinetics of the CO2 adsorption reaction, which was mostly not addressed when simulating a pure CPOM process in the literature for the little effect of CO2.