Applying Thermal-Swing Sorption-Enhanced Reaction Process on Water-Gas Shift Reaction to Separate Hydrogen and Carbon Dioxide

摘要

Global warming, caused by greenhouse gases, has become more and more serious. Cutting down the emission of CO_2 has already become one of the major research topic in the world. In this study we numerically investigate thermal-swing sorption-enhanced reaction (TSSER) process on water-gas shift (WGS) reaction with Na_2O-promoted alumina. According to Le Chatelier's principle, the forward reaction rate and conversion are increased by removing some products selected. Using Le Chatelier's principle, the concept of TSSER simultaneously carries out the WGS reaction and removes by-product CO_2 from the reaction zone by adsorbing it on Na_2O-promoted alumina in merely a single operation, thus (a) surpassing the thermodynamic conversion limit of the WGS reaction, (b) directly producing a fuel-cell grade H_2 product with very high conversion, and (c) capturing CO_2 at the same time. The method of lines is utilized in simulation, combined with upwind differences, cubic spline approximation and LSODE of ODEPACK software to solve the problem. The concentration, temperature, and adsorption quantity in the bed are integrated with respect to time by LSODE of ODEPACK software. The simulation is stopped when the system reaches a cyclic steady state. In this study, we simulate breakthrough curve of Na_2O-promoted alumina cited from literature to validate the accuracy of the simulation program. Varying operating variables of the WGS TSA (temperature swing adsorption) single-bed six-step process, such as feed time, rinse time, feed pressure and the adsorbent-to-catalyst ratio, obtains the optimal operating condition.