CO ₂ + CH ₄ chemistry over Pd: Results of kinetic simulations relevant to environmental issues

Abstract

We have determined the Arrhenius rate constants for 99 chemical reactions on palladium and solved the tightly coupled differential equations describing the chemical kinetics at a number of temperatures ranging from 350 to 700 K. The rate equations were integrated to a week of reactor run time. In this work, we discuss the valuable insights that can be gained by closely examining the chemistry ongoing on the first differential slice of the plug flow reactor. The two-component feed gas consisted of CO 2 and CH 4 with a total pressure of 1 bar. The CO 2-CH 4 partial pressures employed ranged from 20-80% to 80-20%. In these temperature and pressure ranges, the system performs in the low-coverage regime. In addition to the feed gas, formaldehyde, methanol, molecular hydrogen, C 2 hydrocarbons, formic acid, acetic acid, ketene, water, and carbon monoxide evolve from the catalyst surface in the first differential slice of the plug flow reactor. The relative amounts of the desorbing reaction products are dependent on the operating temperature and the relative pressures. The results of our simulations are consistent with results reported in the experimental literature. © 2009 American Chemical Society.