Carbon dioxide hydrogenation combined with an oxidative methane carbonylation over CeO2-HZSM-5 catalyst for acetic acid production

Abstract

Utilization of CO2 into high value-added products, in particular acetic acid, is a promising and in turn challenging strategy. This issue could be resolved using bifunctional CeO2-HZSM-5 catalyst, which simultaneously promotes the CO2 hydrogenation and oxidative methane carbonylation in a one-pot synthesis. Bulk CeO2, HZSM-5 zeolite, and their mechanical mixture were compared in the tandem transformations of CO2, CH4, and CO into acetic acid. The catalysts were analyzed using N2 adsorption-desorption, NH3-TPD, CO2-TPD, XRD, XRF, and Raman spectroscopy. It was shown that CeO2-HZSM-5 yields 0.74 μmol·g−1·h−1 of acetic acid, whereas CeO2 and HZSM-5 give 0.46 and 0.37 μmol·g−1·h−1, respectively. At the same time, the selectivity to acetic acid on CeO2-HZSM-5 is 54.0, as opposed to 26.4 % and 8.6 % on CeO2 and HZSM-5, respectively. Thus, according to the catalytic studies along with the temperature-programmed desorption of NH3 and CO2, metal oxide and zeolite components of CeO2-HZSM-5 physical mixture were established to exhibit the improved performance in the acetic acid production caused by the combined effect of CeO2 base sites and HZSM-5 acid sites. In addition, CeO2-HZSM-5 demonstrates an excellent catalyst stability during 100 h reaction exposure at 500 °C without pronounced reduction of activity and selectivity.