In situ modification of CuO-Fe sub(2) O sub(3) by nonthermal plasma: Insights into the CO sub(2)-to-CH sub(3) OH Hydrogenation Reaction

Abstract

The hydrogenation of CO sub(2) to CH sub(3) OH on the binary mixed metal oxides of CuO-Fe sub(2) O sub(3) under nonthermal plasma discharge has been reported in this study. The catalysts are synthesized using the sol-gel route and characterized by XRD, FTIR, SEM, and XPS techniques. The impact of CuO mixing with Fe sub(2) O sub(3) on CO sub(2) conversion and CH sub(3) OH yield has been investigated. Herein, we have compared two distinct techniques, namely thermal and plasma catalytic processes. The overall outcome shows that the CO sub(2) conversion and CH sub(3) OH production increase with an increase in CuO mixing with Fe sub(2)O sub(3). The synthesized catalyst does not show significant CO sub(2) conversion and CH sub(3) OH formation in the thermal catalytic process (100?250 degrees C). Interestingly, when plasma discharge is combined with thermal heating, CO sub(2) conversion and CH sub(3) OH production significantly improve. The plasma discharges in the CO sub(2)/H sub(2) gas stream, at low temperatures (less than 200 degrees C), reduce Cu sup(+2) to Cu sup(+1) and Fe sup(+3) to Fe sup(+2), which could probably enhance the CO sub(2) conversion and CH sub(3) OH production. Among the catalysts prepared, 15 percent CuO-Fe sub(2) O sub(3) exhibited the best catalytic activity with 13.2 percent CO sub(2) conversion, 7.3 percent CH sub(3) OH yield, and a space-time yield of 13 mmolCH sub(3) OH/h g sub(cat), with 4.67 kJ/L of specific input energy (SIE). The CH sub(3) OH space-time yield is 2.9-fold higher than that of the commercial catalyst Cu/ZnO/Al sub(2) O sub(3), which is operated at 30 degrees C with 45.45 kJ/L SIE.