Direct methane to methanol stepwise conversion over Cu-oxo species in zeolites - Insights on the Cu-zeolite activation in air or helium from in situ UV-Vis analyses

Among the plentiful scientific research focused to find new routes to substitute stronger unsustainable chemical processes, the direct conversion (DC) of methane to methanol (MTM) over exchanged Cu-oxo cations in zeolites has gained great attention. Within that process, the paper proposed that the first activation step of the Cu-zeolite to catalyze the cycling DC-MTM be done with air instead industrial oxidant gases. Thus, Cu-oxo exchanged ferrierites, as model Cu-zeolites, were prepared and evaluated in the DC-MTM at 210 oC. XRD, SEM/EDS, H2-TPR, FTIR of in situ adsorbed CO and pyridine were used to characterize the activated Cu-ferrierites. In situ DRS-UV-Vis evidenced the generation of Cu-oxo species after activation in air or He and their subsequent consumption during methane reaction. The air and He-activated Cu-ferrierites showed a close catalytic behavior that was supported by their similar profile to the formed Cu-oxo clusters. Thus, being more environmentally friendly to select air as an activation agent, instead of the use of pure O-2, inert gases, or even N2O.

Automated summary

This paper focuses on the direct conversion of methane to methanol and proposes the use of air as an activation agent instead of industrial oxidant gases. Experimental results show that air-activated Cu-ferrierites and He-activated Cu-ferrierites exhibit similar catalytic behavior.