Investigation on deactivation of Cu-Cr catalyst for direct ethanol dehydrogenation to ethyl acetate, acetaldehyde, and hydrogen

Abstract

Background: The utilization of bioethanol by converting it into additional high-value-added products including acetaldehyde, ethyl acetate, and hydrogen impresses as an appealing strategy at the present. The Cu-Cr catalysts improved product formation on ethanol dehydrogenation. This research was to assess the stability of the reaction and the deactivation of the catalyst over protracted ethanol dehydrogenation. Methods: The deactivation behaviors of 50 Cu-Cr catalyst on ethanol dehydrogenation reaction was investigated. The co-precipitation technique was used to synthesize the Cu-Cr catalyst, which was then reduced by a mixture of H2/N2 prior to the stability test in the ethanol dehydrogenation reaction. The fresh, reduced, and/or spent catalysts after being used in ethanol dehydrogenation were characterized using XRD, SEM-EDX, HR-TEM, H2-TPR, NH3-TPD, XPS, TGA, and TPO. Significant finding: The proportion of CuCr2O4, Cu+, and Cu0 active sites on the catalyst sample influenced catalytic activity. Based on the results, the activity was related to the oxidation state of copper-chromium in the Cu-Cr catalyst. Fascinatingly, the results of the ethanol dehydrogenation showed that the catalyst deactivation was caused by the change in the copper-chromium oxidation state via the hydrogen self-reduction process and the soft coke formation on active sites after prolonged ethanol dehydrogenation resulting in a decrease in catalytic activity.