Low CO generation on tunable oxygen vacancies of non-precious metallic Cu/ZnO catalysts for partial oxidation of methanol reaction

• A CO-free hydrogen-rich gas could be achieved on non-precious metallic CuZn-based catalysts with fine-tuning oxygen vacancies.
• The concentration of oxygen vacancies can be tuned by adjusting atmosphere and temperature.
• Oxygen atoms from POM gases (methanol and oxygen) would easily adsorb onto catalysts via oxygen vacancies.
• Oxygen vacancies could enhance the formation of formate during POM reaction.

A simple and inexpensive method is proposed to modulate oxygen vacancies on the non-precious metallic CuZn-based catalyst surface. The identification and quantification of these oxygen vacancies on vZ (ZnO containing oxygen vacancies) and the catalytic activities of CvZ (Cu on ZnO containing oxygen vacancies, ca. 30 wt.% Cu and 70 wt.% Zn) during partial oxidation of methanol (POM) reaction are discussed. The vZ was calcined in a nitrogen atmosphere at various temperatures (450 °C, 500 °C and 550 °C), and catalytic activities of CvZ catalysts prepared in deposition precipitation (DP) and co-precipitation (CP) and CZr (Cu on ZrO2, ca. 30 wt.% Cu and 70 wt.% Zr) catalysts were performed. The efficiency of both CP-CvZ-450 and DP-CvZ-450 catalysts are excellent with 100% of CMeOH and 95% of FH2FH2 at 250 °C, and 70% of CMeOH and >75% FH2FH2 at 150 °C. Significantly, FCO was kept at 0–4% at T < 250 °C with better stability for DP-CvZ-450 catalyst, as well. Moreover, a CO-free situation could be achieved for both DP-CvZ-500 and DP-CvZ-550 which contain more oxygen vacancies. These oxygen vacancies on the surface: enhanced an affinity for adsorbing reactant oxygen atoms; induced decomposition of intermediates species, and; can even catalyze CO oxidation at a lower temperature.

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