Effect of acid treatment on the catalytic performance of CuO/Cryptomelane catalyst for CO preferential oxidation in H2-rich streams

Abstract

The effect of acid treatment on the catalytic performance of CuO/Cryptomelane (CuO/CR) for CO preferential oxidation (CO-PROX) in H2-rich streams has been investigated. The CR supports are synthesized via the sol-gel approach. The hydrochloric acid or water is used to treat the CR support, and the corresponding CuO/CR catalysts are prepared by an initial wet impregnation method. Compared with the pristine CuO/CR and water-treated CuO/CRW catalysts, the acid-treated CuO/CRH exhibits the best catalytic activity with almost 100% of CO conversion at 110 °C, which can be maintained at least 100 h. The characterization results show that acid treatment decreases the K+ content in the CuO/CRH catalyst, which is conducive to the formation of more oxygen vacancies, thereby promoting the reducibility of CuO/CRH. This is the main reason for the high catalytic activity of the acid-treated CuO/CRH catalyst. Moreover, the abundant Brönsted acid sites on CuO/CRH are favorable for the desorption of acidic product CO2, which also could result in the significant promotion of the catalytic activity for CO-PROX. This study sheds a light on the importance of acid treatment for cryptomelane and provides an efficient catalyst for hydrogen purification.