Ting Bao,Zhongkui Zhao,Yitao Dai,Xiaoli Lin,Ronghua Jin,Guiru Wang,Turghun Muhammad
CO preferential oxidation (PROX) reactions were performed over the supported Co 3 O 4 -CeO 2 catalysts on modified activated carbon (AC) for eliminating the trace CO from H 2 -rich gases. The effects of support modification by H 2 O 2 oxidation treatment , catalyst calcination temperature, Ce/Co atomic ratio ( n Ce/Co ), Co 3 O 4 -CeO 2 loading and reaction parameters on catalytic properties of the Co 3 O 4 -CeO 2 /AC catalysts were investigated. Various characterization techniques like scanning electron microscopy (SEM), X-ray diffraction (XRD) and H 2 temperature-programmed reduction (H 2 -TPR) were employed to reveal the relationship between catalysts nature and catalytic performance. Results illustrate that the supported Co 3 O 4 -CeO 2 catalyst on modified AC exhibits excellent catalytic properties, which highly depends on dispersity and reducibility of Co 3 O 4 affected by the time of support treatment ( t p ), calcination temperature, n Ce/Co and loading. The supported 35 wt% Co 3 O 4 -CeO 2 catalyst (1:8 of n Ce/Co ) on the modified AC with H 2 O 2 oxidation treatment for 6 h demonstrates the best catalytic properties and the almost complete CO transformation takes place in a wide temperature range of 125–190 °C. Moreover, it is also found that the developed catalyst exhibits an outstanding catalytic stability, and 100% CO conversion can be maintained as the time on stream evolutes up to 1800 min even in the presence of CO 2 and H 2 O in the feed. The optimized Co 3 O 4 -CeO 2 /AC may be a robust and promising catalyst for eliminating trace CO from H 2 -rich gases.
Guangjun Zhai,Jinguo Wang,Zimei Chen,Shuaifeng Yang,Yong Men
Three-dimensionally ordered macroporous (3DOM) Co 3 O 4 -CeO 2 catalysts with controllable Co/Ce molar ratios synthesized by colloidal crystal template method were developed to catalyze the NO x -assisted soot oxidation for the first time, and the obtained 3DOM Co 3 O 4 -CeO 2 catalysts exhibited highly enhanced soot oxidation activity. Detailed characterizations of 3DOM Co 3 O 4 -CeO 2 catalysts revealed that the highly enhanced soot oxidation activity was originated from the synergistic promoting effect by combining the macroporous effect resulted from the unique 3DOM framework, the chemical nature associated with more Co 3+ reactive sites, the surface enrichment of Ce species and the improved redox properties. Meanwhile, the high NO x storage and oxidation capacity resulted from the integrated respective merits of Co 3 O 4 and CeO 2 also accounted for the enhanced soot oxidation activity via NO x -assisted mechanism. Furthermore, the 3DOM Co 3 O 4 -CeO 2 catalysts demonstrated strong stability because of the surface enrichment of Ce species improving the thermal stability and the robust 3DOM framework inhibiting the structural collapse, showing their potential applications under practical conditions.
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