Tailoring catalytic performance of carbon nanotubes confined CuO[sbnd]CeO2 catalysts for CO preferential oxidation

Abstract

Multi-wall carbon nanotubes confined CuOCeO2 binary oxide catalysts (CuxCe1-xO/CNTs, x = 0, 0.2, 0.4, 0.6 and 1.0) have been prepared by a special ultrasound-aided impregnation. The effects of CuCe molar ratios on the structure and catalytic performance for CO preferential oxidation have been systematically investigated. Judging from XRD patterns and Raman analysis, Cu2+ ions incorporate into CeO2 lattice to form ceria-base solid solution, accompanied by oxygen vacancies and an interaction produces between the catalyst particles and inner surface of carbon nanotubes. TEM microstructural analysis shows that CuO and CeO2 particles are uniformly dispersed in carbon nanotubes for the CuxCe1-xO/CNTs (x = 0.4) catalyst. Meanwhile, the reducibility of active copper species is enhanced markedly. In addition, the Cu0.4Ce0.6O/CNTs sample possesses more surface lattice oxygen and oxygen vacancies according to surface species characterization, which can provide more active oxygen species for CO oxidation and promote the mobility of lattice oxygen. The CuxCe1-xO/CNTs (x = 0.4) catalyst exhibits excellent activity, wide temperature span of full CO conversion (120–160 °C) and high selectivity especially above 110 °C (maintaining high selectivity until 140 °C).