One-step synthesis of PtCo/ZSM-5 catalysts for preferential CO oxidation in a hydrogen excess

A new one-step method for the synthesis of the PtCo/ZSM-5 catalysts for CO oxidation was proposed. Heteronuclear acetate complexes of the empirical composition PtCo_x(AcO)_y containing Pt^II and Pt^IV in ratios with Co of 1: 1 or 1: 2 were used as precursors. According to the data of scanning and transmission electron microscopy and XPS, the impregnation of the HZSM-5 zeolite (Si/Al = 28) with a solution of the complexes in glacial acetic acid followed by decomposition at 200 or 300 °C leads to the stabilization of highly dispersed partially reduced Pt^δ+ particles interacting with cobalt ions on the zeolite surface. Their joint action and a possibility of formation of new Pt—O_x—Co sites active in the preferential oxidation of CO ensure high efficiency and selectivity of the process in an H₂ excess. At the relatively low Pt content from 0.1 to 0.3 wt.%, the complete conversion of CO on these catalysts is achieved in the wide temperature range from 50 to 130 °C.