Synthesis of Pt/K2CO3/MgAlOx–reduced graphene oxide hybrids as promising NOx storage–reduction catalysts with superior catalytic performance

摘要

Pt/K2CO3/MgAlOx–reduced graphene oxide (Pt/K/MgAlOx–rGO) hybrids were synthesized, characterized and tested as a promising NOx storage and reduction (NSR) catalyst. Mg–Al layered double hydroxides (LDHs) were grown on rGO via in situ hydrothermal crystallization. The structure and morphology of samples were thoroughly characterized using various techniques. Isothermal NOx adsorption tests indicated that MgAlOx–rGO hybrid exhibited better NOx trapping performance than MgAlOx, from 0.44 to 0.61 mmol · g⁻¹, which can be attributed to the enhanced particle dispersion and stabilization. In addition, a series of MgAlOx–rGO loaded with 2 wt% Pt and different loadings (5, 10, 15, and 20 wt%) of K2CO3 (denoted as Pt/K/MgAlOx–rGO) were obtained by sequential impregnation. The influence of 5% H2O on the NOx storage capacity of MgAlOx–rGO loaded with 2 wt% Pt and 10% K₂CO₃ (2Pt/10 K/MgAlO_x–rGO) catalyst was also evaluated. In all, the 2Pt/10 K/MgAlO_x–rGO catalyst not only exhibited high thermal stability and NO_x storage capacity of 1.12 mmol · g⁻¹, but also possessed excellent H₂O resistance and lean–rich cycling performance, with an overall 78.4% of NO_x removal. This work provided a new scheme for the preparation of highly dispersed MgAlO_x–rGO hybrid based NSR catalysts.