Modification of Cu/SiO2 Catalysts by La2O3 to Quantitatively Tune Cu+‐Cu0 Dual Sites with Improved Catalytic Activities and Stabilities for Dimethyl Ether Steam Reforming.

Abstract: Dimethyl ether steam reforming (DME SR) is a promising route to provide H₂ for on‐board H₂‐based fuel cells. Herein, we synthesized the La₂O₃‐modified Cu/SiO₂ catalyst with dual copper species of Cu⁰ and Cu⁺ for DME SR, which exhibits both the high catalytic performance and long‐term stability. The strong electron donor‐acceptor interaction between the lanthanum and copper species occurs after reduction of the catalysts, which is an essential factor to quantitatively determine the ratio of Cu⁺/(Cu⁰+Cu⁺). The addition of La can improve the dispersion of both metallic Cu and Cu₂O on the catalysts, as well. After modulating the ratio of Cu⁺/(Cu⁰+Cu⁺) to ∼0.5 by varying the La loading, we achieved the highest activity and lowest CO selectivity. After the durability tests, the results of TEM, EXAFS, and XPS reveal that the addition of La on the Cu/SiO₂ catalysts not only stabilizes the copper species from aggregation, especially for the metallic Cu, but also avoids over‐reduction of the Cu⁺ species to Cu⁰. The constant ratio of Cu⁺/(Cu⁰+Cu⁺) on the La‐modified Cu/SiO₂ catalyst ensures the high catalytic stability in DME SR. [ABSTRACT FROM AUTHOR]