Addition of Sodium Additives for Improved Performance of Water-Gas Shift Reaction over Ni-Based Catalysts

The effect of Na loading on water-gas shift reaction (WGSR) activity of Ni@TiOx-XNa (X = 0, 0.5, 1, 2, and 5 wt %) catalysts has been investigated. Herein, we report sodium-modified Ni@TiOx catalysts (denoted as Ni@TiOx-XNa) derived from Ni3Ti1-layered double hydroxide (Ni3Ti1-LDH) precursor. The optimized Ni@TiOx-1Na catalyst exhibits enhanced catalytic performance toward WGSR at relatively low temperature and reaches an equilibrium CO conversion at 300 degrees C, which is much superior to those for most of the reported Ni-based catalysts. The H-2-temperature-programmed reduction (H-2-TPR) result demonstrates that the Ni@TiOx-1Na catalyst has a stronger metal-support interaction (MSI) than the sodium-free Ni@TiOx catalyst. The presence of stronger MSI significantly facilitates the electron transfer from TiOx support to the interfacial Ni atoms to modulate the electronic structure of Ni atoms (a sharp increase in Ni delta- species), inducing the generation of more surface sites O-v-Ti3+) accompanied by more interfacial sites Ni delta--O-v-Ti3+), revealed by X-ray photoelectron spectroscopy (XPS). The Ni delta--O-v-Ti3+ interfacial sites serve as dual-active sites for WGSR The increase in the dual-active sites accounts for improvement in the catalytic performance of WGSR. With the tunable Ni-TiOx interaction, a feasible strategy in creating active sites by adding low-cost sodium addictive has been developed.

Automated summary

The Na-loaded Ni@TiOx-1Na catalyst shows enhanced WGSR activity at lower temperature, with a stronger metal-support interaction and increased interfacial sites serving as dual-active sites for the reaction, leading to improved catalytic performance.