Modifying surface properties of KIT-6 zeolite with Ni and V for enhancing catalytic CO methanation

The surface of the KIT-6 zeolite was modified with different amounts of Ni and V to promote the catalytic properties for CO methanation. A series of xNi-yV/KIT-6 with various Ni and V contents were prepared by the incipient-wetness impregnation method. The modified surfaces were characterized using N2 adsorption-desorption, Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), hydrogen temperature-programmed reduction (H2-TPR), Fourier transformed infrared spectroscopy (FT-IR), Raman, X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), and energy-dispersive X-ray spectroscopy (EDX), respectively. The characterization results illustrated that the modification of V species was able to significantly promote low-temperature catalytic performance below 350 °C compared to that of unmodified Ni/KIT-6, which was likely due to an increase in the H2 uptake accompanied by enhanced CO dissociation derived from stronger electron transfer from V species to Ni0. Correspondingly, the xNi-yV/KIT-6 catalysts exhibited a distinct enhancement in CO conversion, CH4 selectivity and CH4 yield over unmodified Ni/KIT-6. Among all catalysts, 20Ni-2V/KIT-6 showed the best catalytic performance, corresponding to nearly 100% CO conversion and 85% CH4 yield at a low temperature of 300 °C. Furthermore, 20Ni-2V/KIT-6 presented enhanced coking-resistant and anti-sintering properties during a 60h-lifetime test at 500 °C and 1 atm with a high weight hourly space velocity (WHSV) of 60000 ml/g/h.