CTAB-assisted radio frequency discharge plasma treatment enhances catalytic activity at sustained coking resistance of Nickel-based catalysts for CO2/CH4 reforming reaction

Abstract

Carbon deposition or ‘coking’ reaction severely suppresses catalyst activity during the dry reforming reaction of methane (DRM). The MCM-41-loaded nickel catalyst (NM-C) prepared using the conventional impregnation method also faces these issues. In response, this study investigates a novel catalyst preparation approach employing N₂ radio frequency (RF) discharge plasma coupled with surfactant (cetyltrimethylammonium bromide or CTAB) modification. Characterization of the resulting materials was conducted utilizing XRD, H₂-TPR, CO₂-TPD, TEM, XPS, TG-DTA, and other analytical techniques. Experimental findings reveal that both CTAB addition (NM-CTAB-C) and plasma-assisted catalyst preparation (NM-PN2h) outperform the conventional NM-C catalyst in the DRM. Notably, the catalyst prepared by the CTAB-assisted plasma method (NM-CTAB-PN2h) demonstrates significantly enhanced performance, with initial CH₄ and CO₂ conversions of 84.82% and 85.02%, respectively, at 700 °C. Compared to NM-C, NM-CTAB-PN2h exhibits improvements of 24.8% and 19.9% in CH₄ and CO₂ conversions, respectively. The Ni grain size of NM-CTAB-PN2h (4.9 nm) is notably smaller than NM-C (18 nm), indicating enhanced resistance to coking and stability during CO₂ and methane dry reforming. After 20 h of reaction, NM-CTAB-PN2h maintains a particle size of 6.3 nm, significantly smaller than NM-C (21.4 nm). Moreover, NM-CTAB-PN2h exhibits remarkable resistance to carbon accumulation, with only a 2.36% weight loss compared to 23.38% for NM-C after 20 h at 700 °C. Utilization of CTAB-assisted plasma reduces Ni grain size, enhances metal-support interaction, and increases oxygen vacancies, thus improving dry reforming performance.