Modification of Ni/MCF catalyst and its catalytic performance for dry reforming of methane

Dry Reforming of Methane (DRM) to efficiently produce synthesis gas (H₂/CO), an important chemical raw material. Ni-based catalyst has been widely studied due to its abundant reserves, low price and certain catalytic performance, and is a common DRM reaction catalyst with industrialization prospects. However, under the reaction conditions of high temperature (>700 ℃) and carbon-containing sources (CH₄ and CO₂), Ni-based catalysts tend to be deactivated due to sintering and carbon deposition. At present, the sintering and carbon deposition problems of Ni-based catalysts have not been solved. In this work, aiming at the sintering and carbon deposition of Ni-based catalyst in the dry reforming of methane reaction, firstly, mesoporous foam-based silicon MCF support with high specific surface area and abundant pores was synthesized and supported with nickel catalyst. The MCF support was modified by temperature program nitridation with alkaline additives to synthesize N-MCF support and supported with nickel catalyst. Ni dispersion is good on N-MCF and MCF. Ni-based catalysts with strong metal-support interaction were constructed on nitrogenous modified mesoporous silicon foams (MCF) with MOFs as precursor using 2-methylimidazole and Ni²⁺ to form MOFs. XRD, TEM, SEM, BET, H₂-TPR, XPS, TG and other characterization results show that The N doping modification of MCF support by high temperature program nitriding method can improve the dispersion of active metal, reduce the particle size, enhance the metal- support interaction force, reduce the catalyst reduction degree, enhance the metal- support electron interaction force, and increase the content of high price state Ni^δ+ on the catalyst surface. The catalyst precursor was modified into a three-dimensional metal-organic framework structure by complexing 2-methylimidazole with Ni²⁺. After calcination by high temperature air, an embedded massive nickel silicate species was formed on the catalyst surface. The active metals in nickel silicate species mainly exist in the form of high price Ni^δ+ and are highly dispersed on the catalyst surface, showing strong metal- support interaction force, which makes the active metals of the catalyst have good dispersion and small particle size. When the stability test is conducted at 700 ℃, the Ni/MCF-MI catalyst shows excellent DRM catalytic performance. The conversion rates of CH₄ and CO₂ were 72% and 73% respectively, and the reaction performance was stable for 10 h. The Ni/N-MCF-MI catalyst with N doping modified MCF support and 2-methylimidazole modified catalyst precursor showed the best DRM catalytic performance. Under the stability test at 700 ℃, the conversion rates of CH₄ and CO₂ were 78% and 83%, respectively, and the reaction performance was stable for 10 h. After the reaction, the weight loss of Ni/N-MCF-MI catalyst is 16%, the weight loss rate is the lowest, and there is no obvious sintering, agglomeration and growth of active metal nanoparticles. N doping modified MCF support and 2-methylimidazole modified catalyst precursor can both improve the dispersion of active metal, reduce particle size, and enhance the metal- support interaction force. The catalyst modified with both N additive and 2-methylimidazole has the best DRM catalytic performance and certain advantages of inhibiting the growth of carbon nanotubes and the agglomeration and sintering of Ni particles.