Recent Progress in Nickel and Silica Containing Catalysts for CO₂ Hydrogenation to CH₄

The recent unusual weather changes occurring in different parts of the world are caused by global warming, a consequence of the release of extreme amounts of greenhouse gases into the atmosphere. Carbon dioxide (CO2) is one of these greenhouse gasses, which can be captured and reused to generate fuel through the methanation process. Nickel- and silica-based catalysts have been recognized as promising catalysts due to their efficiency, availability, and low prices. However, these catalysts suffer from metal sintering at high temperatures. Researchers have achieved remarkable improvements through altering conventional synthesis methods, supports, metal loading amounts, and promoters. The modified routes have enhanced stability and activity while the supports offer large surface areas, dispersion, and strong metal-support interactions. Nickel loading affects the formed structure and catalytic activity, whereas doping causes CO2 conversion at low temperatures and forms basic sites. This review aims to discuss the CO2 methanation process over Ni- and SiO2-based catalysts, in particular the silica-supported Ni metal in previously reported research works and point out directions for potential future work.