Characteristics of activated carbon modified with alkaline KMnO4 and its performance in catalytic reforming of greenhouse gases CO2/CH4

Abstract

Different potassium permanganate oxidation processes were used to modify activated carbon, and then surface structure and chemical properties of modified activated carbon with different preparation methods as well as their influences on carbon dioxide reforming of methane were studied. BET and SEM surface structure analysis indicated that after modification with potassium permanganate under alkaline condition, specific surface area of activated carbon increased, microspore and mesoporous capacities enlarged, but the pore diameter of activated carbon slightly reduced. XPS and FT-IR characterization indicated that after modification with potassium permanganate under alkaline condition, acid oxygen-containing functional groups dropped and new alkaline active substances like ionic OH− and manganite were generated on the activated carbon surface. Increased specific surface area and pore capacity of activated carbon, reduced acid oxygen-containing groups and generated alkaline active substances like ionic OH− and manganite exerted significant influences on methane activation and carbon dioxide reforming of methane. Under alkaline condition, the activity of the potassium permanganate modified activated carbon and reforming conversion slightly increased because of interaction between alkaline functional groups and acid carbon dioxide; In the meantime, newly generated ionic OH− on the surface and manganite participated in reforming reaction, which also improved activity of potassium permanganate-modified activated carbon for carbon dioxide reforming of methane. Under acid condition, CO2-CH4 reforming conversion and catalyst activity decreased because of interaction between acidic functional groups and acid carbon dioxide.