Effect on the carbon deposit in CO2 reforming of CH4 over Ni/Ce-Zr-Al-Ox catalyst by adding steam

A Ni/Ce-Zr-Al-O-x catalyst was prepared by hydrothermal synthesis-impregnation method. The CO2 reforming of CH4 reaction was performed. By XPS and TPH methods the carbon species deposited on the surface of catalyst during the reaction were characterized; The effect on the carbon deposit by adding a small amount of steam in feed gas and the interaction between steam and carbon species were studied. The results obtained show that there are mainly two types of carbon species alpha-carbon appearing at 250 similar to 350 degreesC should be mainly CH4 decomposed fragment which shows reactive to hydrogenation; beta-carbon appearing at about 700 degreesC should be the unreactive carbon which tends to be graphite or is graphitized carbon and is responsible for catalyst deactivation. beta-carbon is easier to react with steam than a-carbon, therefore adding a small amount of steam in feed gas can obviously suppress beta-carbon deposit. The activity test shows that the Ni/Ce-Zr-Al-O-x catalyst has a CH4 conversion of 89% and a good stability, and the CH4 conversion increases to 94% by adding 3.2% (phi) steam. In addition, due to the suppression to unreactive carbon, it can be expected that the stability of catalyst will be further promoted.