Co/CeO2-ZrO2 catalysts prepared by impregnation and coprecipitation for ethanol steam reforming

Co/CeO2-ZrO2 catalysts for the ethanol steam reforming were prepared by wet incipient impregnation and coprecipitation methods. These catalysts were characterized by nitrogen adsorption, TEM-EDX, XRD, H2-TPR, and CO chemisorption techniques. It was found that the catalyst reducibility was influenced by the preparation methods; catalysts with different reduction behaviors in the pre-reduction showed different catalytic activities toward hydrogen production. The H2-TPR studies suggested the presence of metal–support interactions in Co/CeO2-ZrO2 catalysts during their hydrogen pre-reduction, a necessary treatment process for catalysts activation. These interactions were influenced by the preparation methods, and the impregnation method is a favorable method to induce a proper metal–support effect that allows only partial reduction of the cobalt species and leads to a superior catalytic activity for the hydrogen production through ethanol steam reforming. At 450 °C, the impregnated catalyst gives a hydrogen production rate of 147.3 mmol/g-s at a WHSV of 6.3 h−1 (ethanol) and a steam-to-carbon ratio of 6.5.

Hydrogen production rate as a function of ethanol feeding rate for impregnated and coprecipitated 10% Co/CeO2-ZrO2 catalysts are tested. Steam-to-carbon ratio of 6.5 is used at the reaction temperature of 450 °C. The impregnated catalyst is denoted as IM-10% Co/CeO2-ZrO2. The catalysts coprecipitated at pH = 11.5, pH = 12.2, and pH = 13.1 are denoted as CP11-10% Co/CeO2-ZrO2, CP12-10% Co/CeO2-ZrO2 and CP13-10% Co/CeO2-ZrO2, respectively. A significant difference in the hydrogen production rate is actualized in various samples with increase of the ethanol feeding rate. IM-10% Co/CeO2-ZrO2 catalyst produces the highest amount of hydrogen at a high feeding rate of ethanol (0.0137 mol/h).Figure optionsDownload as PowerPoint slide