Ienwhei Chen

Supported Cu Catalysts with Yttria-Doped Ceria for Steam Reforming of Methanol

The steam reforming of methanol was studied over Cu/Al2O3 catalysts with the addition of yttria-doped ceria (YDC). The YDC-modified catalysts were prepared by impregnating a γ-Al2O3 support with Y and Ce then with Cu. The addition of YDC drastically enhanced the activity of Cu/Al2O3 in the methanol reforming reaction. The enhanced activity was attributed to the increase of Cu+ species by YDC in the methanol reforming environment. However, the addition of YDC decreased the copper dispersion. The Cu dispersion could be enhanced by adding chromium oxide. The addition of YDC and Cr where Al2O3 was first impregnated with Cr then with YDC showed the most pronounced enhancement of the catalyst activity. At reaction temperatures of 200∼250 °C, the CO concentration in the products was smaller than 0.1%.

Resistance to Coking of Nickel-Alumina Catalysts

Summary Resistivity to coke formation was investigated over nickel-alumina catalysts promoted with alkali, alkaline-earth or transition metals, respectively. Catalytic cracking studies of nhexane were carried out in a fixed bed reactor at 733K and 1 atm. Catalysts were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), temperature-programmed desorption (TPD), temperature-programmed hydrogenation of carbon deposits (TPH) and chemical analysis for carbon deposit. The promoters K, Mo, and W were found to decrease coking rates of nickel catalysts. The catalyst prepared at pH=3 has the best resistivity to coke formation. The coking rate of promoted nickel-alumina catalysts can be correlated with the peak temperature of both TPD and TPH spectra and with the initial pH values in preparation.