Abstract
The wet incipient impregnation technique was used for the synthesis of nonpromoted and lanthanide series-promoted (La, Ce, Eu, Pr, and Gd) Ni/γ-Al2O3 catalysts. The physicochemical properties of the catalysts were determined using X-ray diffraction, Brunauer–Emmett–Teller (BET), transmission electron microscopy (TEM), scanning electron microscopy, energy dispersive X-ray, and temperature-programmed reduction (TPR) characterization techniques. Activity and the resistance to coke formation of nonpromoted and lanthanide series-promoted 12%Ni/γ-Al2O3 catalysts were investigated for diesel steam reforming in a fixed-bed reaction system. BET analysis showed no remarkable difference in the surface area of 12%Ni/γ-Al2O3 and 5%Pr–12%Ni/γ-Al2O3 (Pr–Ni) catalyst as compared to other promoted 12%Ni/γ-Al2O3 catalysts. Pr–Ni catalyst also has the higher BET surface area among other synthesized lanthanide-promoted 12%Ni/γ-Al2O3 catalysts. TEM analysis indicated uniform metal dispersion of promoted catalysts. Moreover, TPR analysis indicated an optimum interaction between the metal and the support in the Pr–Ni catalyst. Therefore, experimental results presented the maximum diesel conversion, H2 selectivity, H2 yield, and reforming efficiency over Pr–Ni catalyst as compared to all other studied catalysts during a 40 h run at 620 °C, 1 atm, steam to carbon ratio = 3.0, gas hourly space velocity of 5800 h–1, and 6 ppm sulfur contents in the fuel. Furthermore, thermogravimetric analysis and CHNS analysis also confirmed the low amount of coke formation over the surface of the 5%Pr–12%Ni/γ-Al2O3 catalyst.