Hydrogen Production through Steam Reforming of Diesel over Highly Efficient Promoted Ni/γ-Al₂O₃ Catalysts Containing Lanthanide Series (La, Ce, Eu, Pr, and Gd) Promoters

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.