Combined steam and dry reforming of methanol over Ni-M/Ce–Al2O3 (M=Fe, Cu, and Zn) catalysts to syngas formation

Abstract

In the present work, the influences of different transition metals (Fe, Cu, and Zn) addition to Ni/Ce–Al2O3 catalyst on combined steam and dry reforming of methanol (CSDRM) reaction were evaluated in the temperature range of 500 ºC-900 °C, to achieve the higher conversion and H2 yield following by minimum coke formation on the catalyst surface. The fresh and spent catalysts were characterized via X-ray diffraction (XRD), thermal gravimetric analysis (TGA), inductively coupled plasma atomic emission spectrometer (ICP-AES), temperature programmed oxidation (TPO), N2 adsorption/desorption and temperature programmed reduction (TPR). Their results presented that the addition of these transition metals had a little effect on the crystallinity, surface area, pore volume and mean pore size. However, thermal stability, coke deposition coke amount, reducibility and catalytic activity were improved. The methanol conversion was approximately fixed up to 50 h initial on stream with no obvious deactivation for Ni/Ce–Al2O3 catalyst, while this time was 55 h for the modified catalyst with transition metals (Cu, Fe, and Zn). The maximum methanol and CO2 conversions and anti-coke deposition ability were obtained from Ni–Zn/Ce–Al2O3 which was remarkably related to synergism between Ni and Zn, also the larger reducibility. However, the maximum value of H2 yield was 85.2% at 900 °C over Ni–Cu/Ce–Al2O3 catalyst. Ni–Zn/Ce–Al2O3 catalyst in the CSDRM reaction produced syngas with an H2/CO ratio of 2.06, suggesting to a suitable feed for Fischer-Tropsch synthesis.