Synthesis of Mesoporous Cu-Ni/Al2O4 Catalyst for Hydrogen Production via Hydrothermal Reconstruction Route

Abstract

Mesoporous Cu-Ni/Al2O4 catalyst of high surface area (176 m2g−1) is synthesized through a simple hydrothermal reconstruction process by using low-cost activated alumina as the aluminate source without organic templates. The desired mesoporous structure of the catalyst is formed by the addition of Cu2+ and Ni2+ metal ions in the gel solution of the activated alumina followed by hydrothermal treatment at 70 °C and calcination at temperatures in the range of 600 to 800 °C. To consider the environmental concern, we found the concentration of the Cu2+ and Ni2+ ion in the residual filtrate is less than 0.1 ppm which satisfies the effluent standard in Taiwan (<1.0 ppm). The effects of the pH value, hydrothermal treatment time, and calcination temperature on the structure, morphology and surface area of the synthesized Cu-Ni/Al2O4 composites are investigated as well. In addition, the Cu-Ni/Al2O4 catalyst synthesized at pH 9.0 with a hydrothermal treatment time of 24 h and a calcination temperature of 600 °C is used for hydrogen production via the partial oxidation of methanol. The conversion efficiency is found to be >99% at a reaction temperature of around 315 °C, while the H2 yield is 1.99 mol H2/mol MeOH. The catalyst retains its original structure and surface area following the reaction process, and is thus inferred to have a good stability. Overall, the hydrothermal reconstruction route described herein is facile and easily extendable to the preparation of other mesoporous metal-alumina materials for catalyst applications.

Catalytic Dehydrogenation of Methane to Hydrogen and Carbon Nanostructures with Fe–Mo Bimetallic Catalysts

“…This could be due to the facilitation of an easier diffusion of metal salts over the AC surface due to the elevated pressures in the autoclave, which would better overcome the mass transfer resistance. 45 The higher dispersion also supports the average crystallite size of Fe to be the least for the hydrothermal route of synthesis that was determined using eq 6, the values of which are 24.9, 31.1, and 36.8 nm for 30%Fe/ AC (H), 30%Fe/AC (W), and 30%Fe/AC (I), respectively (FWHM calculated from Gaussian fitting for the plane (110)) (Figure S6). On the other hand, a more uneven distribution of metal species was visible over the sample prepared via the wet impregnation route and the incipient wetness impregnation route.…”

“…It could be seen that a more uniform dispersion was achieved over the catalyst prepared via the hydrothermal route, the phase of which corresponded to the plane (110), as depicted by the XRD peak analysis in Figure (d). This could be due to the facilitation of an easier diffusion of metal salts over the AC surface due to the elevated pressures in the autoclave, which would better overcome the mass transfer resistance . The higher dispersion also supports the average crystallite size of Fe to be the least for the hydrothermal route of synthesis that was determined using eq , the values of which are 24.9, 31.1, and 36.8 nm for 30%Fe/AC (H), 30%Fe/AC (W), and 30%Fe/AC (I), respectively (FWHM calculated from Gaussian fitting for the plane (110)) (Figure S6).…”