Steam reforming of isobutanol for the production of synthesis gas over Ni/γ-Al2O3 catalysts

Abstract

Bio-isobutanol has received widespread attention as a bio-fuel and a source of chemicals and synthesis gas as part of an integrated biorefinery approach. The production of synthesis gas by steam reforming (SR) of isobutanol was investigated in a down-flow stainless steel fixed-bed reactor (FBR) over Ni/γ-Al₂O₃ catalysts in the temperature range of 723–923 K. The NiO/γ-Al₂O₃ catalysts were prepared by the wet impregnation method and reduced in the FBR prior to the reaction. The surface area, metal dispersion, crystalline phase, and reducibility of the prepared catalysts were determined using BET, chemisorption, XRD and TPR, respectively. From the TPR studies, the maximum hydrogen consumption was observed in the temperature range of 748–823 K for all the catalysts. The presence of nickel species was confirmed through the characterization of the catalysts using powder XRD. The time-on-stream (TOS) studies showed that the catalysts remained fairly stable for more than 10 h of TOS. The conversion of carbon to gaseous products (CCGP) was increased by increasing the nickel loading on γ-Al₂O₃ and the temperature and by decreasing the weight hourly space velocity (WHSV). The hydrogen yield was increased by increasing the nickel loading on γ-Al₂O₃, the WHSV, the steam-to-carbon mole ratio (SCMR), and the temperature. The selectivity to methane decreased at high reaction temperatures and SCMRs. The selectivity to CO decreased with increasing SCMRs and decreasing temperatures. The work was further extended to the thermodynamic equilibrium analysis of the SR of isobutanol under experimental conditions using Aspen Plus, and the equilibrium results were then compared to the experimental results. A reasonably good agreement was observed between the trends in the equilibrium and the experimental results.