Exploring varied nickel loadings on highly active and mesoporous Ni/Al2O3 catalysts for acetone steam reforming

Abstract

This research explored the process of acetone steam reforming using Ni/Al₂O₃ catalysts. Different contents of nickel, ranging from 5 to 20% by weight, were applied to a commercial alumina support with a surface area of 158 m²/g. It was observed that increasing the nickel concentration from 5 to 20% resulted in a reduction of the catalyst's specific surface area from 146 to 127 m²/g, alongside an increase in the crystallite size from 4.9 to 6 nm. The amount of nickel was found to significantly influence the catalyst's performance, its durability, and the formation of carbon deposits on its surface. The catalyst containing 20% weight of nickel on alumina, achieving an 86% rate of acetone conversion and a 74% yield of hydrogen at a temperature of 550 °C, was identified as the most effective. Experiments to determine optimal processing conditions were conducted with this catalyst, varying the temperatures of reduction and calcination, gas hourly space velocity (GHSV), and the steam-to-acetone ratio. The calcination temperature was varied at 600, 700, and 800 °C, revealing that calcination at 600 °C provided the best acetone conversion rate of 100% at 550 °C, correlating with a decrease in specific surface area as calcination temperature increased. Reduction temperatures tested were 500, 600, and 700 °C for a duration of 2 h, where the sample reduced at 700 °C exhibited superior performance with an 86% conversion rate of acetone at 550°C. Evaluating the catalyst's efficacy at steam-to-carbon molar ratios of 4, 6, and 8 demonstrated the highest efficiency at a ratio of 8, achieving complete conversion at 550 °C. Moreover, catalyst activity was tested at GHSVs of 12,000, 18,000, and 24,000 (ml/h.g_cat), finding the highest conversion rate of 90% at the lowest GHSV of 12,000 at 550 °C.