Catalytic reforming of glycerol in supercritical water with nickel-based catalysts

The catalytic performance of nickel catalysts supported on La2O3, α-Al2O3, γ-Al2O3, ZrO2, and YSZ for supercritical water reforming of glycerol was investigated. Experiments were conducted in a tubular reactor made of Inconel-625 with the temperature range of 723–848 K under a pressure of 25 MPa. Carbon formation causing operation failure was observed for α-Al2O3, γ-Al2O3 and ZrO2 at temperatures higher than 748, 798 and 823 K, respectively. Ni/La2O3 exhibited the highest H2 yield where almost complete conversion was obtained at 798 K. Moderate space velocities (WHSV = 6.45 h−1) and glycerol feed concentration (5wt.%) favor high hydrogen selectivity and yield. Methanation is favored at a low WHSV or high glycerol feed concentration, resulting in a lower H2 yield. Increasing Ni loading on the Ni/La2O3 catalyst strongly promoted the reforming, water–gas shift, and methanation reactions, which contributed significantly to the product species distribution.