Experimental study on characteristics of hydrogen production from exhaust gas-fuel reforming in a catalytic fixed-bed reactor

Abstract Since the hydrogen-rich gas can be generated on-board by the catalytic reforming of exhaust gas from the engine, reformed exhaust gas-fuel recirculation is an attractive method for waste-heat recuperation and performance enhancement for the engines fueled by natural gas (NG). In the present study, the industrial Ni/Al2O3 catalyst was selected to investigate the effects of wall temperature, feed ratio and gas hourly space velocity (GHSV) on hydrogen production from exhaust gas-fuel reforming in a catalytic fixed-bed reactor. Meanwhile, Ni/Al2O3 fresh catalyst was characterized by the X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) techniques. The simulated exhaust gas was prepared based on the exhaust gas from a marine NG engine at 75% propeller load. The experimental results show that the higher wall temperature is favored for steam reforming to deliver higher H2 concentration in the reformate gas, which result in the increase of the H2 volume fraction at reformer outlet, H2 yield and CH4 conversion with the wall temperature. The maximum values of H2 yield and H2 volume fraction from the reformer outlet can reach up to approximately 0.96 and 22%, respectively. From the view of reforming process, that CH4/O2 = 2 and H2O/CH4 = 2 is considered as the optimum matching feed ratio. When a GHSV is approximately 7500 h−1, the H2 volume fraction at reformer outlet can be maximized. Under the given conditions, a more preferable reforming energy efficiency can be achieved when H2O/CH4 = 2, CH4/O2 = 3, GHSV = 6000 h−1 and high wall temperature.