Hydrogen production from aqueous phase reforming of glycerol over attapulgite-supported nickel catalysts: Effect of acid/base treatment and Fe additive

In this paper, a series of nickel-based catalysts supported on modified attapulgite (ATP) by acid (citric acid and EDTA) and base (NaOH) were prepared and applied to the aqueous phase reforming of glycerol (APRG). The modified ATP (MA) and as-prepared catalysts were detected using N-2 adsorption-desorption, ICP-OES, XRD, FT-IR, SEM-EDS, HRTEM, XPS, H-2-TPR, NH3-TPD. The results manifested that the acid/base treatment of ATP significantly increased the surface area and pore volume, enhanced the metal-support interaction (MSI) and decreased the Ni particle size, resulting in the better glycerol conversion and H-2 selectivity, especially for Ni/MA-E catalyst, where the ATP was pretreated using EDTA. In addition, the bimetallic NiFe/MA-E catalyst exhibited the highest conversion of glycerol to gas product (54.4%) and H-2 selectivity (84.6%) at very low temperature (280 degrees C). These results were attributed to the strongest the interplay of active metal with support by the formation of Ni-Fe alloy, resulting in the highest active metal dispersion, smallest metal particle size, lowest the reducibility of active metal and most surface Ni-0 content. According to the characterizations of spent catalysts, it demonstrated that monometallic Ni catalysts presented obvious sintering of Ni metal particle and larger accumulation of carbon deposition, which led to the deactivation of the catalyst. While NiFe/MA-E catalyst showed less particle agglomeration and coke formation attributed to the lower content of surface acid site. Apart from that, another cause of catalyst deactivation might be the destruction of ATP skeleton during APRG. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

In this study, nickel-based catalysts supported on modified attapulgite (ATP) were prepared and applied to the aqueous phase reforming of glycerol (APRG). The results showed that the acid/base treatment of ATP significantly improved the catalytic performance, resulting in higher glycerol conversion and hydrogen selectivity. The bimetallic NiFe/MA-E catalyst exhibited the best performance at low temperature. Catalyst deactivation was mainly caused by particle agglomeration and carbon deposition.