Highly Efficient Al-Doped Ni–Mn–O Catalysts for Auto-Thermal Reforming of Acetic Acid: Role of MnAl₂O₄ for Stability of Ni Species

Abstract

Auto-thermal reforming (ATR) of acetic acid (HAc) from renewable bio-oil is an alternative route for hydrogen production, and a series of Ni/Mn­(II)­Al­(III)­O x±δ catalysts were prepared via co-precipitation method and tested in the ATR of HAc. Different parameters including reaction temperatures, O/C molar ratios, gas-hourly space velocity (GHSV), and stability were investigated. The optimal Ni0.39Mn1.61AlO4.31±δ catalyst exhibited excellent catalytic performance in a 50 h ATR test: HAc was converted to H2-rich gas with conversion near 100% and hydrogen yield at 2.7 mol H2/mol HAc. Characterization results demonstrate that with strong interaction among nickel, manganese, and aluminum, a thermally stable spinel structure of MnAl2O4 over the MnO support was formed and restrained the growth of Ni particle; meanwhile, oxygen vacancies were found and were beneficial for oxygen transfer in the gasification of carbon. As a result, deactivation by carbon deposition and sintering was restrained. Moreover, high GHSV up to 120,000 mL/(gcat.·h) and fast response to startup were recorded, showing potential for hydrogen feeding via the ATR process.

Mullite-like SmMn2O5-Derived Composite Oxide-Supported Ni-Based Catalysts for Hydrogen Production by Auto-Thermal Reforming of Acetic Acid

“…It has been reported that manganese oxides exhibit multivalent properties, including Mn 2+ , Mn 3+ and Mn 4+ ionic states [ 19 , 20 ]. The redox reactions occurring between these multivalent states can generate surface oxygen species and lattice oxygen vacancies, which in turn enhances the mobility of oxygen species and facilitates gasification of carbon precursors (C*) [ 21 , 22 , 23 , 24 , 25 ]. For example, Deng et al reported that the incorporation of Ag through a hydrothermal method promoted the formation of oxygen defects within the MnO x matrix, while the abundant reactive oxygen species facilitated the combustion of volatile organic compounds (VOCs) and the elimination of O 3 [ 26 ].…”

Autothermal Reforming of Acetic Acid to Hydrogen and Syngas on Ni and Rh Catalysts

“…The research group of Huang, Wang, Xie and co-workers has been prolific in recent years in successfully investigating Ni, Co, Ni-Mn, Ni-Co based catalysts for ATR of HAc on various novel supports such as perovskites and double layered hydroxides at laboratory scale [10][11][12][13][14][15][16][17]. Steady conversion efficiencies (2.7-3 mol H 2 /mol HAc.)…”