Mechanistic studies of chemical looping desulfurization of Mn-based oxides using in situ X-ray absorption spectroscopy
Journal article, 2014

Cleaning of producer gas from biomass gasification is required for further processing, e.g. to avoid catalyst poisoning in subsequent conversion steps. High-temperature gas cleaning, of which sulfur removal is an important part, is a promising way to improve the overall efficiency of biomass conversion. In a high temperature "chemical looping desulfurization" process, a sorbent material, here manganese oxide, is cycled between producer gas from the gasifier to remove sulfur species, and an oxidizing atmosphere, in which the sulfur species are released as SO2. Alternatively, the use of such material as reactive bed material could be integrated into an allothermal dual fluidized bed gasifier. In a laboratory reactor, we subjected manganese-based materials to a periodically changing gas atmosphere, simulating a "chemical looping desulfurization" reactor. The "fuel reactor" gas contained H2, CO, CH4 and H2S, similar as in the producer gas, and the "oxidizing reactor" contained diluted O2. Mass spectrometry showed that most of the H2S is taken up by the sample in the "fuel reactor" part, while also some unwanted SO2 is generated in the "fuel reactor" part. Most of the sulfur is released in the oxidizing reactor. Simultaneous in situ X-ray absorption spectroscopy (XAS) of the Mn materials during different stages of the chemical looping desulfurization process showed that the initial Mn3O4 is transformed in the presence of H2S to MnS via a MnO intermediate in the fuel reactor. Oxygen from the reduction of Mn3O4 oxidizes some H2S to the undesired SO2 in the fuel reactor. Upon exposure to O2, MnS is again oxidized to Mn3O4 via MnO, releasing SO2. The presence of CO and/or CH4 in the fuel reactor has no effect on this mechanism. Measuring the structure-performance relationship of gas cleaning materials with in situ methods will enable knowledge-based materials development for improved performance. © 2013 Elsevier Ltd. All rights reserved.

Gas cleaning




Chemical looping


C.F.J. König

Paul Scherrer Institut

M. Nachtegaal

Paul Scherrer Institut

Martin Seemann

Chalmers, Energy and Environment, Energy Technology

F. Clemens

Swiss Federal Laboratories for Materials Science and Technology (Empa)

N. van Garderen

Swiss Federal Laboratories for Materials Science and Technology (Empa)

S.M.A. Biollaz

Paul Scherrer Institut

T.J. Schildhauer

Paul Scherrer Institut

Applied Energy

0306-2619 (ISSN) 18729118 (eISSN)

Vol. 113 1895-1901

Subject Categories

Materials Engineering

Energy Engineering

Analytical Chemistry

Chemical Process Engineering

Areas of Advance




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