title: Steam reforming of methanol over oxide decorated nanoporous gold catalysts: a combined in situ FTIR and flow reactor study.
abstract: Methanol as a green and renewable resource can be used to generate hydrogen by reforming, i.e., its catalytic oxidation with water. In combination with a fuel cell this hydrogen can be converted into electrical energy, a favorable concept, in particular for mobile applications. Its realization requires the development of novel types of structured catalysts, applicable in small scale reactor designs. Here, three different types of such catalysts were investigated for the steam reforming of methanol (SRM). Oxides such as TiO2and CeO2and mixtures thereof (Ce1Ti2Ox) were deposited inside a bulk nanoporous gold (npAu) material using wet chemical impregnation procedures. Transmission electron and scanning electron microscopy reveal oxide nanoparticles (1-2 nm in size) abundantly covering the strongly curved surface of the nanoporous gold host (ligaments and pores on the order of 40 nm in size). These catalysts were investigated in a laboratory scaled flow reactor. First conversion of methanol was detected at 200 °C. The measured turn over frequency at 300 °C of the CeOx/npAu catalyst was 0.06 s-1. Parallel investigation by in situ infrared spectroscopy (DRIFTS) reveals that the activation of water and the formation of OHadsare the key to the activity/selectivity of the catalysts. While all catalysts generate sufficient OHadsto prevent complete dehydrogenation of methanol to CO, only the most active catalysts (e.g., CeOx/npAu) show direct reaction with formic acid and its decomposition to CO2and H2. The combination of flow reactor studies and in operando DRIFTS, thus, opens the door to further development of this type of catalyst.
authors.affiliation: Institute of Applied and Physical Chemistry and Center for Environmental Research and Sustainable Technology, University Bremen, Leobener Str. UFT, 28359 Bremen, Germany. awittstock@uni-bremen.de.
authors.forename: J
authors.initials: J
authors.lastname: Shi
authors.affiliation: Institute of Solid State Physics, University Bremen, Bremen, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Mahr
authors.affiliation: Solid State Chemical Crystallography, Institute of Inorganic Chemistry and Crystallography/FB02, University Bremen, Leobener Str. NW 2, 28359, Bremen, Germany.
authors.forename: M M
authors.initials: MM
authors.lastname: Murshed
authors.affiliation: Solid State Chemical Crystallography, Institute of Inorganic Chemistry and Crystallography/FB02, University Bremen, Leobener Str. NW 2, 28359, Bremen, Germany.
authors.forename: T M
authors.initials: TM
authors.lastname: Gesing
authors.affiliation: Institute of Solid State Physics, University Bremen, Bremen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Rosenauer
authors.affiliation: Institute of Applied and Physical Chemistry and Center for Environmental Research and Sustainable Technology, University Bremen, Leobener Str. UFT, 28359 Bremen, Germany. awittstock@uni-bremen.de.
authors.forename: M
authors.initials: M
authors.lastname: Bäumer
authors.affiliation: Institute of Applied and Physical Chemistry and Center for Environmental Research and Sustainable Technology, University Bremen, Leobener Str. UFT, 28359 Bremen, Germany. awittstock@uni-bremen.de.
authors.forename: A
authors.identifier: http://orcid.org/0000-0002-0139-3710
authors.initials: A
authors.lastname: Wittstock