title: Coatings of active and heat-resistant cobalt-aluminium xerogel catalysts.
abstract: The application of catalytically coated metallic foams in catalytic processes has a high potential for exothermic catalytic reactions such as CO2 methanation or Fischer-Tropsch synthesis due to good heat conductivity, improved turbulent flow properties and high catalyst efficiencies. But the preparation of homogenous catalyst coats without pore blocking is challenging with conventional wash coating techniques. Here, we report on a stable and additive free colloidal CoAlOOH suspension (sol) for the preparation of catalytically active Co/Al2O3 xerogel catalysts and coatings. Powders with 18wt% Co3O4 prepared from this additive free synthesis route show a catalytic activity in Fischer-Tropsch synthesis and CO2 methanation which is similar to a catalyst prepared by incipient wetness impregnation (IWI) after activating the material under flowing hydrogen at 430°C. Yet, the xerogel catalyst exhibits a much higher thermal stability as compared to the IWI catalyst, as demonstrated in catalytic tests after different heat agings between 430°C and 580°C. It was also found that the addition of polyethylene glycol (PEG) to the sol influences the catalytic properties of the formed xerogels negatively. Only non-reducible cobalt spinels were formed from a CoAlOOH sol with 20wt% PEG. Metallic foams with pores sizes between 450 and 1200μm were coated with the additive free CoAlOOH sol, which resulted in homogenous xerogel layers. First catalytic tests of the coated metal foams (1200μm) showed good performance in CO2 methanation.
authors.affiliation: Institute of Applied and Physical Chemistry, University of Bremen, Germany; Center for Environmental Research and Sustainable Technology and MAPEX Center for Materials and Processes, University of Bremen, Germany. Electronic address: Miriam.b.schubert@gmail.com.
authors.forename: Miriam
authors.initials: M
authors.lastname: Schubert
authors.affiliation: Institute of Chemistry, Carl v. Ossietzky University of Oldenburg, Germany. Electronic address: Lennart.schubert@gmail.com.
authors.forename: Lennart
authors.initials: L
authors.lastname: Schubert
authors.affiliation: Institute of Chemistry, Carl v. Ossietzky University of Oldenburg, Germany. Electronic address: andreas.georg.thome@uni-oldenburg.de.
authors.forename: Andreas
authors.initials: A
authors.lastname: Thomé
authors.affiliation: Center for Environmental Research and Sustainable Technology and MAPEX Center for Materials and Processes, University of Bremen, Germany. Electronic address: kiewidt@uni-bremen.de.
authors.forename: Lars
authors.initials: L
authors.lastname: Kiewidt
authors.affiliation: Foundation Institute of Materials Science (IWT), University of Bremen, Germany. Electronic address: crosebrock@iwt.uni-bremen.de.
authors.forename: Christopher
authors.initials: C
authors.lastname: Rosebrock
authors.affiliation: Center for Environmental Research and Sustainable Technology and MAPEX Center for Materials and Processes, University of Bremen, Germany. Electronic address: thoeming@uni-bremen.de.
authors.forename: Jorg
authors.initials: J
authors.lastname: Thöming
authors.affiliation: Institute of Chemistry, Carl v. Ossietzky University of Oldenburg, Germany. Electronic address: frank.roessner@uni-oldenburg.de.
authors.forename: Frank
authors.initials: F
authors.lastname: Roessner
authors.affiliation: Institute of Applied and Physical Chemistry, University of Bremen, Germany; Center for Environmental Research and Sustainable Technology and MAPEX Center for Materials and Processes, University of Bremen, Germany. Electronic address: mbaeumer@uni-bremen.de.
authors.forename: Marcus
authors.initials: M
authors.lastname: Bäumer
keywords: CO(2) methanation; Coatings; Cobalt catalyst; Fischer-Tropsch; Xerogel