화학공학소재연구정보센터
Journal of Colloid and Interface Science, Vol.477, 64-73, 2016
Coatings of active and heat-resistant cobalt-aluminium xerogel catalysts
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 Co-AlOOH suspension (sol) for the preparation of catalytically active Co/Al2O3 xerogel catalysts and coatings. Powders with 18 wt% 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 degrees 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 degrees C and 580 degrees 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 Co A100H sol with 20 wt% PEG. Metallic foams with pores sizes between 450 and 1200 Lim were coated with the additive free Co-AlOOH sol, which resulted in homogenous xerogel layers. First catalytic tests of the coated metal foams (1200 mu m) showed good performance in CO2 methanation. (C) 2016 Elsevier Inc. All rights reserved.