(684g) Catalytic Hot-Gas Cleaning of Biomass Derived Syngas by CaMgO Nanocrystals

Rownagi, A., Missouri University of Science and Technology
Kumar, A., Oklahoma State University
Huhnke, R., Oklahoma State University


Gasification of biomass is a promising source of renewable fuels and chemicals [1]. However, the removal of contaminants such as tars and other impurities from the syngas is required [2].   Tars can present a number of process challenges, including coking of catalysts and condensation on downstream piping, filters, and other equipment [3],and the cost of tar removal can be as much as the overall process cost to produce ethanol [4]. Moreover, too much tar in product gases will reduce the biomass utilization efficiency. Therefore, the reduction or decomposition of tar in biomass-derived synthesis gas is one of the biggest obstacles in its utilization for fuels, chemicals and power generation.  The gas clean-up technology that offers many advantages is catalytic hot gas conditioning downstream of the gasifier [5,6]. Dolomite with general chemical formula CaMg(CO3)2, is generally used as a highly efficient catalyst for removing tar from the product gases of gasifier. Because dolomite possesses a relatively low surface area, catalytic activity is greatly limited [6,7]. From this point of view, the performance of dolomite can be enhanced by using nanostructure catalyst particles. CaMgO nanocrystals have been prepared with varius CaO/MgO ratios by the coprecipitation, hydrothermal and solvothermal methods [8,9]. In order to investigate the effect of physico-chemical properties on the catalytic activity, catalysts were characterized using various techniques. Compared to dolomite, the CaMgO nanocrystals exhibited significantly higher surface area. The cracking reactions of toluene, a model tar compound, were carried out in fixed bed reactor under atmospheric pressure to evaluate the catalytic resistance to coke poisoning. In addition, the effects of catalysts particle size, reaction temperature, catalyst amount on the reaction rate have been investigated to evaluate the catalytic activity of all catalysts.


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