Improvement of selectivity of plate type catalyst for methanol decomposition at low temperature using anodic oxidation of aluminum

An energy network system, in which low level waste heat from industry region is recovered by endothermic methanol decomposition into H-2/CO, is proposed. In this investigation, a prate type catalyst for methanol decomposition applicable to such systems is developed. Plate catalysts were prepared under various conditions by impregnating Pd into porous layer of anodized aluminum plate and activity and selectivity of each catalyst were examined by a labo-scale reactor. Those catalysts prepared by directly impregnating Pd using aqueous solution formed a large amount of dimethyl ether as by-product. Such inferior selectivity is supposed to originate in the acid sites of Al2O3, and therefore silica coating, addition of alkali metals on anodized layer, and/or impregnation of Pd by acetone solution are tested to decrease the formation of by-products by reducing the acidity of the support layer. Test results show that the catalysts prepared by these procedures have higher selectivity and Pd impregnation by acetone solution, with Na addition into the support layer combined, is most effective to improve the selectivity. Further, it is found that the activity of the catalyst is dependent on the Pd surface area, and turn over frequency (TOF) is scarcely affected by Pd particle size.