エマルション燃焼合成した中空アルミナの粉末特性及び三元触媒活性

概要

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Lanthanum-doped hollow alumina particles (A-E) were made by the emulsion combustion method (ECM). Powder characteristics and three-way catalytic performance were evaluated and compared with those of precipitation-made alumina (A-P). The A-E powder was gamma alumina and 40m^2/g in specific surface area (SSA). The unique hollow structure resulted in a broad peak at 130nm in the pore size distribution and a large pore volume (3.0cm^3/g) with pore diameters of >20nm. The A-E powder primarily maintained its shape, crystalline phase and SSA up to 1200℃, indicating high thermal stability. Conversion of total hydrocarbon (THC) started at higher temperatures for the Rh-loaded A-E pellets (Rh/A-E) than for Rh-loaded A-P pellets (Rh/A-P) because of the low dispersion of Rh for Rh/A-E. However, a gradient of the THC conversion-temperature curve was higher for Rh/A-E than for Rh/A-P. The large pore volume can promote good gas accessibility inside the pellets for Rh/A-E, resulting in the high gradient of the THC conversion-temperature curve and thus the high activity at high temperatures where gas diffusion is likely to determine the conversion efficiency. The conversion-temperature curves of CO and NO_x showed primarily similar behavior to the THC ones.
社団法人日本セラミックス協会の論文
2005-07-01