The role of suprafacial oxygen in some perovskites for the catalytic combustion of soot
The role of suprafacial oxygen in some perovskites for the catalytic combustion of soot
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DOI：
10.1016/s0021-9517(03)00143-x
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发表时间：
2003-07-25
影响因子：
7.3
通讯作者：
Speechia, V
中科院分区：
文献类型：
--
作者：
Fino, D;Russo, N;Speechia, V
采用燃烧合成法合成了高比表面积块状钙钛矿（18-25 m2/g）催化剂，用于柴油机排放的主要污染物碳烟的燃烧。碳烟燃烧的活性顺序为LaCrO_3> LaFeO_3> LaMnO_3，这正好与钙钛矿的另一个主要应用领域甲烷燃烧的本征活性相反。基于XRD、SEM、TEM、TPD和TPR分析以及反应运行的表征，铬铁矿催化剂的普遍活性可以通过其较高浓度的表面、弱化学吸附氧来解释，该表面、弱化学吸附氧在300-500 ℃的温度范围内通过溢出积极地促进烟灰燃烧，但对甲烷燃烧可忽略不计。制备的最佳催化剂（La0.9K0.1Cr0.9O3-δ）可以在远低于400 ℃的温度下点燃碳烟燃烧，这在柴油发动机排气管所达到的温度范围内。最大限度地提高表面氧的浓度被指出是开发新的、更活性的催化剂的主要途径。(C)2003 Elsevier Science（美国）。All rights reserved.
High specific-surface-area bulk perovskites (18-25 m(2)/g) have been synthesized by the combustion synthesis method as catalysts for the combustion of soot, a major pollutant emitted by diesel engines. The activity order for soot combustion was found to be LaCrO3 > LaFeO3 > LaMnO3, which is just the reverse of the intrinsic activity toward methane combustion, another major application field for perovskites. On the grounds of a characterization based on XRD, SEM, TEM, TPD, and TPR analyses as well as on reactive runs, the prevalent activity of the chromite catalyst could be explained by its higher concentration of suprafacial, weakly chemisorbed oxygen, which contributes actively to soot combustion by spillover in the temperature range 300-500 degreesC, but negligibly to methane combustion. The best catalyst prepared (La0.9K0.1Cr0.9O3-delta) could ignite soot combustion well below 400 degreesC, which is inside the range of temperatures reached at the exhaust line of a diesel engine. Maximization of the concentration of suprafacial oxygen is pointed out as the main pathway to follow for the development of new, more active catalysts. (C) 2003 Elsevier Science (USA). All rights reserved.