Effect of water treatment and Ce doping of Pt/Al2O3 catalysts on Pt sintering and propane oxidation
Effect of water treatment and Ce doping of Pt/Al2O3 catalysts on Pt sintering and propane oxidation
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DOI：
10.1007/s11164-021-04449-z
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发表时间：
2021-04
影响因子：
3.3
通讯作者：
A. Tomita;T. Miki;Y. Tai
中科院分区：
文献类型：
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作者：
A. Tomita;T. Miki;Y. Tai
考察了催化剂老化后Ce掺杂和Pt/Al_2O_3表面处理对其丙烷氧化催化性能的影响。通过改变Ce加入量和前处理条件，测定了催化剂的丙烷氧化活性。用X射线衍射仪、扫描电子能谱、傅立叶变换红外光谱和氢-程序升温还原等手段对催化剂的性能进行了表征。掺少量Ce的水处理催化剂的铂纳米颗粒(PtNPs)尺寸变小，表明掺Ce催化剂水处理抑制了铂的烧结。最小PtNP尺寸约为3.6wt%的Ce。低于3.6wt%的Ce以分散状态存在，高于3.6wt%时，CeO2颗粒共存。水处理催化剂的丙烷氧化温度随Ce含量的增加而降低。这一趋势与催化剂中的PtNP尺寸是一致的。认为高度分散的Ce物种在PtNPs上促进丙烷氧化起主要作用。FT-IR测试表明，经水处理的催化剂上Ce物种的还原温度低于未处理的催化剂，这可能是由于铂和Ce之间的相互作用更强所致。Ce物种的还原能力增加可能是催化剂氧化活性提高的原因。
The effect of Ce doping and pretreatment of Pt/Al2O3on its catalysis of propane oxidation was investigated after aging the catalysts. The Ce amount and pretreatment conditions were varied, and the propane oxidation activity was measured. The properties of the catalysts were investigated by means of XRD, STEM-EDX, FT-IR, and H2-TPR. The size of the Pt nanoparticles (PtNPs) decreased for water-treated catalysts doped with a small amount of Ce, suggesting that water treatment of Ce-doped catalysts inhibits Pt sintering. The minimum PtNP size was obtained with ca. 3.6 wt% of Ce. The Ce species with less than 3.6 wt% existed in a dispersed state, whereas above this value, CeO2particulates co-existed. The propane oxidation temperature of the water-treated catalysts was lowered to an extent that depended on the Ce content. This tendency is consistent with the PtNP size in the catalysts. It is considered that highly dispersed Ce species take a primary role in promoting propane oxidation on PtNPs. The reduction temperature of Ce species on water-treated catalysts was lower than that of untreated catalysts, probably owing to a stronger interaction between Pt and Ce, demonstrated by FT-IR measurements. The increased reducibility of Ce species may be the reason for the improved oxidation activity of the catalysts.Graphic abstract