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Variability of particle configurations achievable by 2-nozzle flame syntheses of the Au-Pd-TiO2 system and their catalytic behaviors in the selective hydrogenation of acetylene
Applied Catalysis A: General ( IF 5.5 ) Pub Date : 2017-09-12 , DOI: 10.1016/j.apcata.2017.09.014
Boontida Pongthawornsakun , Okorn Mekasuwandumrong , Francisco J.Cadete Santos Aires , Robert Büchel , Alfons Baiker , Sotiris E. Pratsinis , Joongjai Panpranot

Catalysts with Au and Pd supported on TiO2 (Au:Pd 1:1 wt/wt%) were prepared by 1- and 2-nozzle flame spray pyrolysis (FSP). The 2-nozzle configuration allowed to synthesize various particle configurations by separate or co-feeding of the metal precursor solutions to the two nozzles. For the Au-Pd/TiO2 system, four different catalyst particle configurations were investigated: “TiO2 + AuPd”, “Pd/TiO2 +Au”, “Au/TiO2 +Pd”, and “Pd/TiO2 + Au/TiO2”, where + separates the corresponding precursor solutions fed to the two nozzles. There were no significant differences in the specific surface areas and the average TiO2 crystallite sizes of the catalysts (100 m2/g and 16–17 nm, respectively) with the exception of “Pd/TiO2 +Au/TiO2”, which exhibited larger surface area and smaller crystallite size (152 m2/g, 12 nm) due to halving of the Ti precursor concentration in each nozzle. As revealed by CO chemisorption, XPS, and STEM-EDX results, the catalyst properties varied largely in terms of bimetallic AuPd particle compositions, the interaction between metal–metal and metal-support, and the location of Pd (or AuPd) on the TiO2. Among the catalysts studied, “TiO2 + AuPd” prepared with the 2-nozzle system exhibited the highest conversion of acetylene (∼50%) at 40 °C with high selectivity to ethylene ( > 95%). Co-feeding the noble metal precursors together with the Ti precursor afforded less active catalysts due to the formation of Ti-O species partially covering the most active bimetallic AuPd particles. Compared to the commercially available acetylene hydrogenation catalyst and the AuPd/TiO2 prepared by conventional co-impregnation and deposition-precipitation, all the FSP-AuPd/TiO2 catalysts showed superior performances under the reaction conditions used.



中文翻译:

Au-Pd-TiO 2系统的两喷嘴火焰合成可获得的颗粒构型变化及其在乙炔选择性加氢中的催化行为

通过1-和2-喷嘴火焰喷雾热解(FSP)制备了负载有TiO 2(Au:Pd 1:1 wt / wt%)的Au和Pd的催化剂。通过将金属前体溶液分开或共同进料到两个喷嘴,2-喷嘴构型允许合成各种颗粒构型。对于Au-Pd / TiO 2系统,研究了四种不同的催化剂颗粒构型:“ TiO 2  + AuPd”,“ Pd / TiO 2 + Au”,“ Au / TiO 2 + Pd”和“ Pd / TiO 2  + Au / TiO 2”,其中+分隔送入两个喷嘴的相应前体溶液。比表面积和平均TiO 2没有显着差异。催化剂的微晶尺寸(分别为100 m 2 / g和16-17 nm),“ Pd / TiO 2 + Au / TiO 2”除外,其表现出较大的表面积和较小的微晶尺寸(152 m 2 / g ,因为每个喷嘴中的Ti前驱物浓度减半,所以12 nm)。正如CO化学吸附,XPS和STEM-EDX结果所揭示的,催化剂性能在双金属AuPd颗粒组成,金属-金属与金属载体之间的相互作用以及TiO上Pd(或AuPd)的位置方面有很大差异。2。在研究的催化剂中,“ TiO 2 用2-喷嘴系统制备的“ AuPd”在40°C时表现出最高的乙炔转化率(〜50%),对乙烯的选择性高(> 95%)。由于形成了部分覆盖最具活性的双金属AuPd颗粒的Ti-O物质,将贵金属前体与Ti前体一起共进料提供的催化剂活性较低。相比于市售的乙炔加氢催化剂和金钯/氧化钛2通过常规共浸渍和沉积-沉淀法制备,所有的FSP-金钯/氧化钛2催化剂显示所用的反应条件下优异的性能。

更新日期:2017-09-12
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