Detection and quantification of steady-state ethylene oxide formation over an Ag(111) single crystal
Detection and quantification of steady-state ethylene oxide formation over an Ag(111) single crystal
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DOI：
10.1016/j.jcat.2012.12.005
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发表时间：
2013-03-01
影响因子：
7.3
通讯作者：
Wintterlin, J.
中科院分区：
文献类型：
--
作者：
Boecklein, S.;Guenther, S.;Wintterlin, J.
用流动反应器进行了大量的实验，以可靠地检测在Ag（111）单晶上由乙烯和氧催化形成环氧乙烷的稳态。对于表面小的单晶，这是一个主要的实验问题，因为乙烯的反应概率低，质谱中的交叉灵敏度。使用O-16（2），可以在质量碎片m/z = 43上检测到环氧乙烷，使用O-18（2），可以在m/z = 31和m/z = 45上检测到环氧乙烷，但必须减去强的时间依赖性背景信号。这是通过反应器的周期性温度变化来实现的。在适当包括所有影响后，环氧乙烷相对于反应气体混合物的摩尔分数仅为3 × 10（-5），其明确地由Ag样品上的催化产生，可以以高于检测限一个数量级的信噪比来确定。(C)2012 Elsevier Inc. All rights reserved.
Extensive experiments with a flow reactor were performed to reliably detect the steady-state catalytic formation of ethylene oxide from ethylene and oxygen on an Ag(111) single crystal. For single crystals with their small surfaces, this had been a major experimental problem because of the low reaction probability of ethylene and cross-sensitivities in the mass spectra. Using O-16(2) ethylene oxide could be detected on mass fragment m/z = 43, using O-18(2) on m/z = 31 and m/z = 45, but strong time-dependent background signals had to be subtracted. This was achieved by periodic temperature changes of the reactor. After proper inclusion of all effects, a mole fraction of ethylene oxide of only 3 x 10(-5) with respect to the reaction gas mixture, which was unequivocally produced by catalysis on the,Ag sample, could be determined with a signal-to-noise ratio of more than one order of magnitude above the detection limit. (C) 2012 Elsevier Inc. All rights reserved.