d(18) O analysis of organic compounds: problems with pyrolysis in molybdenum-lined reactors.
d(18) O analysis of organic compounds: problems with pyrolysis in molybdenum-lined reactors.
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d(18) 有机化合物的 O 分析：钼衬里反应器中的热解问题。
DOI：
10.1002/rcm.6356
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Lombino A
中科院分区：
文献类型：
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作者：
Lombino A
采用高温热解装置，用钼(Mo)箔代替玻璃碳作为氧化层，对有机化合物进行了有效的δ18O测定。在这项研究中，我们使用标准的高温转化元素分析仪(TC/EA)评价了钼衬里反应器在苯甲酸δ18O测定过程中的性能。我们的钼衬里反应堆与糟糕的性能统计数据有关。为了验证这一假说，我们在两个用于苯甲酸分析的钼衬里反应器上进行了扫描电子显微镜能谱(SEM-EDX)和拉曼光谱分析。结果EDX分析表明，在与炉子最热部分对应的区域内，钼金属已经变得严重的点蚀和腐蚀，整个过程中都与氧化钼铜层有关。结论CO、Mo和C之间的复杂循环反应可能是导致部分样品被隔离成钼氧化物的原因分离我们的样本。因此，只有将样品氧定量地返回到气态CO中，防止随着时间的推移，在反应器内积累钼氧化物，才能实现对苯甲酸和其他化合物的准确分析。如果样品气体在反应性玻璃碳床中有足够的停留时间，从而优化样品氧的回收，则最有可能实现这一点。然而，这些条件不太可能在我们的标准TC/EA系统中得到满足，导致与其他HTP单元相比，钼衬垫的性能较差。版权所有©2012 John Wiley&Sons，Ltd.
RATIONALEEffective δ18O determinations of organic compounds have been made using high‐temperature pyrolysis (HTP) units that employ molybdenum (Mo) foil as an oxidation barrier instead of glassy carbon. In this investigation we evaluated the performance of a Mo‐lined reactor during δ18O determinations from benzoic acid using a standard high‐temperature conversion elemental analyser (TC/EA) unit. Our Mo‐lined reactor was associated with poor performance statistics. It was hypothesised that this was as a consequence of the partitioning of oxygen within our system.METHODSIn order to test this hypothesis scanning electron microscopy energy‐dispersive X‐ray spectroscopy (SEM‐EDX) and Raman spectroscopy was conducted on two Mo‐lined reactors, which had been used for the analysis of benzoic acids.RESULTSThe EDX analysis revealed that the Mo metal, which had become severely pitted and corroded in the region corresponding to the hottest part of the furnace, was associated with Mo‐oxide patinas throughout its entire length.CONCLUSIONSA complex circular reaction between CO, Mo and C is likely to be responsible for the sequestering of a portion of sample oxygen into Mo‐oxides, fractionating our sample. Accurate analysis of benzoic acid and other compounds can therefore only be achieved if sample oxygen is quantitatively returned to gaseous CO, preventing the buildup of Mo‐oxides within the reactor over time. This is most likely to be achieved if sample gases have a sufficient residence time within the reactive glassy carbon bed, optimising the recovery of sample oxygen. However, such conditions are unlikely to have been met within our standard TC/EA system resulting in poor performance of the Mo‐liner compared with other HTP units. Copyright © 2012 John Wiley & Sons, Ltd.