In situ soft X-ray absorption spectroscopy applied to solid-liquid heterogeneous cyanopyrazine hydration reaction on titanium oxide catalyst
In situ soft X-ray absorption spectroscopy applied to solid-liquid heterogeneous cyanopyrazine hydration reaction on titanium oxide catalyst
复制标题
原位软X射线吸收光谱应用于二氧化钛催化剂固液非均相氰基吡嗪水合反应
DOI：
10.1021/jp512891t
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Nobuhiro Kosugi
中科院分区：
文献类型：
--
作者：
Hayato Yuzawa;Masanari Nagasaka;Nobuhiro Kosugi
在传统的固-液多相催化反应原位光谱技术中，由于底物、反应物、产物、溶剂和固体催化剂的混合物中目标信号难以分离，且灵敏度低，难以测定液体底物在固体催化剂上的转化率。元素特异性软X射线吸收光谱（XAS）是一种利用化学性质不同的内壳层激发能分别检测目标底物和产物的方法。本工作建立了一种透射模式下的XAS光谱原位测量装置，并将其应用于TiO_2催化剂上氰基吡嗪（PzCN）水合生成吡嗪酰胺（PzCONH_2）的固-液多相催化反应（PzCN + H_2O → PzCONH_2）。我们已经成功地在明确的观察光谱的变化，在C K-边缘和N K-边缘XAS由于生产PzCONH 2从PzCN在反应过程中，无论共存的散装液体成分，水（反应物）和乙醇（溶剂）。此外，我们得到了合理的动力学性质的PzCN水合反应从光谱分析，如反应级数（一级），速率常数，和活化能。因此，本方法可广泛应用于化学反应中微量液体组分的识别。
In conventionalin situspectroscopies of solid–liquid heterogeneous catalytic reactions, it is difficult to measure the conversion of liquid substrates on solid catalysts due to the lack of sensitivity and the difficulty in separation of target signals in the mixture of substrates, reactants, products, solvents, and solid catalysts. Element-specific soft X-ray absorption spectroscopy (XAS) is a promising method to detect target substrate and product separately from the other components using chemically different inner shell excitation energies. In the present work, we have developed anin situsample cell to measure time- and temperature-dependent XAS spectra in transmission mode and applied it to one of the solid–liquid heterogeneous catalytic reactions, cyanopyrazine (PzCN) hydration to produce pyrazinamide (PzCONH2) on the TiO2catalyst (PzCN + H2O → PzCONH2). We have succeeded in unambiguous observation of the spectral change in the C K-edge and N K-edge XAS due to the production of PzCONH2from PzCN during the reaction regardless of the coexistence of the bulk liquid components, H2O (reactant) and EtOH (solvent). Furthermore, we have obtained reasonable kinetic properties in the PzCN hydration reaction from the spectral analysis such as the reaction order (first order), the rate constant, and the activation energy. Thus, the present method can be widely applicable to distinguish the minor liquid components in chemical reactions.