Investigation of synthesis route of unsaturated alcohols in the selective dehydration of diols

我们最近发现氧化铈（CeO_2）催化1,3-丁二醇选择性脱水成不饱和醇。为了弄清二元醇在氧化铈上脱水成不饱和醇的反应机理，我们购买了气相色谱质谱分析仪（GC-MS）、傅里叶变换红外光谱仪（FT-IR）和量子分析计算软件。本研究引进的设备和软件使研究工作得到了很好的发展。采用气相色谱-质谱联用技术，鉴定了少量二醇反应生成的各种副产物。副产物为考虑反应路线提供了有用的信息。利用密度泛函数理论（DFT）和配对相互作用轨道理论（PIO）的量子计算方法研究了1,3-丁二醇在Ce_2表面氧缺陷上的吸附。在用DFT计算优化的结构中，OH的两个氧原子与暴露的Ce阳离子在氧缺陷处相互作用较多。在最稳定的吸附结构中，2位亚甲基的一个氢原子与CeO_2（111）表面氧缺陷部位的第三个Ce阳离子相互作用。在1,3-丁二醇- ceo_2（111）体系的PIO计算中，明确了相互作用轨道。提出了1,3-丁二醇在CeO_2上脱水的反应机理。研究了丁二醇在不同粒径的CeO_2上脱水制备不饱和醇。CeO_2的煅烧温度控制了颗粒的大小。1,3-丁二醇脱水的催化性能受颗粒大小的影响较大。对3-丁醇和反式2-丁醇等不饱和醇的选择性随粒径的增大而增大，而1,3-丁二醇分解为3-丁醇-2- 1和丁酮的反应以小颗粒CeO_2为催化剂。在1,3-丁二醇脱水反应中，CeO_2具有结构敏感的催化作用：CeO_2{111}面具有生成不饱和醇的活性位点，其他表面催化副反应。由于1,3-丁二醇挥发性低，我们还没有在FT-IR测量中建立对其吸附模式的观察。然而，在本研究的支持下，我们还发现CeO_2， ZrO_2和几种稀土氧化物对1,4-丁二醇脱水成3-丁-1-醇是有效的。少

We have recently found that cerium oxide (CeO_2) catalyzed the selective dehydration of 1,3-butanediol into unsaturated alcohols. We purchased equipment of gas chromatography with mass analyzer (GC-MS), Fourier transform infrared spectroscopy (FT-IR), and a soft ware for the calculation of quantum analysis in order to clarify the reaction mechanism for the dehydration of diols into unsaturated alcohols over cerium oxide. The research work has been well developed with the equipment and software introduced in this work.We were able to identify various by-products formed with a small amount in the reaction of diols by using GC-MS. The by-products provide useful information to consider the reaction route. In the model adsorption of 1,3-butanediol on an oxygen-defect site of a Ce_2 surface was investigated with quantum calculations of Density Functional Theory (DFT) and Paired Interacting Orbital (PIO) theory. In the structures optimized with DFT calculation, the two oxygen atoms of the OH … More groups interact with exposed Ce cations at an oxygen-defect site. In the most stable adsorption structure, one hydrogen atom of the 2-position methylene group interacts with the third Ce cation at the oxygen-defect site of the CeO_2(111) surface. In the PIO calculations of 1,3-butanediol-CeO_2(111) systems, the interacting orbitals are clarified. We proposed a reaction mechanism for the dehydration of 1,3-butanediol over CeO_2.We investigated the dehydration of butanediol into unsaturated alcohols over CeO_2 with different particle sizes. The particle size was controlled by the calcination temperature of CeO_2. Catalytic performance in the dehydration of 1,3-butanediol was greatly affected by the particle size. The selectivity to unsaturated alcohols such as 3-buten-2-ol and trans-2buten-1-ol increased with increasing the particle size, while decomposition of 1,3-butanediol into 3-buten-2-one and butanone was catalyzed by CeO_2 with small particles. In the dehydration of 1,3-butanediol, CeO_2 has structure-sensitive catalysis : CeO_2 {111} afacets have active sites for the formation of unsaturated alcohols, and the other surfaces catalyze the side reactions.We have not yet established the observation of adsorption mode of 1,3-butanediol in the FT-IR measurement because of its low volatility. However, in the support of this grant, we have also found that CeO_2, ZrO_2 and several rare earth oxides are effective for the dehydration of 1,4-butanediol into 3-buten-1-ol. Less