论文总字数：16998字

摘 要

在水热法中，我们可以通过调节前驱体溶液浓度合成不同长径比的盘状和柱状六边形ZnO晶体。对合成的ZnO晶体通过电子显微镜（SEM）表征其形状和尺寸，通过X射线粉末衍射（XRD），透射电子显微镜（TEM）及选区电子衍射（SAED）表征其纤锌矿结构和生长习性。研究发现，随着前驱体溶液浓度减小，ZnO晶体沿着c轴延长，并且{001}极性面的直径减小，导致其形状由六方盘状向六棱柱转变。因此，不同ZnO晶体在{100}非极性面和{001}极性面所占比重各不相同。我们把这些结构清晰，形状明确的ZnO晶体作为Cu基催化剂的助剂用于醋酸异丙酯的加氢反应，结果发现，产物乙醇的选择性很明显与ZnO的形状效应有关，极性面比例大的ZnO纳米棒的选择性更高。{001}极性面的表面积和乙醇的选择性呈线性关系，这是因为ZnO非极性面酯加氢反应过程中增强了催化剂的碱性，加剧了醋酸异丙酯与乙醇的酯交换副反应，从而降低了产物乙醇的选择性。

关键词：ZnO晶体 极性面 醋酸异丙酯 乙醇 加氢

Shape Effect of ZnO Crystals as Cocatalyst in the hydrogenation reaction of isopropyl acetate to prepare ethanol and isopropanol

Abstract

In hydrothermal method, Disk- and rod-shaped hexagonal ZnO crystals with various length-to-diameter aspect ratios were synthesized by adjusting the precursor concentration. The shape and the dimension of the synthesized ZnO crystals were observed by scanning electron microscopy (SEM). The wurtzite structure and the growth habit were determined by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and selected-area electron diffraction (SAED). It is found that with the lowering of the precursor concentrations, the ZnO crystals were elongated along the c-axis, and the diameter of the {001} planes was reduced, leading to shape evolution from hexagonal disk to prismatic rod. As a result, the ZnO crystals were different from each other in the proportion of the {100} nonpolar planes and the {001} polar planes. The well-defined ZnO crystals were used as the cocatalyst with Cu-based catalyst in the hydrogenation reaction of isopropyl acetate. A remarkable shape-dependent effect on the selectivity of ethanol was identified. ZnO with a larger proportion of the nonpolar planes was more effective in the hydrogenation reaction of isopropyl acetate. An excellent linear relationship between the surface area of the {100} nonpolar planes and the selectivity to the product ethanol was identified. This is attributed to the enhancement of the basicity of the nonpolar planes of ZnO in the ester hydrogenation reaction, which greatly accelerates the ester exchange side reactions of isopropyl acetate and ethanol, thereby reducing the selectivity of ethanol.

Key words: zinc oxide, polar planes, isopropyl acetate, ethanol, hydrogenation

目录

摘 要 I

Abstract II

第一章 前言 1

1.1 课题背景 1

1.2 乙醇简介 1

1.2.1 乙醇的物化性质 1

1.2.2 乙醇的应用 2

1.2.3 乙醇的研究进展 3

1.2.4 乙醇各工艺路线对比 4

1.3 异丙醇简介 6

1.3.1 异丙醇的物化性质 6

1.3.2 异丙醇的合成 6

1.4 催化剂的选择 7

1.5 醋酸酯加氢原理 8

第二章 实验部分 10

2.1 试剂及药品 10

2.2 催化剂的制备 10

2.3催化剂的评价 10

2.3.1实验装置 10

2.3.2反应产物的分析方法 11

2.3.3计算方法 12

2.4催化剂的表征 12

第三章 结果与讨论 13

3.1晶相和形态 13

3.1.1 X射线衍射（XRD） 13

3.1.2 扫描电镜（SEM） 14

3.1.3 透射电镜（TEM） 15

3.2光学特性 15

3.2.1 拉曼光谱 15

3.3酯加氢催化结果与讨论 16

第四章 结论及展望 20

参考文献 21

致谢 23

第一章 前言

1.1 课题背景

乙醇，俗称酒精，是目前世界上生产历史最悠久，产量最大的发酵工业产品，广泛应用于食品、燃料、化工、医药等领域，是一种十分重要的清洁能源，其中燃料乙醇可作汽车的动力，可补充化石燃料资源，降低石油资源对外依存度，减少温室气体和污染物排放，受到世界各国的广泛关注。

近年来，随着国内醋酸行业的不断扩张，醋酸已经成为中国重要煤化工产品之一，产能迅速过剩，价格低迷不振，国内醋酸将面临严重的醋酸过剩问题。

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