摘 要

H₂O₂作为绿色清洁的化工产品之一，在其使用过程中仅产生氧气和水，在化工、食品、医药、电子和环保等领域得到了广泛应用。目前，国内外工业中最常见的H₂O₂生产方法是蒽醌法，占总产量的99%以上。该方法的关键步骤是蒽醌的氢化，而该加氢反应的核心就是催化剂。目前蒽醌加氢催化剂尚存在氢化效率低、Pd基催化剂稳定性差等问题，研制一种氢化活性高，选择性好、耐磨损和制备工艺简单的蒽醌加氢催化剂对于生产低成本、高浓度的H₂O₂具有极其重要的意义。

本文的研究内容主要针对目前的蒽醌法制备H₂O₂存在的固定床反应器氢化效率低和Pd催化剂稳定性差的问题。本文中，以六水氯化铝作为铝源，六水氯化镁或六水氯化镍作为助剂，通过加入环氧丙烷作不可逆的质子清除剂来制备氧化铝。最终在温和的条件下合成了织构性质可控的助剂体相分布的氧化铝微球。并以该微球作为载体采用等体积浸渍法负载活性组分Pd，经洗涤、干燥、焙烧制得了Pd-Mg/Ni/γ-Al₂O₃基复合催化剂。样品的物相结构、微观形貌和孔道结构等使用X射线粉末衍射（XRD）、扫描电镜（SEM）和氮气吸附-脱附等表征技术分析。并利用微型浆态床反应器和高效液相色谱对负载型Pd催化剂的2-乙基蒽醌加氢性能进行了测试，并对比了采用新型溶胶-凝胶法自制的γ-Al₂O₃通过浸渍法制备催化剂的加氢性能。

结果表明，催化剂中助剂的种类和加入量对其织构性质产生了多方面影响。催化剂的比表面积、孔容和平均孔径随着助剂引入量的增加均有所减小，并且Ni的引入比Mg的引入减小更多。这可能是由于助剂的引入导致微球的密度增加，使其熟化程度比未添加助剂时小。另外，Ni的相对原子质量较大，使得微球熟化程度比Mg修饰的催化剂的熟化程度低，最后导致Ni的引入使得织构性质下降得更加明显。通过分析N₂吸附-脱附等温线曲线，可以发现本实验所制备的催化剂具有较大的孔容和孔径，其中孔径集中分布介孔部分（10-14 nm）。经分析，虽然助剂的引入使得蒽醌氢化效率有所降低，从11.22 g/L降到10.30 g/L，但是大大的提高了选择性，由49 %提高到了93 %，使得催化剂更加稳定。

关键词：γ-Al₂O₃，助剂体相分布，环氧丙烷，表征，蒽醌加氢

Abstract

As one of the most environmentally friendly chemical products, hydrogen peroxide only produces oxygen and water during its use, and is widely used in the chemical industry, food, medicine, electronics and environmental protection. At present, the anthraquinone method is the most widely used production method for the industrial production of H₂O₂ at home and abroad, which accounts for more than 99% of the total production. The central stage of the process is the hydrogenation of anthraquinone, and the key of the hydrogenation lies in the catalyst. At present, anthraquinone hydrogenation catalysts still have problems such as low hydrogenation efficiency and poor stability of Pd-based catalysts. Development of an anthraquinone hydrogenation catalyst with high hydrogenation activity, good selectivity, wear resistance and simple preparation process is extremely important for the production of low-cost and high-concentration H₂O₂.

The research content of this work is mainly directed to the problems of low hydrogenation efficiency of fixed bed reactors and poor stability of Pd catalysts for producing H₂O₂ according to the existing anthraquinone method.In this paper, aluminum chloride hexahydrate is used as the aluminum source, magnesium chloride hexahydrate or nickel chloride hexahydrate as the auxiliary, and alumina is prepared by adding propylene oxide as an irreversible proton scavenger. Under mild conditions, alumina microspheres with controllable texture and auxiliary phase distribution were synthesized. And using the microspheres as the carrier to load the active component Pd by equal volume impregnation method, and then washing, drying and roasting to prepare Pd-Mg/Ni/γ-Al₂O₃ based composite catalyst. Various characterization techniques such as X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and nitrogen adsorption desorption are used to study the phase structure, microscopic morphology and pore structure of the product. The micro-slurry bed reactor and high-performance liquid chromatography were used to test the hydrogenation performance of 2-ethylanthraquinone on the supported Pd catalyst, and the hydrogenation performance of the catalyst prepared by the new sol-gel method of γ-Al2O3 by impregnation was compared.

The results show that the type and amount of additives in the catalyst have many effects on the texture properties of the catalyst. The specific surface area, pore volume and average pore diameter of the catalyst all decreased with the increase of the introduction amount of the auxiliary agent, and the introduction of Ni decreased more than the introduction of Mg. This may be due to the introduction of auxiliary agents leading to an increase in the density of the microspheres, making it less mature than when no auxiliary agents were added. In addition, the relative atomic mass of Ni is large, which makes the degree of maturation of microspheres lower than that of Mg-modified catalysts. Finally, the introduction of Ni makes the texture properties decrease more obviously. It can be attributed that the increase in the density of the microspheres with the introduction of additives, resulting in a lower degree of maturation than when no additives are added. Moreover, the relative atomic mass of Ni is large, which makes the degree of maturation of microspheres lower than that of Mg, and finally leads to the introduction of Ni, which makes the texture properties decrease more obviously. It can be found that the prepared catalyst has larger pore volume and pore size, and the pore size is concentrated in the mesoporous part (mesopores are concentrated in 10-14 nm) by analyzing the N₂ adsorption-desorption isotherm curve. Although the introduction of additives reduced the anthraquinone hydrogenation efficiency from 11.22 g/L to 10.30 g/L, the selectivity was greatly improved, from 49% to 93%, making the catalyst more stable.

Key Words: γ-Al₂O₃, additives bulk distribution, propylene oxide, characterization, anthraquinone hydrogenation

目录

第1章 绪论 1

1.1 蒽醌法生产H₂O₂简介 1

1.1.1 H₂O₂简介 1

1.1.2 蒽醌法简介 1

1.1.3 蒽醌氢化催化剂概述 2

1.1.4蒽醌氢化用Pd基催化剂的发展现状 2

1.2 氧化铝简介 3