【作者】 吕小兵；

【导师】 何仁；

【作者基本信息】 大连理工大学 ， 工业催化， 2002， 博士

【摘要】 本论文从CO₂的催化活化着手，研究在超临界状态下CO₂和环氧烷烃的环加成反应。探索超临界化学反应中，CO₂既作反应溶剂又作反应底物的优势。 为了解超临界状态下均相催化CO₂和环氧乙烷生成碳酸乙烯酯反应过程中的相变化，研究了恒定组成的CO₂／环氧乙烷二元体系在不同温度下和CO₂／环氧乙烷／碳酸乙烯酯三元体系在反应温度下的相平衡，发现了CO₂／环氧乙烷二元体系的混合临界性质，推测出超临界状态下CO₂和环氧烷烃的环加成反应过程中必将发生相分离。 实现了超临界条件下均相催化CO₂和环氧乙烷生成碳酸乙烯酯，探讨了反应过程中的相变及其对环加成反应速率的影响。 设计合成了一系列四齿席夫碱铝配合物，它们可以溶解在超临界CO₂／环氧乙烷混合物中，是CO₂和环氧烷烃环加成反应的有效催化剂。席夫碱铝配合物轴向基团、苯环上的取代基团以及助催化剂等对其催化性能有很大影响。其中，SalenAl-OCH₂CH₂（OCH₂CH₂）₂Cl／n-Bu₄NBr双组分催化剂在110℃时的催化活性高达2340转化数╱小时，是迄今报道活性最高的环加成反应催化剂。同样的催化体系和反应温度下，超临界条件下CO₂与环氧乙烷的环加成反应速率约是4.0MPa-CO₂恒压下的2倍。 用NMR光谱方法，证实了环氧乙烷对四齿席夫碱铝配合物（SalenAlX）中心金属离子的配位作用，提出了环氧乙烷是按碱式催化机理开环并插入SalenAlX的Al-X键。用FTIR光谱方法，研究了CO₂的活化及对铝配合物Al-O键的插入反应，提出了碳酸乙烯酯是由形成的线形碳酸酯中间体经分子内环消除而产生的。阐明了碱性配体对铝配合物催化性能的促进作用机理，以及四齿席夫碱金属配合物／季铵盐或季膦盐双功能催化剂对环氧烷烃和CO₂环加成反应的协同作用。 大连理工大学博士学位论文 将可溶性氯铝酞菩和席夫碱铝、钻等配合物化学负载在一维有序8。型介孔材料上，并用FT－IR、XRD、UV－VIS、TGA等光谱仪器表征了它们的性质。负载后的这些配合物仍呈现较高的催化活性。 用负载化的席夫碱钻配合物作为主催化剂填充在固定床反应器中，将助催化剂季铰盐溶解在环氧乙烷中，实现了超临界条件下由CO。和环氧乙烷反应高效率得到碳酸乙烯酯，环氧乙烷的转化率高达85．6％。这是迄今第一例超临界CO。兼具溶剂和反应物双重功能用于连续化反应的成功报道。 甲醇／二氯甲烷混合物改性的超临界 CO。是 MCM＊ 介孔材料模板剂的良好荤取剂，革取率超过92％；且革取出的模板剂仍保持其基本结构，可以重复用于 MCM－41的合成。较之高温烧结方法，用超临界流体革取方法获得 MCM－41材料的介孔未发生收缩，且孔径分布均匀、材料骨架结晶性亦更高。 在以上工作的基础上，以乙二胺基硅烷偶联剂与无水CUO。形成的铜－乙二胺配合物【叮PED)厂。】作为模式配合物，利用其硅氧烷基团与 MCM＊ 材料表面的自由羟基（St－OH）之间醇解缩合反应，将铜配合物化学键合到MCM－41材料的表面，初步实现了 MCM－41 介孔材料中模板剂的移走和材料表面的同时改性，所获得材料仍然保持 MCM＊ 基本性质，且孔径分布较均匀。更多还原

【Abstract】 The present thesis originates from catalytic activation of CO2, and studies the cycloaddition of CO2 with epoxides to produce corresponding cyclic carbonates under supercritical conditions. Some advantages for the utilization of supercritical CO2 as both a solvent and a reactant will be discussed in catalytic synthesizes of some organic compounds.For understanding the phase behavior during homogeneous catalytic reaction of CO2 and ethylene oxide to form ethylene carbonate under supercritical conditions, vapour-liquid equilibria in the system CO2/ethylene oxide at various temperatures and in the system CO2/ethylene oxide/ethylene carbonate at 110’Chave been studied in detail. It can be confirmed that the binary system of CO2 and ethylene oxide has a continuous critical locus between both critical points of the pure components. The results also indicate that phase change must occur during the cycloaddition reaction of CO2 and ethylene oxide under supercritical conditions.Homogeneous catalytic formation of ethylene carbonate from supercritical CO2/ethylene oxide mixture was realized by using tetradentate Schiff-base aluminum complexes as catalysts. The effect of phase change during the reaction on the rate was also explored.Various tetradentate Schiff-base aluminum complexes, which can be dissolved in supercritical CO2/ethylene oxide mixture, are effective catalysts for the cycloadditions of CO2 and epoxides. Axial group, substitution on the aromatic rings of SalenAlX, and co-catalyst all affect catalytic properties of these aluminum complexes. Among them, the binary catalyst consisted of SalenAl-(OCH2CH2)3Cl and n-Bu4NBr was found to be most effective and exhibited a catalytic activity of upto 2340 turnovers/h at 110"C, which was one of the highest for the cycloaddition of CO2 to epoxides amongst the reported catalysts. With the same binary catalyst, the formation rate of ethylene carbonate under supercritical condition was about 2 times of that under 4.0MPa CO2 pressure at same temperature.The interactions between ethylene oxide and tetradentate Schiff-base aluminum complexes (SalenAlX) were confirmed by means of NMR method. It was proposed that ethylene oxide was ring-opened according to base-catalyzed cleavage, and then inserted the Al-X bond of SalenAlX. Activation of CO2 and its insertion towards Al-O bond of aluminum complexes to form intermediate條inear carbonates, which formed cyclic carbonate by intermolecular substitution, were studied by using FTIR methods. The plausible mechanisms for cycloaddition of CO2 and ethylene oxide are proposed with aluminum complex alone, or combined with a Lewis base as co-catalyst. The synergistic effect of SalenAlX/n-Bu4NBr bifunctional catalyst for the cycloaddition reaction was discussed in detail.Soluble aluminum phthalocyanine and Schiff-base aluminum, cobalt complexes were covalently bonded to the silica surface of ordered mesoporous MCM-41 molecular sieve. The anchoring resulted complexes were characterized by means of FTIR, XRD, UV-VIS and TGA methods, and all exhibited high catalytic activities towards the cycloaddition of CO2 and ethylene oxide, when a quaternary ammonium salt was used as co-catalyst.In the presence of n-Bu4NBr, the cobalt complex anchored onto MCM-41 was used as catalyst for the cycloaddition of CO2 and ethylene oxide to continuous produce ethylene carbonate in a fixed bed reactor. The conversion of ethylene oxide is up to 85.6%. This is first successful example that supercritical CO2 was used as both a solvent and a reactant for continuous catalytic syntheses of organic compound.IVThe removal of up to 92% of the template from mesopores has been successfully achieved by treating as-synthesized pure siliceous MCM-41 with supercritical CO2 modified with CH2Cl2/MeOH mixture. The extracted template retained its structure and property, and thus could be reused for preparation of MCM-41 material. Compared to high temperature calcination, the proposed method can avoid structure shrinkage, and retain highly uniform更多还原