乙炔和甲酸甲酯催化合成丙烯酸甲酯的研究 ——镍基催化剂的制备及丙烯酸甲酯常压合成初探
摘要
随着甲酸甲酯工业化的实现，加速开发利用其下游产品日益成为普遍关心的研究课题。自从1983年，Sneeden等人的开创工作以来，利用甲酸甲酯与不饱和的加氢酯化反应合成酯，在近二十年来逐渐受人关注。利用甲酸甲酯替代CO/CH3OH参与相当成熟的Reppe反应：
CH2=CH2 +CO +CH3OH CH2=CH2 + HCOOCH3
CH3CH2COOCH3 CH3CH2COOCH3
一方面解决了CO的存储和运输问题，另一方面反应的工艺条件在一定程度上得到优化。在甲酸甲酯与乙炔加氢酯化均相催化结果的基础上，我们对本反应进行更进一步探索:
CH≡CH +HCOOCH3 CH2=CHCOOCH3
本实验室利用固定床反应器，对甲酸甲酯与乙炔的加氢酯化反应进行了探索性研究。通过大量的催化剂筛选工作，发现只有镍催化剂对目标反应有较好的活性，而且氧化态的镍是催化反应的活性中心，金属态的镍对目标反应没有催化活性。对载体也进行了一定的筛选，载体不仅起到稳定活性组份的作用，而且其与活性组分的作用对反应性能也有一定的影响。
对本反应的工艺条件进行了优化，反应温度、反应总压、原料配比、反应时间对反应都有很大影响。甲酸甲酯与乙炔的加氢酯化反应和甲酸甲酯的脱碳反应是一对竞争反应，当丙烯酸甲酯的选择性高时，甲醇的产物就少。相反地，大量的甲酸甲酯发生脱碳反应时，丙烯酸甲酯的选择性就低。因此丙烯酸甲酯的选择性与甲醇的生成具有相关性。 关键词: 甲酸甲酯 乙炔 丙烯酸甲酯 加氢酯化
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Catalytic Synthesis of Methyl Methacrylate by
Acetylene and Methyl Formate
——Preparation of Nickel-based Catalysts and Low Pressure
Synthesis of acrylic acid methyl ester
Undergraduate:QIN Jinfeng Advisor:WANG Wei
Abstract
With the industrial realization of methyl formate ,considerable attention has been paid to the uses and developments of its downstream products.Since the pioneering work of Sneeden and co-workers in 1 986,special attention has also been devoted to the hydroesterification of alkene using methyl formate instead of CO/CH3OH for synthesis of esters in two decades.The Reppe reaction by using methyl formate instead of CO/CH3OH was given as follows：
CH2=CH2 +CO +CH3OH
CH3CH2COOCH3
CH2=CH2 + HCOOCH3 CH3CH2COOCH3
Via methyl formate,firstly the transport and handling CO/CH3OH at locations where the latter are difficult to obtain or to handle can be simplified;Secondly the reaction condition was optimized.The hydroesterification of acetylene with methyl formate for synthesis of methyl acrylate has been found to proceeds uccessfully,We make further study on the reaction in fixed-bed：
CH≡CH + HCOOCH3
CH2=CHCOOCH3
The hydroesterification of acetylene with methyl formate for synthesis of methyl acrylate in fixed-bed has been studied in our labouratory.Through plenty of catalysts screening work,we find nickel-based catalyst shows certain activity to the target reaction,and NiO is the active site,while the metalic nickel does not exhibit any activity to the target reaction.Support screening work has also been made,the main role of support is to carry the active species particles in highly dispersed form for high thermal stability,it has been recognized,that the nature of the supportedly inert carrier exterts an influence on the behavior of the whole
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catalyst.
The reaction condition was optimized such as reaction temperature,reaction pressure,the moler ratio of acetylene to methyl forrmate space velocity reaction time etc。Hydroesterification of acetylene with methyl formate and decarboxylation of methyl formate are a pair of competition reaction.When the selectivity to methyl acrylate is high.The selectivity to methanol is low,on the other way,large decarboxylation reactions run,the selectivity to methyl acrylate is low accodingly.The selectivity of methyl acrylate was correlated to the selectivity of methonal.
Keywords：methyl formate acetylene methyl acrylate hydoesterification
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1.7研究内容
1.7.1合成丙烯酸甲酯的工艺条件 1.7.1.1实验工艺条件研究。
制备技术和实验条件直接影响了丙烯酸甲酯的选择性和甲酸甲酯转化率。因此对实验条件进行研究，选出优化的实验条件是制备丙烯酸甲酯和如何提高甲酸甲酯转化率和丙烯酸甲酯的选择性的关键。针对目前研究中主要存在的转化率较小等问题，本实验将通过对改变反应温度、原料配比、反应时间及催化剂等条件的研究来解决上述问题。 1.7.1.2催化剂的制备 1.7.1.2.1活性组分
根据参考文献得知：对乙炔的加氢酯化反应有效的催化剂为第VIII 族的金属化合物或配合物, 其中以镍、钯、钌、铂、铑的催化剂活性最好。在均相反应条件下，乙炔与甲酸甲酯的加氢酯化合成丙烯酸甲酯的反应, 这几种物质均有使用, 其中负载镍的催化剂, 虽然催化活性稍微差一点, 但对目标产物的选择性是最好的。而当中负载钌和钯的催化剂易使甲酸甲酯产生脱羰, 对目标产物的选择性不好, 还有担载铑和铂的催化剂是得不到目标产物。综合以上可得在乙炔与甲酸甲酯的气固相反应中, 负载镍是最有效的催化剂, 而且不同于前面研究的均相反应[24-25], 基本上没有与目标产物难分离的丙酸甲酯生成。因此, 我们选择了以硝酸镍为催化剂的前驱物, 进行了一系列的研究。 1.7.1.2.2载体
载体主要用于支持活性组分，使催化剂具有特定的物理性状，其本身一般并不具有催化活性。载体能使制成的催化剂具有合适的形状、尺寸和机械强度，以符合工业反应器的操作要求；载体可使活性组分分散在载体表面上，获得较高的比表面积，提高单位质量活性组分的催化效率。如果
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