【作者】 王越；

【导师】 董国君；

【作者基本信息】 哈尔滨工程大学 ， 应用化学， 2008， 硕士

【摘要】 本文采用沉淀法制备了ZrO₂载体,选取硝酸钠、硝酸钾、硝酸钙为前驱体,通过浸渍法经高温焙烧得到Na₂O/ZrO₂、K₂O/ZrO₂、CaO/ZrO₂固体碱催化剂。选取活性氧化铝为载体,采用同样的前驱体,通过浸渍法经高温焙烧得到Na₂O/Al₂O₃、K2O/Al₂O₃、CaO/Al₂O₃固体碱催化剂。通过碳酸二甲酯和异辛醇反应合成碳酸二异辛酯的反应评价各种催化剂的活性。查阅参考文献,确定反应条件,实验条件为常压,第一步反应温度130℃,反应时间4 h,n（DMC）:n（EHOH）=1:2,催化剂用量为原料总质量的1.5%。通过X射线衍射仪对Na₂O/ZrO₂、K₂O/ZrO₂、CaO/ZrO₂固体碱催化剂进行表征,在低温焙烧时,ZrO₂载体主要呈现四方相,载体为四方相时活性比较好。但是随着焙烧温度的升高,出现单斜相氧化锆晶相,此时比表面积下降,活性较差。随着温度的升高,硝酸盐在氧化锆表面分解更彻底,但是比表面积随着焙烧温度的增加呈下降趋势。Na₂O/ZrO₂、K₂O/ZrO₂、CaO/ZrO₂分别在600℃、500℃、700℃达到其最大活性。通过CO₂-TPD对催化剂的碱性进行表征,Na₂O/ZrO₂在600℃焙烧的样品存在强碱性,K₂O/ZrO₂催化剂也存在强碱中心及中等强度的碱中心,CaO/ZrO₂催化剂只有中等强度的碱中心,不存在强碱中心,并发现碱性与催化剂的活性存在顺变关系,碱性强,活性高。在氧化锆为载体的催化剂中添加稀土元素铈可以提高催化剂的碱性,Na₂O/ZrO₂-CeO₂（0.92%）样品活性较高,产率可达到66.1%。能谱表明Na₂O/ZrO₂-CeO₂（0.92%）催化剂的铈的含量为0.65%。通过X射线衍射仪对Na₂O/Al₂O₃、K₂O/Al₂O₃、CaO/Al₂O₃进行表征,不同焙烧温度对氧化铝的晶相没有产生影响。硝酸盐在氧化铝载体上的分解也不如在氧化锆载体上分解的彻底,Na₂O/Al₂O₃、K₂O/Al₂O₃、CaO/Al₂O₃均在700℃达到活性最大值,但是活性较氧化锆为载体的催化剂稍差。CO₂-TPD测试证明氧化铝为载体的固体碱大多只具有弱碱的脱附峰和中等碱性的脱附峰,基本不具有强碱的脱附峰,活性也不高,可见碱性与活性存在对应关系。在活性氧化铝为载体的催化剂中添加稀土铈,发现存在铝酸铈及铝酸盐的衍射峰,由于形成新的物质造成硝酸盐的分解受到一定影响,比表面积也有所下降。总体来看,添加稀土元素铈对于改性氧化铝负载钠盐,钾盐效果较好,活性都有一定提高,但是对于氧化铝负载钙盐并没有更好的效果。能谱表明Na₂O/Al₂O₃-CeO₂（3%）催化剂的铈的含量为1.14%。通过红外光谱测试、核磁共振测试、质谱测试、气相色谱测试等方法表征产物,证明样品与碳酸二异辛酯的结构相吻合,色谱在线跟踪反应也表明反应进行2 h时已经产生碳酸二异辛酯,进行4 h时中间产物消失,说明催化剂的催化效果较高。更多还原

【Abstract】 ZrO₂ was prepared by the coprecipitation,Na₂O/ZrO₂,K₂O/ZrO₂,CaO/ZrO₂ solid base catalyst were prepared by impregnation method with NaNO₃,KNO₃, Ca（NO₃）₂ and calcined at different temperature.γ-alumina as the supporter, Na₂O/Al₂O₃,K₂O/Al₂O₃,CaO/Al₂O₃ solid base catalyst were prepared by impregnation method with the same precursors and calcined at different temperature.The catalytic performances were evaluated in the synthesis of di-2-ethylhexyl carbonate from dimethyl carbonate and 2-ethyl-hexanol.Accord to the literature,the operation conditions for the reaction were obtained as follows: atmospheric conditions,reaction temperature 130℃（first step）,reaction time 4 h, n（DMC）:n（EHOH）=1:2,catalyst loadings 1.5%of mass of the feed.The characterization by XPD of Na₂O/ZrO₂,K₂O/ZrO₂,CaO/ZrO₂ solid base catalyst showed there were tetragonal ZrO₂ phases calcined at low temperature, tetragonal ZrO₂ phases is beneficial for activity.With the calcination temperature increasing,there monoclinic ZrO₂ phases were appeared,the specific surface area and activity decreased at the same time.With the calcination temperature increasing,the nitrate decomposed thoroughly on zirconia surface,but the specific surface area decreased with the increase of calcination temperature.Na₂O/ZrO₂, K₂O/ZrO₂,CaO/ZrO₂ reached their highest activity at 600℃,500℃,700℃, respectively.The characterization by CO₂-TPD showed strengths of basicity of catalysts. There were strong basic sites appeared on Na₂O/ZrO₂ calcined at 600℃.K₂O/ZrO₂ had strong basic centres and also moderate basic centres,only moderate basic centres appeared on CaO/ZrO₂,there were no strong basic centres. The more basicity,the higher activity.It was proved that the rare earth cerium added should enhance the basic of zirconia-supporter.The activity of Na₂O/ZrO₂-CeO₂（0.92%）was good,it reached 66.1%。Energy spectrum show that cerium content of Na₂O/ZrO₂-CeO₂（0.92%） is 0.65%.The characterization by XRD of Na₂O/Al₂O₃,K₂O/Al₂O₃,CaO/Al₂O₃ solid base catalyst showed no impact on alumina phase calcined at different temperature.There were added rare earth cerium alumina-supporter solid base,it was diffraction peaks of aluminate and aluminate cerium.The decomposition of nitrate and the specific surface area decreased.The decomposition of nitrate on zirconia were more completely than it on alumina.Na₂O/Al₂O₃,K₂O/Al₂O₃, CaO/Al₂O₃ both reached their highest activity at 700℃.But,the activity of alumina-supporter was lower than zirconia-supporter.CO₂-TPD test of alumina-supporter proved alumina-supporter solid base only had weak basic centres and moderate basic centres.As a whole,the addition of rare earth cerium enhance the basic of Na₂O/Al₂O₃,K₂O/Al₂O₃,but had little impact on CaO/Al₂O₃. Energy spectrum show that cerium content of Na₂O/Al₂O₃-CeO₂（3%） is 1.14%.The synthesized samples were analysed by FT-IR,¹H-NMR,gas chromatography,MS,which proved the structure of the synthesized samples conformed to di-2-ethyl-hexyl carbonate.The analysis gas chromatography online tracking reaction showed that there appeared di-2-ethylhexyl at 2 h,intermediate product disappeared at 4 h.lt also showed catalysts had high catalytic activity.更多还原