【作者】 侯红美；

【导师】 厉刚；

【作者基本信息】 浙江大学 ， 化学， 2010， 硕士

【摘要】 丝光沸石是一类高硅沸石,晶胞组成为Na₈[（AlO₂）₈（SiO₂）₄₀]24H₂O,具有相互平行的椭圆形直孔道,孔径为0.695nm×0.581nm。由于具有较高的热稳定性、耐酸性、亲水性及合适的孔径大小,因此在催化反应和酸性介质分离领域有广泛的应用前景,同时也是较为理想的无机膜材料。本论文包括两大部分:（1）丝光沸石及催化剂的制备与裂解催化性能评价;（2）丝光沸石膜的合成、修饰及其渗透汽化分离性能的评价。具体内容如下:1、研究了硅源对丝光沸石结晶过程的影响机制。研究发现,分别以硅溶胶和固体硅胶为硅源时,采用组成为n（Na₂O）/n（SiO₂）=0.2,n（SiO₂）/n（Al₂O₃）=30,n（H₂O）/n（SiO₂）=26的晶化液,在相同的水热合成条件下,所得产物差异很大。通过设计一系列实验,探讨了硅源的影响机制。研究发现,凝胶硅铝比对结晶产物起决定性影响。2、研究了微波辐射法合成丝光沸石的特性,并与常规水热法进行了比较。研究发现,采用组成为n（Na₂O）/n（SiO₂）=0.2,n（SiO₂）/n（Al₂O₃）=30,n（H₂O）/n（SiO₂）=26的晶化液,以固体硅胶为硅源时,微波辐射法不仅可加快晶化速率,还可以抑制杂晶的生成,同时还能提高产物的比表面积;而以硅溶胶为硅源时,无论采用常规水热法或微波辐射法,在考察的反应条件内得到的产物均为硬块。3、采用水热法合成的钠型丝光沸石粉末为原料,采用不同的方法制备了三种氢型丝光沸石催化剂（HMOR、HMOR-OH和HMOR-H）,考察了三种催化剂对JP-10高密度碳氢燃料在常压、400℃下裂解转化率及产物分布的影响。研究表明,钠型丝光沸石具有良好的耐酸碱性。三种氢型丝光沸石催化剂中,催化剂的酸量顺序HMOR-OH＞HMOR＞HMOR-H;催化裂解过程中初始催化活性顺序与酸量顺序一致;失活快慢顺序为HMOR-OH＞HMOR＞HMOR-H。在HMOR、HMOR-OH和HMOR-H三种催化剂作用下,JP-10的裂解转化率分别为69.7%、60.9%和54.1%,气态裂解产物的收率大小与转化率大小顺序一致,而液态裂解产物的收率大小刚好相反。4、采用二次生长法对丝光沸石膜的制备进行了研究,并以水/乙醇混合物的分离为目标,研究了丝光沸石膜的渗透汽化分离性能及其影响因素。研究结果表明,晶种液浓度、硅源及晶化液的硅铝比对丝光沸石膜的渗透汽化性能均有不同程度的影响。晶种液浓度过高或过低均不利于高性能丝光沸石膜的合成;采用硅溶胶为硅源比采用固体硅胶为硅源更易获得高性能的丝光沸石膜;铝含量较高的晶化液有利于获得对水具有高选择性的丝光沸石膜。最后,本文还研究了后处理对丝光沸石膜渗透汽化分离性能的影响。研究发现,直接合成的丝光沸石膜经EDTA水溶液或NH₄F水溶液在一定条件下水热处理后,可同时提高丝光沸石膜的渗透通量及水/乙醇的分离系数。更多还原

【Abstract】 Mordenite（MOR） is a kind of high-silica zeolite,which has elliptical pore channels（0.695nm×0.581nm） parallel to each other with the cell composition of Na₈[（AlO₂）₈（SiO₂）₄₀]24H₂O.Due to its high thermal and acid stabilities, hydrophilicity and appropriate pore size,MOR zeolite has been widely used for catalytic reactions and separation processes in acidic media.In addition,MOR zeolite has also been extensively studied as an inorganic membrane material.This paper is consisted of two parts:（Ⅰ） Preparation and catalytic properties of powdery mordenite;and（Ⅱ） Preparation,modification and pervaporation performance of mordenite membranes.The details are discussed below:Firstly,the influence of silica source（silica sol and silica gel） on the crystallization process of mordenite zeolite was investigated using a synthesis mixture with n（Na₂O）/n（SiO₂）=0.2,n（SiO₂）/n（Al₂O₃）=30,n（H₂O）/n（SiO₂）=26.It was found that the products of the crystallization were totally different using silica sol or silica gel as silica source even if the other conditions were the same.A series of experiments were designed to give highlights on these results.It was proved that the n（SiO₂）/n（Al₂O₃） ratio of the gel rather than the apparent n（SiO₂）/n（Al₂O₃） ratio of the synthesis mixture was the determining factor for the products of crystallization.Secondly,the effect of heating methods（microwave heating versus conventional heating） on the crystallization process of mordenite was also studied using a synthesis mixture with n（Na₂O）/n（SiO₂）=0.2,n（SiO₂）/n（Al₂O₃）=30, n（H₂O）/n（SiO₂）=26.It was shown that microwave heating can not only accelerate the crystallization rate but also inhibit the formation of impurities and increase the specific surface area of the products when using silica gel as silica source.However, the products obtained were all in the form of hard solid using either microwave heating or conventional heating when using silica sol as silica source.Thirdly,the conversion and yields of the gaseous and liquid products for JP-10 cracking were studied at 400℃and atmospheric pressure over three H-mordenite catalysts（HMOR,HMOR-OH and HMOR-H）,which were prepared by different methods using Na-mordnite powder as the starting materials.The results show that the synthesized mordenite samples have satisfactory stability against strong acid and alkali solution.Among these three H-mordenite catalysts,the acid quantities, initial catalytic activity and the deactivation rate all follow the same order as HMOR-OH＞HMOR＞HMOR-H.Based on the results obtained during the first 60 min reaction period,the average conversions of JP-10 cracking are 69.7%,60.9% and 54.1%for HMOR,HMOR-OH and HMOR-H catalysts,respectively.The yields of the gaseous cracking products follow the same order as the conversion, whereas the yields of the liquid products follow the opposite order.Finally,factors influencing pervaporation performance of mordenite membranes prepared using seeded hydrothermal synthesis（secondary growth） were discussed.The results demonstrate that the factors such as concentration of seed solution,silica source and Si/Al ratio in the synthesis mixture have influences with different degree on the pervaporation performance of mordenite membranes.It was found that the too high or too low concentration of seed solution is not favorable for the formation of high quality mordenite membranes.The use of silica sol as silica source is better than silica gel for the formation of high quality mordenite membranes.The higher content of Al in the synthesis mixture also favors the formation of high quality mordenite membranes.In addition,effect of post-treatment by EDTA and NH₄F aqueous solution has also been explored on pervaporation performance of mordenite membranes.The results show that post-treatment either using EDTA or using NH₄F aqueous solution can improve both the total fluxes and the water/ethanol separation factors of the mordenite membrane under appropriate treatment conditions.更多还原