【作者】 韩玲；

【导师】 王金渠；

【作者基本信息】 大连理工大学 ， 化学工艺， 2005， 硕士

【摘要】 目前石化公司尾气处理装置用氮气密封苯,解封时有一部分苯会随氮气挥发到大气中,不仅浪费资源,而且严重污染了环境。目前企业用活性碳纤维吸附进行苯和氮气的分离,成本高,消耗能量大。开发一种新技术回收苯,既可以为企业带来可观的经济效益,又保护了生态环境,具有重要的科学、经济和社会意义。根据上述研究背景,本文主要进行了以下研究:系统研究了在孔径为3～5μm的α-Al₂O₃陶瓷管载体上二次生长法合成NaX型沸石膜。探讨了在载体表面制备过渡层合成膜的新方法,并将合成的膜应用于苯和氮气混合体系的分离,取得了较好的分离效果。 通过对形成沸石膜的最佳NaX沸石晶粒的合成条件进行考察,发现晶化温度、碱度、硅铝比和晶化时间对分子筛合成质量的影响很大,铝源的选择直接对分子筛的晶体产生影响。采用硅溶胶、异丙醇铝和氢氧化钠作为原料,可得到质量良好的分子筛晶体。预涂晶种的摩尔配比为:SiO₂:Al₂O₃=3.85,Na₂O:SiO₂=1.2-1.5,H₂O:Na₂O=46-55;沸石膜合成液的摩尔配比为:SiO₂:Al₂O₃=4.2,Na₂O:SiO₂=1.2-1.5,H₂O:Na₂O=60。 采用自制0.5-1μm的NaX沸石分子筛为晶种,用热浸渍方法引入晶种,在旋转晶化的方式下,重复晶化4次以上可以合成出完整连续的NaX沸石膜。针对大孔载体,首次采用氧化铝（Al₂O₃）及羧甲基纤维素（CMC）胶粘晶种作为过渡层,在孔径为3～5μm的多孔α-Al₂O₃陶瓷管载体表面成功合成出NaX沸石膜。Al₂O₃作为过渡层合成出的膜渗透通量比较小,H₂为4.88×10^-7mol·m²·s^-1·pa^-1,C₃H₈为6.91×^-8mol·m²·s^-1·pa^-1,分离因数相对较高,H₂/C₃H₈的理想选择因数为7.18;CMC胶粘晶种作为过渡层合成出的膜渗透通量比较大,H₂在2.09×10^-6mol·m²·s^-1·pa^-1,C₃H₈为3.02×^-7mol·m²·s^-1·pa^-1,分离因数也相对较高,H₂/C₃H₈的理想选择因数为7.08。 通过对分子筛改性的研究,认为Ag⁺改性后的X型沸石膜可以更好的用于苯和氮气混合气的分离。分子筛改性的最佳交换时间为5-8小时,交换溶液浓度为0.2-0.25mol/L。NaX沸石膜经过离子改性后,膜的性质发生了很大的变化,渗透数据表明比未改性前分离因数增大。NaX沸石膜对苯和氮气混合系统的分离因数随膜两侧的压差、原料气浓度和原料气流速的变化而变化,当离子交换度达到最大值时,分离因数也达到最大值。在压差为40KPa,进气流速为180ml/min,浓度为17%时,改性完全的X型沸石膜达到最好分离效果,分离因数为30.1,实现了苯和氮气混合气的分离。更多还原

【Abstract】 In many petrochemical plants, a mass of benzene and nitrogen mixture in benzene stock tanks is discharged into atmosphere. The precious resource is wasted and the environment is polluted. Because of this background, synthesis of continuous NaX membranes by seeded method are studied thoroughly on the outer surface α -alumina tube support with pores of 3⁵ μm （13 mm o.d, and 9 mm i.d.）. The membranes apply to separate the benzene and nitrogen mixture successfully as a new separation method. The main work of this thesis is:Effects of some important factors such as tempreture, alkalinity, Si/Al and synthesis time on the preparation of zeolite are thoroughly studied. When the Al fountain is changed, the crystal size also changes thoroughly. The molar composition of the seeding is SiO₂/Al₂O₃=3.85, Na₂O/SiO₂=1.2-1.5, H₂O/Na₂O=46-55; The molar composition of the starting gel of NaX membranes is SiO₂:Al₂O₃=3.85⁴.2,Na₂O:SiO₂=1.2¹.5,H₂O:Na₂O=40⁶0.The influence of crystallization methods, crystallization times and the methods of introducing seeds are studied thoroughly. The result shows that using self-product 500-1000nm NaX zeolite as seeds and using hot-dipping method crystallize about 4 times, integrated and continuous membranes are gained. The NaX zeolite membranes are successfully synthesized using Al₂O₃ crystal and CMC as transition layers for the first time. The penetration of H₂ is 4.88 × 10-7 mol·m2 ·s-1 · Pa-1, C3H8 is 6.91 × -8 mol · m2 · s-1 · Pa-1, and the ideal selectivity of H₂/C₃H₈ is 7.19 when the membranes transition layer is Al2O3. The penetration of H2 is 2.09 × 10-6 mol m2 ·s-1 ·Pa-1, C3H8 is 3.02 × -7 mol ·m2 ·s-1·Pa-1, and the ideal selectivity of H2/C3Hg is 7.19 when the membranes transition layer is CMC .NaX zeolite membranes are used to separate the mixture of benzene and nitrogen as a new method. The influence of pressure difference, the speed and concentration of the mixture and ion-exchanged degree are studied thoroughly. The result shows that the separation factor is changed with the pressure difference, speed and concentration change. Membranes show better separation ability when they are exchanged with Ag+. When the pressure is 40KPa, the speed is 180ml/min and the concentration is 17%, Ag+-exchanged completely membranes gain the best separation factor, 30.1.更多还原