金属有机骨架结构材料合成及其吸附正构烷烃性能研究

发布时间：2018-01-15 16:22

本文关键词：金属有机骨架结构材料合成及其吸附正构烷烃性能研究　出处：《华东理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：沸石咪唑酯骨架(ZIF)材料由于具有比表面积和孔体积大、结构可调控性好、结构稳定性好等特点,被广泛应用于吸附分离过程研究,具有潜在良好的应用前景。本文通过溶剂热法合成ZIF-8材料,优化合成工艺条件,并对其吸附性能进行研究,以期为该MOF材料应用于石脑油中正构烷烃吸附分离工艺提高分离效率和分子管理功能提供理论依据。论文首先以溶剂热法合成ZIF-8,优化了合成工艺条件,并对合成ZIF-8进行分析表征。结果表明,在原料配比 n(C4H6N2):n(Zn(N03)2 6H20):n(HCOONa):n(MeOH)= 2:1:2.63:29.14、晶化温度90℃、晶化时间15 h、搅拌速度800 r/min的优化工艺条件下,ZIF-8收率为75.7%,合成ZIF-8晶体为十二面体方钠石结构,平均粒径1.58 μm,298 K下对正己烷的静态饱和吸附容量为225.1 mg/g,较5A分子筛高出85%以上,吸附容量和吸附速率优于巴斯夫产商业ZIF-8产品。随后论文研究了石脑油中所含主要正构烷烃在合成ZIF-8上的吸附平衡行为和动力学特性。结果表明,Langmuir-Freundlich吸附模型能够较好地描述正构烷烃在合成ZIF-8样品上的吸附平衡行为,在283～313 K的吸附温度条件下,正己烷、正庚烷和正辛烷在ZIF-8上的吸附焓变分别为-27.90 kJ/mol、-28.00 kJ/mol和-28.70 kJ/mol,吉布斯自由能变分别为(-5.81～-3.46)kJ/mol、(-6.15～-3.82)kJ/mol 和(-6.46～-4.08)kJ/mol,熵变分别为-77.56(J/(mol.K))、-76.67(J/(moI K))和-78.03(J/(mol K))。各正构烷烃在 ZIF-8 上吸附等温线的分子模拟计算结果与实验测定值吻合较好。283～313 K下,正己烷、正庚烷和正辛烷在 ZIF-8 中的扩散系数分别为(3.38～5.33)×10-12cm2/s、(2.02～3.30)×10-12cm2/s 和(1.21～2.09)×10-12cm2/s,扩散活化能分别为 11.12 kJ/mol、12.11 kJ/mol 和 13.41 kJ/mol。以模型油为原料的动态吸附实验结果表明,随着正构烷烃碳数的增加,正构烷烃在ZIF-8床层上吸附的托马斯速率常数增大、动态吸附容量略有降低。在此基础上,对ZIF-8成型工艺进行研究并考察成型后ZIF-8对石脑油中正构烷烃的吸附分离效果。结果表明,以田菁粉和酸性白土为成型助剂,成型后球形ZIF-8产品的机械强度为17N/cm,对正己烷、正庚烷和正辛烷的静态饱和吸附量分别为209.7 mg/g、207.6 mg/g和204.3 mg/g。成型ZIF-8对石脑油中总正构烷烃的静态饱和吸附量随吸/脱附循环次数增加无明显变化,均维持在205 mg/g左右,表明ZIF-8具有良好的再生性能和循环使用效果。经ZIF-8吸附分离吸余油的芳烃潜含量较原料石脑油提高了约11个百分点,达到了与5A分子筛一致的吸附分离效果,且ZIF-8在吸附容量和吸附速率方面较5A分子筛有优势。
[Abstract]:Imidazole ester (ZIF) zeolite skeleton materials with specific surface area and pore volume, structure adjustment, structure stability, is widely used in adsorption separation process research, has a potential application prospect is good. This paper through the solvothermal synthesis of ZIF-8 materials, the optimum technological conditions of the synthesis, and to study the adsorption performance, in order for the application of MOF material in naphtha of n-alkanes in adsorption separation process and provide a theoretical basis for improving the separation efficiency and molecular management functions. Firstly on the solvothermal synthesis of ZIF-8, the synthesis process conditions optimization, analysis and characterization of the synthesis of ZIF-8. The results showed that the ratio of raw materials n (C4H6N2) n (Zn (N03) 2 6H20): n (HCOONa): n (MeOH) = 2:1:2.63:29.14, the crystallization temperature of 90 DEG C, the crystallization time of 15 h, optimization of process conditions for the stirring speed of 800 r/min, the yield of ZIF-8 was 75.7%, ten for the synthesis of ZIF-8 crystal Two face sodalite structure, the average particle size of 1.58 m, 298 K static in n-hexane saturated adsorption capacity is 225.1 mg/g, a 5A molecular sieve is 85% higher than that of adsorption capacity and adsorption rate is better than the BASF commercial ZIF-8 products. The paper studies the main content of n-alkanes in the synthesis of ZIF-8 the adsorption behavior and dynamics of naphtha. The results showed that the Langmuir-Freundlich adsorption model can describe the adsorption equilibrium is the constitutive behavior in the synthesis of ZIF-8 sample alkane and adsorption temperature at 283 ~ 313 K, n-hexane, n-heptane and n-octane enthalpy of adsorption on the ZIF-8 variable -27.90 kJ/mol respectively. -28.00, kJ/mol and -28.70 kJ/mol, the Gibbs free energy respectively (-5.81 ~ -3.46) kJ/mol (-6.15 ~ -3.82) and kJ/mol (-6.46 - -4.08) kJ/mol, respectively -77.56 (J/ entropy (mol.K), -76.67 (J/) (moI K) and -78.03 (J/ (MO) L K)). The molecular structure is on the ZIF-8 adsorption isotherms of alkanes in the simulated values are in good agreement with the.283 ~ 313 K results with experiment, n-hexane, n-heptane and n-octane diffusion coefficient in ZIF-8 respectively (3.38 ~ 5.33) * 10-12cm2/s (2.02 ~ 3.30) and 10-12cm2/s (x 1.21 ~ 2.09) * 10-12cm2/s, diffusion activation energies were 11.12 kJ/mol, 12.11 kJ/mol and 13.41 kJ/mol. in model oil as raw material and dynamic adsorption experiment results show that with the increase of n-alkanes, increase the Thomas rate constant of n-alkanes in ZIF-8 adsorption bed, dynamic adsorption capacity decreased slightly on the basis. On the study of ZIF-8 on the adsorption of naphtha and n-alkanes in separation of forming effect on ZIF-8 process. The results show that with Sesbania powder and acidic clay as a molding aid after molding, the mechanical strength of spherical ZIF-8 products for 17N/ Cm, of n-hexane, n-heptane and n-octane static saturated adsorption capacity were 209.7 mg/g, 207.6 mg/g and 204.3 mg/g. ZIF-8 for forming naphtha total n-alkanes the static saturated adsorption capacity with the adsorption / desorption cycles showed no obvious change was maintained at about 205 mg/g, show that ZIF-8 has the regeneration performance and the cycle of good use effect. The separation of aromatics content of raffinate oil was about 11 percentage points higher than the feedstock of ZIF-8 adsorption, and 5A zeolite reached consistent adsorption separation effect, and ZIF-8 in the adsorption capacity and adsorption rate compared with the 5A molecular sieve has advantages.

【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O647.3;TE626.9

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