【作者】 曾勇平；

【导师】 居沈贵；

【作者基本信息】 南京工业大学 ， 化学工程， 2004， 硕士

【摘要】 采用正交试验的方法,研究锌离子在 13X 和活性氧化铝上负载条件及锌离子负载机理,并采用室温浸渍法,将锌离子和铜离子负载于 13X 分子筛、活性氧化铝、5A 分子筛上,制备了一系列改性型的脱硫吸附剂,考察了这些脱硫吸附剂在汽油模拟体系中的脱硫性能。采用微波浸渍的方法将铜离子负载于活性氧化铝和 5A 分子筛制得脱硫吸附剂,考察在真实汽油体系中的脱硫性能。构建了MFI 和 MOR 两种拓扑结构沸石的数学模型,以乙硫醇分子作为被吸附的目标物,采用偏倚蒙特卡罗方法模拟乙硫醇在MFI和MOR沸石上的吸附行为及分子分布密度,并利用分子动力学模拟乙硫醇在这两种拓扑结构的扩散行为,为实现面向硫化物进行吸附剂的微观结构设计作初步探索。研究表明,在本文所做的正交试验范围内,对于 13X 和氧化铝,锌离子浓度对锌在载体上的负载量影响最大,温度次之,溶液的 pH 值在 2-3 的范围内影响较小。在一定的浓度范围内,随着锌离子浓度的增加,13X 和氧化铝的负载量也增加,锌离子浓度为 16000mg/L 时,锌离子与氧化铝的负载量达到最大,浓度与负载量的关系可以用 Freundlich 模型拟合。而对于 13X,浓度为 24000mg/L时,负载量达到最大,浓度与负载量的关系符合 Langmuir 模型。锌离子与 13X的负载在 30 小时达到平衡,而与氧化铝的负载在 10 小时达到平衡。锌离子与固体吸附剂之间的负载平衡,可以作拟一级反应处理。对三种载金属离子吸附剂脱硫性能研究表明,负载锌离子的 13X、氧化铝、5A 分子筛,温度升高,吸附剂的吸附容量升高,硫醇去除率也大,温度升高,增大了活化能克服了势能障碍。模拟体系硫醇浓度增高,吸附容量增大,但是去除率下降。未经过焙烧载锌吸附剂的吸附量的明显小于经过焙烧过的,但是进一步提高焙烧温度,对吸附容量没有太大影响。锌离子的引入,对吸附容量有较大的提高。提高温度对载铜吸附剂的硫醇去除率有利,对于 13X 和氧化铝,2 个小时后,去除率达到 98%左右,5A 分子筛要 6 个小时以上才能达到 95%。不经过焙烧的载铜吸附剂,硫醇吸附量小于经过焙烧的。铜离子的引入,增大了吸附剂对硫化物的吸附量。硫醇浓度高,对硫醇去除率不利。再生采用直接加热再生效果好,但是会产生 SO2等有害气体,而采取极性溶剂乙醇清洗周期较长,再生效果差。利用分子模拟手段,对于 MFI 型沸石,得到的吸附等温线和采用红外光谱所得的实验值基本一致,从模拟的结果来看,所选取的参数是恰当的。在相同的温度下,乙硫醇在 MFI 上的吸附量要比在 MOR 沸石上的吸附量大得多, 对于MFI 沸石,直型孔道比之型孔道表现出更优良的吸附性能。乙硫醇在 MOR 体系中的扩散系数要比在 MFI 体系中的扩散系数大很多,表明乙硫醇分子在 MOR 体系孔道中有更快的传质速率。I<WP=4>南京工业大学硕士论文 摘要更多还原

【Abstract】 The conditions and mechanism of Zn2+ loaded on zeolite 13X and alumina werestudied by the orthogonal test. A series of desulfurizing adsorbents were prepared withzeolite 13X, alumina and 5A molecular sieves loaded with Zn2+ and Cu2+ by themethod of impregnation at ambient termperature and desulfurizing capability of thosewere investigated in model gasoline. The desulfurizing adsorbents were prepared withalumina and 5A loaded with metallic ions by the method of wave and thedesulfurizing capability were investigated in gasoline. The topology models of MFIand MOR were built and the method of Configurational-bias Monte Carlo(CBMC)simulation was used for investigating the adsorption and distributions of ethanethiolas adsorbate in MFI and MOR type zeolites. The diffusion of ethanethiol in MFI andMOR type zeolites was studied by molecular dynamics simulation.The results show, the concentration of Zn2+ is the most important factor of theloading quantity of zeolite 13X and alumina, and the temperature secondly. The pHvalue which range from 2 to 3 effects on the loading quantity faintly. The more thequantity of loading for zeolite 13X and alumina becomes, the heavier the Zn2+concentration is at a definite scale. The loading quantity for the zeolite 13X gets to themaximal capacity at about 16000mg/L and the Langmuir model satisfactorily fits forthe zeolite 13X. But for the alumina, the loading quantity gets to the maximal capacityat about 24000mg/L and the Freundlich model fits for the alumina well. The loadingof Zn2+ seems to reach the saturation which means the metallic ions had filled theavailable sites for zeolite 13X for about 30 hours and for alumina for about 10 hours.Loading of Zn2+ from the liquid phase to the solid phase can be considered as areversible first order reaction with an equilibrium being established between the twophases.The desulfurizing capability results show that the adsorptive amount anddemercaptan rate increase with the temperature increasing for zeolite 13X, aluminaand 5A loaded with Zn2+. The adsorbate molecules need a certain energy of activationto cross the potential barrier, so the adsorbed amount is enhanced with the increase ofthe temperature. The adsorptive amount of the unbaked adsorbents loaded with Zn2+ isless than the baked obviously, but the adsorbed amount is not enhanced distinctly bythe way of increasing the baking temperature. The desulfurizing capability increasesdue to the Zn2+ impregnated. It is effective to rise the demercaptan rate by enhancingthe temperature of Model gasoline for the zeolite 13X and alumina loaded with Cu2+.For 13X and alumina loaded with Cu2+, the demercaptan rate reach about 98% after 2 III<WP=6>南京工业大学硕士论文 ABSTRACThours adsorption, but it will need 6 hours to reach 95% for the 5A molecular sievesloaded with Cu2+. The adsorbed amount of the unbaked adsorbents loaded with Cu2+is less than the baked. The adsorptive capacity increases due to the Cu2+ impregnated.It is disadvantageous to the desulfurizing rate in the heavier concentration modelgasoline for the desulfurizing adsorbents.Desulfurizing Adsorbents regenerated by heat at 300℃ is better than by washedwith alcohol, but SO2 was brought into being by the way of regeneration by heat.However the period is long by the way of regeneration by washing with alcohol andeffect is not well.The calculated adsorption quantity by CBMC for MFI is close agreement withthe experimental data by means of IR spectroscopy and thermogravimetry. Thecalculated results show the adsorption quantity for ethanethiol in MFI is much morethan that in MOR under coequal conditions. The observation of distribution of MFI isattributed to preferential adsorption of the ethanethiol molecules in the straight andzig-zag channels. The diffusion coefficient for MOR is bigger than that for MFI., sothe velocity of mass transfer in MOR is quicker than that in MFI.更多还原