【作者】 艾硕；

【导师】 李鑫钢；

【作者基本信息】 天津大学 ， 化学工程， 2012， 博士

【摘要】 含硫燃油燃烧生成的尾气已经成为主要的大气污染源之一，脱除油品中的噻吩硫是环境保护的重点和难点。和其他脱硫方法相比，选择性吸附脱硫对含芳烃燃油品质的影响较小。考虑到纤维材料的外表面开放度很高、能促进流体传质，本文采用水相还原-脱水法把单质银负载于脱脂棉纤维表面，从而制备出了新型吸附脱硫剂。这种吸附剂具有银负载量极低、制备简便、能耗低、无毒物释放等优点。通过分析吸附试验、热重分析（TG）/差热分析（DTA）、环境扫描电子显微镜（ESEM-EDX）的有关数据，首次确定了含银吸附剂的活性组分是金属银而不是银离子。提出了关于络合吸附的表面极性协调机理：硝酸银和噻吩-正辛烷（模拟油）的极性相差很大，分子相互排斥；而单质银和噻吩-正辛烷的极性接近，分子相互吸引。在吸附试验中，预先不用溶剂排气，避免了无硫溶剂对硫含量检测的干扰。直接把500ppm的模拟油压入吸附柱，在恒温环境中进行固液吸附脱硫，考察了温度和停留时间对吸附容量的影响。通过场发射扫描电镜（FESEM）解释了在一定范围内的银棉脱硫率随负载量的降低而升高的现象。从吸附速率随温度升高而增加可以看出这种络合吸附的本质是化学反应。50℃时，脱硫率较大，2小时内的脱硫率达到27.6%。温度高于60℃时，脱硫率下降。绘制了30℃时的银棉的吸附等温线，从等温线可以看出络合吸附受噻吩浓度和吸附位点浓度的双重限制，也可以看出银棉吸附剂适于处理硫含量高于500ppm的模拟油。单位质量银棉吸附剂的床层压降为0.62KPa/g，而氧化铝和硅胶床层相应的压降值达到2.35和3.73KPa/g，分别是银棉吸附剂的3.8和6.0倍。56cm装填高度的氧化铝、硅胶的床层压降高达58.2KPa和63.8KPa，而相同装填高度银棉吸附剂的床层压降却仅有5.3KPa，氧化铝、硅胶单位床层高度的压降分别是银棉吸附剂的11和12倍。纤维吸附剂本身的开放式立体结构和低装填密度对床层压降的降低都有一定程度的贡献。在100℃下加热0.5h，用蒸发脱油法对银棉吸附剂进行了简单再生；提出了用浓缩-电解法回收银元素的工艺路线。对过氧化氢氧化脱硫进行了研究。脉冲式超声场对油水两相强烈的乳化作用会导致萃取效果的下降，不利于氧化-萃取脱硫。在60℃下，磷钨酸催化-司班80反胶团催化-DMF萃取氧化脱硫体系的平均脱硫率能达到84.6%。并提出了DMF、固体酸的再生方案。更多还原

【Abstract】 Exhaust gas generated from the combustion of sulfur-containing fuel oils hasbeen one of the main polluting sources of ambient air and the removal of thiophenicsulfur has been of great importance and difficulties. Selective adsorption hasdemonstrated minimal influence on the quality of aromatics containing fuelscomparing with other desulfurization pathways. Considering the exposed exterior offibers for mass transfer, metallic silver was supported on adsorbent cotton fibers and anovel adsorbent was prepared by aqueous reduction-dehydration method with virtuessuch as extra low silver loading （0.2wt%）, facile preparation, low energy consumptionand no toxics emission.On the basis of adsorption tests, thermo gravimetric analysis （TG）/differentialthermal analysis （DTA） and energy-dispersive X-ray spectroscopy （ESEM-EDX）, it isfirstly confirmed that the active component of adsorption is Ag⁰instead of Ag⁺. It isattributed to the distinct polarities of thiophene-octane （model oil） and AgNO₃thatthese molecules repulse with each other, while thiophene-octane and Ag⁰contactmutually on account of similar polarity. Superficial polarity congruity mechanismabout coordinative adsorption was proposed firstly.During adsorption tests, model oil （500ppmw sulfur） was pressed into anadsorption column without solvent for degassing to avoid the interference ofsulfur-free solvent. Temperature and retention time dependences of capacity wereinvestigated below60℃and at flow rates of0.2and0.3ml/min. The phenomenonthat sulfur removals increased as the declination of silver loadings has been elucidatedby Field Emission Scanning Electron Microscopy （FESEM）. The adsorption issubstantially coordinative reaction in view of the adsorption rate elevating as theimprovement of temperature. Higher capacities were determined at50℃in2h withan average sulfur removal of27.6%and the sulfur removal declined at above60℃.Adsorption isotherm was drawn on the basis of static adsorption tests at30℃. As canbe seen from the isotherm curve, the coordinative adsorption was constrained byeither the concentration of thiophene or the density of adsorption sites, andsilver/cotton is adaptive to deal with model oil with sulfur contents above500ppm. The bed pressure drop of per gram of silver/cotton is0.62KPa/g, while thepressure drops of alumina and silica are2.35and3.73KPa/g respectively, which are3.8and6.0times the amount of that of silver/cotton. Bed pressure drops of aluminaand silica with a loading height of56cm are58.2KPa and63.8KPa respectively,while that of silver/cotton is only5.3KPa. The pressure drops of alumina and silicawith a unit of loading height are11and12times the amount of that of silver/cotton.The open dimensional structure of fiber adsorbents with characteristics and lowloading density both contribute to the low pressure drop to some extent.The simple regeneration of silver/cotton was conducted via removing oil usingevaporation at100℃for0.5h. A recovery route of silver by concentration-electrolysiswas proposed.Oxidative desulfurization using peroxide has been investigated. Intenseemulsification effect on oil-water system resulting from pulsed ultrasound results inthe decrease of extractive efficiency, which is a disadvantage to oxidation-extractiondesulfurization.The oxidative desulfurization system comprising tungstophosphoric acid, reversemicelles catalyst and DMF extraction can reach an average sulfur removal of84.6%at60℃. A regeneration scheme of DMF and solid acid has been proposed.更多还原