【作者】 张瑾；

【导师】 孙印勇；

【作者基本信息】 哈尔滨工业大学 ， 化学工程与技术， 2019， 硕士

【摘要】 对苯二甲酸铬多孔材料如MIL-53(Cr)和MIL-101(Cr)因其具有较高比表面积和丰富孔隙结构等优点在诸多领域有着潜在的应用前景。然而,目前该类材料的合成需要在高温的水热条件下进行,这必然会带来高耗能和反应设备难以操控的问题,因此,对苯二甲酸铬多孔材料的低温合成是一项具有挑战性的研究工作。另外,燃油的吸附脱硫(ADS)因耗能低和易于操作等优点吸引了研究者的广泛关注,为此,新型燃油脱硫吸附剂的研发是一项热门的研究课题。针对以上课题,本论文探索了低温条件下对苯二甲酸铬多孔材料的合成,并在具有优异吸附脱硫性能对苯二甲酸铬材料MIL-53(Cr)的基础上进行了改性,研究了改性后MIL-53(Cr)的吸附脱硫性能,主要内容如下:首先,探索了低温条件下对苯二甲酸铬多孔材料的合成。在该合成体系下,探究了合成温度、合成时间、原材料的摩尔比、溶液的p H值等参数对所得材料性质的影响。研究结果表明,通过合成条件的优化,可制备出新的具有较低结晶度的对苯二甲酸铬多孔材料Cr-BDC-LT。由于Cr-BDC-LT结构的低有序性,使其能暴露出了丰富的金属催化活性位点,因而,与MIL-53(Cr)和MIL-101(Cr)相比,该材料作为催化剂在环己烯氧化反应中展现了较优异的催化性能。其次,评价了三种对苯二甲酸铬多孔材料在模拟燃油中的吸附脱硫性能,结果表明MIL-53(Cr)展现了较优异的吸附脱硫性能。为进一步改善其性能,在MIL-53(Cr)材料中尝试引入不同的金属作为吸附位点,结果发现金属银的负载对进一步提升MIL-53(Cr)的吸附脱硫性能最有效。在此基础上,系统考察了Ag负载的溶剂、负载物的浓度、煅烧时间、不同初始硫含量以及含硫分子的种类等参数对MIL-53(Cr)吸附脱硫性能的影响,发现在乙醇为溶剂、Ag与Cr原子比为0.12、空气下300℃煅烧6 h情况的吸附剂吸附DBT的效果最好。由于银与硫化物具有π相互作用,因而银负载的MIL-53(Cr)在DBT的ADS中展现出更为优异的吸附脱硫性能(94.2 mg S/g),比已报道的MIL-53(Cr)的吸附性能(86.4 mg S/g)更高。最后,针对MIL-53(Cr)-Ag吸附DBT后的再生问题,探索了MIL-53(Cr)-Ag吸附剂的再生方法,结果发现高温煅烧是一种有效的再生方法,利用此方法,吸附剂重复使用5次后其吸附量仍可达90 mg S/g,表明该材料可重复循环使用具有潜在的工业应用前景。更多还原

【Abstract】 Chromium terephthalate porous materials have potential applications in many fields due to their high specific surface areas and abundant pore structures such as MIL-53(Cr)and MIL-101(Cr).However,at present,the synthesis method of such materials needs to be carried out under high temperature hydrothermal conditions,which inevitably leads to problems of high energy consumption and difficulty in handling the reaction equipment.Therefore,the synthesis of chromium terephthalate porous material at low temperature is a challenging research work.In addition,the adsorption desulfurization(ADS)of fuel attracts the researchers’ attention because of its low energy consumption and easy operation.Therefore,the development of new fuel desulfurization adsorbents is a hot research topic.In view of above problems,this thesis explores the synthesis of chromium terephthalate porous materials under low temperature conditions,and modified it based on MIL-53(Cr)with excellent adsorption and desulfurization performance.The adsorption and desulfurization performance of modified MIL-53(Cr)is as follows:Firstly,the synthesis of chromium terephthalate porous materials under low temperature conditions was explored.Under the synthesis system,the effects of parameters such as synthesis temperature,synthesis time,molar ratio of raw materials,pH value of the solution on the properties of the obtained materials were investigated.The results show that a new chromium-terephthalate porous material Cr-BDC-LT with lower crystallinity can be prepared by optimization of synthesis conditions.Due to the low order of the Cr-BDC-LT structure,it can expose a rich metal catalytic active site.Therefore,Cr-BDC-LT exhibits a superior catalytic performance in the oxidation reaction of cyclohexene compared with MIL-53(Cr)and MIL-101(Cr).Secondly,the adsorptive desulfurization performance of three kinds of chromium terephthalate porous materials in simulated fuel oil was evaluated.The results show that MIL-53(Cr)exhibits superior adsorption desulfurization performance.In order to further improve its performance,we attempt to introduce different metal as adsorption sites in MIL-53(Cr)materials.The results show that silver is the most effective loading metals for further enhancing the adsorption desulfurization performance of MIL-53(Cr).Then,based on the Ag loaded MIL-53(Cr)materials,the effects of parameters such as solvent,load concentration,calcination time,different initial sulfur content and sulfur-containing molecules on the adsorption and desulfurization performance of MIL-53(Cr)were investigated systematically.Adsorbent in the case of ethanol as solvent,Ag to Cr atomic ratio of 0.12,and air calcination at 300 °C for 6 h performed the best effect of DBT adsorption.Silver-supported MIL-53(Cr)performs a superior DBT adsorption desulfurization properties(94.2 mgS/g)using ADS method due to the π interaction of silver with sulfide which is higher than the reported MIL-53(Cr)with the adsorption performance of 86.4 mgS/g.Finally,for the regeneration of MIL-53(Cr)-Ag after adsorption of DBT,the regeneration method of MIL-53(Cr)-Ag adsorbent was explored.It was found that high temperature calcination is an effective regeneration method.After 5 times of repeated use of the adsorbent by the high temperature method,the adsorption amount can still reach 90 mgS/g,indicating that the material can be recycled and has potential industrial application prospects.更多还原