【作者】 李江；

【导师】 刘洪涛； 刘波；

【作者基本信息】 北京化工大学 ， 化学工程（专业学位）， 2019， 硕士

【摘要】 介孔分子筛可作为FCC催化剂的活性功能组分,在重油催化裂化中具有重要的应用价值。本课题组采用前驱体组装法将微孔沸石的初级/次级结构单元引入到介孔孔壁中,合成了高水热稳定性介孔分子筛(其稳定性与USY相当),并在国际上首次进行了工业化生产及应用。然而,该合成过程中仍然存在模板剂利用率低(成本较高)和废水排放量大等不足。为了解决这些问题,论文进行了如下研究:1.聚乙二醇(PEG)与水形成氢键,可以降低溶液表面张力,部分PEG分子可以进入P123胶束内部与PEO作用,增强了胶束的亲水性和分散性,提高了高浓度体系中胶束的活性,进而降低了模板剂和水的消耗量。该合成过程中模板剂利用率和耗水量分别为1.05 g P123/g zeolite和20.8 g H2O/g zeolite,与传统常规方法相比,P123利用率提高约26.6%,耗水量降低约51.6%,合成成本降低约18.20%。样品总比表面积和总孔容分别为695.0 m2·g-1和0.79 cm3·g-1,水热处理后,保留率分别为36.9%和53.2%。另外,还考察了不同浓度和不同分子量的PEG对合成样品的结构和物化性质的影响。2.十二烷基醇醚硫酸钠(AES)的烷基链与P123的PPO段在疏水力作用下,可以形成P123-AES混合胶束。在AES的醚键和极性基头(—SO4-)的共同作用下,水分子向混合胶束靠拢,增强了胶束的亲水性和分散性,有利于前驱体围绕胶束进行组装,导向合成了高水热稳定性介孔分子筛。该合成过程中模板剂利用率和耗水量分别为1.0 g P123/g zeolite和19.9 g H20/gzeolite,与传统常规方法相比,P123利用率提高约30.0%,耗水量降低约53.7%,合成成本降低约24.9%。样品总比表面积和总孔容分别为693.5 m2·g-1和0.89 cm3·g-1,水热处理后,保留率分别为38.6%和48.3%。3.母液循环法通过回收再利用母液中残留的反应物(如硅、铝、P123和水等)合成介孔分子筛,大幅降低了模板剂和水的消耗量。但是随着母液循环次数增加,溶液浓度逐渐升高,P123胶束分散性降低且容易发生团聚,严重阻碍了无机物种围绕胶束进行组装,导致合成样品的有序性和水热稳定性较差。将AES引入母液循环工艺中,通过AES与P123作用,可以增强胶束的亲水性和分散性,有效抑制胶束的团聚。结合P123/AES复合模板剂和母液循环工艺合成了高水热稳定性介孔分子筛,模板剂利用率和耗水量分别为0.80 g P123/g zeolite和15.0 g H20/g zeolite。与传统常规方法相比,该合成过程中P123利用率提高约42.0%,耗水量降低约65.1%,合成成本降低约32.0%。样品总比表面积和总孔容分别为665.4 m2·g-1和0.77 cm3·g-1,水热处理后,保留率分别为32.1%和45.4%。综上所述,本文通过二元模板剂/母液循环合成了高水热稳定性介孔分子筛,同时大幅降低了合成成本,并降低了废水排放量,为介孔分子筛工业化应用奠定了基础。更多还原

【Abstract】 Mesoporous aluminatesilicates(MAs),which is an active functional component of FCC catalysts,play an important role in the process of heavy oil catalytic cracking.Our research group reported that MAs with high hydrothermal stability was obtained by introducing the primary/secondary building units of microporous zeolite into the mesoporous wall by precursor assembly strategy.The process had successfully realized the industrial production and application of MAs in the world for the first time,and hydrothermal stability of products was equivalent to that of USY.However,this method suffers from low utilization efficiency of the template and large wastewater discharge.In order to solve these problems,the following studies were carried out in this paper.1.Polyethylene glycol(PEG)formed hydrogen bonds with water to reduce the surface tension of the solution;meanwhile,some PEG molecules could enter the interior of P123 micelles and interact with PEO.It enhanced the hydrophilicity and dispersibility of the micelles,increasing the activity of the micelles in the high concentration system,and thus reduced the consumption of the template and water.In this process,the template utilization efficiency and the water consumption were 1.05 g P123/g zeolite and 20.8 g H2O/g zeolite,respectively.Compared with conventional method,P123 utilization increased by about 26.6%,water consumption decreased by about 51.6%,and synthesis cost decreased by about 18.2%.The total specific surface area(SBET)and total pore volume(VTotai)of the sample were 695.0 m2.g-1 and 0.79 cm3.g-1,respectively.The retention ratios were 36.9%and 53.2%after hydrothermal treatment,respectively.In addition,the effects of different concentration and molecular weights of PEG on the structure and physicochemical properties of samples were also investigated.2.P123-AES composite micelles were obtained by hydrophobic force between the alkyl chain of sodium alcohol ether sulphate(AES)and the PPO segment of P123.Meanwhile,the synergy of AES ether bond and polar head(—SO4-)induced water molecules moving closer to the composite micelles,which enhanced the hydrophilicity and dispersibility of the micelles.This strategy was conducive to the assembly of precursors around micelles,which guided the synthesis of MAs with high hydrothermal stability.In this process,the template utilization efficiency and the water consumption were 1.0 g P123/g zeolite and 19.9 g H2O/g zeolite,respectively.Compared with conventional method,P123 utilization increased by about 30.0%,water consumption decreased by about 53.7%,and synthesis cost decreased by about 24.9%.The total specific surface area(SBET)and total pore volume(VTotai)of the sample were 693.5 m2.g-1 and 0.89 cm3.g-1,respectively.The retention ratios were 38.6%and 48.3%after hydrothermal treatment,respectively.3.Mother liquor recycling method could realize the obtaining of MAs by recycling the reactants(such as silicon,aluminum,P123,water,etc.)remaining in the mother liquor,which greatly reduced the consumption of the template and water.However,as the mother liquor cycles increased,the enhanced concentration of solution would lead to the decreased dispersibility and subsequent agglomeration of P123 micelles.This seriously hindered the assembly of inorganic species around the micelles,resulting in poor orderliness and hydrothermal stability of the sample.AES was introduced into the mother liquor recycling process through the action of AES and P123,enhancing the hydrophilicity and dispersibility of the micelles.By combination of binary templates and mother liquor recycling,MAs with high hydrothermal stability was obtained effectively.In this process,the template utilization efficiency and the water consumption were 0.80 g P123/g zeolite and 15.0 g H2O/g zeolite,respectively.Compared with conventional method,P123 utilization increased by about 42.0%,water consumption decreased by about 65.1%,and synthesis cost decreased by about 23.0%.The total specific surface area(SBET)and total pore volume(VTotal)of the sample were 665.4 m2.g-1 and 0.77 cm3.g-1,respectively.The retention ratios were 32.1%and 45.4%after hydrothermal treatment,respectively.In summary,MAs with high hydrothermal stability was synthesized by binary composite templates/mother liquor recycling,which significantly reduced the synthesis cost and the wastewater discharge.This novel strategy sheds a light on the industrial application of MAs.更多还原