【作者】 刘静；

【导师】 刘东；

【作者基本信息】 中国石油大学(华东) ， 化学工程与技术， 2016， 硕士

【摘要】 减压馏分油（VGO）是催化裂化生产汽油和柴油的重要原料,但大部分VGO原料中含有大量的硫化物,因此减压馏分油的脱硫过程是生产低硫或超低硫燃料油的关键。VGO中的硫大部分是以大分子硫化物如苯并噻吩,二苯并噻吩,4,6-二甲基二苯并噻吩及其复杂衍生物的形式存在,采用加氢脱硫工艺脱除这些硫化物时具有较大的难度,对设备、工艺条件及催化剂的要求较高。因此,非加氢脱硫工艺逐渐被众多研究人员重视,其中氧化脱硫工艺因具有反应条件温和、脱硫效率较高、操作成本较低的优点,成为研究热点。本文采用溶胶-凝胶法合成了氧化硅,采用阴-阳离子双水解法合成了氧化铝,以氧化硅和氧化铝为载体,采用等体积浸渍法制备MoO₃/SiO₂和MoO₃/Al₂O₃负载型催化剂。分别考察了氧化硅和氧化铝的合成条件对催化剂孔结构和VGO脱硫效果的影响。结果表明,氧化硅的最佳合成条件:硅源浓度为0.68 mol/L,十六烷基三甲基溴化铵与正硅酸乙酯的摩尔比为11∶50,陈化时间为2 h;氧化铝的最佳合成条件:P123与H₂O的质量比为1∶21.5,反应体系的pH为8,晶化温度为120℃。对MoO₃/SiO₂催化剂,引入了络合剂柠檬酸,金属助剂硝酸铈、硝酸镧和硝酸铁进行改性,研究表明改性催化剂的脱硫活性顺序为:Ce-MoO₃/SiO₂>Fe-MoO₃/SiO₂>CA-MoO₃/SiO₂>La-MoO₃/SiO₂。对MoO₃/Al₂O₃催化剂,引入了络合剂柠檬酸,金属助剂硝酸铈和碳酸钾进行改性,并对氧化铝载体进行了离子交换预处理。结果表明,改性催化剂的脱硫活性顺序为:MoO₃/Al₂O₃-IX>Ce-MoO₃/Al₂O₃>K-MoO₃/Al₂O₃>CA-MoO₃/Al₂O₃。通过不同催化剂的脱硫效果及催化剂表征分析对比,发现催化剂表面四配位的[MoO₄]^2-和六配位的[MoO₆]^6-都是氧化脱硫的活性中心,但六配位的[MoO₆]^6-的催化活性高于四配位的[MoO₄]^2-。以Ce-MoO₃/SiO₂为催化剂,30 wt%H₂O₂为氧化剂进行VGO的催化氧化脱硫实验研究,优化其工艺条件。研究表明,VGO氧化过程的最佳工艺条件为:氧化温度为70℃,n（O/S）为8,氧化时间为2 h,催化剂加入量为15 wt%;萃取过程的最佳工艺条件为:选取DMF为萃取剂,萃取时间为45 min,萃取温度为30℃,此时脱硫率为68.5%。以自制的氧化铝为吸附剂载体,采用液相离子交换法用0.1 mol/L的Ce（NO₃）₃、La（NO₃）₃、Fe（NO₃）₃、Cu（NO₃）₂溶液在固液比为1∶20时制备不同的阳离子改性吸附剂,并考察了改性吸附剂的静态吸附脱硫性能。结果表明,改性吸附剂的脱硫效果依次为Cu-Al₂O₃>Fe-Al₂O₃>La-Al₂O₃>Ce-Al₂O₃。以Cu-Al₂O₃为吸附剂,在油剂比为10∶1,吸附温度为50℃,吸附时间为3 h时,VGO静态吸附脱硫的脱硫率为40.5%。更多还原

【Abstract】 Vacuum gas oil（VGO）is the major feed to produce gasoline and diesel by FCC.There are so many sulfides in the most VGO feed that desulfurization process of VGO is quite important to produce low-sulfur or ultra-low-sulfur fuel oil.The sulfides in VGO exist in form of benzothiophene,4,6-dimethyldibenzothiophene and their derivatives,which increase the difficulties to HDS,such as high temperature,high hydrogen pressure and high activity catalysts.As a result,non-hydrogenation desulfurization processes（NHDS）are taken seriously by a large number of researchers.And among those NHDS,oxidative desulfurization process（ODS）is chosen to research because it has many advantages such as mild reaction conditions,high desulfurization efficiency and low operating cost.In this paper,SiO₂ was synthesized by sol-gel method and Al₂O₃ was synthesized by cation-anion double hydrolysis method.The supported catalysts MoO₃/SiO₂ and MoO₃/Al₂O₃ were prepared by incipient impregnation method with the SiO₂ and Al₂O₃ as support respectively.The effect of different synthesis conditions of SiO₂ and Al₂O₃ on the pore structure and oxidative desulfurization have been investigated respectively.The results indicate that the optimum synthesis conditions of SiO₂ are concentration of silica source of0.68 mol/L,CTAB/TEOS mole ratio of 11:50 and aging time of 2 h;the optimum synthesis conditions of Al₂O₃ are P123/H₂O mass ratio of 1:21.5,pH of 8 and crystallization temperature of 120^oC.Then MoO₃/SiO₂ was modified by the introduced citric acid（CA）,Ce（NO₃）₃·6H₂O,Fe（NO₃）₃·9H₂O and La（NO₃）₃·6H₂O.The order of their desulfurization performance is Ce-Mo O₃/SiO₂>Fe-MoO₃/SiO₂>CA-MoO₃/SiO₂>La-MoO₃/SiO₂.And MoO₃/Al₂O₃ was also modified by the introduced citric acid（CA）,Ce（NO₃）₃·6H₂O and K₂CO₃;what’s more the Al₂O₃ support was pretreated by NH₄Cl solution.The order of their desulfurization performance is MoO₃/Al₂O₃-IX（Ion Exchange）>Ce-MoO₃/Al₂O₃>K-MoO₃/Al₂O₃>CA-MoO₃/Al₂O₃.The researches indicate that both tetra-coordinated[MoO₄]^2-and hexa-coordinate[MoO₆]^6-are the active sites of oxidative desulfurization reaction,whereas the activity of hexa-coordinate[MoO₆]^6-is superior to tetra-coordinated[MoO₄]^2-.The conditions of catalytic oxidative desulphurization reactions were optimized with Ce-MoO₃/SiO₂ as catalyst and H₂O₂ as oxidant.And the best conditions of oxidation process are reaction temperature of 70^oC,n（O/S）of 8,reaction time of 2 h and dosage of catalyst of 15wt%;The best conditions of extraction process are DMF as extractant,extraction time of 45min and extraction temperature of 30^oC.The desulphurization rate under the optimal condition was as high as 68.5%.Different cationic modified adsorbents named as Ce-Al₂O₃,La-Al₂O₃,Cu-Al₂O₃,Fe-Al₂O₃ were obtained by liquid-phase ion exchange between 0.1 mol/L Ce（NO₃）₃,La（NO₃）₃,Cu（NO₃）₂,Fe（NO₃）₃ solution and Al₂O₃,respectively.The results indicated the order of their static adsorptive desulfurization performance was Cu-Al₂O₃>Fe-Al₂O₃>La-Al₂O₃>Ce-Al₂O₃.Then the conditions of adsorptive desulfurization were researched with Cu-Al₂O₃ as adsorbent.And the optimal conditions are adsorbent/oil ratio of 10:1,reaction temperature of 50^oC and reaction time of 3 h,under which conditions the desulfurization rate was 40.5%.更多还原