【作者】 张娟；

【导师】 赵地顺；

【作者基本信息】 天津大学 ， 工业催化， 2009， 博士

【摘要】 为了满足新的燃料油硫含量标准,人们加大了工业化加氢脱硫技术的改进研究和非加氢脱硫技术的开发研究力度。在众多的非加氢脱硫中,光化学氧化脱硫因其具有反应条件温和、工艺简单、非临氢操作等特点,成为近年来一个新的研究热点。本文以模型硫化物和柴油为研究对象,分别研究了核黄素/O₂、TiO₂/竹炭/ H₂O₂、钛硅分子筛/H₂O₂,两亲性钛硅分子筛/H₂O₂（O₂）体系的光催化氧化脱硫性能和影响因素,并研究了氧化反应机理和反应动力学,取得了创新性研究成果。1.以廉价无毒的核黄素为光敏剂,水为溶剂对DBT进行光敏化氧化脱硫。考察了核黄素浓度和空气流量对DBT脱硫效果的影响。结果表明,核黄素浓度为20mg/L,空气流速为80¹00mL/min,在最佳条件下反应2h,DBT脱硫率高达60%。核黄素是通过1O₂历程来敏化DBT的;该条件下的脱硫反应符合一级反应的动力学特征。质谱分析DBT氧化后的产物有DBT亚砜、DBT砜和硫酸根离子。2.以有着和洋葱状富勒烯（C60）和碳纳米管类似结构的竹炭（BC）为载体负载TiO₂,H₂O₂为氧化剂,光催化氧化DBT脱硫。考察了竹炭对DBT的吸附效果,TiO₂负载量、TiO₂/BC的用量和H₂O₂的浓度对DBT脱硫率的影响。结果表明,BC对DBT有着很好的吸附效果,吸附行为遵循Freundlich吸附等温线,吸附动力学为二级动力学。TiO₂/BC光催化氧化DBT的最佳反应条件为:TiO₂负载量15%（wt%）;H₂O₂的浓度O/S为14（mol）;催化剂用量为0.02g/10mL模型硫化物。在最佳条件下反应2h,DBT脱硫率高达66%。另外,我们还发现了TiO₂/BC可以位于油水界面处的这一特点,从而导致TiO₂/BC不同于其他光催化剂的反应模型。3.利用Ti（SO4）2液相同晶取代法和改进的微波法（在家用微波炉中）制备了含钛微孔分子筛Ti-NaY与Ti-β和介孔分子筛Ti-MCM-41。采用XRD,FT-IR,SEM和TEM,EDS和UV-Vis吸收光谱等表征手段,证明了液相同晶取代法成功了把Ti引进了分子筛骨架;证实了改进的微波法合成的Ti-MCM-41具有规则的MCM-41孔道结构和很好的长程有序性,且微波法合成的Ti-MCM-41孔径和紫外吸收强度均大于水热法合成的分子筛,光催化活性测试表明微波法合成的Ti-MCM-41光催化活性更高;并且此微波合成法晶化仅需40分钟,不仅节省了晶化时间,更重要的是大幅度降低了能耗,简化了操作方法,降低了设备要求。光催化氧化脱硫的活性顺序为:Ti-MCM-41>TS-1>Ti-NaY>Ti-β。4.使用三甲基氯硅烷（TMS）,二甲基二氯硅烷（DMS）和十八烷基氯硅烷（OTS）对实验室自制的几种不同孔径的钛硅分子筛进行表面改性制成两亲性钛硅分子筛,经过一系列XRD、FT-IR、SEM和BET等表征手段表征。结果表明,TS-1、Ti-β和Ti-MCM-41部分表面的均被三种表面改性剂改性,但是Ti-NaY仅被OTS进行了部分表面的改性,而其他两种没有改性成功。而且发现OTS-Ti-NaY结构严重塌陷,而其他几种两亲性分子筛晶相、形貌和孔结构没有明显变化。两亲性钛硅分子筛的活性顺序为: OTS-Ti-MCM-41> DMS-TS-1>TMS-Ti-β> OTS-Ti-NaY。光催化活性均比亲水性钛硅分子筛高,且催化剂用量大大减少。活性提高最大的是OTS-Ti-MCM-41,静止光照反应2h,DBT脱硫率就高达98%。两亲性钛硅分子筛重复使5次后,活性没有明显下降。用活性最高的OTS-Ti-MCM-41为光催化剂,改为空气为氧化剂,光照反应2h,DBT脱硫率也可高达85%。5.在前几章实验的基础上,以几种光催化体系,对含硫量为1500μg/g的真实柴油进行脱硫,以达到深度脱硫的目的。结果表明,在最佳反应条件下,反应8h,真实柴油脱硫的活性顺序为OTS-Ti-MCM-41>OTS-Ti-MCM-41/O₂>TiO₂/BC> RF/O₂。活性最好的OTS-Ti-MCM-41可以脱硫至30μg/g,OTS-Ti-MCM-41/O₂也可脱硫至50μg/g,均达到欧Ⅲ标准。另外又考察了烷烃,烯烃,芳烃和氮化物对DBT脱硫率的影响。结果发现烯烃和芳烃对脱硫均有一定程度的影响,而烷烃没有影响。实验中的几种光催化体系对含氮化合物均有不同程度的脱除,脱除氮化物活性顺序和脱硫顺序相同。更多还原

【Abstract】 Improvement of industrialized hydrodesulfurization and development of non-hydrodesulfurization have been steped up, in order to meet the new standards for sulfur content in the fuel oil. In the non-hydrodesulfurization, photochemical desulfurization is a novel method, which is easy to control and save energy, etc. This paper uses the model compounds and diesel oil as object. Photocatalytic oxidation desulfurization performance and factors of Riboflavin/O₂, TiO₂/BC/H₂O₂, Ti-containing molecular sieve/H₂O₂, amphiphilic Ti-containing molecular sieve/H₂O₂ and amphiphilic Ti-containing molecular sieve/O₂ are investigated in detail. The oxidation reaction mechanism and the reaction kinetics are also studied. The innovation research results are acquired.The following are the five parts of the paper.1.Oxidation desulfurization of DBT was carried out by using riboflavin （RF） as photosensutizer and water as sovent. Effect of RF concentration and air flow on removal ratio of DBT were investigated.The results show that the removal ratio of DBT is up to 60% under condition which are RF concentration 20 mg/mL, air flow 80¹00mL/min and irradiation time 2h. DBT was sensitized by RF through 1O₂ mechanism; the kinetics of oxidation of DBT is fist-order. Oxidation products are DBT monoxide, DBT sulfone and SO4-2 by mass spectra.2.Oxidation desulfurization of DBT was carried out by using TiO₂ supported on banmboo carbon （BC） which has a similar structure to C60 and carbon nanometer tube as photocatalyst and H₂O₂ as oxidant. Effect of adsorption of BC on DBT and effect of amount of loaded TiO₂ on BC, H₂O₂ concentration and amount of TiO₂/BC on removal ratio of DBT were investigated in detail. The results show that BC has very large adsorption capacity of DBT, the adsorption behaviour is described better by a monolayer Freundlich type isotherm and kinetic data follows a pseudo second-order model. The optimum reaction conditions are amount of loaded TiO₂ 15% （wt%）, H₂O₂ concentration O/S 14（mol） and amount of TiO₂/BC 0.02g/10mL model diesel. Removal ratio of DBT is up to 66% under optimum reaction conditions. In addition,we also found TiO₂/BC can locate just at the oil-water phase boundary, which lead to a different reaction model from other photocatalysts.3. Ti-NaY and Ti-βwere prepared using liquid-solid isomorphous substitution of Ti（SO₄）₂ method and Ti-MCM-41 was prepared using improved microwave heating method （in domestic microwave oven）. Prepared Ti-NaY, Ti-βand Ti-MCM-41 were characterized by XRD, FT-IR,SEM and TEM,EDS and UV-Vis. The results show that Ti was introduced in framework of molecular sieve successfully; Prepared Ti-MCM-41 has a regular structure, a good long order hexagonal arrangement and a stronger UV absorbance. Compared with the reported synthesis methods, the remarkable vantage of this method are simpler operation, shorter crystallization time （only 40 min）, lower energy consumption and facility request. The order of photocatalytic activity of Ti-containing molecular sieve is Ti-MCM-41>TS-1>Ti-NaY>Ti-β.4. Amphiphilic Ti-containing molecular sieve were prepared by partial modification of the external surface of TS-1, Ti-NaY, Ti-βand Ti-MCM-4 with trimethylchlorosilane （TMS）, dimethyldichlorosilane （DMS） octadecyltrichlorosilane （OTS）. XRD、FT-IR、SEM and BET were used to characterize the surface properties of these modified samples. The results show that partial modification of the external surface of TS-1, Ti-βand Ti-MCM-4 with three modifiers is successful,but partial modification of the external surface of Ti-NaY is only successful with OTS. In addition,the structure of OTS-Ti-NaY collapsed seriously,while other modified samples have no change for crystalline,pattern and pore structure. The order of photocatalytic activity of these modified samples is OTS-Ti-MCM-41> DMS-TS-1>TMS-Ti-β> OTS-Ti-NaY. Photocatalytic activity of these modified samples are higher and amount of photocatalysts is fewer than that of unmodified these samples. Removal ratio of DBT is up to 98% after static irradiation 2h by using OTS-Ti-MCM-41 as photocatalyst. Photocatalytic activity of amphiphilic samples don’t decrease obviously after reused for 5 times. Removal ratio of DBT can be up to 85% after static irradiation 2h by using OTS-Ti-MCM-41 as photocatalyst and air as oxidant.5. In order for deep desulfurization, oxidation desulfurization of diesel （sulfur content 1500μg/g） was carried out by using several photocatalytic systems mentioned in previous chapters. The results show that the order of photocatalytic activity to desulfurization of diesel is OTS-Ti-MCM-41 > OTS-Ti-MCM-41/O₂ > TiO₂/BC > RF/O₂. Sulfur content was reduced to 30μg/g in OTS-Ti-MCM-41 system and 50μg/g in OTS-Ti-MCM-41/O₂ system, which can meet European-Ⅲstandard. In addition, effects of paraffin, olefin, aromatic hydrocarbon and nitrogenous compounds on removal ratio of DBT were investigated. We found that olefin had greater effect on desulfurization than aromatic hydrocarbon, while paraffin had no effect on desulfurization. Nitrogenous compounds were also removed partly in these photocatalytic systems. The order of denitrification activity is the same as that of desulfurization activity in these photocatalytic systems.更多还原