【作者】 贾玉华；

【导师】 宁桂玲； 李钢；

【作者基本信息】 大连理工大学 ， 化学工艺， 2011， 博士

【摘要】 由于燃油燃烧所导致的环境破坏越来越严重,世界各国对油品中的硫、氮化物的限制也因此越来越严格,不断提出硫含量更低的燃油标准,传统的加氢脱硫工艺受到较大挑战。因此,探究其他更为经济、有效的脱硫途径已经是世界范围内关注的热点。氧化脱硫法因具有反应条件温和,不耗氢,操作简单,并能有效脱除加氢工艺中难以去除的硫化物等优点,而备受关注。本课题组在钛硅分子筛催化氧化脱除硫化物方面已经取得了较好的效果,鉴于氮化物与硫化物共存于油品中,本文首先研究了在钛硅分子筛/H202体系下,油品中典型的氮化物对硫化物脱除的影响。然而由于钛硅分子筛合成成本较高,大量极性溶剂的存在造成了油品损失,因此本文还在无溶剂的条件下,在MoO3/γ-Al2O3/H2O2体系中研究了硫或氮化物的氧化脱除。论文主要内容分为三部分。一、典型的含氮化合物对模拟油品中硫化物氧化脱除的影响。在以钛硅分子筛为催化剂,H202为氧化剂,有溶剂存在的条件下,研究了油品中典型的氮化物吡啶、喹啉、吡咯和吲哚对小分子的硫化物噻吩(Th)以及大分子的苯并噻吩(BT)和4,6-二甲基二苯并噻吩(4,6-DMDBT)氧化脱除的影响。结果表明：1.在TS-1/H2O2/H2O体系下,小分子的氮化物吡啶和吡咯对噻吩的氧化脱除存在较大的抑制作用,Th的脱除率均大大降低,碱性的吡啶较中性的吡咯影响更大。大分子的氮化物喹啉和吲哚由于分子较大,对噻吩的最终脱除率没有影响。2.在Ti-HMS/H2O2/Methanol体系中,分别引入氮化物喹啉和吲哚以及咔唑时, BT的初始脱除速率受到抑制,最终脱除率没有变化,均达到100%。氮化物喹啉、吲哚和咔唑及其氧化产物与BT分子在Ti-HMS活性中心上的竞争吸附限制了BT的吸附及氧化,从而降低了BT的氧化脱除速率。三环的咔唑分子对BT氧化脱除的影响小于喹啉和吲哚。3.通过喹啉和吲哚对4,6-DMDBT在Ti-HMS/H2O2/Methanol体系中脱除影响的研究,发现在体系中氮化物和硫化物之间的竞争吸附作用,是导致4,6-DMDBT的氧化脱除率降低的主要原因；碱性喹啉的对硫化物脱除的影响略高于中性的吲哚。二、模拟油品中硫化物在MoO3/γ-Al2O3/H2O2/无溶剂体系下的氧化脱除以MoO3/y-Al2O3为催化剂、无溶剂条件下,研究了硫化物的氧化脱除,得到如下的结果：1.发现硫化物的反应活性顺序为4,6-DMDBT>DBT>BT>Th,Th的氧化产物为H2SO4,其他三种硫化物的产物分别为各自的砜,反应过程中没有检测到亚砜的存在。而且硫浓度为150μg/g的4,6-DMDBT在反应至5 min时就已经被完全氧化脱除。2.在无溶剂条件下DBT的氧化脱除速度较快。由于溶剂(甲醇、乙腈)分子在催化剂活性中心上的吸附作用,大大的抑制了DBT的反应速率；当剂(甲醇)油比为1时,DBT在反应至120 min时的脱除率为91.5%；硫化物初始浓度越低,脱除速率越快；Mo03负载量为14 wt.%时的催化剂具有最好的催化氧化活性。3.使用过的催化剂通过甲醇溶液洗涤并烘干过夜,催化活性可以恢复,多次再生不影响MoO3/γ-Al2O3的活性,再生9次后催化剂活性没有降低。4.氮化物吡啶和喹啉的存在降低了Th的脱除率三、氮化物在MoO3/Al2O3/H2O2/无溶剂体系下的氧化脱除1.氮化物在MoO3/γ-Al2O3催化剂上的反应活性顺序为吡咯≈吲哚>喹啉≈吡啶,中性的氮化物较碱性的反应活性高。2.经过优化,在较佳的氧化脱除反应条件下喹啉的脱除率为74.9%。3.含磷钼源的使用提高了催化剂活性中心的分散度,增加了催化氧化中心的利用率,使得催化剂的活性提高约10%；当焙烧温度为873 K时,MoO3/γ-Al2O3具有较好的催化活性。4.研究了以MoO3/γ-Al2O3为催化剂,H202为氧化剂,无溶剂的条件下真实柴油和汽油中的氮化物的氧化脱除,结果表明柴油中氮化物的脱除率可达87.5%,汽油中的脱氮率为37.8%；柴油中的中性氮化物可完全被氧化脱除,碱性氮化物最难脱除。更多还原

【Abstract】 The automobile exhaust pollution becomes more and more serious, most countries establish very stringent sulfur and nitrogen level for liquid oil to reduce the pollution emission, and the traditional HDS technology is facing a great challenge to produce ultra-low sulfur level fuel. So it is necessary to find an economical and efficient process to obtain low sulfur and nitrogen level fuel.The oxidative desulfurization technology is focused widely, because the advantages of mild reaction conditions, hydrogen free, simple operational conditions, and the sulfur compounds have the best reactivity in oxidative processes which are the most refractory in hydrodesulfurization. Our group had worked on oxidative desulfurization under Titanium silicalite/H2O2 system for some years, sulfur containing compounds can be removed successfully in our oxidative system, but the N-containing compounds co-exist with S-containing compounds in the liquid fuel, so we investigate the effect of N-containing compounds on oxidative desulfurization over Titanium silicalite catalysts. Considering the high cost of the Titanium silicalite catalysts and the loss caused by the use of solvent, the oxidative desulfurization or denitrogenation are investigated over MoO3/Y-Al2O3 catalyst under mild and solvent free conditions. The paper includes major three parts:1. The effect of N-containing compounds on oxidative desulfurization of model liquid fuelThe effect of N-containing compounds (pyridine, pyrrole, quinoline, indole and kabazole) on oxidative removal of organosulfur compouds (Thiophene/Th, Benzothiophene/BT and 4, 6-Dimethyl dibenzothiophene/4,6-DMDBT) in model fuel is studied over Titanium silicalite with hydrogen peroxide, and get the following results:1. In the TS-1/H2O2/H2O system, the effect of pyridine and pyrrole on oxidative removal of Th is due to the competitive adsorption between sulfides and nitrides on the active centers of TS-1, the effect from pyridine is worse than that of pyrrole; quinoline and indole have no influence on the final removal rate of Th.2. In the Ti-HMS/H2O2/methanol system, BT initial removal rate decreases by the introduction of quinoline, indole or carbazole, and their oxidized products, no effect on the final BT removal rate. The effect from carbazole with three rings is less than that of quinoline and indole.3. The competitive adsorption between S and N-containing compounds on the active centers result in the decrease of removal rate of 4,6-DMDBT, the effect from Quinoline is worse than that of indole. 2. Efficient oxidative desulfurization (ODS) of model fuel with H2O2 catalyzed by MoO3/γ-Al2O3 under mild and solvent free conditionsTh, BT, DBT (Dibenzothiophene) and 4,6-DMDBT is dissolved in n-octane separately as model fuel. The oxidative removal of S-containing compounds in model fuel is carried out with H2O2 over MoO3/γ-Al2O3 and solvent free conditions, the results are:1. The trend of oxidative reactivity of sulfur containing compounds is:4,6-DMDBT> DBT> BT> Th,4, 6-DMDBT can be oxidized in 5 min completely with initial sulfur concentration of 150μg/g, DBT and BT can be oxidized efficiently over MoO3/γ-Al2O3. The oxidized products of BT and DBTs are their corresponding sulfones under the conditions described above, and sulfoxides were not detected in the products, the product of Th is H2SO4.2. The employments of solvents (methanol and acetonitrile) have decreased the reaction rate of DBT, DBT removal rate is 91.5% after reaction 120 min when methanol was used as the solvent, and the efficient removal can be achieved under solvent free conditions, the technology is applied to process low sulfur fuel. The catalyst with 14.2 wt.% MoO3 loading shows the best activity on oxidative removal of DBT.3. The activity of spent catalyst is as well as the fresh one which is washed by methanol at 333 K and dried at 373 K in air over night, the regeneration processing have no influence on the activity of the catalyst.4. Pyridine and quinoline dreacrse the removal rate of Th under solvent free conditions.3. Oxidative denitrogenation with MoO3/y-Al2O3 and H2O2 under solvent free conditionsIn this part, the oxidation of N-containing compounds is studied with H2O2 over MoO3/γ-Al2O3 under solvent free conditions, there are several findings as results:1. The reactivity of the N-containing compounds trend as follow:pyrrole≈indole> pyridine≈quinoline, the neutral compounds can be oxidized easier than the basic ones.2. Removal rate of quinoline can be achieved at 74.9% over 0.1 g MoO3/γ-Al2O3 at 333 K with a molar ratio H2O2 to N is 4.3. The removal rate of quinoline increases over MoO3/γ-Al2O3 with keggin structure Mo precursor, which is due to the formation of well disperately Mo-O particles. The catalyst calcined at 873 K shows best oxidative denitrogenation activity.4. The oxidative denitrogenation of real gasoline and diesel with H2O2 over MoO3/γ-Al2O3 under solvent free conditions are investigated. The result of oxidative denitrogenation of diesel is better than that of gasoline, which removal rate is 87.5%, and that of gasoline is 37.8%. The neutral N-containing compounds ones can be oxidized completely in this oxidative processing, and the basic are the most refactory ones.更多还原