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多金属氧酸盐催化油品深度脱硫的方法研究

Study on Deep Desulfurization of Fuel Oil with Polyoxometalates as Catalysts

【作者】 张高飞

【导师】 王睿;

【作者基本信息】 山东大学 , 环境工程, 2009, 硕士

【摘要】 油品消耗过程中产生的二氧化硫(SO2)是主要的大气污染物之一,也是形成酸雨的前驱物之一。因此,各国对油品制定了严格的标准来控制硫含量,油品脱硫受到了广泛的重视。油品脱硫方法主要分为加氢脱硫(HDS)和非加氢脱硫(NHDS)两大类。加氢脱硫技术比较成熟,在工业中已经得到广泛的应用,但是其一次性投资较大,运行成本高、需要消耗大量的氢气,而且难以达到深度脱硫的效果。非加氢脱硫不需要氢源,而且能够满足深度脱硫的要求,因此成了各国研究人员的研究重点,而近几十年来研究最多的非加氢脱硫法是氧化脱硫(ODS)技术。氧化脱硫是在常压、100℃以下利用氧化剂将有机硫化物转化成极性较强的物质,再通过萃取或吸附将其分离脱除。氧化脱硫一般都需要催化剂,因此,选择优良的催化剂对脱硫效果至关重要。将环境友好型杂多化合物(heteropoly compounds,简写为HPCs)应用于油品的催化氧化脱硫,显示了很好的研究开发前景。本论文通过系统的实验设计与优化,制备并考察了杂多化合物及其负载型的催化剂对油品中两种比较难脱除的硫化物-噻吩(TH)和二苯并噻吩(DBT)的脱除效果,从而选择出合适的氧化脱硫催化剂,并考察了其反应机理。主要内容分为:第一部分,考察了杂多酸及其盐的催化氧化脱除噻吩的效果,结果表明:H3PMo6W6O40为最佳的杂多酸催化剂,其最佳的工艺条件为:反应温度为60℃,氧硫比为15,硫含量为500ppm,反应210min,此时,噻吩的转化率为94.3%;当选择容易回收的杂多酸铯盐为催化剂时,Cs2.5H0.5PMo12O40具有最高的噻吩转化率,其工艺条件为:当硫含量为800ppm时,反应温度为65℃,氧硫比为20,最佳反应时间为40min,此时,噻吩的转化率为73.8%。第二部分,考察了杂多酸、负载杂多酸盐的催化氧化脱除二苯并噻吩的效果,结果表明:H3PMo6W6O40为最佳的杂多酸催化剂,其最佳的工艺条件为:催化剂用量为模拟油品质量的1%,反应温度为60℃,氧硫比为15,硫含量为500ppm,反应90min,此时,DBT的转化率为100%;当选择容易回收的Cs2.5H0.5PW12O40/CNT为催化剂时,达到最高的DBT转化率时其工艺条件为:当硫含量为500ppm时,反应温度为60℃,氧硫比为20,Cs2.5H0.5PW12O40/CNT中Cs2.5H0.5PW12O40的量为模拟油品质量的0.5%,DBT的转化率为86.4%;当以10%H3PMo12O40-NaY为杂多酸催化剂,其最佳的工艺条件为:催化剂用量为模拟油品质量的1%,反应温度为60℃,氧硫比为20,硫含量为500ppm,反应180min,此时,DBT的转化率为84.1%;(3)对模拟油品中硫化物的氧化产物进行了分析,结果表明:噻吩的氧化产物大部分为SO42-,并产生微量的苯乙烯生成;DBT的氧化产物为相应的砜。

【Abstract】 A large amount of sulfur dioxide (SO2) ,which is one major air pollutants and the precursors of acid rain , are generated in the fuel oil consumption process. Therefore, strict standards have been issued by many countries to control the sulfur content in the fuel oil, and desulfurization technology has received much attention. The desulfurization technologies are divided into two main categories: hydrodesulfurization (HDS) and non-hydrodesulfurization(NHDS). HDS is one kind of matural technology, and has been widely applied commercially, but it has several disadvantages, such as high investmentin one lump sum, high operating costs, large consumption of hydrogen,and it cannot reach the goal of deep desulfurization. NHDS does not require hydrogen and is in accordance with the requirements of the deep desulfurization, so NHDS has becoming the focus of worldwide researches. In the last decade, oxidative desulfurization (ODS) has been studied intensively. ODS is operated at atmospheric pressure and a reaction temperature of below 100℃, the organic sulfides are oxidized to stronger polarity matters by oxidatants, and the products can be seperated by extraction or absorption. However, catalysts are necessary in ODS, therefore, good catalysts are particularly important. Heteropoly compounds (HPCs) are functional material which are unharmful to the environment. Using heteropoly compounds as catalysts for oxidative desulfurization has shown good prospect of research and process development.In this paper, several kinds of HPCs and supported HPCs were prepared and evaluated concerning their desulfurization efficiencies to two kind of sulfides that are difficult to remove: thiophene(TH) and dibenzothiophene(DBT), among which excellent catalysts for ODS are selected. The mechanism of the process of ODS was also revealed in this paper.The paper is composed of three sections.In the first section, the desulfurization of TH by heteropoly acid and their salts are evaluated. Results showed that H3PMo6W6O40 is the best heteropoly acid catalyst for the desufuriztion of TH, and the optimum conditions were as follows: reaction temperature, 60℃; oxygen to sulfur ratio, 15; the sulfur content, 500ppm; the reaction time, 210min; thiophene conversion rate was of 94.3%. When the cesium salts of heteropoly acid were used as the desulfurization catalyst, Cs2.5H0.5PMo12O40 achieves the highest thiophene conversion rate of 86.4%, the process conditions were as follows: sulfur content, 800ppm; reaction temperature, 65℃; oxygen to sulfur ratio, 20, reaction time, 40min; corresponding to a thiophene conversion rate of 73.8%.In the second section, the desulfurization of DBT by heteropoly acid and their supported salts were evaluated, results showed that H3PMo6W6O40 is the best heteropoly acid catalyst for the DBT desufuriztion , and the optimum conditions were as follows: the amount of catalyst, 1% the mass of the simulation fuel oil; reaction temperature, 60℃; oxygen to sulfur ratio, 15; sulfur content, 500ppm; reaction lasted time 90min; corresponding to a DBT conversion rate of nearly 100%. When Cs2.5H0.5PW12O40/CNT was chosen as the desulfurization catalyst, the highest conversion rate of DBT was achieved at the following conditons: sulfur content, 500ppm; reaction temperature, 60℃; oxygen to sulfur ratio, 20; reaction time, 150min. When 10%H3PMo12O40-NaY was selected as catalyst, the optimum conditions were as follows: the amount of catalyst, 1% the mass of the simulated fuel oil, reaction temperature, 60℃; sulfur to oxygen ratio, 20; sulfur content, 500ppm; reaction time, 180min; the corresponding DBT conversion rate, 84.1%.In the third section,the products from the oxidation of the simulated fuel oil were analysed, results showed that the oxidation products of thiophene were mostly SO42-, and also trace amount of styrene was generated; and the oxidation products of DBT was the corresponding sulfone species only.

  • 【网络出版投稿人】 山东大学
  • 【网络出版年期】2010年 05期
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