INVESTIGATION OF FACTORS AFFECTING ADSORPTION CAPACITY AND SELECTIVITY OF ACTIVATED CARBON IN HIGHLY EFFICIENT DESULFURIZATION OF DIESEL FUEL

最近的环境法规将汽油中的硫含量限制为30 ppm，柴油中的硫含量限制为15 ppm（2006年）。尽管在越野燃料中，含硫量500 ppm仍然是可以接受的水平，但到2010年，这一限制被设定为15 ppm。加氢脱硫（HDS）是一种能够脱除化石燃料中大部分含硫化合物的方法。尽管HDS具有高效率和已确立的技术重要性，但它不能完全去除二苯并噻吩。特别是4,6 -二甲基二苯并噻吩被认为对任何化学反应都具有抗性。在这里提出的研究计划中，我们试图定义控制深度脱硫过程的碳质吸附剂的特征，并开发高效的柴油脱硫介质。我们目标的去除过程是基于DBT和4,6 - dmdbt从极低浓度的20 ppm硫中的反应吸附。在“最佳情况”下，噻吩分子首先会被特异性吸附在催化金属中心/杂原子基团上，然后碳硫键断裂，硫保留在表面，碳氢化合物分子返回到燃料流中。在“最坏情况”下，DBT和4,6- dmdbt分子将在孔系统中特异性吸附在金属氧化物、硫化物、硫、氮、磷或含氧中心上。可以存在各种介于两者之间的交互场景。我们将提供详细的实验程序，以制备最有效的去除介质（从容量，选择性和再生可行性的角度）以及该过程的机制。吸附剂的液相脱硫性能与其表面特征有关。这将为设计更高效和更具成本效益的吸附剂和催化剂开辟新的途径。我们对文献和研究经验的回顾导致了以下与实现我们的目标和开发新技术相关的研究问题：1)哪种碳化温度可以产生最有效的吸附剂/催化剂？2)哪些杂原子增强了吸附的能力和选择性？3)哪些金属/表面基团或它们的组合是最有效的脱硫催化剂？4)哪种金属含量的容量最大？5)表面反应的产物是什么（如果有）？6)吸附机理是什么？7)我们能有效地再生废吸附剂吗？8)能否设计一种吸附剂（基于商业碳质前驱体），其表面特征可以有效地对柴油进行深度脱硫？所提出的研究直接关系到新材料的开发和柴油及其他重质燃料馏分脱硫技术的改进。由于新的环境法规，不仅在美国，而且在世界范围内，石油化工、化工和发电行业对从噻吩类中提取硫的新型吸附剂和催化剂产生了极大的兴趣。该技术除了降低未来低硫燃料的成本外，还可能对燃料电池的发展具有重要意义，因为在燃料电池中，无硫氢源是第一优先考虑的技术，因为重整催化剂被硫化合物中毒。这项研究还将产生一类新的吸附剂和催化剂，它们可能会在涉及分子分离的其他科学挑战中得到应用。此外，广泛的表面表征方法的应用将对更好地理解碳和碳质吸附剂的表面化学产生影响。建议的研究与当代社会面临的环境问题有关。首先，它将开发相对简单的技术，以符合将在不久的将来开始实施的环境法规。通过降低燃料中的硫含量，将减少二氧化硫的排放，从而减少酸雨事件及其对环境和人类健康的有害影响。而且，昂贵的汽车尾气催化剂的使用寿命也会延长。一名研究生和一名本科生将参与该项目。由于CCNY是一所少数族裔服务机构，因此来自代表性不足群体的学生很有可能参与这项研究。这将对少数民族环境意识的培养产生积极的影响。其他重要的教育方面是新环境/物理的发展。化学实验由本科生参与研究（自主研究本科生课题）和研究生共同完成？本科团队的工作方法，包括研究/解决问题的所有步骤，包括检索文献资源，熟悉科学仪器的操作原理，能够概述研究论文和研究计划。

0930858BandoszRecent environmental regulations set the limits of sulfur in gasoline to 30 ppm and in diesel fuel to 15 ppm (2006). Even though in the off-road fuel 500 ppm of sulfur is still an acceptable level, the limits are set to be 15 ppm by 2010. Hydrodesulfurization (HDS) is a method, which is able to remove the majority of sulfur-containing compounds from fossil fuel. In spite of the high efficiency and established technological importance of HDS it is not able to remove completely dibenezothiophenes. Especially 4,6 - dimethyldibezothiophene is considered as resistant to any chemical reactions. In the research program proposed here we seek to define the features of carbonaceous adsorbents that govern the deep desulfurization process and to develop efficient diesel fuel desulfurization media. The removal process we target is based on reactive adsorption of DBT and 4, 6-DMDBT from very low concentration of 20 ppm sulfur. In the "best case scenario", thiophenic molecules will first be specifically adsorbed on the catalytic metal center/ heteroatom containing groups and then the breaking of the carbon sulfur bond will occur with retention of sulfur on the surface and a return of the hydrocarbon molecule to the fuel stream. In the "worse case scenario", the DBT and 4,6-DMDBT molecules will be specifically adsorbed in the pore system on metal oxides, sulfides, sulfur, nitrogen, phosphorus or oxygen containing centers. Various scenarios of the in-between interactions can exist. We will provide the detailed experimental procedure for the preparation of the most efficient removal media (from the point of view of the capacity, selectivity and regeneration feasibility) along with the mechanism of the process. The performance of adsorbents in desulfurization from liquid phase will be linked to their surface features. This will open new routes for designing more efficient and cost effective adsorbents and catalysts. Our review of the literature and research experience lead to the following research questions related to achieving our objectives and to the development of new technology: 1) Which temperature of carbonization does lead to the most effective adsorbent/catalyst? 2) Which heteroatoms do enhance the capacity and selectivity of adsorption? 3) Which metals/ surface groups or their combinations are the most effective desulfurization catalysts? 4) Which content of metal does result the highest capacity? 5) What are the products of surface reactions (if any)? 6) What is the mechanism of adsorption? 7) Can we efficiently regenerate the spent adsorbents? 8) Can we design an adsorbent (based on the commercial carbonaceous precursors) with the surface features leading to the effective deep desulfurization of diesel fuel? The proposed research is directly relevant to developing new materials and improving technologies of desulfurization of diesel fuel and other heavy fuel fractions. Due to new environmental regulations, not only in the US but also worldwide, there is a great interest in petrochemical, chemical and power generating industries in new adsorbents and catalysts for withdrawal of sulfur from thiophenic species. The technology developed besides lowering the cost of future low sulfur level fuel, may also prove to be important for development of fuel cell, cutting edge of technology, where sulfur free hydrogen source is the first priority due to the poisoning of the reforming catalysts by sulfur compounds. The research will also lead to a new class of adsorbents and catalysts, which may find application in other scientific challenges where the separation of molecules is involved. Moreover, the broad spectrum of surface characterization methods applied will have an impact on better understanding the surface chemistry of carbon and carbonaceous adsorbents in general. The proposed research is relevant to environmental problems facing contemporary society. First, it will develop the relatively simple technology in compliance with environmental regulations to be commenced in the near future. By decreasing the level of sulfur in fuel, the emissions of SO2 will be reduced, which will lead to the reduction in acid rain incidents and their detrimental effects on the environments and human health. Moreover, the lifetime of the automobile exhaust expensive catalyst will be prolonged. One graduate student and one undergraduate student will work on the project. Since CCNY is a minority serving institution there is a high probability that students from underrepresented groups will be involved in the research. This will have a positive effect on the development of environmental awareness in the minority group. Other important educational aspects are the development of new environ./phys. chemistry experiments by the undergraduate student involved in the research (independent research undergraduate project) and the graduate ?undergraduate teem working approach with all steps of research/problem solving including searching literature resources, familiarity with the principles of operation of scientific instruments and the ability to outline research theses and research plans.