NSF/EPA: Hydrogen Formation and Transfer in Alkane Reactions Catalyzed by Cation-Modified Zeolites

摘要- Enrique Iglesia CTS-9613632 通过有效利用氢气，可以减少燃料及其前体加工过程中的环境影响。这是许多石油加工操作的关键组成部分，通常用于异构化（涉及氢转移步骤的反应）、脱氢环化、脱硫和加氢处理等反应中。目前用于这些反应的催化剂的选择性的限制是对催化位点要求的了解不足。该建议制定了一项研究的阳离子交换到pentasil沸石的网站，在结构，光谱学，和催化反应，作为表征手段。作者在最近的项目中进行了相关的工作，并成功地展示了在该项目中要开发的技术的使用。交换的阳离子的结构将通过X射线吸收光谱测定。将使用动力学和H-D交换反应和原位红外光谱来检查这些站点的H-转移和处置。通过添加氢清除剂如O2、CO2、CnHx等，将增强耦合的加氢-加氢反应，并确定这种偶联对烷烃脱氢选择性的作用。含硫化合物将被探索作为活化烷烃的氢受体，并且将测试这样的假设：通过偶联氢转移可以更有效地对此类化合物进行加氢脱硫。在轻质烷烃或H2存在下，ZSM 5中刘易斯酸位点上吸附的噻吩类化合物的红外光谱、同位素交换和与含硫分子的化学测试反应也将是本研究的一部分。

Abstract - Enrique Iglesia CTS-9613632 Environmental impact during processing of fuels and their precursors can be reduced via efficient utilization of hydrogen. This critical component of many petroleum processing operations is used nonselectively in reactions such as isomerization (those that involve hydrogen-transfer steps), dehydrocyclization, desulfurization and hydrotreatment in general. A limit to the selectivity of current catalysts used for those reactions is the insufficient knowledge about catalytic sites requirements. This proposal formulates a study of cationic sites exchanged into pentasil zeolites, in terms of structure, spectroscopy, and catalytic reactions, as means of characterization. The author has produced related work in recent projects, and successfully demonstrated the use of the techniques to be exploited in this project. The structure of exchanged cations will be determined by X ray absorption spectroscopy. The H-transfer and disposal by those sites will be examined using kinetic and H-D exchange reactions and in-situ infrared spectroscopy. Coupled dehydrogenation-hydrogenation reactions will be enhanced by addition of hydrogen scavengers such as O2, CO2, CnHx, etc., and the role that such coupling has on alkane dehydrogenation selectivity will be determined. Sulfur-containing compounds will be explored as hydrogen acceptors for activation of alkanes, and the hypothesis will be tested that more efficient hydrodesulfurization of such compounds is possible by means of coupled hydrogen transfer. Infrared spectroscopy of adsorbed thiophenic compounds on Lewis acid sites in ZSM5 in the presence of light alkanes or H2, isotopic exchange and chemical test reactions with sulfur-containing molecules will also be part of this study.