CAREER: Synthesis Methods to Control Framework Aluminum Distribution in Zeolites for NOx Pollution Abatement Catalysis

摘要(Gounder；1552517)这项研究将开发新的合成策略来控制沸石催化剂中铝(Al)活性中心的分布，用于减少氮氧化物(NOx)和将碳原料转化为燃料和化学品。调整沸石中活性中心的接近程度和分布将为环境保护和碳转化领域的催化创新提供新的机会，同时也为沸石结晶的化学提供新的见解。这项研究将与STEM领域的各级学生的教育和指导倡议相联系。目前，人们对沸石中铝原子的原子排列与用于合成分子筛的前体溶液和凝胶的化学之间的关系知之甚少。这项工作是基于这样一个假设，即沸石中与催化相关的孤立和成对的Al中心的分布可以通过合成凝胶的电荷密度来控制。主要研究者已经证明，孤立和成对的铝中心在铜(铜)交换沸石选择性催化还原NOx(SCR)中起着重要作用。本研究将建立一系列沸石合成凝胶电荷密度与成对铝密度之间的预测关系，建立骨架铝分布与骨架外铜分布之间的关系，并确定它们在NOx SCR反应中的动力学和机理作用。在之前合作研究的基础上，PI将利用表征工具，快速量化质子和金属交换沸石上的总酸位和配对酸位的数量，从而促进合成-结构-功能关系的发展，这些关系可用于为一系列应用量身定制沸石。

Abstract (Gounder; 1552517)This study will develop new synthesis strategies to control the distribution of aluminum (Al) active sites in zeolite catalysts used for nitrogen oxides (NOx) abatement and carbon feedstock conversion to fuels and chemicals. Tailoring active site proximity and distribution in zeolites will open new opportunities for catalytic innovation in both the environmental protection and carbon conversion areas, while also providing new insight into the chemistry of zeolite crystallization. The research will be linked with educational and mentoring initiatives in the STEM areas for students at all levels.Currently, there is little understanding of the relationships between the atomic arrangement of Al atoms in zeolites and the chemistry of the precursor solutions and gels used to synthesize them. This work is based on the hypothesis that the distribution of catalytically-relevant isolated and paired Al sites in zeolites can be controlled by the charge density of the synthesis gel. Isolated and paired Al sites have been shown by the principal investigator to play important roles in the selective catalytic reduction (SCR) of NOx using copper (Cu)-exchanged chabazite zeolites. The present study will develop predictive relations between synthesis gel charge density and paired Al density for a range of zeolites, establish relationships between the framework Al distribution and extraframework Cu distribution in Cu-zeolites, and determine their kinetic and mechanistic roles in the NOx SCR reaction. Building on prior collaborative research, the PI will utilize characterization tools that provide rapid quantification of the numbers of total and paired acid sites on proton- and metal-exchanged zeolites, thereby facilitating the development of synthesis-structure-function relationships that can be used to tailor zeolites for a range of applications.