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

Purdue University, West Lafayette IN

Investigators

Abstract

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.