CAREER: Cationic Microporous and Layered Metal Oxides for Anion-Based Applications

University Of California-Santa Cruz, Santa Cruz CA

Investigators

Abstract

This CAREER award seeks to develop a new class of microporous inorganic materials, where the charge of the material is positive. Microporous materials (see, for example, http://www.bza.org/zeolites.html) are extremely important industrially, with a global market of several million tons per year. They are used primarily to convert heavy petroleum to fuel, or to soften or purify water. In water softening, for example sodium or potassium inside the pores are exchanged with "hard" magnesium or calcium. Despite their enormous significance, all such materials known to date are negative in charge and the species in the pores can only be cationic. They would be considerable scientific and industrial interest in obtaining a new class discovery would lead to new applications based on the anions that reside in the pores. For example, anionic pollutants could be trapped by the material, releasing an environmentally benign species in the process. Separations of anionic mixtures, exchange for making new compounds, as well as new catalytic where the size and shape of the template complements that of the material. Preliminary work has been successful in making the switch. Our cationic material can exchange for a variety of other anions in high capacity. It may be possible to "recycle" these anion-exchangers or absorb priority anionic pollutants, such as arsenates. The research plan is integrated with the educational plan. A series of laboratory experiments and lecture course modules will be developed that study advanced physical techniques for characterizing these materials. The target courses range from freshman to graduate levels. This project is highly interdisciplinary, encompassing chemistry, physics, materials science and engineering, and will give excellent training to graduate and undergraduate students. This CAREER award seeks to develop a new methodology for the synthesis of cationic, inorganic microporous hosts. Layered and microporous metal oxides are a class of materials central to a wide variety of industrial and environmental processes, but currently all hosts are anionic or neutral in charge. This project focuses to create a new class of cationic hosts using anionic structure directing agents (SDAs). The size and shape of the SDA will allow us to tune the channel size and porosity of the cationic host. The potential for scientific and industrial payoff is considerable, opening up a range of possible anion-based applications, including environmental trapping of pollutants, anion-exchange, separation and catalysis. Preliminary work with anionic SDAs has been successful in obtaining our first cationic layered materials, which is highly stable and can exchange for a variety of other anions in high capacity. It may be possible to "recycle" these anion-exchangers by reversing the intercalation, or absorb other priority anionic pollutants, such as arsenates. Expertise and experience gained in the research plan will be incorporated into the educational plan, building upon the PI's past and present experience in microporous materials. A series of laboratory experiments and lecture course modules, ranging from the freshman to graduate levels, will be developed based on open-frameworks and advanced characterization techniques. This project is highly interdisciplinary, encompassing chemistry, physics, materials science and engineering, and will give excellent training to graduate and undergraduate students. The project will allow the PI to make a significant contribution to materials chemistry, research and education over the course of his career.