Date on Master's Thesis/Doctoral Dissertation

12-2013

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Chemical Engineering

Committee Chair

Carreon, Moises A.

Author's Keywords

ZIF-8; Cyclic carbonates; Catalyst; CO2 conversion

Subject

Carbon dioxide; Carbonates

Abstract

The effective utilization of CO2 as a renewable raw material for the production of useful chemicals is an area of great interest. There are several motivations for producing chemicals from CO2 whenever possible: (1) CO2 is a cheap, non-toxic and nonflammable feedstock that can frequently replace toxic chemicals such as phosgene or isocyanates; (2) CO2 is a totally renewable feedstock compared to oil or coal; (3) the production of chemicals from CO2 can lead to totally new materials such as polymers; (4) new routes to existing chemical intermediates and products could be more efficient and economical than current methods; and (5) the production of chemicals from CO2 could have a small but significant positive impact on the global carbon balance. In particular, the catalytic conversion of CO2 into cyclic carbonates, which are useful chemical intermediates employed for the production of plastics and organic solvents, represents an attractive route for the efficient use of carbon dioxide. The development of superior performance catalysts requires novel materials with fundamentally different structural, compositional, adsorption and transport properties than those of conventional zeolites, metal oxides or metal phases which have been used in the past for CO2 conversion to carbonates. In this respect, metal organic frameworks have emerged as a novel type of crystalline porous materials, which combine highly desirable properties, such as uniform micropores, high surface areas, flexible chemistries, and exceptional thermal and chemical stability, making them ideal candidates for catalytic applications. Particularly, zeolitic imidazolate framework-8 (ZIF-8) is an appealing metal organic framework that could be used as catalyst for the conversion of CO2 into carbonates. The Lewis acid sites, associated with Zn2+ in ZIF-8 structure, are known to catalyze the coupling reaction of CO2 and epoxides. The basic sites in organic linker attract CO2 to be trapped in the structure. With the active catalytic site and promoted CO2 adsorption capacity, ZIF-8 could potentially be an effective catalyst for the conversion of CO2 to cyclic carbonates. The intellectual thrust of this proposal is the rational design of ZIF-8, which offers the possibility of demonstrating high catalytic performance for CO2 conversion to cyclic carbonates.

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