Gaining New Insight into Chemical Structure of Carbon-Based Catalysts

Achievement date: 
2014
Outcome/accomplishment: 

Researchers at the Center for Biorenewable Chemicals (CBiRC), an NSF-funded Engineering Research Center (ERC) headquartered at Iowa State University, have developed solid-state nuclear magnetic resonance (NMR) techniques that provide unprecedented insight into the chemical structure of the carbon backbone in sulfonated (SO3H-bearing) carbon catalysts.

 

Impact/benefits: 

For the first time the researchers demonstrated “average” chemical structures for these materials. This result was a significant advance over previous studies in which detailed characterization of these materials was problematic. The current work has systematically demonstrated the structures resulting from various synthetic approaches, a feat that has allowed researchers to evaluate what chemical structures are required to generate the desired catalysts and to characterize the relationship between the chemical structure of the sulfonated carbons and their hydrothermal stability.

 

Explanation/Background: 

A large challenge in the development of heterogeneous catalysts for biomass conversion is the need for the catalysts in many instances to be stable in a high-temperature aqueous environment. Of particular interest are hydrothermally stable solid-acid catalysts. A number of research reports have extolled the potential of sulfonated-carbon materials for this application. Although interesting results have been reported (i.e., indications that carbonization of carbohydrates followed by sulfonation leads to solid-acid catalysts with good hydrothermal stability), the analytical techniques used to characterize these materials missed key carbon-structural information. The CBiRC researchers developed new solid-state NMR characterization protocols that provide this structural information.