(621a) Examining Routes to P-Cymene through Integrating Biological and Chemical Catalysis

Authors: 
Lin, H. H., Iowa State University
Shanks, B. H., Iowa State University
Cheng, Y., Iowa State University
Wang, X., Joint BioEnergy Institute
Mendez-Perez, D., UNIVERSITY OF WISCONSIN-MADISON
Lee, T. S., Joint BioEnergy Institute (JBEI)
p-Cymene is an interesting renewable product for fuel and polymer applications if biological and chemical conversions can be efficiently integrated for its production. An important aspect of efficient integration for the overall processes is determining what is the preferred chemical intermediate for the handoff from biological to chemical conversion. While limonene has been examined previously as the intermediate, recent work has shown that stopping earlier in the same metabolic pathway at 1,8-cineole leads to a significantly higher titer than with limonene. In this study, the direct comparison of converting these potential intermediate reactants to p-cymene was performed. Pd on γ-Al2O3 catalysts were found to convert efficiently either reactant, as it appeared that the additional dehydration required with 1,8-cineole conversion was facile. To examine the importance of acidity for the catalysts studies were also performed with silica-aluminum or SiO2 supports. Also, alternative metals, Cu and Ni, as well as stability performance of Pd-based catalysts were examined. By examining the overall biological and chemical production pathway, it was found that the most efficient strategy was to target 1,8-cineole as the biological intermediate that is subsequently converted to p-cymene. This study demonstrates the importance of biological and chemical catalysis development informing each other for creating efficient conversion pathways to chemical products.