(6bn) Designing Catalysts for Conversion of Alternative Carbon Feedstocks to Fuels and Chemicals

Authors: 
Krishna, S. H., University of Wisconsin-Madison
Research Interests: While fuels and chemicals have traditionally been produced from petroleum resources, we face growing challenges including diminishing petroleum reserves and environmentally harmful emissions. These challenges necessitate the development of alternative carbon sources to supply the fuels and chemicals our society needs. Heterogeneous catalysts are a critical component of many chemical processes, transforming lower value feedstocks into higher value products. I am interested in the upgrading of alternative carbon sources to fuels and chemicals using catalysis. In order to design new catalytic technologies to valorize diverse feedstocks, we must gain a deeper understanding of the relevant reaction mechanisms and the relationship between catalyst structure and reactivity.

My PhD research has focused on understanding the mechanisms of biomass conversion to chemicals. Lignocellulosic biomass is an abundant, renewable source of carbon which could be used to produce a variety of oxygenated chemicals, forming the basis for a sustainable chemical industry. Target products include direct replacements for petroleum as well as “new” molecules which cannot be easily derived from petroleum. Co-producing valuable products from biomass could also improve the economics of biofuel production.

Specifically, I have investigated the catalytic conversion of the cellulose-derived intermediate levoglucosenone (LGO) to a variety of valuable chemicals. Relevant reactions include hydrogenation of C=C and C=O bonds over metal catalysts and C-O cleavage over acid catalysts. We used a variety of analytical techniques (HPLC, GC, MS, 13C NMR) in combination with catalyst activity measurements in high-pressure batch and continuous flow reactors, to elucidate the reaction network for these transformations. Mechanisms were additionally studied using 13C radio-labeling and molecular simulations in collaboration with computational chemists. We gained a fundamental understanding of the mechanisms of catalytic conversion of LGO over metal and acid catalysts. Through these insights we have developed new strategies to selectively produce target products with controlled stereochemistry which are being investigated as precursors to bio-based polymers.

Future work should focus on the design of well-defined model catalysts using advanced synthesis techniques to selectively deposit metal oxides onto catalyst surfaces. We propose to design catalysts with i) controlled proximity between different active sites and ii) controlled micropore structure. Ultimately, the goal is to use reaction kinetics measurements over model catalysts to better understand the relationship between catalyst structure and reactivity, leading to control over reaction outcomes.

Teaching Interests: I have numerous teaching experiences including teaching assistantships for two undergraduate courses (Thermodynamics; Materials Science for Chemical Engineers) and a graduate course (Kinetics and Catalysis). I also trained and mentored three undergraduate researchers who made significant contributions to our research efforts. I am highly involved in informal hands-on STEM education with local elementary and high school students to share my passion for science with the broader community. I look forward to teaching any undergraduate chemical engineering course, especially kinetics and reaction engineering, thermodynamics, and an elective course on alternative energy technologies. I would also be able to teach a graduate course in heterogeneous catalysis.