Title: Liquid Metal Catalysts for Bio and Synthetic Polymer Pyrolysis              

Abstract: Decomposition of bio or synthetic polymers to valuable products – such as lignocellulosic biomass conversion to biofuels, and recycling plastics to its monomers – is still a challenging process. Pyrolysis is known as one of the most feasible and scalable thermal conversion processes. Biomass conversion leads to production of heavily oxygenated oil with wide carbon distributed mixture. Heterogeneous catalysts such as zeolites and alumina were studied to produce deoxygenated narrowly distributed oil. But this class of catalysts suffer from deactivation due to coke deposition on active sites which hinders their commercialization. There is an emerging class of metal catalysts in liquid phase that has been known to address the deactivation from coking. Liquid metals (LMs) have been proven to show separation from coke during reaction due to the inherent density difference between coke and metal in liquid phase thereby promoting a renewed catalyst surface. But there is lack of research into investigating LMs as a robust catalyst alternative for bio and synthetic polymer pyrolysis process.

This motivates our work, firstly to establish the evidence of catalysis when using low melting monometallic LMs such as bismuth, tin, and indium as reaction media for pyrolysis of cellulose and lignin (major biomass model compounds) and commercial biomass. We also explore using the same LMs for depolymerization of synthetic polymer, polycarbonate. Secondly, we aim to prove the primary motivating factor for this work by demonstrating the robustness of LM catalysts by cycling the same batch of LM catalyst for the same pyrolysis reaction with cellulose as model compound. Furthermore, we aim to examine improving the catalytic activity of the LM by alloying them with known transition metals for biomass pyrolysis.

Finally, we obtain a broader insight about the greenhouse gas (GHG) emissions associated with the biomass pyrolysis via LMs for the purpose of diesel production and compare it with conventional non-catalytic pyrolysis process using life cycle assessment (LCA).

Chair:

Dr. Mohammad Masnadi

Department of Chemical and Petroleum Engineering, University of Pittsburgh

Committee: 

Dr. Götz Veser

Department of Chemical and Petroleum Engineering, University of Pittsburgh 

Dr. Giannis Mpourmpakis

Department of Chemical and Petroleum Engineering, University of Pittsburgh 

Dr. Vikas Khanna

Department of Civil and Environmental Engineering, University of Pittsburgh