CHE Seminars  

Speaker Dr. Vishal Agarwal
Postdoctoral scholar at University of California, Santa Barbara, USA
Topic Molecular Modeling of Cellulose Pyrolysis
Date 15,March 2016 (Thursday)
Place L-2
4 pm. - 5 pm.

Lignocellulosic biomass is a significant pool of energy resource, which can be harnessed to supplement or replace the dwindling fossil fuel reserves. Biomass can be converted to energy by physical, biological and thermochemical processes; of which pyrolysis is one of the most promising and burgeoning technology to obtain liquid fuels. However, there are several challenges before liquid fuels from pyrolysis can be economically at par with fossil fossils. Biomass is mainly composed of the biopolymer cellulose; therefore, understanding of cellulose pyrolysis chemistries is important for efficiently modeling and optimizing pyrolysis reactors.
In this seminar, I will present the results of modeling studies we performed to understand conversion of crystalline cellulose to precursors of major products during pyrolysis. Cellulose when subjected to heat undergoes structural transformation at ~400K. I will discuss the role of intrachain and interchain hydrogen bonding in this transformation. At temperatures > 550K cellulose undergoes chemical transformation to a variety of products—distribution of which depends on temperature and residence time. We modeled the decomposition of cellulose at 600 and 873 K using Car-Parrinello molecular-dynamics and the metadynamics method. CPMD-metadynamics implemented with various sets of collective variables yielded a variety of chemical reactions such as depolymerization, fragmentation, ring opening, and ring contraction. I will discuss why levoglucosan (LGA) is the major product observed during cellulose pyrolysis at higher temperatures (~873 K) and the bottleneck to formation of LGA. The molecular insights from this research can be used to develop a detailed picture of cellulose pyrolysis paving way for better design of such processes.

Dr. Vishal Agarwal is presently working as a postdoctoral scholar with Prof. Horia Metiu at University of California, Santa Barbara. Previously, he obtained his PhD in Chemical Engineering from University of Massachusetts, Amherst working with Prof. Scott M. Auerbach, Prof. George W. Huber and Prof. Wm. Curtis Conner. He has a Master's degree in Chemical Engineering from IIT Bombay under the guidance of Prof. Sanjay M. Mahajani. His research has focused on using and developing computational tools to model complex reaction systems. Through his research he has addressed problems in the areas of catalysis, biomass conversion, nucleation, and reactive distillation. He has published over 15 referred papers. His research on cellulose pyrolysis was highlighted in North American Clean Energy and BioDigest. He has also been awarded Best Master’s Research Thesis Award for his research efforts on reactive distillation.

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