Seminar - Ambarish Kulkarni

Ambarish Kulkarni

Postdoctoral Associate

SUNCAT Center for Interface Science and Catalysis

Department of Chemical Engineering

Stanford University

Multiscale Computational Methods for Accelerated Materials Discovery

Abstract

Rapid developments in the design and synthesis of novel materials have revolutionized the fields of separations and catalysis. In particular, nanoporous materials like zeolites and metal-organic frameworks (MOFs) have received considerable attention because of their diversity and tunability. As only a small fraction of synthetically accessible structures can be experimentally studied, reliable strategies for fast and accurate screening of prospective candidates are required. Computational molecular modeling approaches are ideally suited for this scenario and offer a very powerful tool towards accelerated materials development. By discussing two specific applications, this talk will highlight the increasing role of molecular simulations in the rational design and discovery of new functional materials.

The first part of talk will focus on discovering high-performing MOF adsorbents for the industrially relevant separation of light olefin/paraffin mixtures. Although a handful of MOFs have been experimentally evaluated, large-scale computational screening studies are limited by the difficultly in describing the complex interactions of olefins with the coordinatively unsaturated adsorption site. In this regard, I will present a general strategy for deriving transferrable force fields using higher level Density Functional Theory (DFT) calculations. By evaluating a large library of structures (~100) for propane/propylene mixtures, a subset of highly selective MOFs was identified for further experimental studies. In the second part of this talk, I will present a unified computational framework for understanding C-H bond activation in heterogeneous catalysis. Motivated by the increasing availability of new natural gas resources, technologies for direct conversion of methane to methanol are gaining in interest. Starting with a detailed analysis of the reaction for Cu-exchanged zeolites, I will subsequently discuss a universal model for predicting transition state energies for methane activation in diverse material classes (e.g. zeolites, MOFs, oxides, metals etc.) Furthermore, by combining this descriptor approach with a thermodynamic analysis, a catalyst screening strategy that identifies promising active site motifs will be presented. Future research in these and related areas will be discussed.

Bio

Dr. Ambarish Kulkarni is a Postdoctoral Associate at the SUNCAT Center of Interface Science and Catalysis at Stanford University. Working with Prof. Nørskov, his research is targeted towards discovering new catalysts for methane activation and for fuel cell applications. He obtained his B.S. from Institute of Chemical Technology (formerly UDCT), Mumbai (India) and Ph.D. from Georgia Tech, Atlanta, both in Chemical Engineering. Working with Prof. David Sholl at Georgia Tech, Dr. Kulkarni’s projects spanned a range of modeling methods including wave function theory, Density Functional Theory, classical methods and process level analyses. Very recently (Jan 2017), Dr. Kulkarni has been appointed to a Research Engineer/ Staff Scientist position at SUNCAT.