The Department of Chemical and Biological Engineering welcomes Sanjeev Rao, Development Specialist at Honeywell UOP, to give a talk titled, “Rational Design of Hierarchically Structured Catalysts: Multiscale Modeling, Optimization, and Experiments” for the 2021 fall seminar series. The event will take place on September 22 from 3:35 p.m.-4:40 p.m.

What: “Rational Design of Hierarchically Structured Catalysts: Multiscale Modeling, Optimization and Experiments” with Sanjeev Rao, PhD, Development Specialist at Honeywell UOP

When: September 22, 2021, 3:35—4:40 p.m.
Where: Perlstein Hall 131 – Auditorium

Abstract
Industrial nanoporous catalysts suffer from diffusion limitations and catalyst deactivation caused by active site poisoning and pore blockage. While significant attention has been paid to designing new and improved catalysts at the nanoscale, there has been no concerted effort at linking the nanoscale to the macroscale within the framework of rational catalyst design. The questions that need to be answered are: (i) which pore network is optimal to best resist catalyst deactivation, and (ii) how to establish a framework for rational catalyst design at all length and time scales? To answer the first question, model driven numerical optimizations of the broad pore network in hierarchically structured catalysts are carried out with the goal of minimizing diffusion limitations and increasing stability to catalyst deactivation. It is shown that a broad pore network with an optimized uniform macroporosity and an optimized uniform broad pore size is nearly as optimal as a broad pore network with an optimized distribution in macroporosities and broad pore sizes. For catalyst deactivation in the hydrodemetalation of crude oil containing a single asphaltene species, a doubling in useful lifetime at the pellet scale and a nearly 40 % increase in lifetime at the reactor scale is demonstrated, as compared to a non-hierarchical structure.

To answer the second question, the total meso- plus macroporosity of a hierarchically structured zeolite is numerically optimized to maximize the production of ethylbenzene in the alkylation of benzene with ethylene. The optimum structure maximizes the catalytic yield nearly two-fold over a zeolite catalyst pellet containing only macropores at the same macroporosity. To bridge the gap between modeling and experiments, a series of physical mixtures of ZSM-5 crystals and mesoporous silica, containing different weight fractions of zeolite is synthesized and used in fixed bed reactor experiments to determine the optimal pellet structure to maximize the conversion of ethylene. Comparison with reactor simulations of the zeolite composites shows that the performance of the zeolite composites might be limited by surface barriers at the external surface of the zeolite crystals, rather than by diffusion limitations within the meso-macropore network of the pellets.

Short Biography

Sanjeev Rao is a Development Specialist in the Olefins, Detergents and FCC group at Honeywell UOP. In this role, he leads the development of next generation detergents technologies and supports other technology areas of importance to UOP. Sanjeev has also worked in the kinetic modeling group at UOP and for SABIC at their technology center in Houston where he ran programs on natural gas conversion and polymers.

Sanjeev holds a PhD in chemical engineering from Rensselaer Polytechnic Institute (RPI), Troy, NY where he worked with Prof. Marc-Olivier Coppens on the rational design of hierarchically structured porous catalysts by combining mathematical modeling, simulations, and experiments. At RPI he was a recipient of the Founders Award of Excellence and the Philip A. Groll Class of 1921 Teaching Assistant award. Sanjeev is the author of some 5 papers, 15 conference presentations and 2 patent applications. He has most recently served as the Area 20B (chemical reaction engineering) technical programming chair for the CRE division of the AIChE.