Title: Operando spectroscopy of chemically reacting flows in heterogeneous catalysis

 

Abstract: 

 

An overwhelming majority of chemical industry products employ heterogeneous catalysis that function at a gas-solid interface. Consequently, considerable resources are devoted to improving catalytic efficiency and process conditions. However, reaction optimization requires knowledge of internal reactor thermodynamics and chemical kinetics, which is difficult to model without understanding the reactor’s internal workings. Our group develops nuclear magnetic resonance (NMR) methods to visualize non-equilibrium thermodynamics in situ. Such “internal views” inside reactors will provide a quantitative basis for reactor optimization. We measure spatial distributions of velocities, concentrations, and temperatures, and use a theoretical framework to extract images of pressure, entropy production, heat capacity, thermal conductivity, reaction kinetics, and reaction enthalpies. By using NMR the reacting flow remains unperturbed, allowing studies of reaction thermodynamics coupled to heat and mass transport. In this seminar I will discuss work we did on mapping events of catalytic conversion, signal enhancement by hyperpolarization techniques, and mapping temperatures of reacting gases (all in the context of non-perturbative measurements). While this arsenal of tools is currently limited by acquisition time, extensions to video frame rate imaging could be achieved by compressive sensing thereby leading to the study of transient effects in catalysis.