NSF-DFG MISSION: Elucidating the mechanism of alcohol coupling to form acrolein using operando spatiotemporal spectrokinetics

Reducing the carbon and energy footprint of the chemical industry will require developing new chemical transformations that use non-fossil carbon sources to make high-volume commodity chemicals. To that end, the project explores the feasibility of catalytically converting ethanol and methanol (both potentially manufactured via green technology) to acrolein – a chemical intermediate used in the manufacture of acrylate polymers.

The project represents a collaborative effort between Lehigh University and the Hamburg University of Technology under joint funding from NSF and the Deutsche Forschungsgemeinschaft (German Research Foundation, DFG). The research explores molecular level details of how the chemical reaction progresses over an iron molybdate catalyst, obtaining information related to the site on the catalyst surface where reactions occur (active site) and the sequence of reaction steps to form the product (the reaction pathway).

The molecular-level insights will aid in the discovery of novel catalytic materials and optimal reactor operating conditions, thereby reducing process energy requirements. Taken together, the use of green feedstocks, combined with energy-efficient catalysts and intensified process technology, has potential to greatly decrease the carbon footprint of acrylic polymer manufacture.

In addition to the technical aspects, the collaborative project will catalyze an international exchange of ideas, methodologies, and educational materials, thereby fulfilling the broader objectives of the NSF-DFG research initiative.

The project supports a synergistic and unique US-German collaboration to develop a novel spatial- and time-resolved analysis of catalytic systems whereby variation in the structure of the catalyst and the concentration of surface reaction intermediates, both along the reactor length and over time, is leveraged to obtain underlying information about the catalytic active site and the reaction pathway. The project combines research expertise at Hamburg and Lehigh to employ: (1) operando molecular spectroscopy techniques in the modulation excitation spectroscopy (or MES) mode to understand the fast transients of the catalytic system and elicit kinetically relevant surface intermediate species and reaction pathways; (2) a novel compact profile reactor (CPR) coupled with spectroscopy and mass spectrometry - a unique set up not currently available in the US - to understand the slow evolution of catalyst active sites, surface and gas phase species, and reaction rates along the reactor bed; and (3) spatial (CPR) and temporal (MES) data of the catalytic system along with hierarchical modeling tools (Density Functional Theory (DFT), microkinetic modeling, and optimization methods) to develop a mechanistic model of acrolein synthesis on FeMoOx catalysts from non-fossil methanol and ethanol.

This work will allow deep contrasting spatiotemporal studies to elicit molecular insights about the catalyst and aid in the development of tools to create mechanistic models from DFT, MES, and CPR data that will be applicable to a wide range of catalytic reaction systems.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.