Research
The Reece Lab’s goal is to use an integrated theoretical-computational-experimental approach to understand and control catalytic behaviour by obtaining fundamental insight into how catalytic surfaces behave in response to stimuli. Using techniques inspired by ultra-high vacuum surface science we combine time-resolved measurements of catalytic activity with advanced kinetic modelling, spectroscopy, and density functional theory to achieve an atomic-scale understanding of functional catalytic processes.
We are also committed to increasing accessibility in academia through low-cost, open-source instrumentation design. Many aspiring young researchers are often 'gatekept' from cutting-edge scientific experimentation due to limited funding and access to support facilities. By making all of our instrumentation open-source, low-cost, and easily accessible, we hope to empower the wider heterogenous catalysis community with the tools necessary for success.
Temporal Analysis of Products Reactor
Based upon the methodology outlined by John Gleaves in 1997 [ 1 ] our group has developed a simplified and miniaturised Temporal Analysis of Products (TAP) reactor system. By sending small, well defined pulses of gas into the reactor it is possible to generate a kinetic snapshot of the catalyst surface at a given state using the shape of the exit flux response curves. Then, by repeatedly pulsing over the catalyst surface it becomes possible to incrementally modify the catalyst state utilising the concept of chemical calculus. Compiling a series of kinetic snapshots allows us to measure and precisely model gas-surface interactions across a continuum of catalyst states and gain fundamental kinetic and mechanistic insight into catalytic reactions.
[ 1 ] Gleaves, J. T., Yablonskii, G. S., Phanawadee, P. & Schuurman, Y. TAP-2: An interrogative kinetics approach. Applied Catalysis A: General 160, 55–88 (1997).
Transient Flow Reactor
We have developed a transient flow reactor [ 1 ] which can be used to rapidly switch the gas stream through a packed bed flow reactor, with complete stream switching achievable in <500 ms. Using this rapid stream switching it is possible to perform complex experimentation under applied reaction conditions such as: Chemical Transient Kinetics, Temporal Analysis of Products, psuedo-Moecular Beams, and Modulation-Excitation with Phase Sensitive Detection. The Transient Flow Reactor will also be coupled with in-situ DRIFTS.
[ 1 ] High, E.A., Lee, E. and Reece, C., 2023. A transient flow reactor for rapid gas switching at atmospheric pressure. Review of Scientific Instruments, 94(5).
In-Situ and Pulse-Probe DRIFTS
By combining the pulsing system developed for our Temporal Analysis of Products reactor with a commercial Harrick Scientific reaction chamber we have assembled a Pulse-Probe Diffuse Reflectance Infrared Fourier Transform Spectroscopy system [ 1 ]. The gas outlet line is connected to a UHV chamber housing a RGA and, similar to the TAP experiment, the flux of gas out of the DRIFTS cell is recorded. By coupling time-resolved kinetics and surface sensitive IR spectroscopy we plan to gain new insight into catalytic processes. In the example above we are able to titrate of adsorbed CO from a supported Pt catalyst using sequential O2 pulsing.
[ 1 ] O’Connor, C. R., Kim, T.-S. & Reece, C. Active Site Titration for CO Oxidation Catalyzed by Pt/SiO2 using Pulse−Probe Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). https://harricksci.com/application-notes/.
Temperature Programmed Reaction Spectroscopy
Our home-build Temperature Programmed Reaction Spectroscopy system is specifically designed for studying powdered samples. With the ability to heat samples from 77 K to 1200 K we aim to combine classic surface science experiments with working catalytic systems.
Kinetic Modelling
The TAP pulse experiment is precisely defined by a series of ODEs. The ODEs can be evaluated as a function of both the reactor bed length and time. At time > 0 the inlet pulse diffuses through the catalyst bed via Knudsen diffusion. Over the catalyst zone CO can react with adsorbed atomic oxygen (O*) on the surface to make CO2. The exit flux curves are calculated by measuring the concentration of gas at the reactor exit as a function of time. The shape and magnitude of the exit flux curves for CO and CO2 are dependent on the underlying reaction kinetics.
With complex experimentation comes complex data analysis and processing. We utilise state-of-the-art kinetic modelling techniques in order to model our transient experiments and gain deep kinetic and mechanistic insight into our catalytic systems.