The NIMROD instrument at ISIS has been used to study benzene hydrogenation, allowing time-resolved catalytic chemistry to be probed directly in situ. The work, published in the journal Chemical Science, opens the way for new investigations of heterogeneous catalytic reactions.
Heterogeneous catalysis is where the catalyst and reactant are in different phases – commonly a solid catalyst and liquid reactant. It is difficult to monitor these systems in situ and current methods for gathering spatial and chemical information are limited to micron resolution. Neutron scattering can provide higher resolution but historically, long data acquisition times have made it unsuitable for measuring the kinetics of real systems.
NIMROD is a high count rate wide Q-range total neutron scattering instrument at ISIS. It benefits from the highly optimized performance of the facility’s recently constructed second target station. This research has shown that it is now possible to obtain kinetic information on useful timescales for investigating chemical reaction processes, whilst at the same time gaining structural insight into the interactions of atoms and molecules over multiple length scales spanning the atomic to nanometric regimes.
The study, funded by EPSRC and STFC, looked at what happens within the pores of a heterogeneous catalyst during the liquid phase reduction of benzene. This reaction is of particular commercial importance due to the widespread use of the product in producing nylon and in the drive for cleaner fuels through the removal of benzene from gasoline.
Tristan Youngs, instrument scientist on NIMROD, led the study. He says, “We’ve shown that NIMROD is able to completely characterise the atomic, molecular and mesoporous length scales in the system simultaneously, and monitor the reactionin a time-resolved manner. We wereable to pinpoint several different processes with distinct timescales occurring in the reacting system, offering a way to directly relate chemical species and their spatial distribution to the underlying kinetics. This work promises to open many new doors for novel investigation of heterogeneous catalysis reactions and should draw plenty of interest from major players in both academia and industry.”
Sara Fletcher and Tristan Youngs
Research date: July 2013
Probing Chemistry and Kinetics of Reactions in Heterogeneous Catalysts, Tristan G. A. Youngs, Haresh Manyar, Daniel T. Bowron, Lynn F. Gladden and Christopher Hardacre, Chem. Sci., 2013, 4 (9), 3484 - 3489