State-of-the-art total neutron scattering methods spanning a wide Q-range have been applied to study the heterogeneous catalytic hydrogenation of benzene over Pt/SiO2 in situ. The approach yields complete structural information for the system, encompassing the atomic, molecular, and mesoscopic length scales, and allows characterisation of the system from the chemical species present through to the underlying porous support. By collecting this data as a function of time, the kinetics of changes within the system are also revealed. Figure 1. <img src='https://acs-archive-assets2.s3.amazonaws.com/239nm/uploads/2453_1.jpg' alt='' />We show that total neutron scattering techniques are able to characterise the initial state and the fully hydrogenated cyclohexane product. By using reduced pressure conditions and short data acquisition times we are able to extract time-resolved F(Q) data from the reaction, and hence pinpoint structural changes occurring in the system along with their relative kinetics. Three distinct process timescales are evident from the results, which are assigned to the initial adsorption/dissociation of H2 at the catalyst sites, the hydrogenation process itself, and the diffusion of product through the porous network. These results suggest that total neutron scattering over a wide Q-range can provide structural, chemical, and kinetic information of a heterogeneous catalytic reaction, fully characterising the process in its natural state.

Atomically-resolved chemistry and kinetics of a heterogenous catalytic reaction with total neutron scattering

246th National Meeting (2013)

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