2, Argonne National Laboratory, Argonne, Illinois, United States
3, SLAC National Laboratory, Menlo Park, California, United States
4, Brookhaven National Laboratory, New York, New York, United States
Ion exchanged zeolites are promising heterogeneous catalysts in selective reduction chemistry and in vehicle exhaust purification. The chemically active site of the zeolite channels acts as an ion trap and supplies an ion to reactants selectively. Local strain affects the pore size and the channel connectivity of the zeolite catalyst related to the catalytic efficiency. Here, we report the kinetics of local deformation field distribution of Cu-ZSM-5 zeolites during the nitrogen oxide reduction catalysis using in situ time resolved coherent X-ray diffraction imaging with an X-ray Free Electron Laser. The adsorption of hydrocarbons to Cu-ZSM-5 catalysts, essential component for activating the Cu ions at low temperature, generates unusual lattice displacement. It reflects inhomogeneity of the host crystals and then is released during the subsequent steps of the catalytic process of the nitrogen oxide reduction. The observed time dependence should therefore be considered as a major factor in the design of future catalytic materials.