Silverwood Ian P
ISIS Neutron and Muon Facility, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Oxon, OX11 0QX, UK.
Chemphyschem. 2019 Jul 2;20(13):1747-1751. doi: 10.1002/cphc.201900230. Epub 2019 Jun 4.
Neutron scattering data was recorded from SAPO-34 using the OSIRIS instrument before and after repeated ammonia adsorption at pressures up to 8 bar. Coherent scattering from the zeolite framework provides the neutron powder diffraction pattern and gave evidence for anisotropic contraction on ammonia dosing. Incoherent quasielastic scattering from the hydrogen of the ammonia showed that mobile ammonia was present in the framework. The quasielastic data was fitted to a model where the ammonia was confined within the chabazite cage in the c direction of the crystal lattice, with diffusion solely occurring through the perpendicular 8-membered rings. The calculated diffusion constant reached a maximum of 6.3×10 m s at 5 bar.
