We propose to use MERLIN to measure INS from commercial zeolite catalyst samples extracted from a reactor in which they have been exposed to dimethylether for different lengths of time on stream. We have shown previously (RB1320360) that INS is the only form of vibrational spectroscopy able to observe the hydrocarbon species in the pores of the working catalyst. We wish now to establish how these species evolve throughout the catalyst lifetime. Dimethylether is the main component of the feed into the commercial MTG process over ZSM-5. The INS is a core component of a project funded by the EPSRC Catalysis Hub; samples extracted for INS will also be analysed by NMR, thermal analysis and electron microscopy. A complementary QENS application will investigate how diffusion within the catalyst pores is influenced by the presence of hydrocarbon deposits as the catalyst ages on stream.