Vertex 80 5 ftir

HZSM-5 crystals were sprinkled on CaF2 windows and placed on the heated sample stage of an environmental Linkam FTIR600 cell (c.a. 50 mL internal volume) mounted on a (Bruker) Hyperion 3000 IR microscope coupled to a Vertex 80V FTIR at MIRIAM beamline B22 of Diamond Light Source. The infrared experiment requires only single crystals of the catalyst. To improve the sensitivity of the MS detection we typically added around 1 mg (up to 3 mg) of zeolite to the cell and checked that the spectra seen from one crystal were reproducibly seen from other crystals in the sample. The infrared experiments were collected in transmission from individual crystals at spatial resolution down to 10 × 10 micron at the sample using a 36× objective/condenser optics, averaging 16 scans at 4 cm -1 resolution, i.e. typically collecting an IR spectrum every two seconds. The output of the gas phase products from the cell was analysed by mass spectrometry (Pfeiffer or EcoSys) and correlated with the time-resolved IR spectral changes. Gases or liquids were introduced into a nitrogen flow (100 mL min -1 ) upstream of the heated cell at temperatures up to 673 K and ambient pressure. Multiple methanol pulses (each pulse 8 µL in volume) were syringe injected, and dimethylether (5 mL min -1 ) was diluted in the nitrogen stream and introduced in a continuous flow.