Dimethylether , adsorption

The microcalorimetric technique has also been applied to investigate the adsorption of acetonitrile, dimethylether, water, pyrrole and ammonia on ferrierite, a small-pore zeolite [58], This investigation showed that the results of the determination of the site-strength distribution are dependent on the basic strength of the probe, on the acidity and porosity of the acid solid, and on the adsorption temperature. A similar calorimetric investigation of the acidity of de-aluminated Y-type zeolites was performed using the same probes [59],... 

It is not always easy to find direct correlations between the heats of adsorption and the catalytic behaviour (activity and/or selectivity). Various attempts at establishing such correlations have been reported in the literature. For instance, a comparison of microcalorimetric measurements with kinetic studies performed over acidic zeolites for methylamine disproportionation reactions, methanol dehydration, and reactions of methanol and dimethylether with methylamines, suggests that acid sites are required in these reactions for the strong adsorption of ammonia and methylamines, while weak adsorption sites are required to facilitate desorption of adsorbed amine species from the acid sites [147]. 

Micro calorimetric measurements of ammonia, pyrrole, dimethylether, and acetonitrile adsorption unveiled various strength distributions among the acid sites population of Y-type zeoUtes with various Si/Al ratios [85]. Ammonia proved to be a reliable probe when only BrOnsted acid sites were investigated. Dimethylether, a very weak base, did not appear to be any better than ammonia to reveal the inhomogeneity of one particular acid sites population, whereas pyrrole appeared as a rather acidic probe which helped visualize the basicity difference between the parent material and the dealuminated samples. Acetonitrile proved to be a reUable probe to monitor quantitatively and qualitatively Lewis acidity. 

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