Silicate structures dealuminated zeolite

The gas phase alkylation reaction of isobutane with 1-butene has been carried out on a series of Y zeolites dealuminated by treatment with HtEDTA solution. Dealuminated zeolites found to contain no extra-ftamework aluminium as evidenced by Al MAS NMR. However, only limited dealumination was achieved as attempts to further dealuminate results in structural collapse. Si MAS NMR spectra show the presence of amorphous siliceous species in highly dealuminated samples. Dealuminated Y zeolites are active for alkylation of isobutane with 1-butene but deactivated rapidly within first few minutes reaction. Mild dealumination improves the selectivity for trimethylpentanes but further dealumination results in the increase of cracked products and faster deactivation. The catalysts are active in the 60-80 C temperature range but beyond that catalyst deactivation was considerable. 

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