Konovalov S. Coke formation in carbonium-ion reactions of hydrocarbons and its behaviour in catalysts deactivated

Coke deposits on zeolite catalysts deactivated. Extending and broadening the ideas about reasons of acid zeolites deactivation in carbonium ion reactions and about coke deposits behavior in samples deactivated for the purpose of developing the approaches to stabilizing the activity of zeolite catalysts. Catalytic testing, gas chromatography, infrared spectroscopy, temperature-programmed desorption of ammonia, discrete successive coke microoxidation, differential thermal gravimetric analysis. It was revealed the oscillatory coke dynamics on samples, based on ZSM-5 and mordenite, with coke content up to 7,6 wt%. and it absence on faujasite sample with coke content of 15,6 wt%. Thermodynamic treatment of carbonaceous deposits oscillatory dynamics phenomena was extended based on ideas of coke physico-chemical properties dependence on coke dispersion degree on the external surface of the catalyst. Based on thermodynamic analysis, it was forecasted the extreme character of dependence of chemical potential, chemical and catalytic activity of substance in form of small particles on its dispersion degree over a wide dimensional range. The guess has been substantiated, that the reason of zeolite alkylation catalyst deactivation may consist in olefins formation during reaction in arising imbalance in Bronsted and Lewis acidity in the limits of active center or as a result of raising of molecular weight of carbocation C8+, initially formed by protonation of isobutane molecule. Field of use - petrochemistry, petroleum processing, heterogeneous catalysis.