Temperature Programmed Oxidation of Coked H-Gallosilicate (MFI) Propane Aromatization Catalyst: Influence of Catalyst Composition and Pretreatment Parameters

Author： Choudhary V.R. Devadas P. Sansare S.D. Guisnet M.

Publisher： Academic Press

ISSN： 0021-9517

Source： Journal of Catalysis, Vol.166, Iss.2, 1997-03, pp. : 236-243

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Abstract

Temperature programmed oxidation (TPO) of H-gallosilicate (MFI) coked in the propane aromatization at 550°C for a time-on-stream of 7–8 h has been investigated by measuring point to point the consumption of oxygen and also the formation of the both CO and CO₂(by GC analysis using a 16-loop gas sampling valve) during the TPO run from 50°to 900°C at a linear heating rate of 20°C min^-1in a flow (50 cm³min^-1) of a O₂–He mixture (8.0 mol% O₂). The Si/Ga and Na/Ga ratios, calcination temperature, and hydrothermal pretreatments of the zeolite and also the presence of binder (silica or kaolin) in the catalyst have a strong influence on the TPO of coked zeolite. The influence is attributed to changes in the zeolite properties (viz., zeolitic acidity or framework Ga and non-FW Ga-oxide species), which affect the coke oxidation both directly and/or indirectly, by controlling the nature of coke formed during the coking process.