The deactivation of silico-aluminophosphate catalysts during methanol conversion reactions
Date
1993
Authors
Cornel, Veronica May
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Abstract
This dissertation focusses on the deactivation of SAP0-34 and modified SAPOs
during methanol conversion under various conditions, in comparison to H-ZSM-5.
SAPO-34 was found to deactivate rapidly during methanol conversdon. This was
shown by the decrease in activity, surface area and pore volume of the
catalyst. The deposited "coke" was analysed by in situ diffuse reflectance
infra-red Fourier Transform spectroscopy,solid-state magic angle spinning
nuclear magnetic resonance, gas chromatography mass spectroscopy (GCMS) of the
HF- and dichloromethane-extracted to "coke"; and GCMS of the organic specfes
released during regeneration of the catalyst and trapped in resin capillary
inlet tubes.The "coke" consisted of alkylated aromatics and naphthalenes
which probably formed on the surface or in the large cavities of SAPO-34.
The amount of "coke" deposited during methanol conversion increased with
reaction temperature, decreased with dilution of the methanol with water or
nitrogen. and decreased with increased pressure, Incorporation of Ni into the
SAPO framework did not decrease the rate of deactivation, but the "coke" that
Has deposited was less bulky than that deposited in SAPO-34. Modification of
the SAPO-34 with trlmethyl silylchloride decreased the rate at deactivation
of the catalyst.
Description
A dissertation submitted to the Faculty of Science,
University of the Wtlwatersrand, Johannesburg,
in fulfilment of the requirements for the degree of
Master of Science
Keywords
Catalysis, Chemistry, Physical and theoretical, Catalyst poisoning., Methanol