Effect of SO42--ZrO2-Al2O3 support synthesis conditions on the activity and selectivity of platinum catalysts in the n-butane isomerisation reaction
A. A. NEPOMNIASHCHII, A. V. MARKELOVA, L. A. BULUCHEVSKAIA, A. V. LAVRENOV
Boreskov Institute of Catalysis SB RAS, Center of New Chemical Technologies BIC SB RAS, Omsk, Russia
Keywords: sulphated zirconia, platinum, n-butane, isobutane, isomerisation
Abstract
Platinum-containing catalysts for n-butane isomerisation based on sulphated zirconium and aluminium oxides differing by synthesis conditions were investigated. It has been demonstrated that the method of mixing initial reagents, temperature, and pH for the precipitation of precursors affect the textural properties of the supports. Precipitation in an alkaline medium at 15 °C with controlled pH (10-12) yields fine crystalline zirconium dioxide with developed specific surface area and a dominant mesoporous structure. It has been determined that, regardless of synthesis conditions, introducing 9.0 wt% sulphate groups suppresses crystallisation of the monoclinic phase and promotes the formation of the tetragonal modification of crystalline ZrO2 after calcining the hydroxide precursor at 710 °C. It has been established that the optimal reaction conditions (H2/n-butane = 0.1, pressure 1.5 MPa, temperature 160-200 °C) enable achieving a high yield of the target product, isobutene (up to 44 wt%), and avoiding excessive formation of side products.
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