The F.t.i.r. spectra of isobutene adsorbed at 170-300 K on the pure oxides silica, alumina, magnesia and titania, as well as on the phosphated samples prepared by impregnation of these pure oxides and of silica-alumina with phosphoric acid have been recorded. At low temperatures (170-220 K), molecularly adsorbed species are observed on pure oxides, with a spectrum similar to that of liquid isobutene, although with specific perturbations of the modes primarily involving the vinylidene moiety. Isobutene is transformed only on titania even at low temperatures into a new compound identified as its dimer 2,4,4-trimethylpent-1-ene. On phosphated samples oligomerization occurs at 293 K, producing oligomeric species identified as 5-10 monomeric unit cationic polymers.
Adsorption and oligomerization of isobutene on oxide catalyst surfaces. A Fourier-transform infrared study
Busca G.;Ramis G.;Lorenzelli V.
1989-01-01
Abstract
The F.t.i.r. spectra of isobutene adsorbed at 170-300 K on the pure oxides silica, alumina, magnesia and titania, as well as on the phosphated samples prepared by impregnation of these pure oxides and of silica-alumina with phosphoric acid have been recorded. At low temperatures (170-220 K), molecularly adsorbed species are observed on pure oxides, with a spectrum similar to that of liquid isobutene, although with specific perturbations of the modes primarily involving the vinylidene moiety. Isobutene is transformed only on titania even at low temperatures into a new compound identified as its dimer 2,4,4-trimethylpent-1-ene. On phosphated samples oligomerization occurs at 293 K, producing oligomeric species identified as 5-10 monomeric unit cationic polymers.
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