A fourier-transform infrared and catalytic study of the evolution of the surface acidity of zirconium phosphate following heat treatment
- 1 January 1987
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases
- Vol. 83 (3) , 853-864
- https://doi.org/10.1039/f19878300853
Abstract
The surface acidity of zirconium phosphate at different stages of dehydration and heat treatments has been studied by Fourier-transform infrared spectroscopy of adsorbed pyridine, acetonitrile and acetone and by catalytic activity in the isomerization of but-1-ene. Brönsted-acidic surface POH and P(OH)2 groups are identified [v(OH)= 3670–3660 and 3600 cm–1, respectively] whose strength increases slightly on bulk dehydration. They are thought to be responsible for the activity in but-1-ene isomerization, which also increases during condensation to pyrophosphate. Lewis-acidic sites of medium-high strength have also been found, and responsible for the formation of chemisorbed forms of pyridine (v8a= 1610 cm–1), acetonitrile [v(CN) Fermi resonance doublet at 2322 and 2295 cm–1] and acetone [v(CO) 1684 cm–1]. Surface ZrOH groups are also detected on the layered ZrP2O7 surface. The results illustrate the role of exposed planes, both parallel and perpendicular to the layered structure.Keywords
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