Spontaneous proton transfer in Na zeolites

First-principles room-temperature molecular dynamics (MD) simulations are c onducted to investigate proton transfer (PT) in Na zeolites. The MD are per formed on the unit cell containing two Al-sites, one of them saturated with H (acid site) and the second one with Na coordinated with three water mole cules. The creation of the charged H3O+ cations is suppressed by the Na cat ion. Spontaneous barrierless PT between the O-sites in the zeolite, however , is possible. The lifetime of the hydronium cation is extremely short (les s than or equal to5 fs). The presence of Na+ cations leads to a modified me chanism but does not suppress the proton transfer around the Al-site in zeo lites. (C) 2000 Elsevier Science B.V, All rights reserved.