Ab initio molecular dynamics simulation of methanol interacting with acidic zeolites of different framework structure

Ab initio molecular dynamics simulations based on density-functional theory together with a plane-wave basis set are performed on the adsorption of a single methanol molecule in the series of acidic zeolites theta-1, ferrierite and ZSM-5. We only find a physisorbed molecule as a stable structure. Comparison is made with previous calculations on methanol in chabazite which used the same techniques. The calculated adsorption energies are -131 (theta-1/O2), - 128 (theta-1/O4), - 121 (ferrierite) and -139 (ZSM-5) kJ mol(-1). The deprotonation energies are 1241 (ZSM-5), 1244 (ferrierite), 1261 (theta-1/O4) and 1262 (theta-1/O2) kJ mol(-1). The adsorption energies as well as the deprotonation energies show differences of only 20 kJ mol(-1). (C) 2000 Elsevier Science B.V. All rights reserved.