S. Senger et L. Radom, Zeolites as transition-metal-free hydrogenation catalysts: A theoretical mechanistic study, J AM CHEM S, 122(11), 2000, pp. 2613-2620
The B3-LYP/6-311+G(3df,2p)//B3-LYP/6-31G(d) procedure has been used to stud
y the zeolite-catalyzed hydrogenation of prototypical doubly bonded systems
. Both Bronsted acid and alkali metal sites in model zeolites have been exa
mined. For the hydrogenation of ethene, the barrier is predicted to be lowe
red by about 50% at the Bronsted acid sites and by about 40% at the alkali
metal sites. The barriers for the hydrogenation of formimine and formaldehy
de are predicted to be lowered even more substantially, with remarkably low
overall barriers of 30 and 60 kJ mol(-1), respectively, at the Bronsted ac
id sites of the zeolites. The alkali metal sites of the zeolites are found
to be not quite as effective as the Bronsted acid sites in lowering the hyd
rogenation barriers in these two cases, as for ethene. Comparisons are made
with relevant experimental data.