Abstract: We studied confined catalysis of the MOR molecular sieve 12ring pore on the chiral transition reaction of lysine molecule by using the combined quantum chemistry ONIOM methods. The results show that conformations of the objects which confined in the MOR molecular sieve 12ring pore are different from that in nude environment, the 1C—5N bond length of transition state a_TS2@MOR has been shortened and the distances of the intermediate SINT1
@MOR between 12H and 9O, 11H and 9O as well as 12H and 10O have also been shortened. There are three channels a,b and c in chiral transition reaction. The channel a is the dominant reaction channel of chiral transition reaction, and the Gibbs free energy barrier of the stepdetermining step is 229.7 kJ/mol, which is significantly lower than that of the Gibbs free energy barrier 252.6 kJ/mol, i.e., the MOR molecular sieve has a confined catalytic effect on the chiral transition reaction of lysine molecule.

Key words: MOR molecular sieve, density functional theory, ONIOM method, lysine, transition state, perturbation, chiral transition