Catalytic performance of H-[beta] nanozeolite microspheres in one-pot dynamic kinetic resolution of aromatic sec-alcohols

• Published in: Journal of catalysis Vol. 288; p. 24
• Main Authors: Li, Xiang, Shi, Yi, Wang, Zhoujun, Zhang, Yahong, Tang, Yi
• Format: Journal Article
• Language: English
• Published: San Diego Elsevier BV 01-04-2012
• Subjects: Alcohol; Catalysis; Enzymes; Kinetics; Molecules
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2011.12.021

Graphical abstract Uniform H-[beta] nanozeolite microsphere ([beta]-ZMS) performs excellently in the racemization of aromatic sec-alcohols in DKR processes. It is found that [beta]-ZMSs show different advantages for the one-pot DKR of small and large substrate molecules, owing to their special shorter micropore channels and more accessible acidic sites compared to commercial zeolites [beta]. Display Omitted Highlights [beta]-ZMS is applied as racemization catalyst to one-pot DKR of various aromatic sec-alcohols. The use of [beta]-ZMS greatly improves the performance of zeolite catalyst in one-pot DKR system. [beta]-ZMS shows very different advantages for the DKR of small and large sec-alcohols molecules. [beta]-ZMS displays high racemization selectivity for small aromatic sec-alcohols. [beta]-ZMS shows high racemization rate for large aromatic sec-alcohols. In this paper, uniform H-[beta] nanozeolite microsphere ([beta]-ZMS) prepared by polymerization-induced colloid aggregation, combined with an immobilized lipase B from Candida antarctica (commercially available Novozym® 435), is applied as a racemization catalyst to the one-pot dynamic kinetic resolution (DKR) of aromatic sec-alcohols. The DKRs of various aromatic sec-alcohols can be carried out with high selectivity and conversion under optimum conditions. Importantly, it is found that, compared to commercial zeolites [beta] (C-[beta]), [beta]-ZMSs display high selectivity for small sec-alcohol molecules because their shorter microporous channels reduce the diffusion time of substrate/product in the three-dimensional framework, and thereby decrease the possibility of secondary reactions. However, the [beta]-ZMSs show a high racemization rate in the DKR of large sec-alcohol molecules, such as racemic 1-(1-naphthyl)-ethanol, thanks to their abundant accessible active sites. This observation will not only benefit the performance of acidic zeolite catalysts in one-pot DKR systems but also provide a new perspective on the application of nanozeolites in catalysis. [PUBLICATION ABSTRACT]