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5964254 
Journal Article 
Design of Hierarchical Zeolite Catalysts for the Manufacture of Polyurethane Intermediates 
Keller, TC; Arras, J; Wershofen, S; Perez-Ramirez, J 
2015 
ACS Catalysis
ISSN: 2155-5435 
5 
2 
734-743 
WOS:000349275300029 
This study undertakes the design of hierarchically structured zeolites for the synthesis of methylenedianiline (MDA) mixtures via the liquid-phase condensation of aniline with formaldehyde. Affordable acid and base treatments enabled the controlled generation of an auxiliary network of intracrystalline mesopores within commercial zeolites of different frameworks, among which the FAU topology is identified as superior. As the micropore structure of the zeolite can be preserved, the unique shape selectivity is retained while improved mass transport in the hierarchical crystals leads to a 7-fold increased activity and a 3-fold prolonged lifetime before thermal regeneration is necessary. The linear correlation between the MDA yield and the product of the Bronsted acidity and the external surface area emphasizes the need to balance acid site and pore quality in the design of an optimal catalyst. Hierarchical USY zeolites outperform the state-of-the-art delaminated zeolites and mesoporous aluminosilicates. These results offer a viable solution for the replacement of the industrially applied homogeneous catalyst (HCl), resulting in an efficient and environmental friendly technology for the production of polyurethanes. © 2014 American Chemical Society. 
catalyst design; hierarchical zeolite; FAU framework; methylenedianiline; polyurethanes