In many catalytic applications of zeolites, diffusion limitations and pore blockage are serious limitations to their efficient use. A well-connected, hierarchical system of micro- and meso-/macropores may solve those problems. Thus, meso-structured zeolites have attracted significant attention. In recent years, due to the development of supra-molecular templating techniques (such as using the tri-block copolymer P123), promising methods were developed to introduce mesopores into zeolites. However, the practical implementation of such materials is limited, since the templates are often expensive or the methods tend to be complicated.

Here, we report a facile one-pot method to synthesize a composite, denoted as TUD-C[1], which consists of fairly uniform ZSM-5 nanocrystals embedded in a mesoporous matrix. This method uses only one organic templating/scaffolding molecule, namely TPAOH, the molecule already used to template ZSM-5. Micro- and mesopores form separately under different conditions, allowing optimized control over the micro- and meso-porosity. The hierarchical micro-mesoporous texture of TUD-C was confirmed by high-resolution transmission electron microscopy (TEM). 27Al MAS NMR and FTIR demonstrate the presence of Brønsted acid sites. The Si/Al ratio and crystallization temperature are important parameters to influence the material texture and composition. TUD-C shows a remarkable hydrothermal stability. Our synthesis method distinguishes itself by its simplicity, low cost, and flexibility, and provides an alternative to another method discussed last year to synthesize the hierarchical composite TUD-M[2].

Reference List

[1] J.Wang, J.C.Groen, W.Yue, W.Zhou, M.-O.Coppens, Chem.Commun. 2007, 14, 4653-4655.

[2] J.Wang, J.C.Groen, W.Yue, W.Zhou, M.-O.Coppens, J.Mater.Chem. 2008, 18, 468-474.