(544bv) A Facile Approach to Prepare Pt Nanoclusters Encapsulated within the Micropores of Zeolite

Lisa Nguyen^a,*, Hui Wang^a, Junjun Shan^a, John Matsubu^a, Yizhi Xiang^b, Fu-Kuo Chiang^c, Jihong Cheng^a

^a NICE America Research Inc, 2091 Stierlin Ct, Mountain View, California USA 94043

^b Dave C Swalm School of Chemical Engineering, Mississippi State University, Mississippi USA 39762

^c National Institute of Clean-and-Low-Carbon Energy(NICE), Future Science & Technology City, Changping District, Beijing China 102211

*Corresponding author: lisanguyen@nicenergy.com

The synthesis of atomically dispersed metal nanoclusters encapsulated within the zeolite micropores have attracted much attentions in recent decades due to many unique benefits offered by these confined nanoclusters. For example, such high metal dispersion can minimize the metal loading while maximizing metal activity. Furthermore, the encapsulation of such metal clusters within the zeolite pores allows one to take full advantage of shape selectivity of zeolite pore channels.

Metal nanoclusters encapsulated within zeolite micopores are difficult to achieve through traditional impregnation or ion-exchanging techniques on zeolites with small or medium pore sizes. This can be attributed to the fact that noble metal precursors in aqueous solutions are relatively large compared to the zeolite pores. Thus, various complicated synthetic methods have been developed to synthesize these type of materials.^1-3 However, these methods are all based on crystallization/transformation of zeolite crystal, which is not desirable for commercialization. Herein, we have developed a simple approach to prepare of Pt/ZSM-5 catalyst, which consists of confined Pt nanoclusters within the micropores of zeolite at relatively mild conditions. The prepared materials have been characterized using various techniques like dynamic CO adsorption, XANES, EXAFS, CO-DRIFTS, and STEM. These characterization results confirm that the prepared Pt/ZSM-5 catalyst consists of mainly subnanometer Pt nanoclusters encapsulated within zeolite micropores. Furthermore, our catalysis measurements also show that such confined subnanometer Pt nanoclusters are highly active for the direct conversion of ethane to aromatics, which is of great interest for industrial applications.⁴

References

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