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Enhancement in the Catalytic Activity of Pd/USY in the Heck Reaction Induced by H2 Bubbling
Department of Chemistry and Biotechnology, Tottori University, 4-101, Koyama-cho Minami, Tottori, Japan
* Author to whom correspondence should be addressed.
Received: 17 November 2010; in revised form: 13 December 2010 / Accepted: 24 December 2010 / Published: 24 December 2010
Abstract: Pd was loaded on ultra stable Y (USY) zeolites prepared by steaming NH4-Y zeolite under different conditions. Heck reactions were carried out over the prepared Pd/USY. We found that H2 bubbling was effective in improving not only the catalytic activity of Pd/USY, but also that of other supported Pd catalysts and Pd(OAc)2. Moreover, the catalytic activity of Pd/USY could be optimized by choosing appropriate steaming conditions for the preparation of the USY zeolites; Pd loaded on USY prepared at 873 K with 100% H2O gave the highest activity (TOF = 61,000 h−1), which was higher than that of Pd loaded on other kinds of supports. The prepared Pd/USY catalysts were applicable to the Heck reactions using various kinds of substrates including bromo- and chloro-substituted aromatic and heteroaromatic compounds. Characterization of the acid properties of the USY zeolites revealed that the strong acid site (OHstrong) generated as a result of steaming had a profound effect on the catalytic activity of Pd.
Keywords: Heck coupling reaction; USY zeolite; palladium; H2 bubbling; acid property
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Okumura, K.; Tomiyama, T.; Moriyama, S.; Nakamichi, A.; Niwa, M. Enhancement in the Catalytic Activity of Pd/USY in the Heck Reaction Induced by H2 Bubbling. Molecules 2011, 16, 38-51.
Okumura K, Tomiyama T, Moriyama S, Nakamichi A, Niwa M. Enhancement in the Catalytic Activity of Pd/USY in the Heck Reaction Induced by H2 Bubbling. Molecules. 2011; 16(1):38-51.
Okumura, Kazu; Tomiyama, Takuya; Moriyama, Sayaka; Nakamichi, Ayaka; Niwa, Miki. 2011. "Enhancement in the Catalytic Activity of Pd/USY in the Heck Reaction Induced by H2 Bubbling." Molecules 16, no. 1: 38-51.