Enhancement in the catalytic activity of Pd/USY in the heck reaction induced by H2 bubbling |
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Authors: | Okumura Kazu Tomiyama Takuya Moriyama Sayaka Nakamichi Ayaka Niwa Miki |
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Institution: | Department of Chemistry and Biotechnology, Tottori University, 4-101 Koyama-cho Minami, Tottori, Japan. okmr@chem.tottori-u.ac.jp |
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Abstract: | Pd was loaded on ultra stable Y (USY) zeolites prepared by steaming NH(4)-Y zeolite under different conditions. Heck reactions were carried out over the prepared Pd/USY. We found that H? bubbling was effective in improving not only the catalytic activity of Pd/USY, but also that of other supported Pd catalysts and Pd(OAc)?. 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% H?O 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 (OH(strong)) generated as a result of steaming had a profound effect on the catalytic activity of Pd. |
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