Synthesis and Comparative Catalytic Study of Zirconia-MnCO3or -Mn2O3for the Oxidation of Benzylic Alcohols.
We report on the synthesis of the zirconia-manganese carbonateZrOx(x%)-MnCO3catalyst (wherex=1-7) that, upon calcination at 500 °C, is converted to zirconia-manganese oxideZrOx(x%)-Mn2O3. We also present a comparative study of the catalytic performance of the both catalysts for the oxidation of benzylic alcohol to corresponding aldehydes by using molecular oxygen as the oxidizing agent.ZrOx(x%)-MnCO3was prepared through co-precipitation by varying the amounts of Zr(NO3)4(w/w %) in Mn(NO3)2. The morphology, composition, and crystallinity of the as-synthesized product and the catalysts prepared upon calcination were studied by using scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and powder X-ray diffraction. The surface areas of the catalysts [133.58 m2g-1forZrOx(1 %)-MnCO3and 17.48 m2g-1forZrOx(1 %)-Mn2O3] were determined by using the Brunauer-Emmett-Teller method, and the thermal stability was assessed by using thermal gravimetric analysis. The catalyst with compositionZrOx(1 %)-MnCO3pre-calcined at 300 °C exhibited excellent specific activity (48.00 mmolg-1h-1) with complete conversion within approximately 5 min and catalyst cyclability up to six times without any significant loss in activity. The specific activity, turnover number and turnover frequency achieved is the highest so far (to the best of our knowledge) compared to the previously reported catalysts used for the oxidation of benzyl alcohol. The catalyst showed selectivity for aromatic alcohols over aliphatic alcohols.
Department of Chemistry College of Science King Saud University P.O. Box 2455 Riyadh 11451 Kingdom of Saudi Arabia.
Mohamed E
ME
Assal
Department of Chemistry College of Science King Saud University P.O. Box 2455 Riyadh 11451 Kingdom of Saudi Arabia.
Mufsir
M
Kuniyil
Department of Chemistry College of Science King Saud University P.O. Box 2455 Riyadh 11451 Kingdom of Saudi Arabia.
Mujeeb
M
Khan
Department of Chemistry College of Science King Saud University P.O. Box 2455 Riyadh 11451 Kingdom of Saudi Arabia.
Abdulrahman
A
Al-Warthan
Department of Chemistry College of Science King Saud University P.O. Box 2455 Riyadh 11451 Kingdom of Saudi Arabia.
Mohammed Rafiq H
MR
Siddiqui
Institute of Inorganic and Analytical Chemistry Johannes Gutenberg-University of Mainz 55128 Mainz Germany.
Wolfgang
W
Tremel
Institute of Inorganic and Analytical Chemistry Johannes Gutenberg-University of Mainz 55128 Mainz Germany.
Muhammad
0000-0002-9031-5537
M
Nawaz Tahir
Department of Chemistry College of Science King Saud University P.O. Box 2455 Riyadh 11451 Kingdom of Saudi Arabia.
Syed Farooq
SF
Adil
benzyl alcohol oxidation; manganese carbonate; manganese oxide; mixed metal oxides; zirconia