Abstract
Soft-templated phosphorylated mesoporous carbons with homogeneous distributions of phosphate groups were prepared by a "one-pot" synthesis method using mixtures of phosphoric acid with hydrochloric, or nitric acids in the presence of Pluronic F127 triblock copolymer. Adjusting the various ratios of phosphoric acid used in these mixtures resulted in carbons with distinct adsorption, structural and surface acidity properties. The pore size distributions (PSDs) from nitrogen adsorption at -196 °C showed that mesoporous carbons exhibit specific surface areas as high as 551 m 2/g and mesopores as large as 13 nm. Both structural ordering of the mesopores and the final phosphate contents were strongly dependent on the ratios of H 3PO 4 in the synthesis gels, as shown by transmission electron microscopy (TEM), X-ray photoelectron (XPS) and energy dispersive X-ray spectroscopy (EDS). The number of surface acid sites determined from temperature programmed desorption of ammonia (NH 3-TPD) were in the range of 0.3-1.5 mmol/g while the active surface areas are estimated to comprise 5-54% of the total surface areas. Finally, the conversion temperatures for the isopropanol dehydration were lowered by as much as 100 °C by transitioning from the least acidic to the most acidic catalysts surface.
Original language | English |
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Pages (from-to) | 12-19 |
Number of pages | 8 |
Journal | Catalysis Today |
Volume | 186 |
Issue number | 1 |
DOIs | |
State | Published - Jun 1 2012 |
Funding
P.F.F. and S.M.M. were supported as part of the Fluid Interface Reactions, Structures and Transport (FIRST) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number ERKCC61. R.T.M. was supported by the U.S. Dept. of Energy, Office of Energy Efficiency and Renewable Energy. G.M.V. was supported by Materials Sciences & Engineering Division, Office of Basic Energy Sciences. X.Q.W., J.C.B., and S.D. were supported by the Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences, U.S. Dept. of Energy under contract DE-AC05-OR22725 with Oak Ridge National Laboratory, managed and operated by UT-Battelle, LLC.
Keywords
- Ammonia-TPD
- Isopropanol dehydration
- Mesoporous carbon
- Phosphorylation
- Soft-templating