TY - JOUR
T1 - Reactivity of a Carbon-Supported Single-Site Molybdenum Dioxo Catalyst for Biodiesel Synthesis
AU - Mouat, Aidan R.
AU - Lohr, Tracy L.
AU - Wegener, Evan C.
AU - Miller, Jeffrey T.
AU - Delferro, Massimiliano
AU - Stair, Peter C.
AU - Marks, Tobin J.
N1 - Funding Information:
Financial support was provided by the Chemical Sciences, Geosciences, and Biosciences Division, U.S. Department of Energy, through grant DE FG02-03ER15457 to the Institute of Catalysis in Energy Processes (ICEP) at Northwestern University. NSF grant CHE-1213235 supported T.L.L. and provided reactor equipment. We gratefully acknowledge Northwestern Clean Cat facilities. Use of the Advanced Photon Source is supported by the U.S. Department of Energy, Office of Science, and Office of Basic Energy Sciences, under Contract DE-AC02-06CH11357. MRCAT operations are supported by the Department of Energy and the MRCAT member institutions. E.C.W. and J.T.M. were supported by start-up funding from Purdue University and the School of Chemical Engineering.
Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/10/7
Y1 - 2016/10/7
N2 - A single-site molybdenum dioxo catalyst, (Oc)2Mo(=O)2@C, was prepared via direct grafting of MoO2Cl2(dme) (dme = 1,2-dimethoxyethane) on high-surface-area activated carbon. The physicochemical and chemical properties of this catalyst were fully characterized by N2 physisorption, ICP-AES/OES, PXRD, STEM, XPS, XAS, temperature-programmed reduction with H2 (TPR-H2), and temperature-programmed NH3 desorption (TPD-NH3). The single-site nature of the Mo species is corroborated by XPS and TPR-H2 data, and it exhibits the lowest reported MoOx Tmax of reduction reported to date, suggesting a highly reactive MoVI center. (Oc)2Mo(=O)2@C catalyzes the transesterification of a variety of esters and triglycerides with ethanol, exhibiting high activity at moderate temperatures (60-90 °C) and with negligible deactivation. (Oc)2Mo(=O)2@C is resistant to water and can be recycled at least three times with no loss of activity. The transesterification reaction is determined experimentally to be first order in [ethanol] and first order in [Mo] with Δ;H‡ = 10.5(8) kcal mol-1 and Δ;S‡ = -32(2) eu. The low energy of activation is consistent with the moderate conditions needed to achieve rapid turnover. This highly active carbon-supported single-site molybdenum dioxo species is thus an efficient, robust, and low-cost catalyst with significant potential for transesterification processes.
AB - A single-site molybdenum dioxo catalyst, (Oc)2Mo(=O)2@C, was prepared via direct grafting of MoO2Cl2(dme) (dme = 1,2-dimethoxyethane) on high-surface-area activated carbon. The physicochemical and chemical properties of this catalyst were fully characterized by N2 physisorption, ICP-AES/OES, PXRD, STEM, XPS, XAS, temperature-programmed reduction with H2 (TPR-H2), and temperature-programmed NH3 desorption (TPD-NH3). The single-site nature of the Mo species is corroborated by XPS and TPR-H2 data, and it exhibits the lowest reported MoOx Tmax of reduction reported to date, suggesting a highly reactive MoVI center. (Oc)2Mo(=O)2@C catalyzes the transesterification of a variety of esters and triglycerides with ethanol, exhibiting high activity at moderate temperatures (60-90 °C) and with negligible deactivation. (Oc)2Mo(=O)2@C is resistant to water and can be recycled at least three times with no loss of activity. The transesterification reaction is determined experimentally to be first order in [ethanol] and first order in [Mo] with Δ;H‡ = 10.5(8) kcal mol-1 and Δ;S‡ = -32(2) eu. The low energy of activation is consistent with the moderate conditions needed to achieve rapid turnover. This highly active carbon-supported single-site molybdenum dioxo species is thus an efficient, robust, and low-cost catalyst with significant potential for transesterification processes.
KW - biodiesel
KW - heterogeneous catalysis
KW - molybdenum
KW - supported catalysts
KW - transesterification
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U2 - 10.1021/acscatal.6b01717
DO - 10.1021/acscatal.6b01717
M3 - Article
AN - SCOPUS:84990955041
VL - 6
SP - 6762
EP - 6769
JO - ACS Catalysis
JF - ACS Catalysis
SN - 2155-5435
IS - 10
ER -