Reactivity of a Carbon-Supported Single-Site Molybdenum Dioxo Catalyst for Biodiesel Synthesis

Aidan R. Mouat; Tracy L. Lohr; Evan C. Wegener; Jeffrey T. Miller; Massimiliano Delferro; Peter C. Stair; Tobin J. Marks

doi:10.1021/acscatal.6b01717

Reactivity of a Carbon-Supported Single-Site Molybdenum Dioxo Catalyst for Biodiesel Synthesis

Aidan R. Mouat, Tracy L. Lohr, Evan C. Wegener, Jeffrey T. Miller, Massimiliano Delferro^*, Peter C. Stair, Tobin J. Marks

^*Corresponding author for this work

Chemistry

Research output: Contribution to journal › Article › peer-review

49 Scopus citations

Abstract

A single-site molybdenum dioxo catalyst, (O_c)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 MoO_x T_max of reduction reported to date, suggesting a highly reactive Mo^VI center. (O_c)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. (O_c)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.

Original language	English (US)
Pages (from-to)	6762-6769
Number of pages	8
Journal	ACS Catalysis
Volume	6
Issue number	10
DOIs	https://doi.org/10.1021/acscatal.6b01717
State	Published - Oct 7 2016

Funding

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.

Keywords

biodiesel
heterogeneous catalysis
molybdenum
supported catalysts
transesterification

ASJC Scopus subject areas

Catalysis
General Chemistry

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10.1021/acscatal.6b01717

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title = "Reactivity of a Carbon-Supported Single-Site Molybdenum Dioxo Catalyst for Biodiesel Synthesis",

abstract = "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.",

keywords = "biodiesel, heterogeneous catalysis, molybdenum, supported catalysts, transesterification",

author = "Mouat, {Aidan R.} and Lohr, {Tracy L.} and Wegener, {Evan C.} and Miller, {Jeffrey T.} and Massimiliano Delferro and Stair, {Peter C.} and Marks, {Tobin J.}",

note = "Publisher Copyright: {\textcopyright} 2016 American Chemical Society.",

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doi = "10.1021/acscatal.6b01717",

language = "English (US)",

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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.

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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DO - 10.1021/acscatal.6b01717

M3 - Article

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VL - 6

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JF - ACS Catalysis

IS - 10

ER -

Reactivity of a Carbon-Supported Single-Site Molybdenum Dioxo Catalyst for Biodiesel Synthesis

Abstract

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Keywords

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