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

Research output: Contribution to journalArticle

20 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)6762-6769
Number of pages8
JournalACS Catalysis
Volume6
Issue number10
DOIs
Publication statusPublished - Oct 7 2016

Keywords

  • biodiesel
  • heterogeneous catalysis
  • molybdenum
  • supported catalysts
  • transesterification

ASJC Scopus subject areas

  • Catalysis

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