From organometallic zinc and copper complexes to highly active colloidal catalysts for the conversion of CO2 to methanol

DOI: 10.1021/cs502038y

Authors: Neil Brown (Imperial College London) , Andrés García-Trenco (Imperial College London) , Jonathan Weiner (Imperial College London) , Edward R. White (Imperial College London) , Matthew Allinson (Imperial College London) , Yuxin Chen (Imperial College London) , Peter Wells (University College London; The UK Catalysis Hub, Research Complex at Harwell) , Emma Gibson (University College London; The UK Catalysis Hub, Research Complex at Harwell) , Klaus Hellgardt (Imperial College London) , Milo S. P. Shaffer (Imperial College London) , Charlotte K. Williams (Imperial College London)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acs Catalysis , VOL 5 (5)

State: Published (Approved)
Published: April 2015
Diamond Proposal Number(s): 8071

Abstract: A series of zinc oxide and copper(0) colloidal nanocatalysts, produced by a one-pot synthesis, are shown to catalyze the hydrogenation of carbon dioxide to methanol. The catalysts are produced by the reaction between diethyl zinc and bis(carboxylato/phosphinato)copper(II) precursors. The reaction leads to the formation of a precatalyst solution, characterized using various spectroscopic (NMR, UV–vis spectroscopy) and X-ray diffraction/absorption (powder XRD, EXAFS, XANES) techniques. The combined characterization methods indicate that the precatalyst solution contains copper(0) nanoparticles and a mixture of diethyl zinc and an ethyl zinc stearate cluster compound [Et4Zn5(stearate)6]. The catalysts are applied, at 523 K with a 50 bar total pressure of a 3:1 mixture of H2/CO2, in the solution phase, quasi-homogeneous, hydrogenation of carbon dioxide, and they show high activities (>55 mmol/gZnOCu/h of methanol). The postreaction catalyst solution is characterized using a range of spectroscopies, X-ray diffraction techniques, and transmission electron microscopy (TEM). These analyses show the formation of a mixture of zinc oxide nanoparticles, of size 2–7 nm and small copper nanoparticles. The catalyst composition can be easily adjusted, and the influence of the relative loadings of ZnO/Cu, the precursor complexes and the total catalyst concentration on the catalytic activity are all investigated. The optimum system, comprising a 55:45 loading of ZnO/Cu, shows equivalent activity to a commercial, activated methanol synthesis catalyst. These findings indicate that using diethyl zinc to reduce copper precursors in situ leads to catalysts with excellent activities for the production of methanol from carbon dioxide.

Journal Keywords: catalysts from organometallic; CO2 reduction; colloidal catalysts; Cu-ZnO catalysts; hydrogenation of CO2; methanol synthesis; nanocatalysts; nanoparticles

Subject Areas: Chemistry, Environment, Energy


Instruments: B18-Core EXAFS

Added On: 09/04/2015 16:07

Documents:
cs502038y.pdf

Discipline Tags:

Earth Sciences & Environment Sustainable Energy Systems Energy Molecular Complexes Climate Change Physical Chemistry Catalysis Chemistry Organometallic Chemistry

Technical Tags:

Spectroscopy X-ray Absorption Spectroscopy (XAS) Extended X-ray Absorption Fine Structure (EXAFS)