Pd2Ga-Based Colloids as Highly Active Catalysts for the Hydrogenation of CO2 to Methanol
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Colloidal Pd2Ga-based catalysts are shown to catalyze efficiently the hydrogenation of CO2 to methanol. The catalysts are produced by the simple thermal decomposition of Pd(II) acetate in the presence of Ga(III) stearate, which leads to Pd0 nanoparticles (ca. 3 nm), and the subsequent Pd-mediated reduction of Ga(III) species at temperatures ranging from 210 to 290 °C. The resulting colloidal Pd2Ga-based catalysts are applied in the liquid-phase hydrogenation of carbon dioxide to methanol at high pressure (50 bar). The intrinsic activity is around 2-fold higher than that obtained for the commercial Cu-ZnO-Al2O3 (60.3 and 37.2 × 10–9 molMeOH m–2 s–1), respectively, and 4-fold higher on a Cu or Pd molar basis (3330 and 910 μmol mmolPd or Cu–1 h–1). Detailed characterization data (HR-TEM, STEM/EDX, XPS, and XRD) indicate that the catalyst contains Pd2Ga nanoparticles, of average diameters 5–6 nm, associated with a network of amorphous Ga2O3 species. The proportion of this Ga2O3 phase can be easily tuned by adjusting the molar ratio of the Pd:Ga precursors. A good correlation was found between the intrinsic activity and the content of Ga2O3 surrounding the Pd2Ga nanoparticles (XPS), suggesting that methanol is formed by a bifunctional mechanism involving both phases. The increase in the reaction temperature (190–240 °C) leads to a gradual decrease in methanol selectivity from 60 to 40%, while an optimum methanol production rate was found at 210 °C. Interestingly, unlike the conventional Cu-ZnO-Al2O3, which experienced approximately 50% activity loss over 25 h time on stream, the Pd2Ga-based catalysts maintain activity over this time frame. Indeed, characterization of the Pd/Ga mixture postcatalysis revealed no ripening of the nanoparticles or changes in the phases initially present.
Date Issued
2017-01-10
Date Acceptance
2017-01-10
Citation
ACS Catalysis, 2017, 7 (2), pp.1186-1196
ISSN
2155-5435
Publisher
American Chemical Society
Start Page
1186
End Page
1196
Journal / Book Title
ACS Catalysis
Volume
7
Issue
2
Copyright Statement
© 2017 American Chemical Society. This is an open access article published under a Creative Commons Attribution (CC-BY)
License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium,
provided the author and source are cited.
License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium,
provided the author and source are cited.
Sponsor
Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000393539200031&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Grant Number
EP/H046380/1
EP/K035274/1
EP/M013839/1
Subjects
Science & Technology
Physical Sciences
Chemistry, Physical
Chemistry
colloidal nanoparticles
nanocatalysts
Pd2Ga alloy
bimetallic PdGa
CO2 hydrogenation
methanol synthesis
STEAM REFORMING CATALYSTS
LIQUID-PHASE METHANOL
CONTACT QUANTIFICATION MODEL
CU-ZNO SYNERGY
CARBON-DIOXIDE
GA2O3-PD/SILICA CATALYSTS
INTERMETALLIC CATALYST
CRYSTAL-STRUCTURES
SUPPORTED PD2GA
IN-SITU
Publication Status
Published