skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Gold Catalysts Synthesized Using a Modified Incipient Wetness Impregnation Method for Propylene Epoxidation
Abstract Propylene epoxidation in the presence of oxygen and hydrogen were measured for a series of Au/TS‐1 catalysts prepared by a modified incipient wetness impregnation (mIWI) method. This method enables precise control of the Au : Ti ratio in the Au/TS‐1 catalysts. The optimized Au/TS‐1 catalyst exhibited 12 % propylene conversion, 87 % PO selectivity, and 25 % hydrogen efficiency. The particle size of gold nanoparticles prepared by the modified IWI was between 2 and 3 nm, as demonstrated by XRD patterns, STEM images, and X‐ray absorption spectroscopy at the Au L3edge. XPS spectra showed that the surface species on the catalysts were similar. UV‐Vis spectra suggested that in the modified IWI method, the chlorine ligands in Au(Cl)4−were replaced by hydroxyl groups, which contributes to form small gold nanoparticles. Kinetic studies showed that the active sites of Au(mIWI)/TS‐1 are similar to the Au(DP)/TS‐1 prepared by deposition precipitation.  more » « less
Award ID(s):
1511820
PAR ID:
10255752
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
ChemCatChem
Volume:
12
Issue:
23
ISSN:
1867-3880
Page Range / eLocation ID:
p. 5993-5999
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; (, Materials Research Express)
    Abstract Gold (Au)- and ceria (CeO2)-based catalysts are amongst the most active catalysts for the gas phase CO oxidation reaction. Nevertheless, nanosized Au and CeO2catalysts may encounter heat-induced sintering in thermochemical catalytic reactions. Herein, we report on the rational one-pot synthesis of ceria-reduced graphene oxide (CeO2-RGO) using a facile ethylenediamine (EDA)-assisted solvothermal method. Standalone RGO and free-standing CeO2were also prepared using the same EDA-assisted method for comparison. We then incorporated Au into the prepared samples by colloidal reduction and evaluated the catalytic activity of the different catalysts for CO oxidation. The RGO-supported CeO2surpassed the free-standing CeO2, exhibiting a 100% CO conversion at 285oC compared to 340oC in the case of CeO2. Interestingly, the RGO-supported Au/CeO2catalysts outperformed the Au/CeO2catalysts and achieved a 100% CO conversion at 76oC compared to 113oC in the case of Au/CeO2. Additionally, the Au/CeO2-RGO catalyst demonstrated remarkable room-temperature activity with simultaneous 72% CO conversion. This outstanding performance was attributed to the unique dispersion and size characteristics of the RGO-supported CeO2and Au catalysts in the ternary Au/CeO2-RGO nanocomposite, as revealed by TEM and XPS, among other techniques. 
    more » « less
  2. ; ; ; ; ; ; ; ; ; (, ChemCatChem)
    Abstract Bulk boron materials, such as hexagonal boron nitride (h‐BN), are highly selective catalysts for the oxidative dehydrogenation of propane (ODHP). Previous attempts to improve the productivity of these systems involved the immobilization of boron on silica and resulted in less selective catalysts. Here, we report that acid‐treated, activated carbon‐supported boron preparedviaincipient wetness impregnation with boric acid (B/OAC) exhibits equal propylene selectivity and improved productivity (kgpropylene kgcat−1 hr−1) as compared to h‐BN. Characterization of the fresh and spent catalysts with infrared, Raman, X‐ray photoelectron, and solid‐state NMR spectroscopies reveals the presence of oxidized/hydrolyzed boron that is clustered on the surface of the support. 
    more » « less
  3. ; ; (, ChemPlusChem)
    Abstract Reaction of (P)AuOTf [P=P(t‐Bu)2o‐biphenyl] with indenyl‐ or 3‐methylindenyl lithium led to isolation of gold η1‐indenyl complexes (P)Au(η1‐inden‐1‐yl) (1 a) and (P)Au(η1‐3‐methylinden‐1‐yl) (1 b), respectively, in >65 % yield. Whereas complex1 bis static, complex1 aundergoes facile, degenerate 1,3‐migration of gold about the indenyl ligand (ΔG≠153K=9.1±1.1 kcal/mol). Treatment of complexes1 aand1 bwith (P)AuNTf2led to formation of the corresponding cationic bis(gold) indenyl complexestrans‐[(P)Au]2(η1,η1‐inden‐1,3‐yl) (2 a) andtrans‐[(P)Au]2(η1,η2‐3‐methylinden‐1‐yl) (2 b), respectively, which were characterized spectroscopically and modeled computationally. Despite the absence of aurophilic stabilization in complexes2 aand2 b, the binding affinity of mono(gold) complex1 atoward exogenous (P)Au+exceed that of free indene by ~350‐fold and similarly the binding affinity of1 btoward exogenous (P)Au+exceed that of 3‐methylindene by ~50‐fold. The energy barrier for protodeauration of bis(gold) indenyl complex2 awith HOAc was ≥8 kcal/mol higher than for protodeauration of mono(gold) complex1 a. 
    more » « less
  4. ; ; ; (, Catalysts)
    null (Ed.)
    Direct propylene epoxidation using Au-based catalysts is an important gas-phase reaction and is clearly a promising route for the future industrial production of propylene oxide (PO). For instance, gold nanoparticles or clusters that consist of a small number of atoms demonstrate unique and even unexpected properties, since the high ratio of surface to bulk atoms can provide new reaction pathways with lower activation barriers. Support materials can have a remarkable effect on Au nanoparticles or clusters due to charge transfer. Moreover, Au (or Au-based alloy, such as Au–Pd) can be loaded on supports to form active interfacial sites (or multiple interfaces). Model studies are needed to help probe the underlying mechanistic aspects and identify key factors controlling the activity and selectivity. The current theoretical/computational progress on this system is reviewed with respect to the molecular- and catalyst-level aspects (e.g., first-principles calculations and kinetic modeling) of propylene epoxidation over Au-based catalysts. This includes an analysis of H2 and O2 adsorption, H2O2 (OOH) species formation, epoxidation of propylene into PO, as well as possible byproduct formation. These studies have provided a better understanding of the nature of the active centers and the dominant reaction mechanisms, and thus, could potentially be used to design novel catalysts with improved efficiency. 
    more » « less
  5. ; ; ; (, ChemNanoMat)
    Abstract Using microwave irradiation, PtCo alloy nanoparticles were deposited within a few minutes on COOH‐functionalized MWCNT supports. The obtained catalysts were used for selective hydrogenation of cinnamaldehyde, a reaction whose products are widely used in various fields. In the selective cinnamaldehyde hydrogenation to cinnamyl alcohol, microwave‐prepared catalysts (generically, PtxCoy‐MW) outperformed a catalyst prepared by the conventional method (Pt1Co2‐con). The highest selective hydrogenation to cinnamyl alcohol, 89%, was obtained using Pt1Co2‐MW, while Pt1Co2‐con showed a selectivity of 76%. Characterization results confirmed that the microwave prepared samples had a stronger interaction between Pt and Co than that in the Pt1Co2‐con sample. The alloyed Co altered the electronic structure of Pt, leading to favorable adsorption of the C=O bond by the lone‐pair electrons of its oxygen atom. Moreover, the Pt1Co2‐MW sample showed neglectable change in catalytic performance (e. g., cinnamaldehyde conversion and selective hydrogenation to cinnamyl alcohol) during recycling experiments. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email