scholarly journals Improved Water–Gas Shift Performance of Au/NiAl LDHs Nanostructured Catalysts via CeO2 Addition

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 366
Author(s):  
Margarita Gabrovska ◽  
Ivan Ivanov ◽  
Dimitrinka Nikolova ◽  
Jugoslav Krstić ◽  
Anna Maria Venezia ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Nanostructured Catalysts ◽  
Water Gas Shift ◽  
Precipitation Method ◽  
Conversion Degree ◽  
Pure Hydrogen ◽  
Medium Temperature ◽  
X Ray ◽  
Supported Gold ◽  
Water Gas

Supported gold on co-precipitated nanosized NiAl layered double hydroxides (LDHs) was studied as an effective catalyst for medium-temperature water–gas shift (WGS) reaction, an industrial catalytic process traditionally applied for the reduction in the amount of CO in the synthesis gas and production of pure hydrogen. The motivation of the present study was to improve the performance of the Au/NiAl catalyst via modification by CeO2. An innovative approach for the direct deposition of ceria (1, 3 or 5 wt.%) on NiAl-LDH, based on the precipitation of Ce3+ ions with 1M NaOH, was developed. The proposed method allows us to obtain the CeO2 phase and to preserve the NiAl layered structure by avoiding the calcination treatment. The synthesis of Au-containing samples was performed through the deposition–precipitation method. The as-prepared and WGS-tested samples were characterized by X-ray powder diffraction, N2-physisorption and X-ray photoelectron spectroscopy in order to clarify the effects of Au and CeO2 loading on the structure, phase composition, textural and electronic properties and activity of the catalysts. The reduction behavior of the studied samples was evaluated by temperature-programmed reduction. The WGS performance of Au/NiAl catalysts was significantly affected by the addition of CeO2. A favorable role of ceria was revealed by comparison of CO conversion degree at 220 °C reached by 3 wt.% CeO2-modified and ceria-free Au/NiAl samples (98.8 and 83.4%, respectively). It can be stated that tuning the properties of Au/NiAl LDH via CeO2 addition offers catalysts with possibilities for practical application owing to innovative synthesis and improved WGS performance.

scholarly journals Effect of Nickel Oxide Doping to Ceria-Supported Gold Catalyst for CO Oxidation and Water-Gas Shift Reactions

Catalysts ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 584 ◽  
Author(s):  
Miao Shu ◽  
Shuai Wei ◽  
Chun-Jiang Jia ◽  
Dao-Lei Wang ◽  
Rui Si
Keyword(s):  
Nickel Oxide ◽  
Co Oxidation ◽  
Gold Catalyst ◽  
Water Gas Shift ◽  
Precipitation Method ◽  
X Ray ◽  
Co Oxidation Reaction ◽  
Metal Metal ◽  
Supported Gold ◽  
Water Gas

Ceria-supported gold catalyst has drew much research interest owing to its high reactivity on CO oxidation and water-gas shift (WGS) reactions. However, till now, there were relatively limited studies on the effect of secondary metal/metal oxide component into gold-ceria system to enhance its catalytic performance. In this work, we synthetized the ceria supported gold-nickel samples via a deposition-precipitation method with the base of NaHCO3 to adjust final pH value of 8~9. We found that the addition of nickel oxide drove off the gold species from the stock solution during synthesis, and thus resulted in a dramatical decrease on doped Au concentration. No crystallized phases of gold and nickel were observed on the surface of ceria nanorods in both X-ray diffraction (XRD) and transmission electron microscopy (TEM). The valence of nickel was maintained as Ni2+ for all the measured samples by X-ray photoelectron spectroscopy (XPS), while gold was oxidized with the increased nickel amount after analysis of X-ray absorption near edge spectroscopy (XANES). The corresponding catalytic tests showed that with the introduction of nickel oxide, the activity of gold-ceria catalyst was promoted for the WGS reaction, but inhibited for the CO oxidation reaction.

scholarly journals Synthesis of CuNi/C and CuNi/γ-Al2O3Catalysts for the Reverse Water Gas Shift Reaction

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Maxime Lortie ◽  
Rima Isaifan ◽  
Yun Liu ◽  
Sander Mommers
Keyword(s):  
Photoelectron Spectroscopy ◽  
Synthesis Method ◽  
Water Gas Shift ◽  
Polyol Synthesis ◽  
Pt Catalysts ◽  
X Ray ◽  
Reverse Water Gas Shift ◽  
Rwgs Reaction ◽  
Shift Reaction ◽  
Water Gas

A new polyol synthesis method is described in which CuNi nanoparticles of different Cu/Ni atomic ratios were supported on both carbon and gamma-alumina and compared with Pt catalysts using the reverse water gas shift, RWGS, reaction. All catalysts were highly selective for CO formation. The concentration of CH4was less than the detection limit. Cu was the most abundant metal on the CuNi alloy surfaces, as determined by X-ray photoelectron spectroscopy, XPS, measurements. Only one CuNi alloy catalyst, Cu50Ni50/C, appeared to be as thermally stable as the Pt/C catalysts. After three temperature cycles, from 400 to 700°C, the CO yield at 700°C obtained using the Cu50Ni50/C catalyst was comparable to that obtained using a Pt/C catalyst.

Importance of the Metal-Oxide Interface in Catalysis: In Situ Studies of the Water-Gas Shift Reaction by Ambient-Pressure X-ray Photoelectron Spectroscopy

2013 ◽  
Vol 125 (19) ◽  
pp. 5205-5209 ◽  
Author(s):  
Kumudu Mudiyanselage ◽  
Sanjaya D. Senanayake ◽  
Leticia Feria ◽  
Shankhamala Kundu ◽  
Ashleigh E. Baber ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Water Gas Shift ◽  
Water Gas Shift Reaction ◽  
Oxide Interface ◽  
X Ray ◽  
Shift Reaction ◽  
Water Gas

Importance of the Metal-Oxide Interface in Catalysis: In Situ Studies of the Water-Gas Shift Reaction by Ambient-Pressure X-ray Photoelectron Spectroscopy

2013 ◽  
Vol 52 (19) ◽  
pp. 5101-5105 ◽  
Author(s):  
Kumudu Mudiyanselage ◽  
Sanjaya D. Senanayake ◽  
Leticia Feria ◽  
Shankhamala Kundu ◽  
Ashleigh E. Baber ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Water Gas Shift ◽  
Water Gas Shift Reaction ◽  
Oxide Interface ◽  
X Ray ◽  
Shift Reaction ◽  
Water Gas

scholarly journals Zn Promoted Mg-Al Mixed Oxides-Supported Gold Nanoclusters for Direct Oxidative Esterification of Aldehyde to Ester

2021 ◽  
Vol 22 (16) ◽  
pp. 8668
Author(s):  
Jie Li ◽  
Shiyi Wang ◽  
Huayin Li ◽  
Yuan Tan ◽  
Yunjie Ding
Keyword(s):  
Photoelectron Spectroscopy ◽  
Mixed Oxides ◽  
Physical Adsorption ◽  
Gold Nanoclusters ◽  
Precipitation Method ◽  
Esterification Reaction ◽  
X Ray ◽  
Oxidative Esterification ◽  
Molar Ratios ◽  
Supported Gold

The synthesis of ester compounds is one of the most important chemical processes. In this work, Zn-Mg-Al mixed oxides with different Zn2+/Mg2+ molar ratios were prepared via co-precipitation method and supported gold nanoclusters to study the direct oxidative esterification of aldehyde and alcohol in the presence of molecular oxygen. Various characterization techniques such as N2-physical adsorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and CO2 temperature programmed desorption (TPD) were utilized to analyze the structural and electronic properties. Based on the results, the presence of small amounts of Zn2+ ions (~5 wt.%) provoked a remarkable modification of the binary Mg-Al system, which enhanced the interaction between gold with the support and reduced the particle size of gold. For oxidative esterification reaction, the Au25/Zn0.05MgAl-400 catalyst showed the best performance, with the highest turnover frequency (TOF) of 1933 h−1. The active center was believed to be located at the interface between metallic gold with the support, where basic sites contribute a lot to transformation of the substrate.

scholarly journals Low Temperature Water-Gas Shift: Enhancing Stability through Optimizing Rb Loading on Pt/ZrO2

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 210
Author(s):  
Caleb Daniel Watson ◽  
Michela Martinelli ◽  
Donald Charles Cronauer ◽  
A. Jeremy Kropf ◽  
Gary Jacobs
Keyword(s):  
Low Temperature ◽  
Hydrogen Transfer ◽  
Water Gas Shift ◽  
Significant Shift ◽  
Catalyst Activation ◽  
X Ray ◽  
Temperature Programmed ◽  
Water Gas ◽  
X Ray Absorption ◽  
Temperature Water

Recent studies have shown that appropriate levels of alkali promotion can significantly improve the rate of low-temperature water gas shift (LT-WGS) on a range of catalysts. At sufficient loadings, the alkali metal can weaken the formate C–H bond and promote formate dehydrogenation, which is the proposed rate determining step in the formate associative mechanism. In a continuation of these studies, the effect of Rb promotion on Pt/ZrO2 is examined herein. Pt/ZrO2 catalysts were prepared with several different Rb loadings and characterized using temperature programmed reduction mass spectrometry (TPR-MS), temperature programmed desorption (TPD), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), an X-ray absorption near edge spectroscopy (XANES) difference procedure, extended X-ray absorption fine structure spectroscopy (EXAFS) fitting, TPR-EXAFS/XANES, and reactor testing. At loadings of 2.79% Rb or higher, a significant shift was seen in the formate ν(CH) band. The results showed that a Rb loading of 4.65%, significantly improves the rate of formate decomposition in the presence of steam via weakening the formate C–H bond. However, excessive rubidium loading led to the increase in stability of a second intermediate, carbonate and inhibited hydrogen transfer reactions on Pt through surface blocking and accelerated agglomeration during catalyst activation. Optimal catalytic performance was achieved with loadings in the range of 0.55–0.93% Rb, where the catalyst maintained high activity and exhibited higher stability in comparison with the unpromoted catalyst.

Activity of faujasite supported gold monomer towards water gas shift reaction: hybrid density functional theory/molecular mechanics approach

RSC Advances ◽  
2015 ◽  
Vol 5 (96) ◽  
pp. 78864-78873 ◽  
Author(s):  
Subhi Baishya ◽  
Ramesh Ch. Deka
Keyword(s):  
Density Functional ◽  
Water Gas Shift ◽  
Hybrid Density Functional Theory ◽  
Water Gas Shift Reaction ◽  
Functional Theory ◽  
Cationic Monomer ◽  
Shift Reaction ◽  
Supported Gold ◽  
Water Gas ◽  
Hybrid Density Functional

Neutral gold monomer supported on faujasite (Au0/FAU) exhibits superior catalytic activity towards water gas shift reaction compared to cationic monomer.

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