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 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 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.

GOLD SUPPORTED CALCIUM DEFICIENT HYDROXYAPATITE FOR ROOM TEMPERATURE CO OXIDATION

2012 ◽  
Vol 11 (03) ◽  
pp. 1240004 ◽  
Author(s):  
E. LINGA REDDY ◽  
A. PRABHAKARN ◽  
J. KARUPPIAH ◽  
N. RAMESHBABU ◽  
CH. SUBRAHMANYAM
Keyword(s):  
Co Oxidation ◽  
Surface Properties ◽  
Microwave Synthesis ◽  
Room Temperature ◽  
Supported Catalysts ◽  
Gold Catalyst ◽  
Precipitation Method ◽  
Optimum Number ◽  
Icp Oes ◽  
Nanostructured Gold

Gold supported hydroxyapatite (HA) and calcium deficient hydroxyapatite (CDHA) was studied for the room temperature CO oxidation. Nanostructured gold catalyst has been prepared by deposition precipitation method, whereas HA was synthesized by microwave synthesis. Inorder to understand the influence of surface properties of HA, support HA was synthesized with different Ca/P ratios (1.67, 1.62, 1.57, 1.534 and 1.5). The gold supported catalysts were characterized by XRD, BET, ICP-OES and TEM. Typical results indicate that gold supported 1.57 HA shows higher activity compared to other HA catalysts (1.67, 1.62, 1.534 and 1.5) which may be due to the presence of optimum number of acidic and basic sites.

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