scholarly journals Study on Ammonia-induced Catalyst Poisoning in the Synthesis of Dimethyl Oxalate

2021 ◽  
Vol 16 (1) ◽  
pp. 1-8
Author(s):  
Hua-wei Liu ◽  
Sheng-tao Qian ◽  
Er-fei Xiao ◽  
Ying-jie Liu ◽  
Jun Lei ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Coupling Reaction ◽  
Industrial Plant ◽  
Dimethyl Oxalate ◽  
Xps Characterization ◽  
Temperature Liquid ◽  
Amine Compounds ◽  
Co Coupling

On an industrial plant, we observed and examined the ammonia-poisoning catalyst for the synthesis of dimethyl oxalate (DMO). We investigated the catalytic activity in response to the amount of ammonia and revealed the mechanism of such poisoning by X-ray photoelectron spectroscopy (XPS) characterization. Our results show that only 0.002% ammonia in the feed gas can significantly deactivate the Pd-based catalyst. Two main reasons were proposed: one is that the competitive adsorption of ammonia on the active component Pd hinders the carbon    monoxide (CO) coupling reaction and the redox cycle between Pd0 and Pd2+; and the other is that the high-boiling nitrogen-containing amine compounds formed by reacting with ammonia have adsorbed on the catalyst, which hinders the progress of the catalytic reaction. The deactivation caused by the latter is irreversible. The catalytic activity can be completely restored by a low-temperature liquid-phase in-situ regeneration treatment. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

In situ DRIFTS study of CO coupling to dimethyl oxalate over structured Al-fiber@ns-AlOOH@Pd catalyst

2016 ◽  
Vol 344 ◽  
pp. 173-183 ◽  
Author(s):  
Chunzheng Wang ◽  
Pengjing Chen ◽  
Yakun Li ◽  
Guofeng Zhao ◽  
Ye Liu ◽  
...  
Keyword(s):  
Pd Catalyst ◽  
In Situ Drifts ◽  
Dimethyl Oxalate ◽  
Co Coupling

Palladium nanoparticles in situ synthesized on Cyclea barbata pectin as a heterogeneous catalyst for Heck coupling in water, the reduction of nitrophenols and alkynes

2021 ◽  
Author(s):  
Van-Dung Le ◽  
T. Cam-Huong Le ◽  
Van-Trung Chau ◽  
T. Ngoc-Duyen Le ◽  
Chi-Hien Dang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Heterogeneous Catalyst ◽  
Palladium Nanoparticles ◽  
Coupling Reaction ◽  
Heck Coupling

This study develops an effective method for in situ synthesis of PdNPs using Cyclea barbata pectin as green reducing and stabilizing reagent. The catalytic activity of nanocomposite was evaluated for Heck coupling reaction, reduction of nitrophenols and reduction of alkynes.

The mechanism of CO coupling reaction to form dimethyl oxalate over Pd/α-Al2O3

2009 ◽  
Vol 314 (1-2) ◽  
pp. 63-70 ◽  
Author(s):  
Yang Ji ◽  
Gang Liu ◽  
Wei Li ◽  
Wende Xiao
Keyword(s):  
Coupling Reaction ◽  
Dimethyl Oxalate ◽  
Α Al2o3 ◽  
Co Coupling

Starch assisted palladium(0) nanoparticles as in situ generated catalysts for room temperature Suzuki–Miyaura reactions in water

RSC Advances ◽  
2016 ◽  
Vol 6 (14) ◽  
pp. 11758-11762 ◽  
Author(s):  
Anindita Dewan ◽  
Pankaj Bharali ◽  
Utpal Bora ◽  
Ashim Jyoti Thakur
Keyword(s):  
Catalytic Activity ◽  
Room Temperature ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Catalyst Loading ◽  
Arylboronic Acids ◽  
Cross Coupling Reaction ◽  
Low Catalyst Loading

The in situ generated PdNPs show excellent catalytic activity in Suzuki–Miyaura cross coupling reaction of electronically diversified arylbromides and arylboronic acids in water at room temperature with low catalyst loading.

scholarly journals One-Pot Synthesized Pd@N-Doped Graphene: An Efficient Catalyst for Suzuki–Miyaura Couplings

Catalysts ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 469 ◽  
Author(s):  
Mufsir Kuniyil ◽  
J. V. Shanmukha Kumar ◽  
Syed Farooq Adil ◽  
Mohammed Rafi Shaik ◽  
Mujeeb Khan ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Catalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Coupling Reaction ◽  
Ammonium Hydroxide ◽  
Coupling Reactions ◽  
One Pot ◽  
Efficient Catalyst ◽  
X Ray ◽  
Doped Graphene

Nitrogen-doped graphene (NDG)-palladium (Pd)-based nanocatalysts (NDG@Pd) can be potentially applied as an efficient catalyst for the preparation of biaryls in a Suzuki–Miyaura coupling reaction. Herein, we report the one-pot facile synthesis of an NDG@Pd nanocatalyst, wherein the nanocatalyst was prepared by the simultaneous reduction of graphene oxide (GRO) and PdCl2 in the presence of hydrazine hydrate as a reducing agent, while ammonium hydroxide was used as a source of “N’’ on the surface of graphene. The as-synthesized NDG@Pd nanocatalyst, consisting of smaller-sized, spherical-shaped palladium nanoparticles (Pd-NPs) on the surface of NDG, was characterized by several spectroscopic and microscopic techniques, including high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET). The nanocatalyst displayed outstanding catalytic activity in the Suzuki–Miyaura cross-coupling reactions of phenyl halides with phenyl boronic acids under facile conditions in water. The catalytic activity of NDG@Pd was found to be a more efficient catalyst when compared to pristine highly reduced graphene oxide (HRG) based Pd nanocatalyst (HRG@Pd). Furthermore, the reusability of the catalyst was also tested by repeatedly performing the same reaction using the recovered catalyst. The N-doped catalyst displayed excellent reusability even after several reactions.

scholarly journals Improving the Performance of Gd Addition on Catalytic Activity and SO2 Resistance over MnOx/ZSM-5 Catalysts for Low-Temperature NH3-SCR

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 324
Author(s):  
Jinkun Guan ◽  
Lusha Zhou ◽  
Weiquan Li ◽  
Die Hu ◽  
Jie Wen ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Low Temperature ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Molar Ratio ◽  
Manganese Sulfate ◽  
Nh3 Scr ◽  
So2 Resistance ◽  
Temperature Programmed

SO2 poisoning is a great challenge for the practical application of Mn-based catalysts in low-temperature selective catalytic reduction (SCR) reactions of NOx with NH3. A series of Gadolinium (Gd)-modified MnOx/ZSM-5 catalysts were synthesized via a citric acid–ethanol dispersion method and evaluated by low-temperature NH3-SCR. Among them, the GdMn/Z-0.3 catalyst with the molar ratio of Gd/Mn of 0.3 presented the highest catalytic activity, in which a 100% NO conversion could be obtained in the temperature range of 120–240 °C. Furthermore, GdMn/Z-0.3 exhibited good SO2 resistance compared with Mn/Z in the presence of 100 ppm SO2. The results of Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction of H2 (H2-TPR) and temperature-programmed desorption of NH3 (NH3-TPD) illustrated that such catalytic performance was mainly caused by large surface area, abundant Mn4+ and surface chemisorbed oxygen species, strong reducibility and the suitable acidity of the catalyst. The in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS) results revealed that the addition of Gd greatly inhibited the reaction between the SO2 and MnOx active sites to form bulk manganese sulfate, thus contributing to high SO2 resistance. Moreover, in situ DRIFTS experiments also shed light on the mechanism of low-temperature SCR reactions over Mn/Z and GdMn/Z-0.3, which both followed the Langmuir–Hinshelwood (L–H) and Eley–Rideal (E–R) mechanism.

Preparation and Photo-catalytic Activity of Cu-Supported Nano-TiO2

2020 ◽  
Vol 1 (1) ◽  
pp. 38-42
Author(s):  
Jun Yan
Keyword(s):  
Catalytic Activity ◽  
Methyl Orange ◽  
Photoelectron Spectroscopy ◽  
Diffuse Reflectance Spectroscopy ◽  
Nano Tio2 ◽  
Hydrolysis Method ◽  
Response Range ◽  
Photo Response ◽  
Forced Hydrolysis ◽  
Visible Photocatalytic Activity

Cu-supported nano-TiO2 catalyst was prepared by forced hydrolysis method under mild condition. The morphology, composition and optical absorption properties of the samples were characterized by means of scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and UV-Vis diffuse reflectance spectroscopy (UV-VIS DRS). Visible photocatalytic activity of the samples was investigated by photocatalytic degradation experiment on methyl orange. The results indicated that nano-TiO2 was about 20nm in size with the main form of anatase, and photo response range was significantly broadened after it was loaded on the surface of Cu. The sample possessed high visible light catalytic activity, with the degradation rate of methyl orange reaching 94% under simulated natural light.

Catalytic activity of rhodium(I) complexes containing (ω-trimethylsilylalkyl)diphenylphosphines

1980 ◽  
Vol 45 (8) ◽  
pp. 2219-2223 ◽  
Author(s):  
Marie Jakoubková ◽  
Martin Čapka
Keyword(s):  
Catalytic Activity ◽  
Nmr Spectroscopy ◽  
Ir Spectroscopy ◽  
Electron Density ◽  
Phosphorus Atom ◽  
Proton Acceptor ◽  
Trimethylsilyl Group ◽  
Kinetics Of

Kinetics of homogenous hydrogenation of 1-heptene catalysed by rhodium(I) complexes prepared in situ from μ,μ'-dichloro-bis(cyclooctenerhodium) and phosphines of the type RP(C6H5)2 (R = -CH3, -(CH2)nSi(CH3)3; n = 1-4) have been studied. The substitution of the ligands by the trimethylsilyl group was found to increase significantly the catalytic activity of the complexes. The results are discussed in relation to the electron density on the phosphorus atom determined by 31P NMR spectroscopy and to its proton acceptor ability determined by IR spectroscopy.

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