scholarly journals “Storage-Discharge” Ethanol Cold Plasma for Synthesizing High Performance Pd/Al2O3 Catalysts

Catalysts ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 907
Author(s):  
Hongyang Wang ◽  
Tengda Zhang ◽  
Yufa Zhou ◽  
Xiuling Zhang ◽  
Lanbo Di
Keyword(s):  
Co Oxidation ◽  
Atmospheric Pressure ◽  
Cold Plasma ◽  
Residual Carbon ◽  
Oxygen Species ◽  
Supported Metal Catalysts ◽  
Oxidation Activity ◽  
X Ray ◽  
Chemisorbed Oxygen ◽  
Novel Method

Atmospheric pressure cold plasma is an environmentally friendly and novel method to synthesize supported metal catalysts, which usually uses active hydrogen species to reduce metal ions. Ethanol is a hydrogen-rich renewable liquid hydrogen source, and it is more convenient to store and transport than H2. In this study, a “storage-discharge” ethanol cold plasma was used to prepare Pd/Al2O3-EP catalysts, and the obtained catalysts are used for CO oxidation. The complete oxidation of CO temperature (T100) over Pd/Al2O3-EP was 145 °C, which was comparable to the performance of Pd/Al2O3-HP that was synthesized by atmospheric pressure hydrogen cold plasma. Pd/Al2O3-EP-C obtained by calcining Pd/Al2O3-EP at 450 °C for 2 h in air atmosphere in order to remove residual carbon species showed much higher CO oxidation activity, and T100 was 130 °C. The Pd/Al2O3 catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron diffraction (XPS), Brunauer–Emmett–Teller (BET), and transmission electron microscopy (TEM), and the structure-performance relationship was analyzed. The results indicate that the “storage-discharge” ethanol cold plasma can reduce the Pd precursor ions into metallic Pd state, and the dissociation of ethanol forms lots of highly active chemisorbed oxygen species, which can enhance the performance of Pd/Al2O3-EP for CO oxidation. In contrast, Pd/Al2O3-EP-C shows much higher CO oxidation activity, which is mainly attributed to the removal of the residual carbon species, and the exposure of more Pd active sites and chemisorbed oxygen species. The “storage-discharge” ethanol cold plasma is a safe and efficient novel method for synthesizing supported Pd catalysts, and it has important potential for the preparation and application of supported metal catalysts.

scholarly journals Atmospheric-Pressure Cold Plasma Activating Au/P25 for CO Oxidation: Effect of Working Gas

Nanomaterials ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 742 ◽  
Author(s):  
Jingsen Zhang ◽  
Lanbo Di ◽  
Feng Yu ◽  
Dongzhi Duan ◽  
Xiuling Zhang
Keyword(s):  
Gold Nanoparticles ◽  
Co Oxidation ◽  
Atmospheric Pressure ◽  
Cold Plasma ◽  
Diffuse Reflectance Spectroscopy ◽  
Catalytic Performance ◽  
Impregnation Method ◽  
High Concentration ◽  
Oxidation Activity ◽  
X Ray

Commercial TiO2 (P25) supported gold (Au/P25) attracts increasing attention. In this work, atmospheric-pressure (AP) cold plasma was employed to activate the Au/P25-As catalyst prepared by a modified impregnation method. The influence of cold plasma working gas (oxygen, argon, hydrogen, and air) on the structure and performance of the obtained Au/P25 catalysts was investigated. X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), and X-ray spectroscopy (XPS) were adopted to characterize the Au/P25 catalysts. CO oxidation was used as model reaction probe to test the Au/P25 catalyst. XRD results reveal that supporting gold and AP cold plasma activation have little effect on the P25 support. CO oxidation activity over the Au/P25 catalysts follows the order: Au/P25-O2P > Au/P25-As > Au/P25-ArP ≈ Au/P25-H2P > Au/P25-AirP. Au/P25-AirP presents the poorest CO oxidation catalytic activity among the Au/P25 catalysts, which may be ascribed to the larger size of gold nanoparticles, low concentration of active [O]s, as well as the poisoning [NOx]s. The poor catalytic performance of Au/P25-ArP and Au/P25-H2P is ascribed to the lower concentration of [O]s species. 100% CO conversion temperatures for Au/P25-O2P is 40 °C, which is 30 °C lower than that over the as-prepared Au/P25-As catalyst. The excellent CO oxidation activity over Au/P25-O2P is mainly attributed to the efficient decomposition of gold precursor species, small size of gold nanoparticles, and the high concentration of [O]s species.

scholarly journals Preparation of Pd/C by Atmospheric-Pressure Ethanol Cold Plasma and Its Preparation Mechanism

Nanomaterials ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1437 ◽  
Author(s):  
Zhuang Li ◽  
Jingsen Zhang ◽  
Hongyang Wang ◽  
Zhihui Li ◽  
Xiuling Zhang ◽  
...  
Keyword(s):  
Co Oxidation ◽  
Photoelectron Spectroscopy ◽  
Atmospheric Pressure ◽  
High Performance ◽  
Cold Plasma ◽  
Carbon Layer ◽  
X Ray ◽  
Catalytic Materials ◽  
Ethanol Decomposition ◽  
Ar Gas

Treatment with atmospheric-pressure (AP) hydrogen cold plasma is an effective method for preparing highly active supported metal catalytic materials. However, this technique typically uses H2 as working gas, which is explosive and difficult to transport. This study proposes the use of PdCl2 as a Pd precursor and activated carbon as the support to fabricate Pd/C catalytic materials (Pd/C-EP-Ar) by using ethanol—which is renewable, easily stored, and safe—combined with AP cold plasma (AP ethanol cold plasma) followed by calcination in Ar gas at 550 °C for 2 h. Both Pd/C-EP and Pd/C-HP fabricated using AP ethanol and hydrogen cold plasma (without calcination in Ar gas) respectively, exhibit low CO oxidation reactivity. The activity of Pd/C-EP is lower than Pd/C-HP, which is mainly ascribed to the carbon layer formed by ethanol decomposition during plasma treatment. However, the 100% CO conversion temperature (T100) of Pd/C-EP-Ar is 140 °C, which is similar to that of Pd/C-HP-Ar fabricated using AP hydrogen cold plasma (calcined in Ar gas at 550 °C for 2 h). The characterization results of X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy indicated that the carbon layer formed by ethanol decomposition enhanced the interaction of metal nanoparticles to the support, and a high Pd/C atomic ratio was obtained. This was beneficial to the high CO oxidation performance. This work provides a safe method for synthesizing high-performance Pd/C catalytic materials avoiding the use of H2, which is explosive and difficult to transport.

scholarly journals Catalytic Behaviour of Flame-Made CuO-CeO2 Nanocatalysts in Efficient CO Oxidation

Catalysts ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 256 ◽  
Author(s):  
Feng Zhao ◽  
Shuangde Li ◽  
Xiaofeng Wu ◽  
Renliang Yue ◽  
Weiman Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Water Vapor ◽  
Co Oxidation ◽  
Photoelectron Spectroscopy ◽  
Co Adsorption ◽  
Synergistic Interaction ◽  
Flame Spray ◽  
Oxidation Activity ◽  
X Ray

CuO-CeO2 nanocatalysts with varying CuO contents (1, 5, 9, 14 and 17 wt %) were prepared by one-step flame spray pyrolysis (FSP) and applied to CO oxidation. The influences of CuO content on the as-prepared catalysts were systematically characterized by X-ray diffraction (XRD), N2 adsorption-desorption at −196 °C, field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and hydrogen-temperature programmed reduction (H2-TPR). A superior CO oxidation activity was observed for the 14 wt % CuO-CeO2 catalyst, with 90% CO conversion at 98 °C at space velocity (60,000 mL × g−1 × h−1), which was attributed to abundant surface defects (lattice distortion, Ce3+, and oxygen vacancies) and high reducibility supported by strong synergistic interaction. In addition, the catalyst also displayed excellent stability and resistance to water vapor. Significantly, in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) showed that in the CO catalytic oxidation process, the strong synergistic interaction led readily to dehydroxylation and CO adsorption on Cu+ at low temperature. Furthermore, in the feed of water vapor, although there was an adverse effect on the access of CO adsorption, there was also a positive effect on the formation of fewer carbon intermediates. All these results showed the potential of highly active and water vapor-resistive CuO-CeO2 catalysts prepared by FSP.

CO oxidation activity of Pt, Zn and ZnPt nanocatalysts: a comparative study by in situ near-ambient pressure X-ray photoelectron spectroscopy

Nanoscale ◽  
2018 ◽  
Vol 10 (14) ◽  
pp. 6566-6580 ◽  
Author(s):  
Ahmed Naitabdi ◽  
Anthony Boucly ◽  
François Rochet ◽  
Robert Fagiewicz ◽  
Giorgia Olivieri ◽  
...  
Keyword(s):  
Comparative Study ◽  
Co Oxidation ◽  
Chemical Reactions ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Oxidation Activity ◽  
X Ray

NAP-XPS allows the monitoring of chemical reactions on nanocatalysts.

scholarly journals Thermal CO Oxidation and Photocatalytic CO2 Reduction over Bare and M-Al2O3 (M = Co, Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au) Cotton-Like Nanosheets

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1278
Author(s):  
Heejung Yoon ◽  
Juhyun Yang ◽  
Sojeong Park ◽  
Youngku Sohn
Keyword(s):  
Electron Microscopy ◽  
Transition Metals ◽  
Co Oxidation ◽  
Photoelectron Spectroscopy ◽  
Co2 Reduction ◽  
Data Sets ◽  
X Ray Diffraction ◽  
Oxidation Activity ◽  
X Ray ◽  
Transmission Electron

Aluminum oxide (Al2O3) has abundantly been used as a catalyst, and its catalytic activity has been tailored by loading transition metals. Herein, γ-Al2O3 nanosheets were prepared by the solvothermal method, and transition metals (M = Co, Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au) were loaded onto the nanosheets. Big data sets of thermal CO oxidation and photocatalytic CO2 reduction activities were fully examined for the transition metal-loaded Al2O3 nanosheets. Their physicochemical properties were examined by scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction crystallography, and X-ray photoelectron spectroscopy. It was found that Rh, Pd, Ir, and Pt-loading showed a great enhancement in CO oxidation activity while other metals negated the activity of bare Al2O3 nanosheets. Rh-Al2O3 showed the lowest CO oxidation onset temperature of 172 °C, 201 °C lower than that of bare γ-Al2O3. CO2 reduction experiments were also performed to show that CO, CH3OH, and CH4 were common products. Ag-Al2O3 nanosheets showed the highest performances with yields of 237.3 ppm for CO, 36.3 ppm for CH3OH, and 30.9 ppm for CH4, 2.2×, 1.2×, and 1.6× enhancements, respectively, compared with those for bare Al2O3. Hydrogen production was found to be maximized to 20.7 ppm during CO2 reduction for Rh-loaded Al2O3. The present unique pre-screening test results provided very useful information for the selection of transition metals on Al2O3-based energy and environmental catalysts.

In situ spectroscopic investigation of a Pd local structure over Pd/CeO2 and Pd/MnOx–CeO2 during CO oxidation

2017 ◽  
Vol 5 (25) ◽  
pp. 12998-13008 ◽  
Author(s):  
Erdem Sasmaz ◽  
Chao Wang ◽  
Michael J. Lance ◽  
Jochen Lauterbach
Keyword(s):  
Fourier Transform ◽  
Co Oxidation ◽  
Local Structure ◽  
Diffuse Reflectance ◽  
Oxidation Activity ◽  
X Ray ◽  
Low Temperature Co Oxidation ◽  
Diffuse Reflectance Infrared ◽  
X Ray Absorption

In situ X-ray absorption fine structure (XAS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments were performed to elucidate the effect of the Pd local structure on low temperature CO oxidation activity of Pd/CeO2 and Pd/MnOx–CeO2.

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