scholarly journals Influence of Cr/Zr Ratio on Activity of Cr–Zr Oxide Catalysts in Non-Oxidative Propane Dehydrogenation

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1435
Author(s):  
Alexander Zubkov ◽  
Tatiana Bugrova ◽  
Mikhail Salaev ◽  
Grigory Mamontov
Keyword(s):  
Oxide Catalysts ◽  
Propane Dehydrogenation ◽  
Precipitation Method ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Mixed Oxide Catalysts ◽  
Uv Visible ◽  
Temperature Programmed ◽  
Co Precipitation ◽  
Adsorption Desorption

Two series of chromium–zirconium mixed oxide catalysts with different Cr/Zr molar ratio are prepared by co-precipitation method. Porous structure of the catalysts is studied by low-temperature N2 adsorption–desorption. Phase composition and chromium states in the catalysts are characterized by X-ray diffraction (XRD), UV-visible spectroscopy, and temperature-programmed reduction with hydrogen (TPR-H2). The mixed catalysts are tested in non-oxidative dehydrogenation of propane at 550 °C. The catalysts synthesized without ageing of precipitate show higher activity in propane dehydrogenation due to the higher content of reducible Cr+5/+6 species due to its stabilization on the ZrO2 surface.

Study of Preparation, Characterization and Temperature-Programmed Reduction of NiO-ZnO Binary Materials

2013 ◽  
Vol 664 ◽  
pp. 515-520
Author(s):  
Chih Wei Tang ◽  
Jiunn Jer Hwang ◽  
Shie Hsiung Lin ◽  
Chin Chun Chung
Keyword(s):  
Weight Percent ◽  
Precipitation Method ◽  
Temperature Programmed Reduction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface Areas ◽  
Temperature Programmed ◽  
Co Precipitation ◽  
Adsorption Desorption

The NiO-ZnO binary materials had been prepared by co-precipitation method. The weight percent of nickel of NiO-ZnO materials were 5, 10 and 20; they were pretreated under air at temperature of 300, 500 and 700°C, respectively. The characterization of NiO-ZnO materials were the thermal gravity analysis(TGA), X-ray diffraction(XRD), N2 adsorption-desorption at 77K, scaning electron microscope(SEM) and temperature-programmed reduction(TPR). The results revealed that surface areas of NiO-ZnO materials order from large to small were 20NiZn(OH)x(66 m2·g-1) > 10NiZn(OH)x(34 m2·g-1) > 5NiZn(OH)x(9 m2·g-1) after being calcined at the temperature of 500°C. Further, NiO-ZnO materials had two main reductive peaks at 390-415°C and 560-657°C, respectively. In all NiO-ZnO materials, 20NiZn(OH)x-C500 material had the highest surface area and the best interaction between NiO and ZnO.

Effect of Gallium Loading on Reducibility and Dispersion of Copper-Based Catalyst

2015 ◽  
Vol 659 ◽  
pp. 211-215
Author(s):  
Parncheewa Udomsap ◽  
Somsak Supasitmongkol
Keyword(s):  
Copper Oxide ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Reduction Peak ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Crystallite Sizes ◽  
Copper Phase ◽  
Temperature Programmed ◽  
Co Precipitation

The effect of gallium-promoted copper-based catalysts has been investigated in connection with the characteristic of the active copper phase. CuO-ZnO-Ga2O3catalysts with different gallium loadings were prepared using oxalate co-precipitation method. The effects of gallium loading on the properties of catalysts were studied by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) and temperature-programmed reduction (TPR). The dispersion and metal area of copper were also determined by dissociative nitrous (N2O) adsorption technique conducted on a metal dispersion analyzer (BELCAT). The TPR profiles showed that the presence of two different reduction regions in the CuO-ZnO catalysts can be attributed to the reduction of highly dispersed copper oxide species (reduced at 246 °C) and bulk-like CuO (reduced at above 390 °C). By contrast, the only low-temperature reduction peak was presented in the TPR profiles after the Ga2O3loading was higher than 4 wt%. With the same molar ratio (Cu/Zn = 2:1), the reducibility of CuO-ZnO-Ga2O3was found to be more facile than CuO-ZnO due to the lower copper oxide crystallite sizes of gallium-promoted catalysts. Higher Ga2O3loadings resulted in an increase in both copper dispersion and metal surface area of all the catalysts studied in good agreement with the reduction behaviors in the TPR profiles, although all the gallium-promoted catalysts were slightly different for the reducibility.

Total oxidation of propane over Cu-Mn mixed oxide catalysts prepared by co-precipitation method

2011 ◽  
Vol 28 (4) ◽  
pp. 1139-1143 ◽  
Author(s):  
Moon Hyeon Kim ◽  
Kyung Ho Cho ◽  
Chae-Ho Shin ◽  
Seong-Eun Kang ◽  
Sung-Won Ham
Keyword(s):  
Mixed Oxide ◽  
Oxide Catalysts ◽  
Precipitation Method ◽  
Total Oxidation ◽  
Mixed Oxide Catalysts ◽  
Co Precipitation

scholarly journals Synthesis of DME by CO2 hydrogenation over La2O3-modified CuO-ZnO-ZrO2/HZSM-5 catalysts

2017 ◽  
Vol 23 (1) ◽  
pp. 49-56 ◽  
Author(s):  
Yajing Zhang ◽  
Yu Zhang ◽  
Fu Ding ◽  
Kangjun Wang ◽  
Wang Xiaolei ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Direct Synthesis ◽  
Catalytic Performance ◽  
Co2 Hydrogenation ◽  
Precipitation Method ◽  
X Ray ◽  
Temperature Programmed ◽  
And Performance ◽  
Co Precipitation ◽  
Adsorption Desorption

A series of La2O3-modified CuO-ZnO-ZrO2/HZSM-5 catalysts were prepared by an oxalate co-precipitation method. The catalysts were fully characterized by X-ray diffraction (XRD), N2 adsorption-desorption, hydrogen temperature pro-grammed reduction (H2-TPR), ammonia temperature programmed desorption (NH3-TPD), and X-ray photoelectron spectroscopy (XPS) techniques. The effect of the La2O3 content on the structure and performance of the catalysts was thoroughly investigated. The catalysts were evaluated for the direct synthesis of dimethyl ether (DME) from CO2 hydrogenation. The results displayed that La2O3 addition enhanced catalytic performance, and the maximal CO2 conversion (34.3%) and DME selectivity (57.3%) were obtained over the catalyst with 1% La2O3, which due to the smaller size of Cu species and a larger ratio of Cu+/Cu.

Co-Precipitation Synthesis of BiFeO3 Powders

2010 ◽  
Vol 105-106 ◽  
pp. 286-288 ◽  
Author(s):  
Hai Yang Bo ◽  
Guo Qiang Tan ◽  
Hong Yan Miao ◽  
Ao Xia
Keyword(s):  
Calcination Temperature ◽  
Bismuth Ferrite ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Diffraction Field ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Infrared Spectrophotometer ◽  
Lower Temperature ◽  
Co Precipitation

Bismuth ferrite powders were synthesized by a simple citric acid complexing co-precipitation method at much lower temperature of 600°C. The work studies the calcination temperature and molar ratio of Fe and Bi on the structure and morphology. The as-prepared BiFeO3 powder was characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscope and Fourier transform infrared spectrophotometer. The result shows that the phase pure BiFeO3 powders with cubic morphology were prepared as the calcination temperature was 600°C and molar ratio of Fe and Bi was 1:1. The nanoparticles was uniform with the size of about 200nm.

The Different Morphology of Co3O4 Catalysts and Application in the Abatement of Carbon Monoxide

2021 ◽  
Vol 21 (12) ◽  
pp. 6082-6087
Author(s):  
Chih-Wei Tang ◽  
Hsiang-Yu Shih ◽  
Ruei-Ci Wu ◽  
Chih-Chia Wang ◽  
Chen-Bin Wang
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Co Oxidation ◽  
Nitrogen Adsorption ◽  
Catalytic Performance ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Programmed ◽  
Adsorption Desorption

The increase of harmful carbon monoxide (CO) caused by incomplete combustion can affect human health even lead to suffocation. Therefore reducing the CO discharged by vehicles or factories is urgent to improve the air quality. The spinel cobalt (II, III) oxide (Co3O4) is an active catalyst for CO abatement. In this study, we tried to fabricate dispersing Co3O4 via the dispersion-precipitation method with acetic acid, formic acid, and oxalic acid as the chelating dispersants. Then, the asprepared samples were calcined at 300 ºC for 4 h to obtain active catalysts, and assigned as Co(A), Co(F) and Co(O) respectively, the amount of the dispersants used are labeled as I (0.12 mole), II (0.03 mole) and III (0.01 mole). For comparison, another CoAP sample was prepared via alkaliinduced precipitation and calcined at 300 ºC. All samples were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), scanning electron microscope (SEM), and nitrogen adsorption/desorption system, and the catalytic activity focused on the CO oxidation. The influence of chelating dispersant on the performance of abatement of CO was pursued in this study. Apparently, the results showed that the chelating dispersant can influence the catalytic activity of CO abatement. An optimized ratio of dispersant can improve the performance, while excess dispersant lessens the surface area and catalytic performance. The series of Co(O) samples can easily donate the active oxygen since the labile Co–O bonding and indicated the preferential performance than both Co(A) and Co(F) samples. The nanorod Co(O)-II showed preferential for CO oxidation, T50 and T90 approached 96 and 127 ºC, respectively. Also, the favorable durability of Co(O)-II sample maintains 95% conversion still for 50 h at 130 ºC and does not emerge deactivation.

Higher Alcohols Synthesis from CO2 Hydrogenation over K2O-Modified CuZnFeZrO2 Catalysts

2013 ◽  
Vol 827 ◽  
pp. 20-24 ◽  
Author(s):  
Wei Guo ◽  
Wen Gui Gao ◽  
Hua Wang ◽  
Jun Jie Tian
Keyword(s):  
Space Time ◽  
Precipitation Method ◽  
Higher Alcohols ◽  
X Ray Diffraction ◽  
Time Space ◽  
Fe Content ◽  
Higher Alcohols Synthesis ◽  
Temperature Programmed ◽  
Space Time Yield ◽  
Co Precipitation

The CuZnFeZrO2 catalysts were synthesized by co-precipitation method.,and then used to synthesize different content of K2O modified CuZnFeZrO2 catalysts by deposition-precipitation method.Hydrogenation of CO2 to higher alcohols over (K2O)x/CuZnFeZrO2 catalysts were investigated at 523 K,3.0 MPa and 3000 h-1.These catalysts were characterized by X-ray diffraction (XRD),temperature programmed reduction of H2 (H2-TPR),and temperature-programmed desorption of CO2 (CO2-TPD).The results showed the addition of an appropriate amount of Potassium to the CuZnZrO2 catalysts improved catalytic activity ,the space time yield (STY) and C2+OH selectivity. When the Fe content is 5% best, at this time the space time yield of selectivity and alcohol of C2+ alcohol reaches the maximum value, this time space and time conversion rate is 0.32g/ml·h.

scholarly journals Mechanochemically synthesized LiAlOx catalyst for aqueous aldol condensation of furfural with acetone

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
L. N. Stepanova ◽  
R. M. Mironenko ◽  
O. B. Belskaya ◽  
V. A. Likholobov
Keyword(s):  
Mixed Oxide ◽  
Aldol Condensation ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Centripetal Acceleration ◽  
Oh Groups ◽  
Short Period ◽  
Temperature Programmed ◽  
Co Precipitation ◽  
Double Hydroxides

AbstractIn the present study, the mechanochemical method is proposed for synthesis of LiAl-layered double hydroxides (LDHs). This method is eco-friendly and allows obtaining LiAl-LDH under relatively mild conditions (centripetal acceleration of milling bodies 300 m s-2) and in a short period of time (15 minutes). The structures of as-prepared LiAl-LDH, LiAl-mixed oxide (calcined LDH) and “activated” LiAl-LDH obtained after rehydration of the corresponding mixed oxide were confirmed by X-ray diffraction. The basicity of LiAlOx was measured by temperature-programmed desorption of CO2 and double isotherm technique. According to data obtained, LiAl-mixed oxide has a significant higher carbon dioxide adsorption capacity compared to MgAlmixed oxides prepared by conventional co-precipitation method. This indicates a large amount of basic surface sites with different strength (strong, medium and weak) for Li-containing systems. The formation of “activated” LiAl-LDH having Bronsted basic sites (OH groups in the interlayer space) provides an increased catalytic activity of LiAlOx in the reaction of aqueous-phase aldol condensation between furfural and acetone.

Pd-Only Catalyst Modified by BaO with Co- Precipitation and Impregnation Methods towards the Methanol Fuel Emission Control

2012 ◽  
Vol 581-582 ◽  
pp. 313-316
Author(s):  
Xue Qiao Zhang ◽  
Zhi Xiang Ye ◽  
Cheng Hua Xu ◽  
Ming Zhao ◽  
Yao Qiang Chen
Keyword(s):  
Co Oxidation ◽  
Photoelectron Spectroscopy ◽  
Palladium Catalysts ◽  
Active Species ◽  
Precipitation Method ◽  
Impregnation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Programmed ◽  
Co Precipitation

Barium oxide was introduced to modify Palladium catalysts supported on CeO2–ZrO2-La2O3-Al2O3 (CZLA) by impregnation and co-precipitation. methods. Various techniques, including X-ray diffraction (XRD), H2-temperature-programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS), were employed to characterize the physicochemical properties of BaO-modified Pd-only catalyst. Catalytic activity for methanol, CO, C3H8 and NO conversions showed that BaO-modified catalyst prepared by impregnation method exhibited the best performance for methanol, C3H8 and NO removals, while the catalyst prepared by co-precipitation method was in favor of CO oxidation. Combined with the results of XRD, H2-TPR and XPS, it is concluded that the co-existence of PdO and Pd-O-Ce active species by impregnation played an important role in the methanol, C3H8 and NO removals, while the higher dispersion of palladium and improved reducibility were mostly favorable to the CO oxidation. The conversion of NO was co-effected by tow active species and the formation of Ba2AlLaO5 mixed oxide.

scholarly journals CHARACTERIZATION AND ANTIBACTERIAL ACTIVITY OF ZnO NANOPARTICLES SYNTHESIZED BY CO PRECIPITATION METHOD

2018 ◽  
Vol 10 (6) ◽  
pp. 224 ◽  
Author(s):  
Manyasree D. ◽  
Kiranmayi P. ◽  
Venkata R Kolli
Keyword(s):  
Antibacterial Activity ◽  
Zno Nanoparticles ◽  
Precipitation Method ◽  
Proteus Vulgaris ◽  
X Ray Diffraction ◽  
Gram Positive ◽  
Gram Negative ◽  
X Ray ◽  
Uv Visible ◽  
Co Precipitation

Objective: In the present study the antibacterial activity of zinc oxide (ZnO) nanoparticles was investigated against gram negative (Escherichia coli and Proteus vulgaris) and gram positive (Staphylococcus aureus and Streptococcus mutans) organisms.Methods: The synthesis of ZnO nanoparticles was carried out by co-precipitation method using zinc sulfate and sodium hydroxide as precursors. These nanoparticles were characterized by XRD (X-Ray Diffraction), FTIR (Fourier Transform Infrared Radiation), UV-Visible spectroscopy and SEM (Scanning Electron Microscope) with EDX (Energy Dispersive X-ray analysis). As well as antibacterial activity and minimum inhibitory concentration of the nanoparticles were carried out by agar well diffusion method and broth dilution method respectively against gram negative (Escherichia coli and Proteus vulgaris) and gram positive (Staphylococcus aureus and Streptococcus mutans) bacteria.Results: The average crystallite size of ZnO nanoparticles was found to be 35 nm by X-ray diffraction. The vibration bands at 450 and 603 cm-1 which were assigned for ZnO stretching vibration were observed in FTIR spectrum. The optical absorption band at 383 nm was obtained from UV-Visible spectrum. Spherical shape morphology was observed in SEM studies. The antibacterial assay clearly expressed that E. coli showed a maximum zone of inhibition (32±0.20 mm) followed by Proteus vulgaris (30±0.45 nm) at 50 mg/ml concentration of ZnO nanoparticles.Conclusion: Zinc oxide nanoparticles have exhibited good antibacterial activity with gram negative bacteria when compared to gram positive bacteria.

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