scholarly journals Enhancing CO2 Hydrogenation to Methane by Ni-Based Catalyst with V Species Using 3D-mesoporous KIT-6 as Support

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2235 ◽  
Author(s):  
Hongxia Cao ◽  
Wenyuan Wang ◽  
Tianlei Cui ◽  
Hongyan Wang ◽  
Guang Zhu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Mesoporous Structure ◽  
Co2 Hydrogenation ◽  
X Ray Diffraction ◽  
Promising Candidate ◽  
Co2 Methanation ◽  
X Ray ◽  
Surface Basicity ◽  
Temperature Programmed

Using renewable H2 for CO2 hydrogenation to methane not only achieves CO2 utilization, but also mitigates the greenhouse effect. In this work, several Ni-based catalysts with V species using 3D-mesoporous KIT-6 (Korea Advanced Institute of Science and Technology, KIT) as support were prepared at different contents of NiO and V2O5. Small Ni nanoparticles with high dispersibility on 20Ni-0.5V/KIT-6 were identified by X-ray diffraction (XRD), TEM and hydrogen temperature-programmed desorption (H2-TPD) analysis, which promoted the production of more Ni active sites for enhancing catalytic activity for CO2 methanation. Moreover, TEM and hydrogen temperature-programmed reduction (H2-TPR) characterizations confirmed that a proper amount of Ni and V species was favorable to preserve the 3D-mesoporous structure and strengthen the interaction between active Ni and KIT-6. The synergistic effect between Ni and V could strengthen surface basicity to elevate the ability of CO2 activity on the 20Ni-0.5V/KIT-6. In addition, a strong interaction with the 3D-mesoporous structure allowed active Ni to be firmly anchored onto the catalyst surface, which was accountable for improving catalytic activity and stability. These results revealed that 20Ni-0.5V/KIT-6 was a catalyst with superior catalytic activity and stability, which was considered as a promising candidate for CO2 hydrogenation to methane.

scholarly journals K-Modified Co–Mn–Al Mixed Oxide—Effect of Calcination Temperature on N2O Conversion in the Presence of H2O and NOx

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1134
Author(s):  
Kateřina Karásková ◽  
Kateřina Pacultová ◽  
Květuše Jirátová ◽  
Dagmar Fridrichová ◽  
Martin Koštejn ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Calcination Temperature ◽  
Mixed Oxide ◽  
Active Sites ◽  
N2o Decomposition ◽  
Temperature Programmed Desorption ◽  
X Ray ◽  
Surface Basicity ◽  
Unit Surface ◽  
Temperature Programmed

The effect of calcination temperature (500–700 °C) on physico-chemical properties and catalytic activity of 2 wt. % K/Co-Mn-Al mixed oxide for N2O decomposition was investigated. Catalysts were characterized by inductively coupled plasma spectroscopy (ICP), X-ray powder diffraction (XRD), temperature-programmed reduction by hydrogen (TPR-H2), temperature-programmed desorption of CO2 (TPD-CO2), temperature-programmed desorption of NO (TPD-NO), X-ray photoelectron spectrometry (XPS) and N2 physisorption. It was found that the increase in calcination temperature caused gradual crystallization of Co-Mn-Al mixed oxide, which manifested itself in the decrease in Co2+/Co3+ and Mn3+/Mn4+ surface molar ratio, the increase in mean crystallite size leading to lowering of specific surface area and poorer reducibility. Higher surface K content normalized per unit surface led to the increase in surface basicity and adsorbed NO per unit surface. The effect of calcination temperature on catalytic activity was significant mainly in the presence of NOx, as the optimal calcination temperature of 500 °C is necessary to ensure sufficient low surface basicity, leading to the highest catalytic activity. Observed NO inhibition was caused by the formation of surface mononitrosyl species bonded to tetrahedral metal sites or nitrite species, which are stable at reaction temperatures up to 450 °C and block active sites for N2O decomposition.

scholarly journals In-Exchanged CHA Zeolites for Selective Dehydrogenation of Ethane: Characterization and Effect of Zeolite Framework Type

Catalysts ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 807
Author(s):  
Zen Maeno ◽  
Xiaopeng Wu ◽  
Shunsaku Yasumura ◽  
Takashi Toyao ◽  
Yasuharu Kanda ◽  
...  
Keyword(s):  
Active Sites ◽  
Temperature Programmed Desorption ◽  
X Ray Diffraction ◽  
Zeolite Framework ◽  
X Ray ◽  
Catalytic Activities ◽  
Ethane Dehydrogenation ◽  
Temperature Programmed

In this study, the characterization of In-exchanged CHA zeolite (In-CHA (SiO2/Al2O3 = 22.3)) was conducted by in-situ X-ray diffraction (XRD) and ammonia temperature-programmed desorption (NH3-TPD). We also prepared other In-exchanged zeolites with different zeolite structures (In-MFI (SiO2/Al2O3 = 22.3), In-MOR (SiO2/Al2O3 = 20), and In-BEA (SiO2/Al2O3 = 25)) and different SiO2/Al2O3 ratios (In-CHA(Al-rich) (SiO2/Al2O3 = 13.7)). Their catalytic activities in nonoxidative ethane dehydrogenation were compared. Among the tested catalysts, In-CHA(Al-rich) provided the highest conversion. From kinetic experiments and in-situ Fourier transform infrared (FTIR) spectroscopy, [InH2]+ ions are formed regardless of SiO2/Al2O3 ratio, serving as the active sites.

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.

Synthesis and Characterization of Co/SBA-15 Catalysts

2016 ◽  
Vol 881 ◽  
pp. 35-40
Author(s):  
Franciele Oliveira Costa ◽  
Carla Gabriela Azevedo Misael ◽  
André Miranda da Silva ◽  
Bianca Viana de Sousa
Keyword(s):  
Molecular Sieve ◽  
Pore Diameter ◽  
Mesoporous Structure ◽  
X Ray Diffraction ◽  
Average Pore ◽  
Wet Impregnation ◽  
X Ray ◽  
Different Temperatures ◽  
Temperature Programmed

The mesoporous silica SBA-15 molecular sieve has been widely studied due to its unidirectional mesoporous structure, its high average pore diameter, its high thermal and hydrothermal stability and its ability to absorb metal ions, allowing its use as support material for catalysts. This study aimed to synthesize the Co/SBA-15 catalyst, and characterize it through the techniques of X-ray diffraction, temperature programmed reduction (TPR) and scanning electron microscopy (SEM). The SBA-15 support was synthesized from the following molar composition of reaction mixture: 1TEOS: 0.017 P123: 5.7 HCl: 173 H2O: 40 EtOH, and after calcined at 550 °C for 6 hours. The Co/SBA-15 catalyst was prepared by incorporating 10% cobalt by wet impregnation. Through the X-ray diffractograms, it was found that the impregnation has not changed the structure of the material. RTP profiles showed the presence of peaks at different temperatures that may be caused by dispersion of the cobalt.

scholarly journals The Effect of Catalyst Calcination Temperature on Catalytic Decomposition of HFC-134a over γ-Al2O3

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1021
Author(s):  
Mahshab Sheraz ◽  
Ali Anus ◽  
Van Cam Thi Le ◽  
Caroline Mercy Andrew Swamidoss ◽  
Seungdo Kim
Keyword(s):  
Catalytic Activity ◽  
Catalytic Pyrolysis ◽  
Catalytic Decomposition ◽  
Temperature Programmed Desorption ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hfc 134A ◽  
Acidic Sites ◽  
Temperature Programmed ◽  
Decomposition Efficiency

This paper explores the thermal and catalytic pyrolysis of HFC-134a over γ-Al2O3 calcined at temperatures of 550 °C (A550), 650 °C (A650), 750 °C (A750), and 850 °C (A850). The physicochemical properties of catalysts were studied through thermogravimetric analysis (TGA), Brunauer–Emmett–Teller equation for nitrogen physisorption analysis (BET), X-ray diffraction (XRD), and temperature-programmed desorption of ammonia (NH3-TPD). The non-catalytic pyrolysis of HFC-134a showed less than 15% decomposition of HFC-134a. Catalysts increased the decomposition as A650 revealed the highest decomposition efficiency by decomposing more than 95% HFC-134a for 8 h followed by A750, A850, and A550. The larger surface area and pore volume paired with a low amount of strong acidic sites were considered as the main contributors to the comparatively longer catalytic activity of A650.

Cerium Incorporated Nanocrystalline ZSM-5: An Efficient Catalyst for Friedel Crafts Acylation of Toluene

2020 ◽  
Vol 20 (9) ◽  
pp. 5823-5832
Author(s):  
O. P. Farsana ◽  
Prajitha Kumari ◽  
P. Aneesh
Keyword(s):  
Acetic Anhydride ◽  
Active Sites ◽  
Temperature Programmed Desorption ◽  
Lewis Acidity ◽  
Acylating Agent ◽  
X Ray Diffraction ◽  
Efficient Catalyst ◽  
X Ray ◽  
Temperature Programmed ◽  
Scanning Electron

In this paper, the application of cerium modified nanocrystalline zeolite ZSM-5 as catalyst for Friedel Crafts acylation of toluene was investigated and compared with nanocrystalline ZSM-5. The acylating agent used was acetic anhydride. The zeolite samples were characterized by means of Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), Thermal analysis, ammonia temperature-programmed desorption (NH3-TPD) and Nitrogen sorption analysis. The results show an enhanced Lewis acidity, pore volume and surface area for cerium modified ZSM-5 providing a superior accessibility for acetic anhydride and toluene to the active sites compared to the unmodified one, thereby leading to 93% conversion of acetic anhydride, which was higher than that of unmodified ZSM-5 sample.

scholarly journals Surface Properties and Denitrification Performance of Impurity-Removed Rare Earth Concentrate

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 580
Author(s):  
Kai Zhang ◽  
Yuze Bai ◽  
Zhijun Gong ◽  
Zengwu Zhao ◽  
Baowei Li ◽  
...  
Keyword(s):  
Rare Earth ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Chemical Properties ◽  
Acid Leaching ◽  
X Ray Diffraction ◽  
Acid Base ◽  
X Ray ◽  
Temperature Programmed ◽  
Physical And Chemical

Acid leaching and alkali roasting were used to remove impurities such as Ca and Si in Baiyun Obo rare earth concentrate. The effects of acid–base treatment on the physical and chemical properties of the samples were analyzed by scanning electron microscopy, X-ray diffraction, Brunauer–Emmett–Teller characterization, X-ray photoelectron spectroscopy, H2-temperature-programmed reduction, NH3-temperature-programmed desorption (TPD), and NO-TPD. Results showed that the content of Ce7O12 in the rare earth concentrates increased and the dispersion was uniform. The grains became smaller, the specific surface area of rare earth concentrates increased, and the active sites were more exposed. Ce coexisted in the form of Ce3+ and Ce4+, whereas Fe coexisted in the form of Fe3+ and Fe2+. The content of Fe3+ was increased. The acid–base-treated rare earth concentrates had a denitration efficiency of 87.4% at a reaction temperature of 400 °C.

scholarly journals Zr-Modified ZnO for the Selective Oxidation of Cinnamaldehyde to Benzaldehyde

Catalysts ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 716 ◽  
Author(s):  
Pengju Du ◽  
Tongming Su ◽  
Xuan Luo ◽  
Xinling Xie ◽  
Zuzeng Qin ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Selective Oxidation ◽  
Active Sites ◽  
Catalyst Surface ◽  
Precipitation Method ◽  
N2 Adsorption ◽  
X Ray ◽  
Temperature Programmed ◽  
Zr Modification ◽  
Adsorption Desorption

ZnO and Zr-modified ZnO were prepared using a precipitation method and used for the selective oxidation of cinnamaldehyde to benzaldehyde in the present study. The results showed that physicochemical properties of ZnO were significantly affected by the calcination temperature, and calcination of ZnO at 400 °C demonstrated the optimum catalytic activity for the selective oxidation of cinnamaldehyde to benzaldehyde. With 0.01 g ZnO calcined at 400 °C for 2 h as a catalyst, 8.0 g ethanol and 2.0 g cinnamaldehyde reacted at an oxygen pressure of 1.0 MPa and 70 °C for 60 min, resulting in benzaldehyde selectivity of 69.2% and cinnamaldehyde conversion of 16.1%. Zr was the optimal modifier for ZnO: when Zr-modified ZnO was used as the catalyst, benzaldehyde selectivity reached 86.2%, and cinnamaldehyde conversion was 17.6%. The X-ray diffractometer and N2 adsorption–desorption characterization indicated that doping with Zr could reduce the crystallite size of ZnO (101) and increase the specific surface area of the catalyst, which provided more active sites for the reaction. X-ray photoelectron spectrometer results showed that Zr-doping could exchange the electrons with ZnO and reduce the electron density in the outer layer of Zn, which would further affect benzaldehyde selectivity. The results of CO2 temperature-programmed desorption showed that Zr-modification enhanced the alkalinity of the catalyst surface, which caused the Zr–ZnO catalyst to exhibit higher catalytic activity.

Efficient Synthesis of Diethyl Carbonate by Mg, Zn Promoted Hydroxyapatite via Transesterification Reaction

2020 ◽  
Vol 18 (4) ◽  
Author(s):  
Kartikeya Shukla ◽  
Vimal Chandra Srivastava
Keyword(s):  
Thermal Analysis ◽  
Active Sites ◽  
Molar Ratio ◽  
Diethyl Carbonate ◽  
X Ray Diffraction ◽  
Reaction Conditions ◽  
X Ray ◽  
High Basicity ◽  
Temperature Programmed ◽  
Adsorption Desorption

AbstractTransesterification of propylene carbonate (PC) and ethanol is a potent non-phosgene route for the synthesis of diethyl carbonate (DEC). In the present study, hydroxyapatite was synthesized and modified using Zn and Mg (Zn/HAP and Mg/HAP). Modified hydroxyapatite was used as catalyst for the synthesis of DEC. The thermal analysis of the catalytic precursor was studied using thermogravimetric-differential thermal analysis. The structural analysis, surface morphology, and nature of active sites over the catalyst surface were studied using techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, N2 adsorption-desorption, scanning electron microscopy, and CO2 temperature-programmed desorption. Effects of reaction conditions like reaction temperature, reaction time and ethanol/PC molar ratio on DEC yield were also studied. The effects of Mg and Zn on HAP were found to be promotional for the synthesis of DEC using PC and ethanol. Mg/HAP was found to be the best among the three catalysts studied owing to its high basicity. Maximum DEC yield of 52.1 % was obtained in 5 h at 433 K using Mg/HAP catalyst.

scholarly journals The Synthesis of Mesoporous TS-1 and Its Performance for Oxidation of Diphenyl Sulfide and Dibenzyl Sulfide

2020 ◽  
Vol 213 ◽  
pp. 01030
Author(s):  
Hua-Qin Wang ◽  
Ya-Long Ding ◽  
Pei Yu ◽  
Ya-Meng Li ◽  
Hai-Xiang Gao ◽  
...  
Keyword(s):  
Active Sites ◽  
Mesoporous Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diphenyl Sulfide ◽  
Tetrapropylammonium Hydroxide ◽  
Good Crystallinity ◽  
Titanium Trichloride ◽  
Ft Ir ◽  
Dibenzyl Sulfide

TS-1 zeolite has outstanding performance in the catalytic reactions with hydrogen peroxide as catalytic promoter. However, the narrow pore size (< 1.0 nm) of traditional TS-1 makes it difficult for bulky organic compounds to contact with the active sites in the pores, which seriously limits application of TS-1. Recently, the introduction of mesoporous structure into microporous TS-1 becomes a hot research topic. Meanwhile, the huge synthesis cost of TS-1 is another main reason hindering its industrial application. In this paper, mesoporous TS-1 was successfully synthesized using sodium silicate as silicon source and titanium trichloride as titanium source under the template conditions of tetrapropylammonium hydroxide (TPAOH) and cationic polymer. The mesoporous TS-1 was characterized by X-ray diffraction (XRD), N2 adsorption, scanning electric microscopy (SEM), transmitting electric microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and UV-Vis Spectrum spectra (UV-Vis). Results show that the synthesized TS-1 zeolites have good crystallinity and tetra-coordinated framework Ti atoms, and there are abundant mesoporous structures in the zeolite crystals. The results of oxidation experiments show that conversion of diphenyl sulfide and dibenzyl sulfide with mesoporous TS-1 are 97.3 % and 85.3 % respectively, while that conversion with microporous TS-1 are 75.7 % and 63.5 respectively.

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