scholarly journals Characteristics and activity of Ni/CeO2 catalyst modified by Cr2O3 in combined steam and CO2 reforming of CH4

2021 ◽  
Vol 10 (1) ◽  
pp. 104-108
Author(s):  
Phuong Phan Hong ◽  
Anh Nguyen Phung ◽  
Huy Tran Anh ◽  
Tri Nguyen ◽  
Loc Luu Cam
Keyword(s):  
Chemical Properties ◽  
Catalytic Performance ◽  
Molar Ratio ◽  
Impregnation Method ◽  
Co2 Reforming ◽  
X Ray ◽  
Co2 Reforming Of Ch4 ◽  
Transmission Electron ◽  
Physico Chemical ◽  
Temperature Programmed

A series of 10%wtNiO/CeO2-nanorod catalyst without and with Cr2O3 additive was prepared by simultaneous impregnation method. Several techniques, including N2 physisorption measurements, X-ray powder diffraction (XRD), temperature-programmed reduction using H2 (H2-TPR), CO2 temperature-programmed desorption (CO2-TPD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) were used to investigate catalysts’ physico-chemical properties. The activity of the catalysts in combined steam and CO2 reforming of CH4 (BRM) was investigated at temperature range of 550-800 °C. The results showed that 10%NiO0.1%Cr2O3/CeO2 catalyst had the best catalytic performance due to a better reducibility and basicity. At 700 °C and CH4:CO2:H2O molar ratio in feed stream of 3:1.2:2.4, both conversion of CH4 and CO2 on this catalyst reached 98.5%.

Improvement of physico-chemical properties by addition of H2O2: An extensive case study on the RE-doped ceria system (RE = Gd, Sm)

2009 ◽  
Vol 24 (9) ◽  
pp. 2845-2854 ◽  
Author(s):  
Balaji P. Mandal ◽  
Vinita Grover ◽  
Mrinal R. Pai ◽  
Avesh K. Tyagi
Keyword(s):  
Surface Area ◽  
Photoelectron Spectroscopy ◽  
Chemical Properties ◽  
Doped Ceria ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Physico Chemical ◽  
Powder Properties ◽  
Temperature Programmed

Effect of H2O2 on synthesis and powder properties such as surface area and agglomerate size of nanocrystalline Ce0.8M0.2O1.90 (M: Sm, Gd) was explored by treating cerium nitrate and rare-earth nitrate with NaOH in the presence/absence of H2O2. The resultant products were characterized by x-ray diffraction, Raman spectroscopy, thermo-gravimetry–differential thermal analysis, dynamic light scattering, surface area analysis, high-resolution transmission electron microscopy, and x-ray photoelectron spectroscopy. The presence of H2O2 was found to have a profound effect on powder properties such as surface area and particle size of these doped ceria samples and results in smaller crystallite size, softer agglomerates, and larger surface area. A mechanism is proposed to explain the observed better powder properties of the samples. It was also shown that the samples prepared in the presence of H2O2 can lower the conversion temperature of CO to CO2, proving these to be better catalysts. Interestingly, temperature-programmed reduction studies on Sm3+-doped samples showed that the doping in conjunction with the use of H2O2 leads to enhanced reduction properties of the samples over multiple cycles.

scholarly journals COMBINED STEAM AND CO2 REFORMING OF CH4 OVER NICKEL CATALYSTS BASED ON Al2O3–MO (M= Mg, Ca, Ba)

2018 ◽  
Vol 55 (1B) ◽  
pp. 49
Author(s):  
Phuong P. H.
Keyword(s):  
Nickel Catalysts ◽  
Precipitation Method ◽  
Impregnation Method ◽  
Co2 Reforming ◽  
Co2 Reforming Of Ch4 ◽  
Transmission Electron ◽  
Catalytic Stability ◽  
Supported Nickel Catalysts ◽  
Temperature Programmed ◽  
Co Precipitation

A series of 10 wt% Ni/Al2O3–MO (M = Mg, Ca, Ba) catalyst was prepared by impregnation method for applying in the combined steam and carbon dioxide reforming of methane (CSCRM). In this study, five supported nickel catalysts were impregnated on different supports. All of the supports have been obtained by co–precipitation method and also have been investigated. Several techniques, including N2 physisorption measurements, X–ray powder diffraction (XRD), temperature–programmed reduction using H2 (H2–TPR), and transmission electron microscopy (TEM) were used to investigate catalysts’ physicochemical properties. The results showed that MgO was the most suitable promoter comparing with CaO and BaO in CSCRM. The presence of MgO in Ni/Al2O3 changed catalysts’ characteristics leading to an increase in the catalytic activity and stability with time on stream (TOS). It was found that the suitable catalyst was Ni–based on Al2O3–MgO of mass ratio 2:1 which showed a high metal dispersion as well as dominated spinel structure. The CH4 and CO2 conversion at 800 °C reached 99.8 % and 51.7 %, respectively. Catalytic stability of this catalyst with TOS at 800 °C could reach to more than 20 hours until it started decreasing.

scholarly journals Influence of Sulfur-Containing Sodium Salt Poisoned V2O5–WO3/TiO2 Catalysts on SO2–SO3 Conversion and NO Removal

Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 541 ◽  
Author(s):  
Haiping Xiao ◽  
Chaozong Dou ◽  
Hao Shi ◽  
Jinlin Ge ◽  
Li Cai
Keyword(s):  
Photoelectron Spectroscopy ◽  
No Reduction ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Impregnation Method ◽  
So2 Oxidation ◽  
Sodium Salts ◽  
X Ray ◽  
Temperature Programmed ◽  
Physical Features

A series of poisoned catalysts with various forms and contents of sodium salts (Na2SO4 and Na2S2O7) were prepared using the wet impregnation method. The influence of sodium salts poisoned catalysts on SO2 oxidation and NO reduction was investigated. The chemical and physical features of the catalysts were characterized via NH3-temperature programmed desorption (NH3-TPD), H2-temperature programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FT-IR). The results showed that sodium salts poisoned catalysts led to a decrease in the denitration efficiency. The 3.6% Na2SO4 poisoned catalyst was the most severely deactivated with denitration efficiency of only 50.97% at 350 °C. The introduction of SO42− and S2O72− created new Brønsted acid sites, which facilitated the adsorption of NH3 and NO reduction. The sodium salts poisoned catalysts significantly increased the conversion of SO2–SO3. 3.6%Na2S2O7 poisoned catalyst had the strongest effect on SO2 oxidation and the catalyst achieved a maximum SO2–SO3-conversion of 1.44% at 410 °C. Characterization results showed sodium salts poisoned catalysts consumed the active ingredient and lowered the V4+/V5+ ratio, which suppressed catalytic performance. However, they increased the content of chemically adsorbed oxygen and the strength of V5+=O bonds, which promoted SO2 oxidation.

scholarly journals Heterogeneous Fenton-like oxidation of p-hydroxybenzoic acid using Fe/CeO2-TiO2 catalyst

2019 ◽  
Vol 79 (7) ◽  
pp. 1276-1286 ◽  
Author(s):  
Tijani Hammedi ◽  
Mohamed Triki ◽  
Mayra G. Alvarez ◽  
Jordi Llorca ◽  
Abdelhamid Ghorbel ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Catalytic Properties ◽  
Molar Ratio ◽  
Hydroxybenzoic Acid ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Temperature Programmed

Abstract This paper is built on the Fenton-like oxidation of p-hydroxybenzoic acid (p–HBZ) in the presence of H2O2 and 3%Fe supported on CeO2-TiO2 aerogels under mild conditions. These catalysts were deeply characterized by X-ray diffraction (XRD), hydrogen temperature programmed reduction (H2-TPR), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) and X-ray photoelectron spectroscopy (XPS). The effect of thermal treatment, pH (2–3, 5, 7), H2O2/p–HBZ molar ratio (5, 15, 20, 25) and reaction temperature (25 °C, 40 °C and 60 °C) on the catalytic properties of supported Fe catalysts are studied. Our results highlight the role of CeO2 and the calcination of the catalyst to obtain the highest catalytic properties after 10 min: 73% of p–HBZ conversion and 52% of total organic carbon (TOC) abatement.

Comparison of Cobalt Based Catalysts Supported on MWCNT and SBA-15 Supporters for Fischer-Tropsch Synthesis by Using Autoclave Type Reactor

2011 ◽  
Vol 364 ◽  
pp. 70-75 ◽  
Author(s):  
Adkham Yakubov ◽  
M.G. Kutty ◽  
Pei Lee Siew ◽  
Maizatul S. Shaharun ◽  
S.B. Abd Hamid ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Multiwall Carbon Nanotubes ◽  
Incipient Wetness Impregnation ◽  
Impregnation Method ◽  
Santa Barbara ◽  
X Ray ◽  
Transmission Electron ◽  
Temperature Programmed ◽  
Multiwall Carbon ◽  
Autoclave Reactor

10 and 40 wt% Co/Multiwall Carbon Nanotubes (MWCNT) and 10 and 40 wt% Co/Santa Barbara Amorphous-15 (SBA-15) catalysts were prepared via incipient wetness impregnation method. It was characterized by Scanning Electron Microscopy, BET, X-ray Diffractometry (XRD), Transmission Electron Microscopy (TEM), Temperature-Programmed Reduction and H2Desorption. A 200 ml hastelloy autoclave reactor was implemented to see the performance of the catalysts. It was observed that the performance of 40 wt% Co/SBA-15 was higher that other catalysts in terms of production of longer chain paraffins.

scholarly journals Influence of Intercalation-Exfoliation-Reduction Technique towards the Physico-Chemical of VPO Catalysts

2013 ◽  
Vol 2013 ◽  
pp. 1-8
Author(s):  
Y. C. Wong ◽  
Y. H. Taufiq-Yap
Keyword(s):  
Electron Microscope ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vpo Catalysts ◽  
Transmission Electron ◽  
Physico Chemical ◽  
Vpo Catalyst ◽  
Temperature Programmed ◽  
Lower Temperature ◽  
Synthesized Materials

Four VPO catalysts were synthesized through intercalation and exfoliation in various alcohols and subsequent reduction of the exfoliated VOPO4sheets with various alcohols to produce VOHPO4⋅0.5H2O. The resulting VOHPO4⋅0.5H2O that undergoes the intercalation-exfoliation-reduction (IER) process will be further activated into VPO catalysts, and addition of 1 mole % Bi(NO3)3⋅5H2O in the first stage of this experiment has also being investigated. The synthesized materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and temperature-programmed reduction (TPR) in H2. Catalytic evaluation of the IER-treated and Bi-doped VPO catalysts was also studied on microreactor. The VPO catalyst produced through IER using 2-butanol and ethanol with addition of Bi, IERC(2Bu-Et)RBi1, gave the highest MA selectivity due to reactive O2−species released from the additional crystalline V5+phase formed by doping 1% bismuth as promoter (O2−-V5+pair) at relative lower temperature. Nevertheless, the VPO catalyst produced through IER using isobutanol, IERC(isoBu), gave the highest activity due to high amount of reactive O−species released from V4+phase (O−-V4+pair) whereby the IERC(isoBu) catalyst synthesized consists of high percentage of V4+(93 %).

Catalytic Activity of Bimetallic Cu-Ag/MgO-SiO2 Toward the Conversion of Ethanol to 1,3-Butadiene

2016 ◽  
Vol 14 (5) ◽  
pp. 945-954 ◽  
Author(s):  
Anamol Tripathi ◽  
Kajornsak Faungnawakij ◽  
Apirat Laobuthee ◽  
Suttichai Assabumrungrat ◽  
Navadol Laosiripojna
Keyword(s):  
Chemical Properties ◽  
Catalytic Performance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Monometallic Catalysts ◽  
Reaction Test ◽  
Spent Catalysts ◽  
Temperature Programmed ◽  
Preparation Techniques ◽  
Microwave Assisted Method

Abstract In the present work, the catalytic conversion of ethanol to 1,3-butadiene (1,3-BD) was studied over monometallic of Cu and Ag, and bimetallic Cu-Ag supported on MgO-SiO2 (with MgO/SiO2 ratio of 2.0) under the temperature range from 250 to 325 °C. All catalysts were prepared by 4 different techniques including (i) conventional impregnation, (ii) microwave-assisted method, (iii) polyvinyl alcohol/sodium borohydride (PVA/NaBH4) assisted method, and (iv) benzoxaxine-assisted method to elucidate the effect of catalyst preparation method on their catalytic performance. All fresh and spent catalysts were also characterized by X-ray diffraction (XRD), N2 adsorption and Temperature-programmed reduction (TPR) techniques to understand the relation between their physical/chemical properties and catalytic performance. From the reaction test, it was found that 5 %Ag/MgO-SiO2 showed greater activity towards 1,3-BD production than 5 %Cu/MgO-SiO2; nevertheless, higher deactivation after 6 h of operation was observed from 5 %Ag/MgO-SiO2. Importantly, this study revealed that bimetallic 2.5 %Cu-2.5 %Ag/MgO-SiO2 enhanced significantly higher activity and stability towards the reaction than monometallic catalysts. In addition, 2.5 %Cu-2.5 %Ag/MgO-SiO2 prepared by benzoxaxine-assisted method enhanced significantly higher reaction activity and stability than other preparation techniques, from which 1,3-BD yield of 46.40 % after 6 h of operation can be achieved. From the characterization, the good activity of this catalyst is mainly due to the dispersion improvement of metal over MgO-SiO2 support.

Nanosized Pt-Co Catalysts for the Preferential CO Oxidation

2006 ◽  
Vol 6 (11) ◽  
pp. 3567-3571 ◽  
Author(s):  
Eun-Yong Ko ◽  
Eun Duck Park ◽  
Kyung Won Seo ◽  
Hyun Chul Lee ◽  
Doohwan Lee ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Peak Shift ◽  
Molar Ratio ◽  
High Catalytic Activity ◽  
Preferential Co Oxidation ◽  
X Ray ◽  
Co Catalysts ◽  
Transmission Electron ◽  
Temperature Programmed

The preferential CO oxidation in the presence of excess hydrogen was studied over Pt-Co/γ-Al2O3. CO chemisorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectrometer (EDX) and temperature programmed reduction (TPR) were conducted to characterize active catalysts. The catalytic activity for CO oxidation and methanation at low temperatures increased with the amounts of cobalt in Pt-Co/γ-Al2O3. This accompanied the TPR peak shift to lower temperatures. The optimum molar ratio between Co and Pt was determined to be 10. The co-impregnated Pt-Co/γ-Al2O3 appeared to be superior to Pt/Co/γ-Al2O3 and Co/Pt/γ-Al2O3. The reductive pretreatment at high temperature such as 773 K increased the CO2 selectivity over a wide reaction temperature. The bimetallic phase of Pt-Co seems to give rise to high catalytic activity in selective oxidation of CO in H2-rich stream.

Microstructural of Cr/MWCNT Composites and its Catalysis in Synthesis of Biodiesel

2012 ◽  
Vol 455-456 ◽  
pp. 1053-1059
Author(s):  
Xue Hai Fan ◽  
Guo Min Xiao
Keyword(s):  
Electron Microscopy ◽  
Potassium Dichromate ◽  
Catalytic Performance ◽  
Impregnation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Multi Walled Carbon Nanotubes ◽  
Ft Ir ◽  
Walled Carbon Nanotubes

Multi-walled carbon nanotubes (MWCNTs), potassium dichromate (K2Cr2O7) and sulphuric acid were used for the preparation of Cr/MWCNT composite by impregnation method. The composites were comprehensively characterized by transmission electron microscopy （TEM），energy dispersive X-ray analysis (EDX), infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and thermal gravity analysis (TGA). Due to its unique electrical and structural properties, this composite was applied to the synthesis of biodiesel (FAME) as a catalyst, showing effectively catalytic performance.

scholarly journals Catalytic Activity of Mixed Al2O3-ZrO2 Oxides for Glucose Conversion into 5-Hydroxymethylfurfural

Catalysts ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 878 ◽  
Author(s):  
Benjamín Torres-Olea ◽  
Sandra Mérida-Morales ◽  
Cristina García-Sancho ◽  
Juan Antonio Cecilia ◽  
Pedro Maireles-Torres
Keyword(s):  
Catalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Molar Ratio ◽  
X Ray ◽  
Zirconium Oxides ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Secondary Reactions ◽  
Temperature Programmed ◽  
Adsorption Desorption

In the present work, a series of catalysts based on aluminum and zirconium oxides was studied for the transformation of glucose into 5-hydroxymethylfurfural. These catalysts were characterized by using experimental techniques, such as X-ray diffraction, N2 adsorption–desorption at −196 °C, X-ray photoelectron spectroscopy, temperature-programmed desorption of NH3 and CO2, and scanning transmission electron microscopy. The catalytic behavior in glucose dehydration was evaluated in a water-methyl isobutyl ketone biphasic system, in the presence of CaCl2, in order to minimize losses due to unwanted secondary reactions. High glucose conversion and 5-hydroxymethylfurfural (HMF) yield values were obtained in the presence of an Al(Zr)Ox catalyst with an Al:Zr molar ratio of 7:3, reaching 97% and 47%, respectively, at 150 °C after 120 min. Under tested conditions, this catalyst retained most of its catalytic activity for four reuses.

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