Dimethyl Ether Catalytic Combustion over Manganese Oxides with Different Structures

2010 ◽  
Vol 146-147 ◽  
pp. 1482-1485 ◽  
Author(s):  
Lin Yu ◽  
Gui Qiang Diao ◽  
Fei Ye ◽  
Ming Sun ◽  
Yue Liu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Dimethyl Ether ◽  
Specific Surface Area ◽  
Acid Treatment ◽  
Catalytic Combustion ◽  
Manganese Oxides ◽  
Mn Species

α-MnO2, β-MnO2 and Mn2O3 were synthesized from birnessite followed by acid treatment and subsequently calcined under different conditions. These catalysts were used for catalytic combustion of dimethyl ether (DME) and characterized by XRD, BET and H2-TPR techniques. The results showed that the catalytic activity of α-MnO2, β-MnO2 and Mn2O3 are higher than that of birnessite. Larger specific surface area as well as the better reducibility of Mn species in the manganese oxides might be the main contribution for the DME combustion activity.

scholarly journals SrFe1−xSnxO3−δ nanoparticles with enhanced redox properties for catalytic combustion of benzene

2020 ◽  
Vol 10 (18) ◽  
pp. 6342-6349
Author(s):  
Kazutaka Hashimoto ◽  
Ryoichi Otomo ◽  
Yuichi Kamiya
Keyword(s):  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Catalytic Combustion ◽  
Redox Properties ◽  
Partial Substitution ◽  
High Catalytic Activity

A series of SrFe1−xSnxO3−δ showed high catalytic activity for benzene combustion. The partial substitution of Fe with Sn increased specific surface area and accelerated redox rates of Fe, resulting in the improvement of the catalytic activity.

The Influence of Fe/Al Molar Ratio on Microreactor-Based Catalyst Preparation and Carbon Nanotube Preparation

2021 ◽  
Vol 1036 ◽  
pp. 130-136
Author(s):  
Ting Qun Tan ◽  
Lei Geng ◽  
Yan Lin ◽  
Yan He
Keyword(s):  
Carbon Nanotubes ◽  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Small Diameter ◽  
High Specific Surface Area ◽  
Detection Methods ◽  
Molar Ratio ◽  
High Catalytic Activity

In order to prepare carbon nanotubes with high specific surface area, small diameter, low resistivity, high purity and high catalytic activity, the Fe-Mo/Al2O3 catalyst was prepared based on the microreactor. The influence of different Fe/Al molar ratios on the catalyst and the carbon nanotubes prepared was studied through BET, SEM, TEM and other detection methods. Studies have shown that the pore structure of the catalyst is dominated by slit pores at a lower Fe/Al molar ratio. The catalytic activity is the highest when the Fe/Al molar ratio is 1:1, reaching 74.1%. When the Fe/Al molar ratio is 1:2, the catalyst has a higher specific surface area, the maximum pore size is 8.63 nm, and the four-probe resistivity and ash content of the corresponding carbon nanotubes are the lowest. The higher the proportion of aluminum, the higher the specific surface area of the catalyst and the carbon nanotubes, and the finer the diameter of the carbon nanotubes, which gradually tends to relax. The results show that when the Fe/Al molar ratio is 1:2, although the catalytic activity of the catalyst is not the highest, the carbon nanotubes prepared have the best performance.

Influence of Acid Treatment on the Loading and Release Behavior of Halloysite with 2-Mercaptobenzothiazole

2019 ◽  
Vol 19 (11) ◽  
pp. 7178-7184 ◽  
Author(s):  
Xuteng Xing ◽  
Jihui Wang ◽  
Qiushi Li ◽  
Wenbin Hu
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Acid Treatment ◽  
Gas Adsorption ◽  
Treatment Time ◽  
Halloysite Nanotubes ◽  
Tubular Structure ◽  
Internal Diameter ◽  
Release Behavior

Halloysite nanotubes (HNTs) are natural clay minerals with a tubular structure. They have attracted considerable attention as a potential nanocontainer due to their abundance, biocompatibility and nontoxicity. In this study, HNTs were handled with H2SO4 at 70 °C. The morphology and structure of these acid-treated and original HNTs were investigated by scanning electron microscopy (SEM), energy dispersion spectrum (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), and their specific surface area was determined by automatic gas adsorption analyzer. The loading efficiency and release behavior of acid-treated HNTs for 2-Mercaptobenzothiazole (MBT) were investigated by UV-vis spectrophotometer. Results show that acid-treated HNTs retained their tubular structure, but their internal diameter expanded by 35–37 nm after 32 h of acid treatment. After 72 h of acid treatment, HNTs can be transferred into amorphous silica nanotubes. Moreover, the specific surface area of these HNTs samples initially increased with the increase in acid treatment time but then started to decrease after 32 h. The specific surface area of acid-treated HNTs at 32 h can reach 251.6 m2/g, which was much higher than that for untreated HNTs (55.3 m2/g). In addition, the loading capacity of acid-treated HNTs can reach 32.1% for HNTs-32, which is about three times higher than that of original HNTs. The acid treatment has slight effect on the release behavior.

scholarly journals Biodiesel Processing Using Sodium and Potassium Geopolymer Powders as Heterogeneous Catalysts

Molecules ◽  
2020 ◽  
Vol 25 (12) ◽  
pp. 2839 ◽  
Author(s):  
Renata F. Botti ◽  
Murilo D.M. Innocentini ◽  
Thais A. Faleiros ◽  
Murilo F. Mello ◽  
Danilo L. Flumignan ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Heterogeneous Catalysts ◽  
Average Pore Size ◽  
Thermal Shrinkage ◽  
Average Pore ◽  
Base Catalysts ◽  
Sodium And Potassium

This work investigates the catalytic activity of geopolymers produced using two different alkali components (sodium or potassium) and four treatment temperatures (110 to 700 °C) for the methyl transesterification of soybean oil. The geopolymers were prepared with metakaolin as an aluminosilicate source and alkaline activating solutions containing either sodium or potassium in the same molar oxide proportions. The potassium-based formulation displayed a higher specific surface area and lower average pore size (28.64–62.54 m²/g; 9 nm) than the sodium formulation (6.34–32.62 m²/g; 17 nm). The reduction in specific surface area (SSA) after the heat treatment was more severe for the sodium formulation due to the higher thermal shrinkage. The catalytic activity of the geopolymer powders was compared under the same reactional conditions (70–75 °C, 150% methanol excess, 4 h reaction) and same weight amounts (3% to oil). The differences in performance were attributed to the influences of sodium and potassium on the geopolymerization process and to the accessibility of the reactants to the catalytic sites. The Na-based geopolymers performed better, with FAME contents in the biodiesel phase of 85.1% and 89.9% for samples treated at 500 and 300 °C, respectively. These results are competitive in comparison with most heterogeneous base catalysts reported in the literature, considering the very mild conditions of temperature, excess methanol and catalyst amount and the short time spent in reactions.

Preparation, characterization and catalytic properties of yttrium-zirconium-pillared montmorillonite and their application in supported Ce catalysts

Clay Minerals ◽  
2015 ◽  
Vol 50 (2) ◽  
pp. 211-219 ◽  
Author(s):  
Bo Xue ◽  
Hongmei Guo ◽  
Lujie Liu ◽  
Min Chen
Keyword(s):  
Catalytic Activity ◽  
Ethyl Acetate ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Active Sites ◽  
Industrial Applications ◽  
High Catalytic Activity ◽  
Total Oxidation ◽  
Pillared Montmorillonite

AbstractA new yttrium-zirconium-pillared montmorillonite (Y-Zr-MMT), was synthesized, characterized and used as a Ce catalyst support. The Y-Zr-MMT is a good support for dispersing cerium active sites and it is responsible for the high activity in the total oxidation of acetone, toluene and ethyl acetate. The Y-Zr-MMT shows greater advantages than the conventional alumina/cordierite honeycomb supports such as large specific surface area, lower cost and easier preparation. Catalytic tests demonstrated that Ce/Y-Zr-MMT (Ce loading 8.0%) was the most active, with the total oxidation of acetone, toluene and ethyl acetate being achieved at 220, 300 and 220°C, respectively. The catalyst displayed better activity for the oxidation of acetone and ethyl acetate than a conventional, supported Pd-catalyst under similar conditions. The special structure of the yttrium-doped zirconium-pillared montmorillonite can strengthen the interaction between the CeO2 and Zr-MMT support and improve the dispersion of the Ce particles, which enhances the catalytic activity for the oxidation of VOCs. The new catalyst, 8.0%Ce/Y-Zr-MMT, could be promising for industrial applications due to its high catalytic activity and low cost. The support and the catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and BET specific surface area measurements.

Enhancing the available specific surface area of carbon supports to boost the electroactivity of nanostructured Pt catalysts

2014 ◽  
Vol 16 (46) ◽  
pp. 25609-25620 ◽  
Author(s):  
Yaovi Holade ◽  
Claudia Morais ◽  
Karine Servat ◽  
Teko W. Napporn ◽  
K. Boniface Kokoh
Keyword(s):  
Catalytic Activity ◽  
Physicochemical Properties ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Platinum Nanoparticles ◽  
Pt Catalysts ◽  
Carbon Supports ◽  
Pre Treatment ◽  
Nanostructured Pt

We report a convenient and straightforward thermal pre-treatment to improve the physicochemical properties of carbon-based substrates to boost the catalytic activity of platinum nanoparticles.

Modification of Cordierite Honeycomb Ceramics Matrix for DeNOx Catalyst

2012 ◽  
Vol 1449 ◽  
Author(s):  
Qingcai Liu ◽  
Yuanyuan He ◽  
Jian Yang ◽  
Wenchang Xi ◽  
Juan Wen ◽  
...  
Keyword(s):  
Acid Solution ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Acid Treatment ◽  
Coefficient Of Thermal Expansion ◽  
Physical Adsorption ◽  
Active Species ◽  
Treatment Temperature ◽  
Cordierite Honeycomb

ABSTRACTTo obtain highly dispersed and highly active catalysts by impregnating of active species onto the monolith directly, cordierite honeycomb ceramics were modified by nitric acid solution of 68wt%. Effects of acid treatment temperature and time on the performance of cordierite were investigated. Specific surface area, pore size distribution, morphology and structure of cordierite were characterized by N2-physical adsorption, SEM, XRD, respectively. Concentrations of ions in the acid solution were measured by AAS. It is shown that the corrosion content of cordierite increases and more micropores are generated with increasing time of acid treatment, leading to an upward trend of specific surface area. The coefficient of thermal expansion and compression strength decrease obviously at a higher temperature, which is mainly attributed to the removal of Al and Mg ions from the silicate structure and delayed formation of free amorphous silica on the surface of the cordierite. The optimal modification process of cordierite matrix acid erosion is at 110°C for 6 h.

scholarly journals Syngas Production via CO2 Reforming of Methane Over SrNiO3 and CeNiO3 Perovskites

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2928
Author(s):  
Naushad Ahmad ◽  
Fahad Alharthi ◽  
Manawwer Alam ◽  
Rizwan Wahab ◽  
Salim Manoharadas ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Active Sites ◽  
Catalyst Deactivation ◽  
Dry Reforming Of Methane ◽  
Volume Number ◽  
Syngas Production

The development of a transition-metal-based catalyst with concomitant high activity and stability due to its distinguishing characteristics, yielding an abundance of active sites, is considered to be the bottleneck for the dry reforming of methane (DRM). This work presents the catalytic activity and durability of SrNiO3 and CeNiO3 perovskites for syngas production via DRM. CeNiO3 exhibits a higher specific surface area, pore volume, number of reducible species, and nickel dispersion when compared to SrNiO3. The catalytic activity results demonstrate higher CH4 (54.3%) and CO2 (64.8%) conversions for CeNiO3, compared to 22% (CH4 conversion) and 34.7% (CO2 conversion) for SrNiO3. The decrease in catalytic activity after replacing cerium with strontium is attributed to a decrease in specific surface area and pore volume, and nickel active sites covered with strontium carbonate. The stability results reveal the deactivation of both the catalysts (SrNiO3 and CeNiO3) but SrNiO3 showed more deactivation than CeNiO3, as demonstrated by deactivation factors. The catalyst deactivation is mainly attributed to carbon deposition and these findings are verified by characterizing the spent catalysts.

Advances in Preparation and Application of Supported Nano-Silver Composites

2019 ◽  
Vol 11 (11) ◽  
pp. 1477-1488
Author(s):  
Yonghang Xu ◽  
Fangya Zhou ◽  
Tao Zhang ◽  
Limiao Lin ◽  
Jingshu Wu ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Research Progress ◽  
Nano Silver ◽  
Silver Composites ◽  
Preparation Techniques

Supported nano-silver composites, famous for large specific surface area, good dispersibility and high catalytic activity, have been widely used in chemistry and chemical engineering, biomedicine and new materials. In this paper, we report recent research progress on supported nano-silver composites as reviewed from preparation techniques (chemical reduction, physical reduction and in-situ formation), types of supporters (organic and inorganic) and anti-microbial/catalytic activity. Firstly, the principles and merits/demerits of three preparation techniques for silver nanoparticles are elaborated. Afterwards, preparation, structures and properties of supported nano-silver composites are summarized through different types of supporters, as well as their applications in catalytic reaction, pollutant control and antimicrobial. Furthermore, it has been demonstrated that silver nanoparticles produced by in-situ formation are more stable and well-distributed, readily meeting the demands for practical applications. Finally, superior supporters for nano-silver composites should be of high specific surface area and good stability, non-expensive, environmentally friendly and low-toxicity.

scholarly journals Influence of Pluronic® P123 Addition in the Synthesis of Bulk Ni Promoted MoS2 Catalyst. Application to the Selective Hydrodesulfurization of Sulfur Model Molecules Representative of FCC Gasoline

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 793 ◽  
Author(s):  
Valentin Hetier ◽  
Diego Pena ◽  
Alexandre Carvalho ◽  
Laurence Courthéoux ◽  
Valérie Flaud ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Intrinsic Activity ◽  
Strong Increase ◽  
Similar Amount ◽  
X Ray ◽  
Mos2 Catalysts ◽  
The Impact

A way to improve hydrotreatment processes is to enhance the intrinsic activity of Ni or Co promoted MoS2 catalysts that are commonly used in such reactions. The aim of this work was to investigate the impact of the presence of Pluronic® P123 as a structuring agent during the synthesis of Ni promoted MoS2 catalysts (named NiMoS) in water at room temperature. A series of analyses, i.e., X-ray diffraction (XRD), chemical analysis, inductively coupled plasma mass spectrometry (ICP-MS), nitrogen adsorption-desorption isotherms, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), helped in characterizing the NiMoS-P123 and NiMoS catalysts, the latter being prepared in the absence of polymer. Both compounds contained MoS2 phase (~85 atomic% considering Mo atoms), a similar amount of mixed Ni-Mo-S phase (40–50% considering Ni) and some amount of NiS and Ni-oxidized impurity phases. The main differences between the two catalysts were a much larger specific surface area (126 m2·g−1 instead of 31 m²·g−1) and a better dispersion of the active phase as shown by the lower slab stacking (2.7 instead of 4.8) for NiMoS-P123, and the presence of C in NiMoS-P123 (9.4 wt.% instead of 0.6 wt.%), indicating an incomplete decomposition of the polymer during thermal treatment. Thanks to its larger specific surface area and lower slab stacking and therefore modification of active Mo site properties, the compound prepared in the presence of Pluronic® P123 exhibits a strong increase of the catalytic activity expressed per Mo atom for the transformation of 3-methylthiophene. Such improvement in catalytic activity was not observed for the transformation of benzothiophene likely due to poisonous residual carbon which results from the presence of Pluronic® P123 during the synthesis.

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