scholarly journals Thermal Modification Effect on Supported Cu-Based Activated Carbon Catalyst in Hydrogenolysis of Glycerol

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 603 ◽  
Author(s):  
Juan Seguel ◽  
Rafael García ◽  
Ricardo José Chimentão ◽  
José Luis García-Fierro ◽  
I. Tyrone Ghampson ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Specific Surface ◽  
Hydrogen Adsorption ◽  
Carbon Support ◽  
Catalytic Performance ◽  
Homogeneous Distribution ◽  
Surface Groups ◽  
Carbon Supports ◽  
Surface Areas ◽  
Oxygen Surface

Glycerol hydrogenolysis to 1,2-propanediol (1,2-PDO) was performed over activated carbon supported copper-based catalysts. The catalysts were prepared by impregnation using a pristine carbon support and thermally-treated carbon supports (450, 600, 750, and 1000 °C). The final hydrogen adsorption capacity, porous structure, and total acidity of the catalysts were found to be important descriptors to understand catalytic performance. Oxygen surface groups on the support controlled copper dispersion by modifying acidic and adsorption properties. The amount of oxygen species of thermally modified carbon supports was also found to be a function of its specific surface area. Carbon supports with high specific surface areas contained large amount of oxygen surface species, inducing homogeneous distribution of Cu species on the carbon support during impregnation. The oxygen surface groups likely acted as anchorage centers, whereby the more stable oxygen surface groups after the reduction treatment produced an increase in the interaction of the copper species with the carbon support, and determined catalytic performances.

Gas phase hydrogenation of crotonaldehyde over Pt/Activated carbon catalysts. Influence of the oxygen surface groups on the support

1997 ◽  
Vol 150 (1) ◽  
pp. 165-183 ◽  
Author(s):  
F. Coloma ◽  
A. Sepúlveda-Escribano ◽  
J.L.G. Fierro ◽  
F. Rodríguez-Reinoso
Keyword(s):  
Activated Carbon ◽  
Gas Phase ◽  
Surface Groups ◽  
Carbon Catalysts ◽  
Oxygen Surface

ESR study of activated carbon fibers: preliminary results

1993 ◽  
Vol 8 (9) ◽  
pp. 2282-2287 ◽  
Author(s):  
S.L. di Vittorio ◽  
A. Nakayama ◽  
T. Enoki ◽  
M.S. Dresselhaus ◽  
M. Endo ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Specific Surface ◽  
Carbon Fibers ◽  
Room Temperature ◽  
Broad Peak ◽  
Activated Carbon Fibers ◽  
Temperature Peak ◽  
Dangling Bond ◽  
Surface Areas ◽  
Spin Resonance

We have carried out Electron Spin Resonance (ESR) measurements on activated carbon fibers (ACF) with specific surface areas (SSA) of 3000 and 2000 m2/g. The ESR spectrum of ACF fibers in air is extremely broad (500 to 1000 Gauss), and the spin susceptibility decreases rapidly with decreasing specific surface area. Also measured was the ESR signal of the desorbed fibers in vacuum. As a result of desorption, the broad peak decreases slightly in intensity, and a narrow (≍65 Gauss at room temperature) peak appears. We report results on the temperature dependence of both peaks. The narrow peak is interpreted as due to spins associated with dangling bonds, whereas we attribute the broad peak to the conduction carrier spins which is broadened by the boundary scattering process (T1 contribution) and the dipolar broadening process (T2 contribution) associated with the dangling bond spins.

scholarly journals Synthesis, characterisation and catalytic performance of Cu- and Co-modified Fe-Al co-precipitated catalysts for the steam reforming of ethanol

2014 ◽  
Vol 16 (6) ◽  
pp. 1111-1120
Keyword(s):  
Specific Surface ◽  
Steam Reforming ◽  
Catalytic Performance ◽  
Precipitation Method ◽  
Partial Substitution ◽  
Iron Species ◽  
Surface Areas ◽  
Steam Reforming Of Ethanol ◽  
And Performance ◽  
And Shifts

<p>This paper reports the synthesis and the investigation of the properties and performance of Fe-Al catalysts modified with Cu or Co for the steam reforming of ethanol. The materials were prepared by the precipitation method with different Fe/Al ratios. The samples were characterised by the S<sub>BET</sub>, TG/DTG, XRD, H<sub>2</sub>-TPR and TPO/DTA analyses. The increase in the Fe/Al ratio leads to a decrease in the specific surface area and shifts the reduction peaks towards higher temperatures. The partial substitution of Fe by Co or Cu modifies the structure of the materials because higher specific surface areas and crystallites of iron oxides with smaller sizes are formed. The promotion also improves the reducibility of the iron species. These changes provide higher activity and selectivity towards H<sub>2</sub> and CO for the modified samples and for the samples with lower Fe/Al ratio. The Co-containing catalyst showed the best performance because this sample exhibited the highest conversions and selectivity towards both H<sub>2</sub> and CO and the lowest formation of coke according to the TPO analysis.</p>

scholarly journals A Case Study of Waste Scrap Tyre-Derived Carbon Black Tested for Nitrogen, Carbon Dioxide, and Cyclohexane Adsorption

Molecules ◽  
2020 ◽  
Vol 25 (19) ◽  
pp. 4445 ◽  
Author(s):  
Zuzana Jankovská ◽  
Marek Večeř ◽  
Ivan Koutník ◽  
Lenka Matějová
Keyword(s):  
Activated Carbon ◽  
Carbon Black ◽  
Specific Surface ◽  
Surface Area ◽  
Sorption Capacity ◽  
Specific Surface Area ◽  
Textural Properties ◽  
Pyrolytic Carbon ◽  
Surface Areas ◽  
Wide Range

Waste scrap tyres were thermally decomposed at the temperature of 600 °C and heating rate of 10 °C·min−1. Decomposition was followed by the TG analysis. The resulting pyrolytic carbon black was chemically activated by a KOH solution at 800 °C. Activated and non-activated carbon black were investigated using high pressure thermogravimetry, where adsorption isotherms of N2, CO2, and cyclohexane were determined. Isotherms were determined over a wide range of pressure, 0.03–4.5 MPa for N2 and 0.03–2 MPa for CO2. In non-activated carbon black, for the same pressure and temperature, a five times greater gas uptake of CO2 than N2 was determined. Contrary to non-activated carbon black, activated carbon black showed improved textural properties with a well-developed irregular mesoporous-macroporous structure with a significant amount of micropores. The sorption capacity of pyrolytic carbon black was also increased by activation. The uptake of CO2 was three times and for cyclohexane ten times higher in activated carbon black than in the non-activated one. Specific surface areas evaluated from linearized forms of Langmuir isotherm and the BET isotherm revealed that for both methods, the values are comparable for non-activated carbon black measured by CO2 and for activated carbon black measured by cyclohexane. It was found out that the N2 sorption capacity of carbon black depends only on its specific surface area size, contrary to CO2 sorption capacity, which is affected by both the size of specific surface area and the nature of carbon black.

Valorization of cellulose-doped lignin: application of cellulose-doped lignin-derived activated carbon in capacitors and investigation of its textural properties and electrochemical performance

2021 ◽  
Author(s):  
Liangcai Wang ◽  
Xin Feng ◽  
Huanhuan Ma ◽  
Jielong Wu ◽  
Yu Chen ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Specific Surface ◽  
Specific Capacitance ◽  
Surface Area ◽  
Specific Surface Area ◽  
Wall Thickness ◽  
Textural Properties ◽  
Pore Wall ◽  
Surface Areas ◽  
Pore Wall Thickness

Abstract This work provides an idea for efficient and harmless utilization of lignin and further evaluated the textural properties of lignin-derived activated carbon/specific capacitance relationship. The yield of cellulose-doped apricot shell lignin (ASLC) was 30.42%. H3PO4/KOH was used to assist the preparation of ASLC-derived activated carbon (AAC) for capacitors. The specific surface areas of the as-obtained AAC-P-3 and AAC-K-2 were 1475.16 m2/g and 2136.56 m2/g, respectively. The specific capacitances of AAC-P-3 and AAC-K-2 were 169.14 F/g and 236.00 F/g, respectively, upon the current density of 0.50 A/g. In capacitors containing aqueous KOH as the electrolyte, the AR2 (0.983) between specific surface area and specific capacitance was highest, followed by the AR2 (0.978) between Vmicro/Vmeso and specific capacitance, the AR2 (0.975) between pore-wall thickness and specific capacitance. Consequently, the specific capacitances of the AACs depend not only the specific surface area, but also on the Vmicro/Vmeso, pore-wall thickness, and Vmicro.

Effect of Different Silicate Supports on the Catalytic Performance of MoVTeO Mixed Oxides in Partial Oxidation of Isobutane

2014 ◽  
Vol 12 (1) ◽  
pp. 623-628
Author(s):  
Jing Hu ◽  
Zhifang Li ◽  
Xiaoyuan Yang ◽  
Wenli Ding ◽  
Jingqi Guan
Keyword(s):  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Partial Oxidation ◽  
Mixed Oxides ◽  
Supported Catalysts ◽  
Catalytic Performance ◽  
Surface Areas ◽  
Specific Surface Areas ◽  
Mcm 41

Abstract A series of 5% MoV0.3Te0.25 supported on different silicates (i.e. SiO2, HMS, MCM-41, and MCM-48) have been prepared, characterized, and tested as catalysts in the partial oxidation of isobutane to methacrolein. Characterization results showed that the supports almost kept intact structures after supporting 5 wt.% MoV0.3Te0.25 and the supported catalysts had large specific surface areas. Catalytic tests showed that the specific surface area played a key role in the catalytic activity for the supported catalysts.

Influence of the Support on the Morphology of Co-Sn, Ni-Sn, Co-Ni Nanoparticles Synthesized Through a Borohydride Reduction Method Applying a Template Technique

2018 ◽  
Vol 55 (1) ◽  
pp. 82-91
Author(s):  
I. N. Markova ◽  
M. B. Piskin ◽  
I. Z. Zahariev ◽  
E. Hristoforou ◽  
V. L. Milanova ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Electrode Materials ◽  
Carbon Support ◽  
Carbon Powder ◽  
Ni Nanoparticles ◽  
Borohydride Reduction ◽  
Carbon Supports ◽  
Intermetallic Nanoparticles

Abstract Intermetallic (Co-Sn, Ni-Sn, Co-Ni) nanoparticles have been synthesized through a borohydride reduction with NaBH4 in aqueous solutions of the chloride salts of Co, Ni, Sn at room temperature using a template technique with a carbon support. As a result nanocomposite materials have been obtained in situ. The ratio of the metallic components has been chosen according the phase diagrams of the relevant binary (Co-Sn, Ni-Sn, Co-Ni) systems: Co:Sn=35:65, Ni:Sn=45:55, Co:Ni=50:50. As carbon supports have been used graphite and carbon powder. To avoid the nanoparticle’s aggregation b-cyclodextrin has been added to the reaction solutions. To study the influence of the supports used on the morphology, specific surface area, elemental and phase composition of the synthesized intermetallic nanoparticles and their carbon nanocomposites SEM, EDS, BET, and XRD investigation techniques have been used. The particle’s morphology varies with the different supports, but in the all cases it is typical for alloyed materials. The nanoparticles are different in shape and size and exhibit a tendency to aggregate. The last-one is due to the unsaturated nanoparticle’s surface and the existing magnetic forces. Regardless of the elemental composition, the nanosized particles are characterized by a relatively high specific surface area (SSA). The Ni-Sn nanoparticle have the largest SSA (80 m2/g), while the Co-Sn particles have the lowest SSA (69 m2/g). The use of a carrier modifies the SSA of the resulting nanocomposites differently depending on the size and shape of the carrier’s particles. The studies conducted on the intermetallic nanoparticles synthesized with various carriers demonstrate that the particle’s morphology, size, and specific surface area for the different supports are suitable for use as catalysts, electrode materials in Li-ion batteries and as magnetic materials for biomedical applications.

Role of Structural Deficiency of Nanoscaled Perovskites Prepared by Reactive Grinding on the Catalytic Purification of Exhaust Pollutants

2009 ◽  
Vol 7 (1) ◽  
Author(s):  
Runduo Zhang ◽  
Wei Yang ◽  
Jun Xue ◽  
Biaohua Chen
Keyword(s):  
Specific Surface ◽  
No Reduction ◽  
Soot Oxidation ◽  
Catalytic Performance ◽  
Surface Areas ◽  
No Reduction By Co ◽  
Cation Deficiency ◽  
Lanthanum Manganites ◽  
Calcination Step ◽  
Reactive Grinding

It is well known that the catalytic characteristics of perovskites for various redox reactions depend primarily on the preparation procedure. The conventional method for perovskite preparation, the so-called "ceramic method," involves a calcination step with a temperature of at least 800 oC, resulting in large grain size and low specific surface area (usually several m2/g). Recently, a new method for perovskite preparation designated as reactive grinding has been proposed by our group, generating a large variety of perovskites at room temperature with extraordinarily high specific surface areas on the order of 100 m2/g when grinding additives are used. Additionally, this novel technology is favorable to yield perovskites with an abundant deficiency structure simultaneously with a nanosized crystallite domain.Series of La(Co, Mn)1-x(Cu)xO3 perovskites were prepared by reactive grinding and characterized by XRD, O2-TPD, and H2-TPR showing anion deficiency (O2 vacancy) in lanthanum cobaltites and cation deficiency (O2 excess) in lanthanum manganites. These samples were thereafter used for catalytic purification of NO, CO and soot pollutants coming from an automobile. For NO reduction by CO, a better catalytic performance was found over LaCoO3 compared to LaMnO3. The deNOx activity of LaCoO3 can be considerably improved via 20% Cu substitution, leading to a 97% N2 yield and nearly complete CO conversion at 450 oC. This improvement was ascribed to the ease of generation of anion deficiencies after Cu incorporation, which plays a crucial role in NO adsorption and dissociation. A mechanism was proposed with dissociation of chemisorbed NO upon oxygen vacancies forming N2 and/or N2O, and oxidized perovskite surface, with continuous reduction by CO with the production of CO2. For soot combustion, the better activity was observed again in the case of LaCoO3 with respect to LaMnO3. A mechanism was proposed with an attack of soot by O- species which immigrates from the perovskite surface. Cation deficiency of lanthanum manganites associates with overstoichiometric oxygen from the perovskite lattice, which can be only utilized for an oxidation process but less active compared to molecular oxygen formed upon anion vacancies. In summary, the anion deficiency of perovskite-typed oxides seems to make more contribution for both NO reduction and soot oxidation in comparison with cation deficiency.

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