Study of hydrogen adsorption onto kenaf sorbent surface by metal impregnation method

2020 ◽  
Author(s):  
S.N. Ezaty ◽  
N. Zaini ◽  
N.J. Farahhin ◽  
K.S.N. Kamarudin
Keyword(s):  
Hydrogen Adsorption ◽  
Impregnation Method ◽  
Sorbent Surface ◽  
Metal Impregnation

scholarly journals Intrinsic Kinetics of Fischer–Tropsch Synthesis over Co/CNTs Catalysts: Effects of Support Interaction

2018 ◽  
Vol 43 (3-4) ◽  
pp. 262-273
Author(s):  
Behnam Hatami ◽  
Ahmad Tavasoli ◽  
Alireza Asghari ◽  
Yahya Zamani ◽  
Akbar Zamaniyan
Keyword(s):  
Carbon Nanotubes ◽  
Hydrogen Adsorption ◽  
Catalyst Support ◽  
Spillover Effect ◽  
Tropsch Synthesis ◽  
Cobalt Catalysts ◽  
High Dispersion ◽  
Impregnation Method ◽  
Fischer Tropsch ◽  
Fischer Tropsch Synthesis

The activities of cobalt catalysts prepared by the microemulsion impregnation method on carbon nanotubes (CNTs) and functionalised carbon nanotubes (FCNTs) supports were evaluated in the Fischer–Tropsch synthesis (FTS). The catalysts were characterised by transmission electron microscopy, X-ray diffraction and Brunauer–Emmett–Teller surface area methods. The results show that the cobalt particles in the FCNTs support are mostly located inside the tubes of the CNTs and show a narrower particle size distribution. The experimental results show that the cobalt catalyst supported on FCNTs leads to a higher CO conversion and FTS activity compared to that supported on normal CNTs. Calculated kinetic results show that the activation energies fall within the narrow range of 101.1–107.1 kJ mol−1 and the heat of hydrogen adsorption was calculated to be −40.2 and −26.2 kJ mol−1 for Co/CNTs and Co/FCNTs catalysts respectively. FCNTs, as a catalyst support of Co nanoparticles, maintain high dispersion which can be attributed to a hydrogen spillover effect of functional groups on the CNT surface.

scholarly journals Hydrogen Adsorption Characteristics for Zeolite-Y Templated Carbon

2019 ◽  
Vol 20 (1) ◽  
pp. 29 ◽  
Author(s):  
Rika Wijiyanti ◽  
Triyanda Gunawan ◽  
Noor Shawal Nasri ◽  
Zulhairun Abdul Karim ◽  
Ahmad Fauzi Ismail ◽  
...  
Keyword(s):  
Adsorption Process ◽  
Hydrogen Adsorption ◽  
Zeolite Y ◽  
Ambient Pressure ◽  
Exothermic Reaction ◽  
Total Pore Volume ◽  
Entropy Change ◽  
Impregnation Method ◽  
Order Kinetic ◽  
Templated Carbon

The hydrogen adsorption, kinetic and thermodynamic of adsorption onto the zeolite templated carbon (ZTC) were examined at the temperature range of 30-50 °C and ambient pressure. The ZTC was prepared from zeolite-Y template and sucrose carbon precursor by impregnation method and showed its specific surface area of 932 m2/g as well as 0.97 cm3/g for total pore volume. Analysis of physical and chemical characteristics for materials were performed using XRD, SEM, TEM and N2 isotherm. The results indicated that the ZTC has some ordered network structure of carbon and also exhibits the formation of carbon layer outside the zeolite micropore. We observed the ZTC for hydrogen adsorption both gravimetric and volumetric method up to 1.72 and 1.16 wt.% at the lowest temperature, respectively. The kinetic process at all studied temperature was best approximated by pseudo second order kinetic model. The aspects of thermodynamic such as heat of adsorption and the entropy change were -14.41 kJ/mol and -40.93 J/K mol, respectively. Both values was negative, indicating an exothermic reaction and low disorder at the hydrogen and ZTC interface, when the adsorption process took place. While, the enthalpy change value exhibits characteristic of physical process. The Gibbs energy change calculated at 30, 40 and 50 °C were -1.99, -1.59 and -1.19 kJ/mol, respectively, indicating a spontaneous adsorption process.

Chemical modification of the bacterial wall to determine sites of metal deposition

1978 ◽  
Vol 36 (2) ◽  
pp. 350-351
Author(s):  
T. J. Beveridge
Keyword(s):  
Electron Scattering ◽  
Metal Salt ◽  
Metal Deposition ◽  
Suitable Model ◽  
X Ray Diffraction ◽  
Subtilis Cell ◽  
Thin Sections ◽  
X Ray ◽  
Section Data ◽  
Metal Impregnation

The Bacillus subtilis cell wall provides a protective sacculus about the vital constituents of the bacterium and consists of a collection of anionic hetero- and homopolymers which are mainly polysaccharidic. We recently demonstrated that unfixed walls were able to trap and retain substantial amounts of metal when suspended in aqueous metal salt solutions. These walls were briefly mixed with low concentration metal solutions (5mM for 10 min at 22°C), were well washed with deionized distilled water, and the quantity of metal uptake (atomic absorption and X-ray fluorescence), the type of staining response (electron scattering profile of thin-sections), and the crystallinity of the deposition product (X-ray diffraction of embedded specimens) determined.Since most biological material possesses little electron scattering ability electron microscopists have been forced to depend on heavy metal impregnation of the specimen before obtaining thin-section data. Our experience with these walls suggested that they may provide a suitable model system with which to study the sites of reaction for this metal deposition.

Conversion of fructose into methyl lactate over SnO2/Al2O3 catalystin flow regime

2020 ◽  
pp. 43-47
Author(s):  
S.V. Prudius ◽  
◽  
N.L. Hes ◽  
A.M. Mylin ◽  
V.V. Brei ◽  
...  
Keyword(s):  
Flow Reactor ◽  
Practical Interest ◽  
Dimethyl Acetal ◽  
Racemic Mixture ◽  
Process Conditions ◽  
Impregnation Method ◽  
Aqueous Methanol ◽  
Methyl Lactate ◽  
Al2o3 Catalyst ◽  
Target Reaction

In recent years, numerous researchers have focused on the development of catalytic methods for processing of biomass-derived sugars into alkyl lactates, which are widely used as non-toxic solvents and are the starting material for obtaining monomeric lactide. In this work, the transformation of fructose into methyl lactate on Sn-containing catalyst in the flow reactor that may be of practical interest was studied. The supported Sn-containing catalyst was ob-tained by a simple impregnation method of granular γ-Al2O3. The catalytic ex-periments were performed in a flow reactor at temperatures of 160-190 °C and pressure of 3.0 MPa. The 1.6-9.5 wt.% fructose solutions in 80% aqueous methanol were used as a reaction mixture. It was found that addition to a reac-tion mixture of 0.03 wt.% potassium carbonate leads to the increase in selec-tivity towards methyl lactate on 15% at 100% conversion of fructose. Prod-ucts of the target reaction С6Н12О6 + 2СН3ОН = 2С4Н8О3 + 2Н2О were ana-lyzed using 13C NMR method. The following process conditions for obtaining of 65 mol% methyl lactate yield at 100% fructose conversion were found: use of 4.8 wt.% fructose solution in 80% methanol, 180 °С, 3.0 МПа and a load on catalyst 1.5 mmol C6H12O6/mlcat/h at contact time of 11 minutes. The cata-lyst productivity is 2.0 mmol C4H8O3/mlcat/h and the by-productі are 1,3-dihydroxyacetone dimethyl acetal (20%) and 5-hydroxymethylfurfural (10%). It should be noted that a racemic mixture of L- and D-methyl lactates has been obtained by conversion of D-fructose on the SnO2/Al2O3 catalyst. The SnO2/Al2O3 catalyst was found to be stable for 6 h while maintaining full fruc-tose conversion at 55–70% methyl lactate selectivity. After regeneration the catalyst completely restores the initial activity.

High-Entropy Alloys as Catalysts for the CO2 and CO Reduction Reactions

2019 ◽  
Author(s):  
Jack Pedersen ◽  
Thomas Batchelor ◽  
Alexander Bagger ◽  
Jan Rossmeisl
Keyword(s):  
Density Functional ◽  
Rational Design ◽  
Hydrogen Adsorption ◽  
Co Adsorption ◽  
Reduction Reaction ◽  
Supervised Machine Learning ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Co Reduction ◽  
Disordered Alloy

Using the high-entropy alloys (HEAs) CoCuGaNiZn and AgAuCuPdPt as starting points we provide a framework for tuning the composition of disordered multi-metallic alloys to control the selectivity and activity of the reduction of carbon dioxide (CO2) to highly reduced compounds. By combining density functional theory (DFT) with supervised machine learning we predicted the CO and hydrogen (H) adsorption energies of all surface sites on the (111) surface of the two HEAs. This allowed an optimization for the HEA compositions with increased likelihood for sites with weak hydrogen adsorption{to suppress the formation of molecular hydrogen (H2) and with strong CO adsorption to favor the reduction of CO. This led to the discovery of several disordered alloy catalyst candidates for which selectivity towards highly reduced carbon compounds is expected, as well as insights into the rational design of disordered alloy catalysts for the CO2 and CO reduction reaction.

Control of hydrogen absorption by nickel films obtained upon magnetic spraying of zirconium alloy using the thermoEMF method

2020 ◽  
Vol 86 (8) ◽  
pp. 32-37
Author(s):  
V. V. Larionov ◽  
Xu Shupeng ◽  
V. N. Kudiyarov
Keyword(s):  
Magnetron Sputtering ◽  
Hydrogen Concentration ◽  
Hydrogen Absorption ◽  
Zirconium Alloy ◽  
Hydrogen Adsorption ◽  
Zirconium Alloys ◽  
Nickel Film ◽  
Protective Film ◽  
Nickel Films ◽  
Hydrogen Penetration

Nickel films formed on the surface of zirconium alloys are often used to protect materials against hydrogen penetration. Hydrogen adsorption on nickel is faster since the latter actively interacts with hydrogen, oxidizes and forms a protective film. The goal of the study is to develop a method providing control of hydrogen absorption by nickel films during vacuum-magnetron sputtering and hydrogenation via measuring thermoEMF. Zirconium alloy E110 was saturated from the gas phase with hydrogen at a temperature of 350°C and a pressure of 2 atm. A specialized Rainbow Spectrum unit was used for coating. It is shown that a nickel film present on the surface significantly affects the hydrogen penetration into the alloy. A coating with a thickness of more than 2 μm deposited by magnetron sputtering on the surface of a zirconium alloy with 1% Nb, almost completely protects the alloy against hydrogen penetration. The magnitude of thermoemf depends on the hydrogen concentration in the zirconium alloy and film thickness. An analysis of the hysteresis width of the thermoEMF temperature loop and a method for determining the effective activation energy of the conductivity of a hydrogenated material coated with a nickel film are presented. The results of the study can be used in assessing the hydrogen concentration and, hence, corrosion protection of the material.

Processing of Iridium Doped Materials and Experimental Investigation of Their Hydrogen Adsorption Capacity

2018 ◽  
Vol 69 (6) ◽  
pp. 1468-1472
Author(s):  
Radu Mirea ◽  
Mihai Iordoc ◽  
Gabriela Oprina ◽  
Gimi Rimbu
Keyword(s):  
Adsorption Capacity ◽  
Hydrogen Adsorption ◽  
Weight Ratio ◽  
H2 Adsorption ◽  
Cyclic Voltametry ◽  
Physical Chemical ◽  
Good Consistency ◽  
Metal Doped ◽  
And Storage ◽  
Poly Aniline

The paper aims to present the investigation of H2 adsorption capacity in metal doped nanostructured materials, by using two methods. Carbonic materials are considered to be one of the most promising materials to be used for hydrogen adsorption and storage. They have different applications and one of the most important is considered to be fuel cells technology. By using metals for doping these materials, the adsorption capacity increases, thus approaching the target of 6.5% weight ratio of H2 adsorbed in a substrate. Within these investigations multi-wall nanotubes and poly-aniline have been used as substrates. The poly-aniline has been prepared and doped in laboratory while the nanotubes used in experiments have been purchased from the market and afterwards doped in laboratory. The doping procedure consists of a physical-chemical method which involves salts of the metal for doping and the use of ultrasounds in order to activate the substrate for doping. The adsorption capacity of the carbonic materials has been determined by using spill over phenomena in a PCT Pro-User apparatus, provided by SETARAM and also by cyclic voltametry, by using VoltaLab-40 apparatus. In order to investigate the adsorption capacity of the nanostructured carbonic materials, the experiments have been carried out at different pressures. Both substrates have been characterized in order to determine their porosity, BET surface and structure. The collected data have been processed by using the PCT Pro-User apparatus�s software. The results have been compared with the available data from literature and a good consistency was found.

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