Hydrogen Production from Ethanol. Comparing Thermal Catalytic Reactions to Photo-catalytic Reactions.

2011 ◽  
Vol 1326 ◽  
Author(s):  
M. Scott ◽  
A.M. Nadeem ◽  
G.I.W. Waterhouse ◽  
H. Idriss
Keyword(s):  
Hydrogen Production ◽  
Thermal Activation ◽  
Room Temperature ◽  
Complete Removal ◽  
Catalytic Reactions ◽  
Hydrogen Yield ◽  
Hydrogen Atoms ◽  
Catalytic Systems ◽  
Thermally Activated ◽  
Sustainable System

ABSTRACTHydrogen production from renewables such as bio-ethanol is one of the most promising processes for energy carriers in a sustainable way. In this work we review and compare two catalytic systems: one based on thermal activation over bimetallic catalysts (Rh-Pd/CeO2) and the other over photo-excited semiconductor catalysts (Au/TiO2 anatine, rutile and anatase/rutile). It is found that the hydrogen yield is far higher on the thermally activated catalysts (at 773K) when compared to that of the photo-exited catalysts (at room temperature); about 60 times. However, the photo-excited catalysts are a promising way to create a fully sustainable system for future applications if the complete removal of hydrogen atoms from water and ethanol are obtained at room temperature.

scholarly journals Catalytic Steam Reforming of Glycerol Over Cerium and Palladium-Based Catalysts for Hydrogen Production

2013 ◽  
Vol 10 (2) ◽  
Author(s):  
Ali Ebshish ◽  
Zahira Yaakob ◽  
Y. H. Taufiq-Yap ◽  
Ahmed Bshish ◽  
Abdulmajid Shaibani
Keyword(s):  
Electron Microscopy ◽  
Hydrogen Production ◽  
Steam Reforming ◽  
Catalytic Reactions ◽  
Fixed Bed Reactor ◽  
Hydrogen Yield ◽  
Water Mixture ◽  
Impregnation Method ◽  
Catalytic Steam Reforming ◽  
Total Average

In this work, catalytic steam reforming of glycerol for hydrogen production was performed over Ce/Al2O3 and Pd/Al2O3 catalysts prepared via the impregnation method. The catalysts were characterized by scanning electron microscopy (SEM-EDX), transmission electron microscopy (TEM), BET surface area, and X-ray diffraction (XRD). Two sets of catalytic reactions were conducted, one comparing 1% Pd/Al2O3 to 1% Ce/Al2O3 and the second comparing 1% Ce/Al2O3 loading to 10% Ce/Al2O3 loading. All catalytic reactions were performed using a fixed-bed reactor operated at 600 °C and atmospheric pressure. Aglycerol–water mixture at a molar ratio of 1:6 was fed to the reactor at 0.05 ml/min. In the first set of experiments, Pd/Al2O3 exhibited higher hydrogen productivity than Ce/Al2O3. A maximum hydrogen yield of 56% and a maximum selectivity of 78.7% were achieved over the Pd/Al2O3 catalyst. For the second set of experiments, the results show that the reaction conversion increased as the cerium loading increased from 1% to 10%. A total average hydrogen yield of 28.0% and a selectivity of 45.5% were obtained over 1% Ce/Al2O3, while the total average hydrogen yield and selectivity were 42.2% and 52.7%, respectively, for 10% Ce/Al2O3.

Comparison of Different Pretreatment Methods to Increase Hydrogen Production from Cornstalk

2013 ◽  
Vol 724-725 ◽  
pp. 216-221 ◽  
Author(s):  
Cristiano Varrone ◽  
Lei Zhao ◽  
Guang Li Cao ◽  
Tao Sheng ◽  
Nan Qi Ren ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Lignocellulosic Biomass ◽  
Room Temperature ◽  
Reducing Sugar ◽  
Chemical Components ◽  
Hydrogen Yield ◽  
Alkali Pretreatment ◽  
Pretreatment Condition ◽  
Fermentative Hydrogen Production ◽  
Fermentative Hydrogen

Lignocellulosic biomass can be an ideal feedstock for fermentative hydrogen production if properly pretreated and hydrolyzed. In this research, to enhance hydrogen production from cornstalk, acid and alkali pretreatments were performed. Alkali pretreatment was conducted at 80°C for 60 min and room temperature for 7 days with the addition of 4% NaOH; acid pretreatments at 190°C, and 120°C for 10 min and 120 min, respectively, with the addition of 1.7% H2SO4. All the chemical components change of the substrates was detected. The highest lignin reduction of 75.6%, compared to untreated samples, was found at 80°C with 4% NaOH dosage. Under this pretreatment condition, highest increase in reducing sugar and hydrogen yield (up to 11.8 g/L and 71.8 ml/g-pretreated cornstalk) was obtained. The present results suggested an efficient pretreatment method to increase hydrogen production from lignocellulosic biomass.

THE MERCURY-PHOTOSENSITIZED DECOMPOSITIONS OF PROPANE AND ETHANE

1959 ◽  
Vol 37 (11) ◽  
pp. 1834-1842 ◽  
Author(s):  
R. A. Back
Keyword(s):  
Steady State ◽  
Hydrogen Production ◽  
Quantum Yields ◽  
Hydrogen Yield ◽  
Steady State Concentration ◽  
Hydrogen Atoms ◽  
Constant Rate ◽  
State Region ◽  
Ethyl Radicals ◽  
State Concentration

The mercury-photosensitized decompositions of propane and ethane have been studied at pressures of 300 and 600 mm, at 24 °C, at very low conversions. Hydrogen was the only product identified and measured. The hydrogen yield fell rapidly at first, with increasing time of irradiation, and finally became constant. This behavior is attributed to the accumulation in the system of propylene or ethylene formed by the disproportionation of propyl or ethyl radicals, and the constant rate of hydrogen production finally achieved is thought to correspond to a steady-state concentration of the unsaturate. Previous values of the quantum yields of these decompositions were probably measured in this steady-state region, and must be corrected upwards.Relative values have been estimated for the various rate constants involved in this mechanism. There is some evidence that energy-rich radicals, formed by the addition of hydrogen atoms to the unsaturates, tend to disproportionate rather than dimerize.

Nickel (II) and oxovanadium (IV) complexes supported on MCM-41 mesoporous and their application in catalytic selective sulfide and thiol oxidation

2020 ◽  
Vol 23 ◽  
Author(s):  
Mohsen Nikoorazm ◽  
Maryam Khanmoradi ◽  
Masoumeh Sayadian
Keyword(s):  
Catalytic Activity ◽  
Room Temperature ◽  
Sol Gel ◽  
Reaction Times ◽  
Significant Loss ◽  
Spectral Studies ◽  
High Catalytic Activity ◽  
Catalytic Systems ◽  
Solvent Free Conditions ◽  
Mcm 41

Introduction:: MCM-41 was synthesized using the sol-gel method. Then two new transition metal complexes of Nickel (II) and Vanadium (IV), were synthesized by immobilization of adenine (6-aminopurine) into MCM-41 mesoporous. The compounds have been characterized by XRD, TGA, SEM, AAS and FT-IR spectral studies. Using these catalysts provided an efficient and enantioselective procedure for oxidation of sulfides to sulfoxides and oxidative coupling of thiols to their corresponding disulfides using hydrogen peroxide at room temperature. Materials and Methods:: To a solution of sulfide or thiol (1 mmol) and H2O2 (5 mmol), a determined amount of the catalyst was added. The reaction mixture was stirred at room temperature for the specific time under solvent free conditions. The progress of the reaction was monitored by TLC using n-hexane: acetone (8:2). Afterwards, the catalyst was removed from the reaction mixture by centrifugation and, then, washed with dichloromethane in order to give the pure products. Results:: All the products were obtained in excellent yields and short reaction times indicating the high activity of the synthesized catalysts. Besides, the catalysts can be recovered and reused for several runs without significant loss in their catalytic activity. Conclusion:: These catalytic systems furnish the products very quickly with excellent yields and VO-6AP-MCM-41 shows high catalytic activity compared to Ni-6AP-MCM-41.

Mass spectrometric study of allyl radical, allyl bromide and 1,5-hexadiene interactions with oxides; Cobalt suboxide Co3O4

1979 ◽  
Vol 44 (7) ◽  
pp. 2009-2014 ◽  
Author(s):  
Jana Nováková ◽  
Zdeněk Dolejšek
Keyword(s):  
Room Temperature ◽  
Allyl Bromide ◽  
Catalytic Properties ◽  
Mass Spectrometric Study ◽  
Spectrometric Study ◽  
Flow Conditions ◽  
Allyl Radical ◽  
Knudsen Flow ◽  
Thermally Activated ◽  
Radical Interaction

Products of (a) allyl radical interaction with unheated Co3O4, (b) thermally activated 1,5-hexadiene or thermally activated allyl bromide with unheated Co3O4, (c) moderately heated Co3O4 with unheated 1,5-hexadiene or allyl bromide were studied under Knudsen flow conditions. Cobalt suboxide Co3O4, a typical catalyst of deep oxidations yielded acrolein in reaction with allyl radicals as early as at the room temperature of the catalyst. A similar acrolein formation was also observed in the allyl radical interaction with other oxides exhibiting different catalytic properties. It appears that acrolein is in general the primary product of the allyl radical interaction with the oxides. The results are discussed and compared with previous data obtained with MoO3.

scholarly journals Hydrogen Production by Fluidized Bed Reactors: A Quantitative Perspective Using the Supervised Machine Learning Approach

J ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 266-287
Author(s):  
Zheng Lian ◽  
Yixiao Wang ◽  
Xiyue Zhang ◽  
Abubakar Yusuf ◽  
Lord Famiyeh ◽  
...  
Keyword(s):  
Machine Learning ◽  
Hydrogen Production ◽  
Fluidized Bed ◽  
Biomass Gasification ◽  
Supervised Machine Learning ◽  
Fluidized Bed Reactors ◽  
Hydrogen Yield ◽  
Carbon Conversion ◽  
Operational Parameters ◽  
Operational Conditions

The current hydrogen generation technologies, especially biomass gasification using fluidized bed reactors (FBRs), were rigorously reviewed. There are involute operational parameters in a fluidized bed gasifier that determine the anticipated outcomes for hydrogen production purposes. However, limited reviews are present that link these parametric conditions with the corresponding performances based on experimental data collection. Using the constructed artificial neural networks (ANNs) as the supervised machine learning algorithm for data training, the operational parameters from 52 literature reports were utilized to perform both the qualitative and quantitative assessments of the performance, such as the hydrogen yield (HY), hydrogen content (HC) and carbon conversion efficiency (CCE). Seven types of operational parameters, including the steam-to-biomass ratio (SBR), equivalent ratio (ER), temperature, particle size of the feedstock, residence time, lower heating value (LHV) and carbon content (CC), were closely investigated. Six binary parameters have been identified to be statistically significant to the performance parameters (hydrogen yield (HY)), hydrogen content (HC) and carbon conversion efficiency (CCE)) by analysis of variance (ANOVA). The optimal operational conditions derived from the machine leaning were recommended according to the needs of the outcomes. This review may provide helpful insights for researchers to comprehensively consider the operational conditions in order to achieve high hydrogen production using fluidized bed reactors during biomass gasification.

scholarly journals A Process for Hydrogen Production from the Catalytic Decomposition of Formic Acid over Iridium—Palladium Nanoparticles

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3258
Author(s):  
Hamed M. Alshammari ◽  
Mohammad Hayal Alotaibi ◽  
Obaid F. Aldosari ◽  
Abdulellah S. Alsolami ◽  
Nuha A. Alotaibi ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Formic Acid ◽  
Activated Charcoal ◽  
Palladium Nanoparticles ◽  
Room Temperature ◽  
Catalytic Decomposition ◽  
Conversion Yield ◽  
Production Of Hydrogen ◽  
Commercial Applications

The present study investigates a process for the selective production of hydrogen from the catalytic decomposition of formic acid in the presence of iridium and iridium–palladium nanoparticles under various conditions. It was found that a loading of 1 wt.% of 2% palladium in the presence of 1% iridium over activated charcoal led to a 43% conversion of formic acid to hydrogen at room temperature after 4 h. Increasing the temperature to 60 °C led to further decomposition and an improvement in conversion yield to 63%. Dilution of formic acid from 0.5 to 0.2 M improved the decomposition, reaching conversion to 81%. The reported process could potentially be used in commercial applications.

Thermal activation in Permalloy nanorectangles at room temperature

2006 ◽  
Vol 372 (1-2) ◽  
pp. 286-289 ◽  
Author(s):  
E. Martinez ◽  
L. Lopez-Diaz ◽  
L. Torres ◽  
C.J. Garcia-Cervera
Keyword(s):  
Thermal Activation ◽  
Room Temperature

Structure and Conductivity of Iodine-Doped C60 Thin Films

1994 ◽  
Vol 359 ◽  
Author(s):  
Jun Chen ◽  
Haiyan Zhang ◽  
Baoqiong Chen ◽  
Shaoqi Peng ◽  
Ning Ke ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Room Temperature ◽  
Conductivity Measurements ◽  
X Ray Diffraction ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
X Ray ◽  
Thermally Activated ◽  
Order Of Magnitude

ABSTRACTWe report here the results of our study on the properties of iodine-doped C60 thin films by IR and optical absorption, X-ray diffraction, and electrical conductivity measurements. The results show that there is no apparent structural change in the iodine-doped samples at room temperature in comparison with that of the undoped films. However, in the electrical conductivity measurements, an increase of more that one order of magnitude in the room temperature conductivity has been observed in the iodine-doped samples. In addition, while the conductivity of the undoped films shows thermally activated temperature dependence, the conductivity of the iodine-doped films was found to be constant over a fairly wide temperature range (from 20°C to 70°C) exhibiting a metallic feature.

Investigation of the Hydrogen Transport Processes in Crystalline Silicon of n-Type Conductivity

2007 ◽  
Vol 131-133 ◽  
pp. 425-430 ◽  
Author(s):  
Anis M. Saad ◽  
Oleg Velichko ◽  
Yu P. Shaman ◽  
Adam Barcz ◽  
Andrzej Misiuk ◽  
...  
Keyword(s):  
Hydrogen Concentration ◽  
Room Temperature ◽  
Crystalline Silicon ◽  
Transport Processes ◽  
Concentration Profiles ◽  
Hydrogen Transport ◽  
Hydrogen Atoms ◽  
Near Surface ◽  
Type Conductivity ◽  
Hydrogen Molecules

The silicon substrates were hydrogenated at approximately room temperature and hydrogen concentration profiles vs. depth have been measured by SIMS. Czochralski grown (CZ) wafers, both n- and p-type conductivity, were used in the experiments under consideration. For analysis of hydrogen transport processes and quasichemical reactions the model of hydrogen atoms diffusion and quasichemical reactions is proposed and the set of equations is obtained. The developed model takes into account the formation of bound hydrogen in the near surface region, hydrogen transport as a result of diffusion of hydrogen molecules 2 H , diffusion of metastable complexes * 2 H and diffusion of nonequilibrium hydrogen atoms. Interaction of 2 H with oxygen atoms and formation of immobile complexes “oxygen atom - hydrogen molecule” (O - H2 ) is also taken into account to explain the hydrogen concentration profiles in the substrates of n-type conductivity. The computer simulation based on the proposed equations has shown a good agreement of the calculated hydrogen profiles with the experimental data and has allowed receiving a value of the hydrogen molecules diffusivity at room temperature.

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