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    Electrochemical charging of H in sour simulated environment in steel

    , Article European Corrosion Congress 2011, EUROCORR 2011 ; Volume 4 , 2011 , Pages 2978-2988 ; 9781618394125 (ISBN) Fallahmohammadi, E ; Dolati, A ; Bolzoni, F ; Lazzari, L ; Sharif University of Technology
    The hydrogen diffusivity and subsurface concentration (C app) were evaluated by fitting a series expansion of the diffusion equation to the permeation data. The hydrogen diffusivity in the steel was found to be approximately in a order of magnitude 10 -7 cm 2 s -1. The influence of the passive layer on the hydrogen permeation and its influence on the evaluation of diffusion and trapping characteristics were discussed. Hydrogen diffusion experiments in A106 GRB carbon steel pipeline were performed electrochemically at 25°C in NACE B, solution in various amount of sulphide ion concentrations. In this case the effect of concentration of sulphide ion evaluated by study the electrochemical... 

    Study of electrochemical hydrogen permeation in iron

    , Article Journal of Corrosion Science and Engineering ; Volume 14 , February , 2011 , 263–267 ; 14668858 (ISSN) Fallahmohammadi, E ; Dolati, A ; Lazzari, L ; Bolzoni, F ; Sharif University of Technology
    Hydrogen diffusion experiments in A106GR B carbon steel pipeline were performed electrochemically at 25°C in NACE,B, solution in various amount of sulfide ion concentration for a thin sample. In this case the effect of concentration of sulfide ion evaluated by study the electrochemical behavior of sample by the galvanostatic way. Generally, sulfur components were found to increase the hydrogen permeation rate. Presence of sulfide layer helped to absorption of hydrogen reduction and exacerbates the amount of hydrogen absorption in steel. this phenomena can be noted that as regard to analysis of corrosion products which formed in the surface sample, the high amount of FeS, The sulfide ion are... 

    Preparation and performance evaluation of a Nano-composite silica membrane for high temperature gas separation

    , Article CHISA 2012 - 20th International Congress of Chemical and Process Engineering and PRES 2012 - 15th Conference PRES ; 2012 Safekordi, A ; Amanipour, M ; Heidari, M ; Ganji Babakhani, E ; Ordookhani, G ; Sharif University of Technology
    Multi-layer ceramic membranes were prepared and used for hydrogen separation at high operating temperatures. The membranes were formed by depositing nano-scale, dense silica layers with a thickness of 80-90 nm on top of porous alumina substrates by atmospheric CVD method. The substrates were prepared by dipping macroporous α-alumina supports with three size-controlled boehmite solutions to obtain a graded structure. Permeation tests were performed at 800°C for single gases of H2, N2, CH4, and CO2. Hydrogen selectivity values of 100, 350, and 780 were obtained as the ratio of H2 permeation flux over CH4, N2, and CO2, respectively. This is an abstract of a paper presented at the CHISA 2012 -... 

    Detecting hydrogen using graphene quantum dots/WO3 thin films

    , Article Materials Research Express ; Volume 3, Issue 11 , 2016 ; 20531591 (ISSN) Fardindoost, S ; Iraji Zad, A ; Hosseini, Z. S ; Hatamie, S ; Sharif University of Technology
    Institute of Physics Publishing 
    In the present work we report an approach to resistive hydrogen sensing based on graphene quantum dots(GQDs)/WO3 thin films that work reproducibly at low temperatures. GQDs were chemically synthesized and evenly dispersed in WO3 solution with 1:1 molar ratio. The structural evaluation and crystallization of the prepared films was studied by X-ray diffraction, Raman and scanning electron microscopy (SEM) techniques. The SEM images showed uniform distribution of the GQDs in WO3 films with sizes around 50 nm. Raman experiment showed the GQDs are partially reduced with high edge defects as hydroxyl and carboxyl groups which involve both in bridging between WO3 grains via bindings as well as... 

    Electronic properties of hydrogenated quasi-free-standing graphene

    , Article Physica Status Solidi (B) Basic Research ; Volume 248, Issue 11 , OCT , 2011 , Pages 2639-2643 ; 03701972 (ISSN) Haberer, D ; Petaccia, L ; Wang, Y ; Quian, H ; Farjam, M ; Jafari, S. A ; Sachdev, H ; Federov, A. V ; Usachov, D ; Vyalikh, D. V ; Liu, X ; Vilkov, O ; Adamchuk, V. K ; Irle, S ; Knupfer, M ; Büchner, B ; Grüneis, A ; Sharif University of Technology
    Tailoring the electronic properties of graphene is of fundamental interest regarding its application in electronic devices. One of the key strategies is chemical functionalization which modifies the p-electron system and thus can induce band gaps. However, in order to control the degree of functionalization it is crucial to know the exact amount of the chemisorbed species. We show with angle-resolved photoemission spectroscopy (ARPES) the formation of a band gap in graphene and estimate the hydrogen coverage from the scattering rate. Using X-ray photoemission spectroscopy (XPS) we identify the chemical environments in hydrogenated graphene and determine the total hydrogen to carbon... 

    Hydrogen storage in single- and multi-walled carbon nanotubes and nanotube bundles

    , Article Australian Journal of Basic and Applied Sciences ; Volume 5, Issue 7 , 2011 , Pages 483-490 ; 19918178 (ISSN) Hamidi, S ; Golnabi, H ; Sharif University of Technology
    This article describes the hydrogen storage capacity in different carbon nanotubes. The hydrogen storage capacities in the armchair, zigzag, and chiral nanotubes are investigated. The hydrogen storing capacities as a function of the carbon nanotube (CNT) diameter are investigated for the single-walled (SWNT), multi-walled (MWNT), and CNT bundles and results are compared. Hydrogen storage capacity in SWNTs is increased by increasing the nanotube diameter. For diameter d=0.3887 nm of (5,0) CNT the hydrogen capacity is 0.99%, while for the (17,17) SWNT with a diameter d=2.289 nm the capacity is increased to 5.06%. In comparison of different MWNTs for a common external diameter d=1.6064 nm the... 

    Hydrogenation of maleic anhydride to tetrahydrofuran using bifunctional catalysts

    , Article 18th International Congress of Chemical and Process Engineering, CHISA 2008, Prague, 24 August 2008 through 28 August 2008 ; 2008 Aghaziarati, M ; Kazemeini, M ; Soltanieh, M ; Khandan, N ; Sharif University of Technology
    A series of bifunctional catalysts, including Cu-ZnO-ZrO 2 and H-Y zeolite catalysts, were prepared and tested for conversion of maleic anhydride (MA) to tetrahydrofuran (THF). Cu-ZnO-ZrO 2 catalyst was used as the hydrogenating component and H-Y zeolite as the dehydrating component. The appropriate ratio of Cu/ZnO in the hydrogenation catalyst was 50:45, for which the conversion of MA and selectivity of THF reached 100 and 46%, respectively, at 50 bar and 493 K. The bifunctional catalyst of Cu-ZnOZrO 2/H-Y can produce THF from MA with high activity, selectivity, and stability. This is an abstract of a paper presented at the 18th International Congress of Chemical and Process Engineering... 

    Hydrogen management in refineries

    , Article Petroleum and Coal ; Volume 54, Issue 4 , 2012 , Pages 357-368 ; 13377027 (ISSN) Rabiei, Z ; Sharif University of Technology
    Environmental restrictions, new transportation fuel specifications, and increased processing of heavier more-sour curds are leading substantial increases in refinery hydrogen consumption for hydrodesulfurisation, aromatic and olefin saturation and improvement of product quality and reduces in refinery hydrogen production from catalytic reformers as a by-product. Therefore above factors make hydrogen management, a critical issue. Generating, recovering and purchasing of hydrogen have significant impact on refinery operating costs. More importantly, overall refinery operations, may be constrained by the availability of hydrogen. Primary consideration, however, should be given to the recovery... 

    Metal hydrides show potential under stress

    , Article Metal Powder Report ; Volume 64, Issue 7 , 2009 , Pages 24-26,28 ; 00260657 (ISSN) Simchi, H ; Kaflou, A ; Simchi, A ; Sharif University of Technology
    Work carried out in Iran seems to indicate that nanostructured materials may hold a key to fuel storage in a future hydrogen economy.... © 2009 Elsevier Ltd. All rights reserved  

    The effects of multi-walled carbon nanotubes graphitization treated with different atmospheres and electrolyte temperatures on electrochemical hydrogen storage

    , Article Electrochimica Acta ; Volume 55, Issue 16 , June , 2010 , Pages 4700-4705 ; 00134686 (ISSN) Reyhani, A ; Nozad Golikand, A ; Mortazavi, S. Z ; Irannejad, L ; Moshfegh, A. Z ; Sharif University of Technology
    Using multi-walled carbon nanotubes (MWCNTs), the present study focuses on their electrochemical hydrogen storage capacities. The results showed that the hydrogen desorption process is composed of two steps with voltages around -0.75 and -0.15 V. Hydrogen adsorption at -0.15 V took place at temperatures above 30 °C, and the amount of energy required for adsorbing hydrogen was 1.68 eV. The hydrogen storage capacity increased with increasing electrolyte temperature from 30 to 60 °C in both steps. The hydrogen storage capacity of the MWCNTs treated at different atmospheres showed that the decrease in the graphitization of MWCNTs led to the increase in hydrogen adsorption. The results also... 

    Control of hydrogen cracking in the welded steel using microstructural traps

    , Article Materials Science and Technology (United Kingdom) ; Volume 33, Issue 4 , 2017 , Pages 408-414 ; 02670836 (ISSN) Beidokhti, B ; He, P ; Kokabi, A. H ; Dolati, A ; Sharif University of Technology
    Taylor and Francis Ltd  2017
    Hydrogen diffusion into steel can embrittle the material in H2S environments, but this effect can be offset by suitable hydrogen trapping sites in the microstructure. Fine Ti(C,N) inclusions have been studied as the trapping sites in high strength low alloy (API X-70) welds, with Ti additions ranging from 0.004 to 0.16 wt.%. The trapping sites were investigated by electron microscopy and thermal desorption spectroscopy. Manganese sulphide particles were the main initiation sites for hydrogen induced cracking as expected. The optimum Ti addition was around 0.02% with no evidence of cracking in the weld. The estimated values of trapping activation energy for dislocations, microvoids, MnS and... 

    A model for investigation of optimal hydrogen pathway, and evaluation of environmental impacts of hydrogen supply system

    , Article International Journal of Hydrogen Energy ; Volume 33, Issue 24 , 2008 , Pages 7314-7325 ; 03603199 (ISSN) Qadrdan, M ; Saboohi, Y ; Shayegan, J ; Sharif University of Technology
    Elsevier Ltd  2008
    In order to achieve a hydrogen economy, developing widespread hydrogen supply systems are vitally important. A large number of technological options exist and are still in development for hydrogen production, storage, distribution., which cause various pathways for supplying hydrogen. Besides the technical factors, there are other effective parameters such as cost, operability, reliability, environmental impacts, safety and social implications that should be considered when assessing the different pathways as optimal and viable long-term alternatives. To aid this decision-making process, we have developed a generic optimization-based model for the long-range energy planning and design of... 

    Hydrogen electrosorption on TiHg alloy in acidic solution

    , Article Journal of Alloys and Compounds ; Volume 432, Issue 1-2 , 2007 , Pages 74-80 ; 09258388 (ISSN) Jafarian, M ; Azizi, O ; Gobal, F ; Mahjani, M. G ; Sharif University of Technology
    Hydrogen evolution and electrosorption on/in TiHg alloy have been investigated in acidic solution using cyclic voltammetry, open circuit potential transient, steady-state polarization, chronopotentiometry and electrochemical impedance measurements. Comparison has been made with pure Ti. Cyclic voltammetry and open circuit potential measurements show that hydrogen absorption into the electrode material occurs during proton discharge. The steady-state polarization curves in the course of positive and negative potential scans illustrate that the formation of absorbed hydrogen slightly improves the electrocatalytic properties of the electrode. The hydrogen diffusion coefficient into the bulk of... 

    Calculating the acidity of silica supported alkyl sulfonic acids considering the matrix effect: A DFT study

    , Article Phosphorus, Sulfur and Silicon and the Related Elements ; Vol. 189, Issue. 6 , 2014 , Pages 849-857 ; ISSN: 10426507 Vafaeezadeh, M ; Fattahi, A ; Sharif University of Technology
    (Equation present) Density functional theory (DFT) was used to investigate the acidity of the various silica alkyl sulfonic acids. In this regard, cluster models with various alkyl spacer lengths were selected to mimic the surface of silica gel. The effects of distance from the surface and the role of hydrogen bond (H-bond) on the ΔHacidity values of these catalysts were investigated. DFT calculations revealed that a notable gap of ΔH acidity values exists between the structures considering lateral hydrogen bonding with the surface of the silica HB structure and the structures with omitted surface interactions (non-HB structures). Natural bonding orbital (NBO) and quantum theory of atoms in... 

    Single-hydrogen dissociation paths for upright and flat acetophenone adsorbates on the Si(001) surface

    , Article Journal of Physical Chemistry C ; Volume 118, Issue 41 , 16 October , 2014 , Pages 23682-23689 ; ISSN: 19327447 Mehdipour, H ; Sharif University of Technology
    Using cluster-based density functional theory we investigate adsorption configurations of an acetophenone molecule on a Si(001) surface and their follow-up proton transfer processes. We examine two possible types of dative-adsorption configurations, up-right standing and flat, as well as compute their follow-up kinetically preferable on-dimer, interdimer, and inter-row proton transfers. Energetics of possible conversions between the achieved adsorption configurations are computed as well. Using all the data obtained, we theoretically illustrate reaction pathways leading to detached hydrogen positions captured in STM imaging of a Si(001) surface exposed to acetophenone vapor at room... 

    Interaction of hydrogen molecules with perfect, defective and scandium doped polycyclic aromatic hydrocarbon structures

    , Article Computational and Theoretical Chemistry ; Volume 1026 , 2013 , Pages 65-71 ; ISSN: 2210271X Lotfi, R ; Saboohi, Y ; Sharif University of Technology
    In the present work the interaction of hydrogen molecules with perfect, defective and scandium doped polycyclic aromatic hydrocarbon (PAH) has been evaluated. At first the potential barrier for the penetration of hydrogen molecules through PAH structures has been investigated and then the adsorption of hydrogen molecules over PAH structures has been studied. To model the graphene surface for barrier calculations, it is shown that coronene can successfully estimate the graphene monolayer. The barrier height is calculated for perfect and two different defective PAH structures including Stone-Wales (SW) and 585. It is found that PAH even with small defects is impermeable to hydrogen molecules.... 

    Study on the acetylene hydrogenation process for ethylene production: simulation, modification, and optimization

    , Article Chemical Engineering Communications ; Volume 200, Issue 7 , Mar , 2013 , Pages 863-877 ; 00986445 (ISSN) Azizi, M ; Zolfaghari Sharak, A ; Mousavi, S. A ; Bakhtiari Ziabari, F ; Shariati, J ; Azizi, S ; Sharif University of Technology
    In this study, an industrial acetylene hydrogenation unit is simulated utilizing three available kinetic models. The results are compared against six-day experimental data and the best model is selected. Effects of feed temperature and the amount of injected hydrogen on ethylene selectivity are also studied. According to the simulation results, the unit is not working under its optimum conditions. Furthermore, by reduction of the hydrogen flow rate to 52 kg/h, process selectivity is increased. In addition, a new approach is proposed to modify the hydrogenation process and reduce undesired by-products. In the simulation of the modified process, hydrogenation reactors temperature, hydrogen... 

    Experimental study of hydrogen fluoride adsorption on sodium fluoride

    , Article Journal of Industrial and Engineering Chemistry ; Volume 16, Issue 1 , 2010 , Pages 147-151 ; 1226086X (ISSN) Afzal, S ; Rahimi, A ; Ehsani, M. R ; Tavakoli, H ; Sharif University of Technology
    In uranium conversion industry, the fluorine is used as chemical raw material gas to produce UF4 and UF6 while its purity is very important. In this study, the adsorption process of hydrogen fluoride, as an impurity in the process of fluorine production, on sodium fluoride pellets is experimentally studied in a lab-scale fixed bed adsorbent. Also, the effects of some operating parameters including inlet concentration and inlet temperature of hydrogen fluoride are precisely investigated on the adsorption process. The data of adsorption are analyzed and correlated by Langmuir, Freundlich and Temkin isotherms. The adsorption capacity is found to be 1.908 and 0.750 g HF/g NaF by the Langmuir... 

    Structural relevance of N2O2-donor naphthodiaza-crown macrocyclic ligands to selective fluorescence signaling behavior towards aliphatic tertiary amines

    , Article Journal of Photochemistry and Photobiology A: Chemistry ; Volume 314 , 2016 , Pages 42-51 ; 10106030 (ISSN) Ghanbari, B ; Zarepour Jevinani, M ; Sharif University of Technology
    Elsevier  2016
    A series of N2O2-donor naphthodiaza-crown macrocyclic ligands, L1-L5, were synthesized and characterized by IR, 1H and 13C NMR spectroscopy, mass spectrometry as well as microanalysis. Preliminary observations employing UV-vis spectrophotometry of L3 in ethanol revealed that triethylamine (TEA) has a significant blue-shift effect on the entire of the spectra. Then, the detection of aliphatic and aromatic amines by L3 were followed by monitoring of fluorescence quenching of the resulting adducts in terms of their binding with L1-L5. Both steady-state and time-resolved spectroscopic measurements in the... 

    Activation of hydrocarbon C-H bonds by iodosylbenzene: How does it compare with iron(iv)-oxo oxidants?

    , Article Chemical Communications ; Issue 12 , 2009 , Pages 1562-1564 ; 13597345 (ISSN) Kim, S. J ; Latifi, R ; Kang, H. Y ; Nam, W ; De Visser, S. P ; Sharif University of Technology
    Combined experimental and theoretical studies on the reactivity of iodosylbenzene (PhIO) show that PhIO is capable of activating weak C-H bonds of hydrocarbons via a hydrogen abstraction mechanism. © 2009 The Royal Society of Chemistry