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temperature-programmed-desorption
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Mechanism of catalytic decomposition of CH3I on the Cu(111) surface: A UBI-QEP approach
, Article Langmuir, Washington, DC, United States ; Volume 16, Issue 21 , 2000 , Pages 8095-8099 ; 07437463 (ISSN) ; Gobal, F ; Sharif University of Technology
ACS
2000
Abstract
The method of unity bond index-quadratic exponential potential (UBI-QEP) and the computer simulation of the temperature programmed desorption (TPD) patterns are employed to derive the kinetic and thermodynamic parameters associated with the steps of the pathway we propose for the catalytic decomposition of methyl iodide on the Cu(111) surface. Assuming a highly reactive `hot methyl' surface intermediate and on the basis of our calculations it is concluded that the desorption of a part of this species is responsible for the reported methyl radical TPD peak at 140 K, while a part of this surface species is trapped in the three-fold sites of the Cu(111) surface and desorbs to form the reported...
Selective storage and evolution of hydrogen on nafion/NaCl/graphene quantum dot mixed matrix using tensammetry as power electrochemical technique
, Article International Journal of Hydrogen Energy ; Volume 42, Issue 15 , 2017 , Pages 9428-9439 ; 03603199 (ISSN) ; Zakipour, M ; Doroodmand, M. M ; Mehrtash, M ; Sharif University of Technology
Abstract
Hydrogen storage/evolution behavior of nafion/NaCl/graphene quantum dot (GQD) mixed matrix as selective hydrogen capacitor (power source) was evaluated in detail through an electrochemical process at two independent potential ranges. For this purpose, a three-electrode system included Pt disk as counter electrode, Ag/AgCl as reference electrode and GQD-based mixed matrix-modified Pt disk as working electrode. For hydrogen storage, the deposition potential and time were evaluated to −1.0 V (vs. Ag/AgCl) and 120 s, respectively under high basic solution generated using NaOH (1.0 M) solution, followed by evolution of hydrogen at +0.8 V (vs. Ag/AgCl) during formation of hydrogen bubbles. The...
Effect of heating profile on desorption curve in temperature programmed desorption analysis: Case study of acid sites distribution of SAPO-34
, Article Journal of Porous Materials ; Volume 16, Issue 5 , 2009 , Pages 599-603 ; 13802224 (ISSN) ; Farhadi, F ; Khorasheh, F ; Yan, Z. F ; Sharif University of Technology
2009
Abstract
Comparison of the traditional linear heating method of TPD with an original stepwise heating scheme was reported for the first time. Stepwise heating TPD was carried out by keeping the temperature constant as soon as ammonia desorption signal rises until the signal returns to the baseline. More ammonia desorption peaks on a SAPO-34 catalyst were identified using TPD with stepwise heating. The effect of temperature ramp on desorption peak broadening in TPD curve was also addressed. The more distinct ammonia desorption peaks in stepwise TPD indicates that ammonia adsorbs in about five or six different ways on SAPO-34, and attribution of different adsorptions may be explained considering some...
Transesterification of waste cooking oil to biodiesel using Ca and Zr mixed oxides as heterogeneous base catalysts
, Article Fuel Processing Technology ; Volume 97 , 2012 , Pages 45-51 ; 03783820 (ISSN) ; Ghasemi, M ; Sharif University of Technology
2012
Abstract
Heterogeneous solid catalysts comprising CaO and ZrO 2 mixed oxides with various Ca-to-Zr molar ratios were synthesized by means of coprecipitation method. These synthesized mixed oxide catalysts were used for the transesterification of waste cooking oil (WCO) as feedstock with methanol to produce biodiesel fuel (BDF) at 65 °C and 1 atm. The influences of Ca-to-Zr molar ratio, catalyst loading, methanol-to-oil molar ratio, and the reaction time on the BDF yield were carefully investigated. In addition, the stability of prepared solid catalysts was studied. These catalysts were characterized by using techniques of X-ray diffraction, X-ray florescence, X-ray photoelectron spectroscopy, surface...
Optimizing parameters affecting synthesis of a novel Co–Mo/GO catalyst in a Naphtha HDS reaction utilizing D-optimal experimental design method
, Article Journal of the Taiwan Institute of Chemical Engineers ; Volume 78 , 2017 , Pages 566-575 ; 18761070 (ISSN) ; Kazemeini, M ; Rashidi, A ; Soltanali, S ; Sharif University of Technology
Abstract
In this research effects of important synthesis parameters upon catalytic performance of a novel graphene based catalyst for an HDS reaction were investigated. The graphene oxide (GO) used as a support was initially prepared through chemical exfoliation of graphite via modified Hummers method. In this venue the impregnation method, promoter/main metallic spices ratio, total metal loading of the active phase and amount of chelating agent were systematically understudied. Thus, GO was impregnated with active metallic phases through the hydrothermal and modified incipient wetness impregnation techniques. In both procedures, 1:2, 1:3 and 1:4 weight ratios of Co/Mo with the percentages of the...
The effect of acid treatment and calcination on the modification of zeolite X in diesel fuel hydrodesulphurization
, Article Canadian Journal of Chemical Engineering ; Volume 100, Issue 11 , 2022 , Pages 3357-3366 ; 00084034 (ISSN) ; Kazemeini, M ; Soltanali, S ; Rashidzadeh, M ; Sharif University of Technology
John Wiley and Sons Inc
2022
Abstract
Faujasite (X, Y) zeolites are considered the main and important catalysts in hydrorefining processes. In order to obtain zeolites with higher acidity and volume of mesopores, post-synthesis modification, dealumination by different pickling techniques (using ethylenediamine tetraacetic acid [EDTA] chelating agent), and thermal treatment (calcination) were employed. The dealumination process led to the removal of the aluminum atoms from the zeolite structure and a rise in acidity while maintaining the zeolite crystalline lattice. X-ray diffraction (XRD), atomic absorption spectrometry (AAS), Fourier-transform infrared (FT-IR), field-emission scanning electron microscopy (FE-SEM),...
Graphene based catalysts for deep hydrodesulfurization of naphtha and diesel fuels: A physiochemical study
, Article Fuel ; Volume 165 , 2016 , Pages 468-476 ; 00162361 (ISSN) ; Kazemeini, M ; Rashidi, A ; Bazmi, M ; Sharif University of Technology
Elsevier Ltd
Abstract
In this study, graphene materials have been synthesized with solid camphor (C10H16O) and methane gas as carbon precursors using atmospheric pressure chemical vapor deposition (CVD) technique at a temperature range of 900-1000 °C for a period of 45 min over copper nanoparticles. Influence of the carbon precursors upon the shape, number of layers and yield of the synthesized graphene samples has been investigated. In this venue, the compounds synthesized were functionalized with oxygen groups and impregnated by cobalt and molybdenum active phases. Moreover, the total metal loading and Co/Mo weight ratio of prepared compounds were adjusted to their industrial nominal values of 10% and 0.33,...
Effect of SAPO-34's composition on its physico-chemical properties and deactivation in MTO process
, Article Applied Catalysis A: General ; Volume 364, Issue 1-2 , 2009 , Pages 48-56 ; 0926860X (ISSN) ; Farhadi, F ; Khorasheh, F ; Sahebdelfar, S ; Asadi, M ; Feng, Y. Z ; Sharif University of Technology
2009
Abstract
Several SAPO-34 samples with different Si/Al ratio (0.05-0.5) of synthesis gel were prepared hydrothermally at crystallization temperature of 190-215 °C. The products were characterized by XRD, SEM/EDX, NH3-TPD, FT-IR and nitrogen adsorption techniques. EDX data showed a deviation of elemental composition of products with respect to the Al, Si, and P from that of the gel mixture, but the increasing trend of Si/Al ratio of the products was confirmed. According to XRD and SEM results, crystallinity of samples increased with Si/Al ratio up to the low to medium range of ca. 0.13. However, a reduction in the crystallinity was observed with further increase of the silicon content of the synthesis...
Synthesis and characterization of mixed–metal oxide nanoparticles (cenio3, cezro4, cecao3) and application in adsorption and catalytic oxidation–decomposition of asphaltenes with different chemical structures
, Article Petroleum Chemistry ; Volume 60, Issue 7 , 2020 , Pages 731-743 ; Ayatollahi, S ; Bahadorikhalili, S ; Esmaeilpour, M ; Sharif University of Technology
Pleiades Publishing
2020
Abstract
Abstract: This study investigates the catalytic activity of mixed–metal oxide nanoparticles with different surface acidities on asphaltene adsorption followed by catalytic oxidation–decomposition. Three different types of mixed–metal oxide nanoparticles (CeNiO3, CeCaO3 and CeZrO4) were synthesized, and their size, structure, and acid properties were characterized by field–emission scanning electron microscopy (FE–SEM), energy-dispersive X-ray spectroscopy (EDX), the high–resolution transmission electron microscopy (HR-TEM), X-ray powder diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area measurement and ammonia temperature-programmed desorption (NH3–TPD). Asphaltenes were extracted...
Light olefin production on the Co-Ni catalyst: Calcination conditions, and modeling and optimization of the process conditions by a statistical method
, Article New Journal of Chemistry ; Volume 44, Issue 18 , 2020 , Pages 7467-7483 ; Akbari, M ; Mirzaei, N ; Abdouss, M ; Sharif University of Technology
Royal Society of Chemistry
2020
Abstract
The present work is comprised of two main parts. In part 1 the Co-Ni/γ-Al2O3 catalyst was prepared using a sol-gel procedure. Then the effect of calcination variables including the calcination temperature and time on the catalytic performance for production of light olefins was investigated and optimized. The obtained results have shown that the catalyst which was calcined at 550 °C for 6 h has revealed the better catalytic performance for production of light olefins. In part 2 the effect of process conditions including the reaction temperature, H2/CO feed ratio and total reaction pressure on the catalytic performance (CO conversion%, (C2-C4) selectivity% and C5+ selectivity%) was...