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  1. Article ; Online: Hydrodesulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene over NiMo and CoMo sulfide catalysts: kinetic modeling approach for estimating selectivity.

    Farag, Hamdy

    Journal of colloid and interface science

    2010  Volume 348, Issue 1, Page(s) 219–226

    Abstract: The hydrodesulfurization (HDS) of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) over two synthesized unsupported CoMo (CMS) and NiMo (NMS) sulfide catalysts was investigated in a batch reactor. The HDS reactions proceeded through ... ...

    Abstract The hydrodesulfurization (HDS) of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) over two synthesized unsupported CoMo (CMS) and NiMo (NMS) sulfide catalysts was investigated in a batch reactor. The HDS reactions proceeded through two parallel-consecutive reaction pathways: direct desulfurization (DDS) and hydrogenation (HYD), in which two main intermediates-biphenyl or 3,3'-dimethylbiphenyl and partially hydrogenated DBT or 4,6-DMDBT-were involved. Kinetic models were developed to account for the partial contributions of these intermediates in the overall reaction network as well as for their selectivities. The models allow a precise estimation of the apparent rate constants of all steps in the reaction network. In the HDS reactions of 4,6-DMDBT, the HYD pathway was more pronounced than the DDS route over the NMS catalyst. Different selectivities in terms of yield fraction (percentage ratio of HYD/DDS) were observed for these two catalysts. The kinetic results according to these models show that the partially hydrogenated 4,6-DMDBT intermediate transformed mainly to 3,3'-dimethylcyclohexylbenzene. Besides, this intermediate is suggested to be partly transformed to 3,3'-dimethylbiphenyl. The rate of sulfur removal from the partially hydrogenated 4,6-DMDBT intermediates was an order of magnitude slower than that from the partially hydrogenated DBT. The NiMo sulfide catalyst was more active than the CoMo sulfide catalyst for the HDS of 4,6-DMDBT. The results are discussed in the context of proposed HDS reaction networks.
    Language English
    Publishing date 2010-08-01
    Publishing country United States
    Document type Journal Article
    ZDB-ID 241597-5
    ISSN 1095-7103 ; 0021-9797
    ISSN (online) 1095-7103
    ISSN 0021-9797
    DOI 10.1016/j.jcis.2010.04.022
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: Selective adsorption of refractory sulfur species on active carbons and carbon based CoMo catalyst.

    Farag, Hamdy

    Journal of colloid and interface science

    2007  Volume 307, Issue 1, Page(s) 1–8

    Abstract: Adsorption technique could be a reliable alternative in removing to a certain remarkable extent the sulfur species from the feedstock of petroleum oil. The performance of various carbons on adsorption of model sulfur compounds in a simulated feed ... ...

    Abstract Adsorption technique could be a reliable alternative in removing to a certain remarkable extent the sulfur species from the feedstock of petroleum oil. The performance of various carbons on adsorption of model sulfur compounds in a simulated feed solution and the sulfur containing compounds in the real gas oil was evaluated. The adsorption experiments have been carried out in a batch scale at ambient temperature and under the atmospheric pressure. In general, the most refractory sulfur compounds in the hydrotreatment reactions were selectively removed and adsorbed. It was found that the adsorbents affinities to dibenzothiophene and 4,6-dimethyldibenzothiophene were much more favored and pronounced than the aromatic matrices like fluorene, 1-methylnaphthalene and 9-methylanthracene. Among the sulfur species, 4,6-dimethyldibenzothiophene was the highest to be removed in terms of both selectivity and capacity over all the present adsorbents. The studied adsorbents showed significant capacities for the polyaromatic thiophenes. The electronic characteristics seem to play a certain role in such behavior. Regeneration of the used adsorbent was successfully attained either by washing it with toluene or by the release of the adsorbates through heat treatment. A suggested adsorptive removal process of sulfur compounds from petroleum distillate over carbon supported CoMo catalyst was discussed.
    Language English
    Publishing date 2007-03-01
    Publishing country United States
    Document type Journal Article
    ZDB-ID 241597-5
    ISSN 1095-7103 ; 0021-9797
    ISSN (online) 1095-7103
    ISSN 0021-9797
    DOI 10.1016/j.jcis.2006.11.024
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: Approach to the prediction of some surface characteristics of carbon-supported CoMo- catalysts from the adsorption/desorption technique.

    Farag, Hamdy

    Journal of colloid and interface science

    2002  Volume 254, Issue 2, Page(s) 316–321

    Abstract: Carbon-supported CoMo- catalyst samples have been prepared through the impregnation (in solution) method using two different Co/Mo loads of 2/10 and 4/20 wt%. The catalytic activities of these catalysts for hydrodesulfurization of dibenzothiophene at 2.9 ...

    Abstract Carbon-supported CoMo- catalyst samples have been prepared through the impregnation (in solution) method using two different Co/Mo loads of 2/10 and 4/20 wt%. The catalytic activities of these catalysts for hydrodesulfurization of dibenzothiophene at 2.9 MPa H(2) and 340 degrees C have been investigated and measured in a sampler microautoclave reactor. Adsorption of dibenzothiophene from decane solution over both carbon and catalysts was studied. The consecutive desorption of adsorbates was followed by the thermal gravimetric technique. Pore volumes and surface areas of carbon and catalysts based on dibenzothiophene desorption data have been estimated. Catalysts exhibit almost the same hydrodesulfurization activity. CoMo catalyst of 4/20 wt% load is speculated to have a tendency to form clusters larger than 2/10 catalyst ratio. Models for catalyst dispersion and agglomeration are suggested.
    Language English
    Publishing date 2002-10-15
    Publishing country United States
    Document type Journal Article
    ZDB-ID 241597-5
    ISSN 1095-7103 ; 0021-9797
    ISSN (online) 1095-7103
    ISSN 0021-9797
    DOI 10.1006/jcis.2002.8603
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: A comparative kinetic study on ultra-deep hydrodesulfurization of pre-treated gas oil over nanosized MoS2, CoMo-sulfide, and commercial CoMo/Al2O3 catalysts.

    Farag, Hamdy / Mochida, Isao

    Journal of colloid and interface science

    2012  Volume 372, Issue 1, Page(s) 121–129

    Abstract: Unsupported nanosized MoS(2) and CoMo-sulfide catalysts were synthesized, and their catalytic performances for the deep hydrodesulfurization (HDS) of treated gas oil were investigated as compared with that of a CoMo/Al(2)O(3) catalyst. The HDS reactions ... ...

    Abstract Unsupported nanosized MoS(2) and CoMo-sulfide catalysts were synthesized, and their catalytic performances for the deep hydrodesulfurization (HDS) of treated gas oil were investigated as compared with that of a CoMo/Al(2)O(3) catalyst. The HDS reactions were carried out in a batch autoclave reactor at 340 °C and 3 MPa H(2). The CoMo-sulfide catalyst shows the highest activity and can reduce the sulfur content to less than 10 ppm. The decrease in total sulfur content as a function of reaction time was found to follow pseudo-second order kinetics (empirical form). The change in the concentration of some individual representative sulfur-containing species in gas oil as a function of time was found to follow pseudo-first-order kinetics. However, the change in combined concentration of these species in the gas oil during HDS with the reaction time was found to corroborate pseudo-second-order kinetics. A kinetic model approach was proposed from which an estimation of the intrinsic kinetic data can be achieved. The model fitted the obtained data reasonably well, suggesting its potential for better assessment of the catalytic activity in the HDS of real feedstock. The study reveals that ranking of catalyst activities using model refractory sulfur-containing compounds does not necessarily imply a typical rank in case of investigating the real feedstocks.
    Language English
    Publishing date 2012-04-15
    Publishing country United States
    Document type Journal Article
    ZDB-ID 241597-5
    ISSN 1095-7103 ; 0021-9797
    ISSN (online) 1095-7103
    ISSN 0021-9797
    DOI 10.1016/j.jcis.2012.01.019
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Bonn / Germany

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  5. Article: Long-term effect of sleeve gastrectomy surgery on Hormonal Profile, Semen Parameters and sexual functions of obese infertile men; a prospective observational study.

    Abouelgreed, Tamer A / Elatreisy, Adel / El-Sherbeiny, Ahmed F / Abdelaal, Mohamed A / Saafan, Tamer / Shalkamy, Osama / Farag, Hamdy / Ghoneimy, Osama M / El-Dydamony, Eman M / Ibrahim, Eman H / Amer, Mohamed / Kutub, Khalid / Zamra, Mohamed / Hussein, Mohamed A / Koritenah, Ayman K / Hefny, Sherin A

    Basic and clinical andrology

    2023  Volume 33, Issue 1, Page(s) 16

    Abstract: Background: The effect of bariatric surgery on impaired semen parameters, hormonal profile and sexual function remains controversial to some extent.: The context and purpose of the study: To look at the long-term effects of sleeve gastrectomy on ... ...

    Abstract Background: The effect of bariatric surgery on impaired semen parameters, hormonal profile and sexual function remains controversial to some extent.
    The context and purpose of the study: To look at the long-term effects of sleeve gastrectomy on hormonal profiles, sperm parameters, and sexual function in infertile men with severe obesity. This prospective study included fifty-four obese patients with primary or secondary infertility who were scheduled for sleeve gastrectomy between February 2018 and March 2021. All participants were given a sperm analysis and a serum hormone profile before, 12, and 18 months after surgery. We used the International Index of Erectile Function questionnaire to assess sexual function.
    Results: There was a significant correlation between weight loss after sleeve gastrectomy and improvement in lipid profile (p < 0.05). No significant detectable effect of post-gastrectomy weight loss on patients with diabetes mellitus, hypertension, or obstructive sleep apnea. As regards the hormonal profile, sex hormone binding globulin, total and free testosterone improved significantly after 12- and 18-months following sleeve gastrectomy. There was a significant increase in sperm count and total sperm number during the follow-up after sleeve gastrectomy (p < 0.05), however, there were no significant changes in other semen parameters. Concerning sexual function, sexual desire, erectile function, and satisfaction improved significantly at 12 and 18 months after surgery.
    Conclusion: Weight loss through sleeve gastrectomy surgery significantly improves testosterone deficiency, sexual performance, and Sperm count in obese infertile men.
    Language English
    Publishing date 2023-06-22
    Publishing country England
    Document type Journal Article
    ZDB-ID 2732675-5
    ISSN 2051-4190
    ISSN 2051-4190
    DOI 10.1186/s12610-023-00191-1
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Textural characterizations and catalytic properties of quasispherical nanosized molybdenum disulfide.

    Farag, Hamdy / Al-Megren, Hamid

    Journal of colloid and interface science

    2009  Volume 332, Issue 2, Page(s) 425–431

    Abstract: Synthesis of sphere nanostructured MoS(2) is reported. Characterization of the synthesized MoS(2) was investigated by X-ray diffraction, nitrogen adsorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that ...

    Abstract Synthesis of sphere nanostructured MoS(2) is reported. Characterization of the synthesized MoS(2) was investigated by X-ray diffraction, nitrogen adsorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that the obtained MoS(2) is composed of layers that bend to form mostly spheres, with an average diameter of approximately 180 nm. The growth in crystallinity is mainly due to the increased number of the round-stacked layers of MoS(2). The catalytic activity and selectivity of the synthesized nanostructured MoS(2) for the dibenzothiophene hydrodesulfurization were investigated. The closed-circle MoS(2) layers exhibited a high selectivity for the direct sulfur removal.
    Language English
    Publishing date 2009-04-15
    Publishing country United States
    Document type Journal Article
    ZDB-ID 241597-5
    ISSN 1095-7103 ; 0021-9797
    ISSN (online) 1095-7103
    ISSN 0021-9797
    DOI 10.1016/j.jcis.2008.12.075
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Bonn / Germany

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  7. Article: comparative kinetic study on ultra-deep hydrodesulfurization of pre-treated gas oil over nanosized MoS₂, CoMo-sulfide, and commercial CoMo/Al₂O₃ catalysts

    Farag, Hamdy / Mochida, Isao

    Journal of colloid and interface science

    Volume v. 372,, Issue no. 1

    Abstract: Unsupported nanosized MoS₂ and CoMo-sulfide catalysts were synthesized, and their catalytic performances for the deep hydrodesulfurization (HDS) of treated gas oil were investigated as compared with that of a CoMo/Al₂O₃ catalyst. The HDS reactions were ... ...

    Abstract Unsupported nanosized MoS₂ and CoMo-sulfide catalysts were synthesized, and their catalytic performances for the deep hydrodesulfurization (HDS) of treated gas oil were investigated as compared with that of a CoMo/Al₂O₃ catalyst. The HDS reactions were carried out in a batch autoclave reactor at 340°C and 3MPa H₂. The CoMo-sulfide catalyst shows the highest activity and can reduce the sulfur content to less than 10ppm. The decrease in total sulfur content as a function of reaction time was found to follow pseudo-second order kinetics (empirical form). The change in the concentration of some individual representative sulfur-containing species in gas oil as a function of time was found to follow pseudo-first-order kinetics. However, the change in combined concentration of these species in the gas oil during HDS with the reaction time was found to corroborate pseudo-second-order kinetics. A kinetic model approach was proposed from which an estimation of the intrinsic kinetic data can be achieved. The model fitted the obtained data reasonably well, suggesting its potential for better assessment of the catalytic activity in the HDS of real feedstock. The study reveals that ranking of catalyst activities using model refractory sulfur-containing compounds does not necessarily imply a typical rank in case of investigating the real feedstocks.
    Keywords models ; feedstocks ; hydrogen ; oils ; sulfur ; catalysts ; catalytic activity ; autoclaves
    Language English
    Document type Article
    ISSN 0021-9797
    Database AGRIS - International Information System for the Agricultural Sciences and Technology

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