Catalytic removal of the S-content from thiophene is a central step in efforts aiming to reduce the environmental burdens of transportation fuels. In this contribution, we investigate the hydrodesulfurization (HDS) mechanisms of thiophene (C4H4S) over γ-Mo2N catalyst by means of density functional theory (DFT) calculations. The thiophene molecule preferentially adsorbs in a flat mode over 3-fold fcc nitrogen hollow sites. The HDS mechanism may potentially proceed either unimolecularly (direct desulfurization) or via H-assisted reactions (hydrogenation). Due to a sizable activation barrier required for the first Csingle bondS bond scission of 54.6 kcal/mol, we predict that the direct desulfurization to contribute rather very insignificantly in the HDS mechanism. Transfer of adsorbed hydrogen atoms on the γ-Mo2N surface to the thiophene ring substantially reduces activation barrier required in the Csingle bondS bond scission to only 24.1 kcal/mol in a process that affords an adsorbed C4H6* species and an S atom. Further hydrogenation of the unsaturated C4H6* produces 2-butene. Kinetics and thermodynamics attributes dictate the occurrence of partial rather than full hydrogenation of C4H6*. Calculated rate constants for all individual steps could be utilized to construct a robust kinetic model for the overall HDS process. Estimated conversion values of thiophene predict 50–70% consumption of thiophene at 700 K and low values of gas hourly space velocities. Reaction routes and kinetic parameters provided herein are useful to design stand-alone γ-Mo2N-based catalysts for applications entailing partial hydrogenation and hydrodesulfurization of severely contaminated S-fuels.
In the present work, pattern recognition is carried out by the contrast and relative variance of clouds. The K-mean clustering process is then applied to classify the cloud type; also, texture analysis being adopted to extract the textural features and using them in cloud classification process. The test image used in the classification process is the Meteosat-7 image for the D3 region.The K-mean method is adopted as an unsupervised classification. This method depends on the initial chosen seeds of cluster. Since, the initial seeds are chosen randomly, the user supply a set of means, or cluster centers in the n-dimensional space.The K-mean cluster has been applied on two bands (IR2 band) and (water vapour band).The textural analysis is used
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The Fountain of poetry Canot be suddenly flow or flood from emptiness. but it is streams and motives drive it to move . Forward tat Calmness and latent in depth of poet ,and try to Chang it in to high wives , go in to details inside the seas of poetry ,to sail threw it on the ships of poetry in creative styel to reach to the point from imaginary meaning , so every poet has direction to competein poetry poetsin Lament of Imam Hussain, There versification of poetry didn’t come from emptiness , but there was clashes motive them threw Calling the personality of Imam Hussain to learn lesson in avery beautiful and greative styel ,to be the expression poem from many sides in the personality of Imam Hussain from that events and facts that happ
... Show MoreBackground: Treatment of invasive prolactinoma, which has several characteristics including invasive growth into cavernous sinuses and formation of giant adenomas compressing adjacent neural structures, resulting in neurological dysfunction, has been very challenging. There are relatively few reports available describing long-term treatment outcome.
Aims of the study: In this study we evaluate the results of cabergoline administration as initial treatment during 4 years follow up period.
Methods: We prospectively categorized 36 patients into four groups according to the results of 3 months of cabergoline treatment: group 1, tumor volume reduction (TVR) ˃25% with normaliz
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This Study is Concerned with (the debate of democracy in the modern islamic political thought ) which discovers the attitudes and this trend of thought so-called democracy . Therefore this study is divided into three sections : the first section is concerned with the democracy in extremist Islamic speech, the second section tackles appropriation of democracy in moderate Islamic speech , while the third section is concerned with the democracy in Aistighrabi Islamic speech . Finally the conclusion sums up the findings of the study
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