The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Ahmed E Awadallah - One of the best experts on this subject based on the ideXlab platform.
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Hydrohalogenation of platinum palladium h zsm 5 catalysts for n hexane hydroconversion
Petroleum Science and Technology, 2015Co-Authors: Ahmed K Aboulgheit, Noha A K Aboulgheit, Ahmed E Awadallah, S M AbdelhamidAbstract:Catalysts containing 0.3%Pt-, 0.3%Pd-, and 0.3%Pt-0.3%Pd-/H-ZSM-5 were prepared and modified via hydrochlorination or hydrofluorination and tested for n-hexane hydroconversion throughout a reaction temperature range of 250–500°C. Bifunctionality parameters of the current catalysts were characterized via acid site strength distribution by NH3-temperature programmed desorption, metal(s) component dispersion by H2 chemisorption, and temperature programmed reduction. Hydrochlorination was found to leach less structural zeolitic Al in the catalyst than hydrofluorination. HCl modification improved n-hexane hydroisomerization activity, whereas HF treatment was deteriorative via causing pore diffusion restriction by excessively formed debris. Acid sites density and strength were higher on hydrofluorination than on hydrochlorination. Surface area and metals dispersion were higher for hydrochlorinated catalyst but lower for the hydrofluorinated one. Maximum isohexanes production (70%) was realized on hydrochlorinat...
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Hydrohalogenation of Platinum–Palladium/H-ZSM-5 Catalysts for n-Hexane Hydroconversion
Petroleum Science and Technology, 2014Co-Authors: Ahmed K. Aboul-gheit, Noha A.k. Aboul-gheit, Ahmed E Awadallah, S. M. Abdel-hamidAbstract:Catalysts containing 0.3%Pt-, 0.3%Pd-, and 0.3%Pt-0.3%Pd-/H-ZSM-5 were prepared and modified via hydrochlorination or hydrofluorination and tested for n-hexane hydroconversion throughout a reaction temperature range of 250–500°C. Bifunctionality parameters of the current catalysts were characterized via acid site strength distribution by NH3-temperature programmed desorption, metal(s) component dispersion by H2 chemisorption, and temperature programmed reduction. Hydrochlorination was found to leach less structural zeolitic Al in the catalyst than hydrofluorination. HCl modification improved n-hexane hydroisomerization activity, whereas HF treatment was deteriorative via causing pore diffusion restriction by excessively formed debris. Acid sites density and strength were higher on hydrofluorination than on hydrochlorination. Surface area and metals dispersion were higher for hydrochlorinated catalyst but lower for the hydrofluorinated one. Maximum isohexanes production (70%) was realized on hydrochlorinat...
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Reactions of Cyclohexane on Platinum, Palladium, or Iridium-loaded H-ZSM-5 Zeolite Hydrohalogenated Catalysts
Petroleum Science and Technology, 2011Co-Authors: Ahmed K. Aboul-gheit, S. M. Abdel-hamid, Ahmed E Awadallah, D. S. El-desouki, Ateyya A. Aboul-eneinAbstract:Abstract The catalytic hydroconversion of cyclohexane using catalysts containing H-ZSM-5 zeolite loaded with 0.35 wt% platinum, palladium, or iridium was studied in a pulse-type microreactor/GC system at atmospheric pressure. These catalysts were also either doped with 3.0% of HCl or HF. The activities of these catalysts and the distribution of the products formed were found to depend on the dispersion of the metallic component as well as on the acidity, acid sites number, and strength in the catalysts. TPD of ammonia and hydrogen chemisorption were applied to evaluate acid site strength distribution and metals dispersion, respectively, in the catalysts. In case of the Pt- and Pd-containing catalysts, hydrochlorination enhanced the isomerization and dehydrogenation activities and selectivities of cyclohexane, but decreased its hydrocracking activity. However, catalyst hydrofluorination resulted in the reverse effects. Nevertheless, for the Ir-loaded catalyst, both Hydrohalogenation treatments decreased th...
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effect of Hydrohalogenation of metal zeolite catalysts for cyclohexene hydroconversion ii rhenium h zsm 5 catalysts
Chinese Journal of Catalysis, 2008Co-Authors: Ahmed K Aboulgheit, Noha A K Aboulgheit, Ahmed E AwadallahAbstract:Abstract A post-preparation treatment of the Re/H-ZSM-5 catalyst with HCl or HF was performed, and its effect on cyclohexene hydroconversion reactions at 50-400 °C in a continuous flow reactor was investigated. The HF treatment significantly improved the catalytic activity for cyclohexene hydrogenation to cyclohexane and methylcyclopentenes to methylcyclopentane in comparison to the HCl treatment. This is principally attributed to the higher Re dispersion and enhancement of the acid site number and strength. Thereupon occurs the highest hydrocracking activity and the lowest dehydrogenation activity for cyclohexene to cyclohexadienes on Re/H-ZSM-5(HF) by virtue of the highest strength of acid sites. The untreated Re/H-ZSM-5 catalyst exhibited the highest dehydrogenation activity for aromatics production, which may be attributed to the lowest quantity of extraframework Al and Si depositing in the pores and cavities of the zeolite support. Industrially, the relative amounts of xylene isomers produced on the hydrohalogenated catalysts are of interest. The amount of p -xylene was higher than m -xylene on the HF-treated catalyst; m - and p -xylenes presented almost equal values on the HCl-treated catalyst; m -xylene exceeded p -xylene on the untreated catalyst. O-xylene was almost equal to the sum of p - and m -xylenes in all cases.
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Effect of Hydrohalogenation of Metal/Zeolite Catalysts for Cyclohexene Hydroconversion II. Rhenium/H-ZSM-5 Catalysts
Chinese Journal of Catalysis, 2008Co-Authors: Ahmed K. Aboul-gheit, Noha A.k. Aboul-gheit, Ahmed E AwadallahAbstract:Abstract A post-preparation treatment of the Re/H-ZSM-5 catalyst with HCl or HF was performed, and its effect on cyclohexene hydroconversion reactions at 50-400 °C in a continuous flow reactor was investigated. The HF treatment significantly improved the catalytic activity for cyclohexene hydrogenation to cyclohexane and methylcyclopentenes to methylcyclopentane in comparison to the HCl treatment. This is principally attributed to the higher Re dispersion and enhancement of the acid site number and strength. Thereupon occurs the highest hydrocracking activity and the lowest dehydrogenation activity for cyclohexene to cyclohexadienes on Re/H-ZSM-5(HF) by virtue of the highest strength of acid sites. The untreated Re/H-ZSM-5 catalyst exhibited the highest dehydrogenation activity for aromatics production, which may be attributed to the lowest quantity of extraframework Al and Si depositing in the pores and cavities of the zeolite support. Industrially, the relative amounts of xylene isomers produced on the hydrohalogenated catalysts are of interest. The amount of p -xylene was higher than m -xylene on the HF-treated catalyst; m - and p -xylenes presented almost equal values on the HCl-treated catalyst; m -xylene exceeded p -xylene on the untreated catalyst. O-xylene was almost equal to the sum of p - and m -xylenes in all cases.
Ahmed K Aboulgheit - One of the best experts on this subject based on the ideXlab platform.
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Hydrohalogenation of platinum palladium h zsm 5 catalysts for n hexane hydroconversion
Petroleum Science and Technology, 2015Co-Authors: Ahmed K Aboulgheit, Noha A K Aboulgheit, Ahmed E Awadallah, S M AbdelhamidAbstract:Catalysts containing 0.3%Pt-, 0.3%Pd-, and 0.3%Pt-0.3%Pd-/H-ZSM-5 were prepared and modified via hydrochlorination or hydrofluorination and tested for n-hexane hydroconversion throughout a reaction temperature range of 250–500°C. Bifunctionality parameters of the current catalysts were characterized via acid site strength distribution by NH3-temperature programmed desorption, metal(s) component dispersion by H2 chemisorption, and temperature programmed reduction. Hydrochlorination was found to leach less structural zeolitic Al in the catalyst than hydrofluorination. HCl modification improved n-hexane hydroisomerization activity, whereas HF treatment was deteriorative via causing pore diffusion restriction by excessively formed debris. Acid sites density and strength were higher on hydrofluorination than on hydrochlorination. Surface area and metals dispersion were higher for hydrochlorinated catalyst but lower for the hydrofluorinated one. Maximum isohexanes production (70%) was realized on hydrochlorinat...
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effect of Hydrohalogenation of ptre h zsm 5 for cyclohexene conversion
Chinese Journal of Catalysis, 2012Co-Authors: Sameh M Aboulfotouh, Ahmed K AboulgheitAbstract:Extended use of supported Pt catalysts causes thermal migration of Pt particles to form large agglomerates, thus decreasing the catalytic activity. The combination of Pt with Re protects Pt against migration. In addition, Cl− injection into the reactor assists Pt particles redispersion to prolong catalyst life. In this work, a PtRe/H-ZSM-5 catalyst was treated with either HCl or HF to investigate their role in activating or deactivating the catalyst. The conversion exceeded 90% in the whole temperature range with the PtRe/H-ZSM-5(HCl) catalyst, and its activity for the direct isomerization of cyclohexene to methylcyclopentenes (MCPEs) was the lowest but the activity for the hydrogenation of the MCPEs to methylcyclopentane was the highest. The reactivities of MCPEs and cyclohexadienes on the catalysts were similar because both are dehydrogenation reactions. Benzene production was significantly higher on the hydrochlorinated catalyst than on the other catalysts, and its hydrocracking activity was the lowest, which is a good characteristic for processing catalysts where cracking is undesired.
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effect of Hydrohalogenation of metal zeolite catalysts for cyclohexene hydroconversion ii rhenium h zsm 5 catalysts
Chinese Journal of Catalysis, 2008Co-Authors: Ahmed K Aboulgheit, Noha A K Aboulgheit, Ahmed E AwadallahAbstract:Abstract A post-preparation treatment of the Re/H-ZSM-5 catalyst with HCl or HF was performed, and its effect on cyclohexene hydroconversion reactions at 50-400 °C in a continuous flow reactor was investigated. The HF treatment significantly improved the catalytic activity for cyclohexene hydrogenation to cyclohexane and methylcyclopentenes to methylcyclopentane in comparison to the HCl treatment. This is principally attributed to the higher Re dispersion and enhancement of the acid site number and strength. Thereupon occurs the highest hydrocracking activity and the lowest dehydrogenation activity for cyclohexene to cyclohexadienes on Re/H-ZSM-5(HF) by virtue of the highest strength of acid sites. The untreated Re/H-ZSM-5 catalyst exhibited the highest dehydrogenation activity for aromatics production, which may be attributed to the lowest quantity of extraframework Al and Si depositing in the pores and cavities of the zeolite support. Industrially, the relative amounts of xylene isomers produced on the hydrohalogenated catalysts are of interest. The amount of p -xylene was higher than m -xylene on the HF-treated catalyst; m - and p -xylenes presented almost equal values on the HCl-treated catalyst; m -xylene exceeded p -xylene on the untreated catalyst. O-xylene was almost equal to the sum of p - and m -xylenes in all cases.
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effect of hydrochlorination and hydrofluorination of h zsm 5 on the catalytic hydroconversion reactions of cyclohexene
Applied Catalysis A-general, 2006Co-Authors: Ahmed K Aboulgheit, Sameh M Aboulfotouh, Samah M Abdelhamid, Noha A K AboulgheitAbstract:Abstract Modifying the acid sites (number and strength) of H-ZSM-5 zeolite via doping with 3.0 wt.% HCl or HF for being used as catalysts for the hydroconversion of cyclohexene (CHE) in a flow-type fixed-bed reactor operated atmospherically in H 2 carrier gas at temperatures of 50–400 °C. The acid sites strength distribution in these zeolite forms was evaluated using temperature programmed desorption (TPD) of presorbed ammonia in a differential scanning calorimeter (DSC). Either HCl or HF incorporation has increased both acid sites number and strength in the zeolite to varying extents. Hydrochlorination enhanced the acid sites number in the zeolite to a larger extent than hydrofluorination, whereas, the latter enhanced the acid sites strength to a larger extent than hydrochlorination. Nevertheless, not only the acid catalysed reactions ; i.e., isomerisation of the six-membered-ring of CHE to the five-membered ring compounds (methylcyclopentenes (MCPEs) plus methylcyclopentane (MCPA)) and hydrocracking reactions to lower molecular weight components, were enhanced via both Hydrohalogenation treatments of the zeolite, but also hydrogenation of CHE to cyclohexane and MCPEs to MCPA and dehydrogenation of CHE to cyclohexadienes (CHDEs) plus benzene were also enhanced.
Gangguo Zhu - One of the best experts on this subject based on the ideXlab platform.
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An Operationally Simple Approach to (E)-α-Halo Vinyl Sulfides and Their Applications for Accessing Stereodefined Trisubstituted Alkenes.
ChemInform, 2013Co-Authors: Zhaozhen Yang, Xiaoyi Chen, Wei Kong, Siyuan Xia, Renwei Zheng, Fang Luo, Gangguo ZhuAbstract:A highly regio- and stereoselective Hydrohalogenation of alkynyl thioethers leads to (E)-α-halo vinyl sulfides (II).
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An operationally simple approach to (E)-α-halo vinyl sulfides and their applications for accessing stereodefined trisubstituted alkenes
Organic & biomolecular chemistry, 2013Co-Authors: Zhaozhen Yang, Xiaoyi Chen, Wei Kong, Siyuan Xia, Renwei Zheng, Fang Luo, Gangguo ZhuAbstract:An operationally simple and practical protocol for the synthesis of (E)-α-halo vinyl sulfides has been achieved via a highly regio- and stereoselective Hydrohalogenation of alkynyl thioethers using lithium halides in HOAc or propionic acid at room temperature. It permits the formation of (E)-α-chloro and (E)-α-bromo vinyl sulfides in satisfactory yields with good to excellent stereoselectivities. Moreover, this work results in a new method for the assembly of stereodefined (E)- or (Z)-trisubstituted alkenes featuring the first coupling of the C–X bond of (E)-α-halo vinyl sulfides followed by a subsequent Ni-catalyzed coupling of the C–S bond with Grignard reagents.
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highly stereoselective synthesis of z 1 2 dihaloalkenes by a pd catalyzed Hydrohalogenation of alkynyl halides
ChemInform, 2012Co-Authors: Gangguo Zhu, Dongxu Chen, Yuyi Wang, Renwei ZhengAbstract:The obtained products are suitable for subsequent reactions such as Sonogashira couplings or Diels—Alder cyclizations.
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Highly Stereoselective Synthesis of (Z)‐1,2‐Dihaloalkenes by a Pd‐Catalyzed Hydrohalogenation of Alkynyl Halides.
ChemInform, 2012Co-Authors: Gangguo Zhu, Dongxu Chen, Yuyi Wang, Renwei ZhengAbstract:The obtained products are suitable for subsequent reactions such as Sonogashira couplings or Diels—Alder cyclizations.
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Highly stereoselective synthesis of (Z)-1,2-dihaloalkenes by a Pd-catalyzed Hydrohalogenation of alkynyl halides
Chemical communications (Cambridge England), 2012Co-Authors: Gangguo Zhu, Dongxu Chen, Yuyi Wang, Renwei ZhengAbstract:An unprecedented Pd-catalyzed Hydrohalogenation of alkynyl halides for the regio- and stereoselective synthesis of (Z)-1,2-dihaloalkenes has been realized using [(allyl)PdCl]2 as the catalyst and cis,cis-1,5-cyclooctadiene as the ligand. The advantages of this protocol are well illustrated by the assembly of trisubstituted (Z)-enynes and multifunctional benzenes via iterative cross-coupling reactions or tandem Diels–Alder–aromatization reactions, respectively.
Tetsuo Iwasawa - One of the best experts on this subject based on the ideXlab platform.
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synthesis of 1 haloethenamides from ynamide through halotrimethylsilane mediated Hydrohalogenation
ChemInform, 2014Co-Authors: Kazuhiro Ohashi, Akihiro H. Sato, Masataka Ide, Shigenori Mihara, Tetsuo IwasawaAbstract:The reaction is initiated by HX which is prepared in-situ from halotrimethylsilane and water.
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Synthesis of 1‐Haloethenamides from Ynamide Through Halotrimethylsilane‐Mediated Hydrohalogenation.
ChemInform, 2014Co-Authors: Kazuhiro Ohashi, Akihiro H. Sato, Masataka Ide, Shigenori Mihara, Tetsuo IwasawaAbstract:The reaction is initiated by HX which is prepared in-situ from halotrimethylsilane and water.
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Regio- and stereoselective Hydrohalogenation of ynamide components in 1,3-butadiynes with in situ generated HX
Tetrahedron Letters, 2014Co-Authors: Masataka Ide, Kazuhiro Ohashi, Shigenori Mihara, Tetsuo IwasawaAbstract:A simple protocol for regio-, and stereoselective Hydrohalogenation of ynamide moieties in 1,3-butadiyne structures is described. The facile approach enables exact syn-addition of HX to the diyne components, giving just single isomer of the corresponding dienes and enynes. 2014 Elsevier Ltd. All rights reserved.
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Synthesis of 1-haloethenamides from ynamide through halotrimethylsilane-mediated Hydrohalogenation
Tetrahedron Letters, 2014Co-Authors: Kazuhiro Ohashi, Akihiro H. Sato, Masataka Ide, Shigenori Mihara, Tetsuo IwasawaAbstract:Abstract A convenient synthesis of 1-haloethenamides has been achieved by utilizing halotrimethylsilane (TMSX, X = Cl, Br, I) and water. Halotrimethylsilane in 1 M CH 2 Cl 2 solution functions as a halogen source of the in situ generated HX, and the HX added to the terminal triple bonds of ynamides in Markovnikov fashion.
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Regio- and stereospecific synthesis of (E)-α-iodoenamide moieties from ynamides through iodotrimethylsilane-mediated hydroiodation
Tetrahedron Letters, 2013Co-Authors: Akihiro H. Sato, Kazuhiro Ohashi, Tetsuo IwasawaAbstract:Abstract A facile approach to ( E )-α-haloenamide moieties from ynamides using bromo- or iodotrimethylsilane is described. The simple protocol enables a regio- and stereospecific Hydrohalogenation of the triple bond in gram-scale and provides a general entry for synthesis of novel enamide analogues.
Ahmed K. Aboul-gheit - One of the best experts on this subject based on the ideXlab platform.
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Hydrohalogenation of Platinum–Palladium/H-ZSM-5 Catalysts for n-Hexane Hydroconversion
Petroleum Science and Technology, 2014Co-Authors: Ahmed K. Aboul-gheit, Noha A.k. Aboul-gheit, Ahmed E Awadallah, S. M. Abdel-hamidAbstract:Catalysts containing 0.3%Pt-, 0.3%Pd-, and 0.3%Pt-0.3%Pd-/H-ZSM-5 were prepared and modified via hydrochlorination or hydrofluorination and tested for n-hexane hydroconversion throughout a reaction temperature range of 250–500°C. Bifunctionality parameters of the current catalysts were characterized via acid site strength distribution by NH3-temperature programmed desorption, metal(s) component dispersion by H2 chemisorption, and temperature programmed reduction. Hydrochlorination was found to leach less structural zeolitic Al in the catalyst than hydrofluorination. HCl modification improved n-hexane hydroisomerization activity, whereas HF treatment was deteriorative via causing pore diffusion restriction by excessively formed debris. Acid sites density and strength were higher on hydrofluorination than on hydrochlorination. Surface area and metals dispersion were higher for hydrochlorinated catalyst but lower for the hydrofluorinated one. Maximum isohexanes production (70%) was realized on hydrochlorinat...
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Effect of Hydrohalogenation of PtRe/H-ZSM-5 for Cyclohexene Conversion
Chinese Journal of Catalysis, 2012Co-Authors: Sameh M K Aboul-fotouh, Ahmed K. Aboul-gheitAbstract:Extended use of supported Pt catalysts causes thermal migration of Pt particles to form large agglomerates, thus decreasing the catalytic activity. The combination of Pt with Re protects Pt against migration. In addition, Cl− injection into the reactor assists Pt particles redispersion to prolong catalyst life. In this work, a PtRe/H-ZSM-5 catalyst was treated with either HCl or HF to investigate their role in activating or deactivating the catalyst. The conversion exceeded 90% in the whole temperature range with the PtRe/H-ZSM-5(HCl) catalyst, and its activity for the direct isomerization of cyclohexene to methylcyclopentenes (MCPEs) was the lowest but the activity for the hydrogenation of the MCPEs to methylcyclopentane was the highest. The reactivities of MCPEs and cyclohexadienes on the catalysts were similar because both are dehydrogenation reactions. Benzene production was significantly higher on the hydrochlorinated catalyst than on the other catalysts, and its hydrocracking activity was the lowest, which is a good characteristic for processing catalysts where cracking is undesired.
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Reactions of Cyclohexane on Platinum, Palladium, or Iridium-loaded H-ZSM-5 Zeolite Hydrohalogenated Catalysts
Petroleum Science and Technology, 2011Co-Authors: Ahmed K. Aboul-gheit, S. M. Abdel-hamid, Ahmed E Awadallah, D. S. El-desouki, Ateyya A. Aboul-eneinAbstract:Abstract The catalytic hydroconversion of cyclohexane using catalysts containing H-ZSM-5 zeolite loaded with 0.35 wt% platinum, palladium, or iridium was studied in a pulse-type microreactor/GC system at atmospheric pressure. These catalysts were also either doped with 3.0% of HCl or HF. The activities of these catalysts and the distribution of the products formed were found to depend on the dispersion of the metallic component as well as on the acidity, acid sites number, and strength in the catalysts. TPD of ammonia and hydrogen chemisorption were applied to evaluate acid site strength distribution and metals dispersion, respectively, in the catalysts. In case of the Pt- and Pd-containing catalysts, hydrochlorination enhanced the isomerization and dehydrogenation activities and selectivities of cyclohexane, but decreased its hydrocracking activity. However, catalyst hydrofluorination resulted in the reverse effects. Nevertheless, for the Ir-loaded catalyst, both Hydrohalogenation treatments decreased th...
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Effect of Hydrohalogenation of Metal/Zeolite Catalysts for Cyclohexene Hydroconversion II. Rhenium/H-ZSM-5 Catalysts
Chinese Journal of Catalysis, 2008Co-Authors: Ahmed K. Aboul-gheit, Noha A.k. Aboul-gheit, Ahmed E AwadallahAbstract:Abstract A post-preparation treatment of the Re/H-ZSM-5 catalyst with HCl or HF was performed, and its effect on cyclohexene hydroconversion reactions at 50-400 °C in a continuous flow reactor was investigated. The HF treatment significantly improved the catalytic activity for cyclohexene hydrogenation to cyclohexane and methylcyclopentenes to methylcyclopentane in comparison to the HCl treatment. This is principally attributed to the higher Re dispersion and enhancement of the acid site number and strength. Thereupon occurs the highest hydrocracking activity and the lowest dehydrogenation activity for cyclohexene to cyclohexadienes on Re/H-ZSM-5(HF) by virtue of the highest strength of acid sites. The untreated Re/H-ZSM-5 catalyst exhibited the highest dehydrogenation activity for aromatics production, which may be attributed to the lowest quantity of extraframework Al and Si depositing in the pores and cavities of the zeolite support. Industrially, the relative amounts of xylene isomers produced on the hydrohalogenated catalysts are of interest. The amount of p -xylene was higher than m -xylene on the HF-treated catalyst; m - and p -xylenes presented almost equal values on the HCl-treated catalyst; m -xylene exceeded p -xylene on the untreated catalyst. O-xylene was almost equal to the sum of p - and m -xylenes in all cases.
