The Experts below are selected from a list of 13011 Experts worldwide ranked by ideXlab platform
Brian F. Woodfield - One of the best experts on this subject based on the ideXlab platform.
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acid site properties of thermally stable silica doped Alumina as a function of silica Alumina Ratio and calcination temperature
Applied Catalysis A-general, 2014Co-Authors: Maryam Khosravi Mardkhe, Kamyar Keyvanloo, Calvin H. Bartholomew, William C. Hecker, Todd M. Alam, Brian F. WoodfieldAbstract:Abstract Acid site properties of silica-doped Aluminas prepared by a simple solvent deficient hydrolysis of the alkoxides was investigated. The total acid concentRation (Bronsted and Lewis sites) of silica-doped Aluminas (SDAs) calcined in the range of 700–1200 °C with Si/Al Ratios of 5, 15, 27 wt% was determined using temperature-programmed desorption of ammonia (ammonia-TPD). 27 Al solid state MAS NMR (Al SS MAS NMR) was used to measure the intrinsic Lewis acid site concentRation, and FTIR was also used as a separate measure of the Bronsted and Lewis acid site concentRation. Results indicate that removing hydroxyl groups in the form of water molecules through calcination result in a lower concentRation of Bronsted acid sites. Calcination at higher temperature also results in the transformation of unsaturated 5-coordinated aluminum (a strong Lewis acid) to higher concentRations of 6 and 4-coordinated aluminum in 5, 15 and 27% silica-doped Alumina samples. Therefore, the total acid site concentRation (Bronsted and Lewis sites) decreases by increasing the calcination temperature. In addition, the data show that increasing the silica/Alumina Ratio increases both the Bronsted and Lewis acid site concentRations. Based on these results, the acid site concentRations can be controlled by altering the Si/Al Ratio and calcination temperature while maintaining high surface areas, large pore volumes, and large pore diameters.
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Acid site properties of thermally stable, silica-doped Alumina as a function of silica/Alumina Ratio and calcination temperature
Applied Catalysis A: General, 2014Co-Authors: Maryam Khosravi Mardkhe, Kamyar Keyvanloo, Calvin H. Bartholomew, William C. Hecker, Todd M. Alam, Brian F. WoodfieldAbstract:Abstract Acid site properties of silica-doped Aluminas prepared by a simple solvent deficient hydrolysis of the alkoxides was investigated. The total acid concentRation (Bronsted and Lewis sites) of silica-doped Aluminas (SDAs) calcined in the range of 700–1200 °C with Si/Al Ratios of 5, 15, 27 wt% was determined using temperature-programmed desorption of ammonia (ammonia-TPD). 27 Al solid state MAS NMR (Al SS MAS NMR) was used to measure the intrinsic Lewis acid site concentRation, and FTIR was also used as a separate measure of the Bronsted and Lewis acid site concentRation. Results indicate that removing hydroxyl groups in the form of water molecules through calcination result in a lower concentRation of Bronsted acid sites. Calcination at higher temperature also results in the transformation of unsaturated 5-coordinated aluminum (a strong Lewis acid) to higher concentRations of 6 and 4-coordinated aluminum in 5, 15 and 27% silica-doped Alumina samples. Therefore, the total acid site concentRation (Bronsted and Lewis sites) decreases by increasing the calcination temperature. In addition, the data show that increasing the silica/Alumina Ratio increases both the Bronsted and Lewis acid site concentRations. Based on these results, the acid site concentRations can be controlled by altering the Si/Al Ratio and calcination temperature while maintaining high surface areas, large pore volumes, and large pore diameters.
Shilun Qiu - One of the best experts on this subject based on the ideXlab platform.
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fast synthesis of submicron aluminosilicate low silica Alumina Ratio zeolites under solventless microwave radiation
RSC Advances, 2015Co-Authors: Shangjing Zeng, Runwei Wang, Yongcun Zou, Zhongtao Zhang, Shilun QiuAbstract:A promising strategy for synthesis zeolites has been reported in this paper. The method combines the advantages of both microwave heating and solventless synthesis. This method can generate zeolites under atmospheric pressure and is safe, highly efficient and environmentally benign.
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Fast synthesis of submicron aluminosilicate (low silica/Alumina Ratio) zeolites under solventless microwave radiation
RSC Advances, 2015Co-Authors: Shangjing Zeng, Runwei Wang, Yongcun Zou, Fu Jingru, Zhongtao Zhang, Shilun QiuAbstract:A promising strategy for synthesis zeolites has been reported in this paper. The method combines the advantages of both microwave heating and solventless synthesis. This method can generate zeolites under atmospheric pressure and is safe, highly efficient and environmentally benign.
Maryam Khosravi Mardkhe - One of the best experts on this subject based on the ideXlab platform.
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acid site properties of thermally stable silica doped Alumina as a function of silica Alumina Ratio and calcination temperature
Applied Catalysis A-general, 2014Co-Authors: Maryam Khosravi Mardkhe, Kamyar Keyvanloo, Calvin H. Bartholomew, William C. Hecker, Todd M. Alam, Brian F. WoodfieldAbstract:Abstract Acid site properties of silica-doped Aluminas prepared by a simple solvent deficient hydrolysis of the alkoxides was investigated. The total acid concentRation (Bronsted and Lewis sites) of silica-doped Aluminas (SDAs) calcined in the range of 700–1200 °C with Si/Al Ratios of 5, 15, 27 wt% was determined using temperature-programmed desorption of ammonia (ammonia-TPD). 27 Al solid state MAS NMR (Al SS MAS NMR) was used to measure the intrinsic Lewis acid site concentRation, and FTIR was also used as a separate measure of the Bronsted and Lewis acid site concentRation. Results indicate that removing hydroxyl groups in the form of water molecules through calcination result in a lower concentRation of Bronsted acid sites. Calcination at higher temperature also results in the transformation of unsaturated 5-coordinated aluminum (a strong Lewis acid) to higher concentRations of 6 and 4-coordinated aluminum in 5, 15 and 27% silica-doped Alumina samples. Therefore, the total acid site concentRation (Bronsted and Lewis sites) decreases by increasing the calcination temperature. In addition, the data show that increasing the silica/Alumina Ratio increases both the Bronsted and Lewis acid site concentRations. Based on these results, the acid site concentRations can be controlled by altering the Si/Al Ratio and calcination temperature while maintaining high surface areas, large pore volumes, and large pore diameters.
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Acid site properties of thermally stable, silica-doped Alumina as a function of silica/Alumina Ratio and calcination temperature
Applied Catalysis A: General, 2014Co-Authors: Maryam Khosravi Mardkhe, Kamyar Keyvanloo, Calvin H. Bartholomew, William C. Hecker, Todd M. Alam, Brian F. WoodfieldAbstract:Abstract Acid site properties of silica-doped Aluminas prepared by a simple solvent deficient hydrolysis of the alkoxides was investigated. The total acid concentRation (Bronsted and Lewis sites) of silica-doped Aluminas (SDAs) calcined in the range of 700–1200 °C with Si/Al Ratios of 5, 15, 27 wt% was determined using temperature-programmed desorption of ammonia (ammonia-TPD). 27 Al solid state MAS NMR (Al SS MAS NMR) was used to measure the intrinsic Lewis acid site concentRation, and FTIR was also used as a separate measure of the Bronsted and Lewis acid site concentRation. Results indicate that removing hydroxyl groups in the form of water molecules through calcination result in a lower concentRation of Bronsted acid sites. Calcination at higher temperature also results in the transformation of unsaturated 5-coordinated aluminum (a strong Lewis acid) to higher concentRations of 6 and 4-coordinated aluminum in 5, 15 and 27% silica-doped Alumina samples. Therefore, the total acid site concentRation (Bronsted and Lewis sites) decreases by increasing the calcination temperature. In addition, the data show that increasing the silica/Alumina Ratio increases both the Bronsted and Lewis acid site concentRations. Based on these results, the acid site concentRations can be controlled by altering the Si/Al Ratio and calcination temperature while maintaining high surface areas, large pore volumes, and large pore diameters.
Shangjing Zeng - One of the best experts on this subject based on the ideXlab platform.
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fast synthesis of submicron aluminosilicate low silica Alumina Ratio zeolites under solventless microwave radiation
RSC Advances, 2015Co-Authors: Shangjing Zeng, Runwei Wang, Yongcun Zou, Zhongtao Zhang, Shilun QiuAbstract:A promising strategy for synthesis zeolites has been reported in this paper. The method combines the advantages of both microwave heating and solventless synthesis. This method can generate zeolites under atmospheric pressure and is safe, highly efficient and environmentally benign.
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Fast synthesis of submicron aluminosilicate (low silica/Alumina Ratio) zeolites under solventless microwave radiation
RSC Advances, 2015Co-Authors: Shangjing Zeng, Runwei Wang, Yongcun Zou, Fu Jingru, Zhongtao Zhang, Shilun QiuAbstract:A promising strategy for synthesis zeolites has been reported in this paper. The method combines the advantages of both microwave heating and solventless synthesis. This method can generate zeolites under atmospheric pressure and is safe, highly efficient and environmentally benign.
P. E. Strizhak - One of the best experts on this subject based on the ideXlab platform.
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Effect of H-ZSM-5/Al_2O_3 Catalyst Acidity on the Conversion of Methanol
Theoretical and Experimental Chemistry, 2017Co-Authors: A. A. Zhokh, A. I. Trypolskyi, P. E. StrizhakAbstract:The conversion of methanol on H-ZSM-5/Al_2O_3 catalyst with a 1/1 zeolite/Alumina Ratio by mass was studied. The presence of acid sites of different strength on the H-ZSM-5/Al_2O_3 catalyst was established by the NH_3-TPD method. It was found that increasing the reaction temperature leads to increase of the degree of conversion of the methanol and the yield of the olefin, while the yield of dimethyl ether passes through a maximum. The obtained results are explained in terms of a proposed kinetic scheme of the process, according to which the dimethyl ether and hydrocarbons are formed on different types of acid sites.
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Two-Path Conversion of Methanol to Olefins on H-ZSM-5/Al_2O_3 Catalyst
Theoretical and Experimental Chemistry, 2017Co-Authors: A. A. Zhokh, A. I. Trypolskyi, P. E. StrizhakAbstract:It was shown that during the transformation of methanol on H-ZSM-5/Al_2O_3 catalyst with zeolite/Alumina Ratio 1/1 increase of the methanol partial pressure leads to an extremal increase in the formation rate of ethylene, propylene, and butylene while the formation rate of dimethyl ether increases monotonically. The yield of the olefins increases with increase of temperature on account of increase in the degree of transformation of the methanol while the dimethyl ether yield passes through a maximum. The results are explained by a kinetic scheme according to which the dimethyl ether and olefin formation follows different routes.
