The Experts below are selected from a list of 7941 Experts worldwide ranked by ideXlab platform
Yu Liang - One of the best experts on this subject based on the ideXlab platform.
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sustainable production of acrolein catalytic performance of hydrated tantalum oxides for gas phase dehydration of glycerol
Green Chemistry, 2013Co-Authors: Lizhi Tao, Bo Yan, Yu LiangAbstract:A series of tantalum oxide samples (Ta2O5-T) were prepared by varying the calcination temperature T in the range of 110–700 °C of a highly hydrated precursor (Ta2O5·2.1H2O), which was obtained from a hetero-phase reaction between tantalum pentachloride and aqueous ammonia. These Ta2O5-T samples were characterized by TG/DTA, XPS, nitrogen adsorption, XRD, and UV-Raman, and were employed to catalyze the gas-phase dehydration of glycerol (GL) to produce acrolein (AC) at around 315 °C. n-Butylamine titration using Hammett indicators, NH3- and CO2-TPD, and IR of adsorbed pyridine were measured to assess the surface acid–base properties of the catalysts. The Ta2O5-350 catalyst, which was in a hydrated amorphous state and showed no basicity but a maximum strong Acidity at −8.2 < H0 ≤ −3.0 (H0 being the Hammett Acidity Function) prior to the reaction, was identified among all Ta2O5-T samples as the best performing catalyst in terms of AC selectivity and GL consumption rate. The AC selectivity increased with increasing the fractional strong Acidity at −8.2 < H0 ≤ −3.0 but the catalytic GL consumption rate increased with increasing the number of strong acid sites on the catalyst prior to the reaction. The partly (Ta2O5-600) and fully (Ta2O5-700) crystallized samples showed almost no strong Acidity but they exhibited some basicity in the CO2-TPD experiments; their much lower AC selectivity (<40 mol%) as compared with that on Ta2O5-350 (75 mol%) indicated that surface basicity was detrimental to the AC selectivity. The best performing Ta2O5-350 catalyst also showed after activation in the initial hours of the reaction a good catalytic stability in long term reactions, regardless of the reaction temperature (305–340 °C) and GHSVGL (80–400 h−1).
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sustainable production of acrolein gas phase dehydration of glycerol over nb2o5 catalyst
Journal of Catalysis, 2007Co-Authors: Songhai Chai, Yu Liang, Haopeng Wang, Boqing XuAbstract:Gas-phase dehydration of glycerol to produce acrolein was investigated at 315 °C over Nb2O5 catalysts calcined in the temperature range of 350–700 °C. The catalysts were characterized by nitrogen physisorption, TG-DTA, XRD, and n-butylamine titration using Hammett indicators to gain insight into the effect of calcination temperature on catalyst texture, crystal structure, and Acidity. Calcination at 350 and 400 °C produced amorphous Nb2O5 catalysts that exhibit significantly higher fractions of strong acid sites at −8.2⩽H0⩽−3.0−8.2⩽H0⩽−3.0 (H0H0 being the Hammett Acidity Function) than the crystallized Nb2O5 samples obtained by calcination at or above 500 °C. Glycerol conversion and acrolein selectivity of the Nb2O5 catalysts were dependent of the fraction of strong acid sites (−8.2⩽H0⩽−3.0−8.2⩽H0⩽−3.0). The amorphous catalyst prepared by the calcination at 400 °C, having the highest fraction of acid sites at −8.2⩽H0⩽−3.0−8.2⩽H0⩽−3.0, showed the highest mass specific activity and acrolein selectivity (51 mol%). The other samples, having a higher fraction of either stronger (H0⩽−8.2H0⩽−8.2) or weaker acid sites (−3.0⩽H0⩽6.8−3.0⩽H0⩽6.8), were less effective for glycerol dehydration and formation of the desired acrolein.
Boqing Xu - One of the best experts on this subject based on the ideXlab platform.
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sustainable production of acrolein gas phase dehydration of glycerol over nb2o5 catalyst
Journal of Catalysis, 2007Co-Authors: Songhai Chai, Yu Liang, Haopeng Wang, Boqing XuAbstract:Gas-phase dehydration of glycerol to produce acrolein was investigated at 315 °C over Nb2O5 catalysts calcined in the temperature range of 350–700 °C. The catalysts were characterized by nitrogen physisorption, TG-DTA, XRD, and n-butylamine titration using Hammett indicators to gain insight into the effect of calcination temperature on catalyst texture, crystal structure, and Acidity. Calcination at 350 and 400 °C produced amorphous Nb2O5 catalysts that exhibit significantly higher fractions of strong acid sites at −8.2⩽H0⩽−3.0−8.2⩽H0⩽−3.0 (H0H0 being the Hammett Acidity Function) than the crystallized Nb2O5 samples obtained by calcination at or above 500 °C. Glycerol conversion and acrolein selectivity of the Nb2O5 catalysts were dependent of the fraction of strong acid sites (−8.2⩽H0⩽−3.0−8.2⩽H0⩽−3.0). The amorphous catalyst prepared by the calcination at 400 °C, having the highest fraction of acid sites at −8.2⩽H0⩽−3.0−8.2⩽H0⩽−3.0, showed the highest mass specific activity and acrolein selectivity (51 mol%). The other samples, having a higher fraction of either stronger (H0⩽−8.2H0⩽−8.2) or weaker acid sites (−3.0⩽H0⩽6.8−3.0⩽H0⩽6.8), were less effective for glycerol dehydration and formation of the desired acrolein.
Songhai Chai - One of the best experts on this subject based on the ideXlab platform.
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sustainable production of acrolein gas phase dehydration of glycerol over nb2o5 catalyst
Journal of Catalysis, 2007Co-Authors: Songhai Chai, Yu Liang, Haopeng Wang, Boqing XuAbstract:Gas-phase dehydration of glycerol to produce acrolein was investigated at 315 °C over Nb2O5 catalysts calcined in the temperature range of 350–700 °C. The catalysts were characterized by nitrogen physisorption, TG-DTA, XRD, and n-butylamine titration using Hammett indicators to gain insight into the effect of calcination temperature on catalyst texture, crystal structure, and Acidity. Calcination at 350 and 400 °C produced amorphous Nb2O5 catalysts that exhibit significantly higher fractions of strong acid sites at −8.2⩽H0⩽−3.0−8.2⩽H0⩽−3.0 (H0H0 being the Hammett Acidity Function) than the crystallized Nb2O5 samples obtained by calcination at or above 500 °C. Glycerol conversion and acrolein selectivity of the Nb2O5 catalysts were dependent of the fraction of strong acid sites (−8.2⩽H0⩽−3.0−8.2⩽H0⩽−3.0). The amorphous catalyst prepared by the calcination at 400 °C, having the highest fraction of acid sites at −8.2⩽H0⩽−3.0−8.2⩽H0⩽−3.0, showed the highest mass specific activity and acrolein selectivity (51 mol%). The other samples, having a higher fraction of either stronger (H0⩽−8.2H0⩽−8.2) or weaker acid sites (−3.0⩽H0⩽6.8−3.0⩽H0⩽6.8), were less effective for glycerol dehydration and formation of the desired acrolein.
Lizhi Tao - One of the best experts on this subject based on the ideXlab platform.
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sustainable production of acrolein catalytic performance of hydrated tantalum oxides for gas phase dehydration of glycerol
Green Chemistry, 2013Co-Authors: Lizhi Tao, Bo Yan, Yu LiangAbstract:A series of tantalum oxide samples (Ta2O5-T) were prepared by varying the calcination temperature T in the range of 110–700 °C of a highly hydrated precursor (Ta2O5·2.1H2O), which was obtained from a hetero-phase reaction between tantalum pentachloride and aqueous ammonia. These Ta2O5-T samples were characterized by TG/DTA, XPS, nitrogen adsorption, XRD, and UV-Raman, and were employed to catalyze the gas-phase dehydration of glycerol (GL) to produce acrolein (AC) at around 315 °C. n-Butylamine titration using Hammett indicators, NH3- and CO2-TPD, and IR of adsorbed pyridine were measured to assess the surface acid–base properties of the catalysts. The Ta2O5-350 catalyst, which was in a hydrated amorphous state and showed no basicity but a maximum strong Acidity at −8.2 < H0 ≤ −3.0 (H0 being the Hammett Acidity Function) prior to the reaction, was identified among all Ta2O5-T samples as the best performing catalyst in terms of AC selectivity and GL consumption rate. The AC selectivity increased with increasing the fractional strong Acidity at −8.2 < H0 ≤ −3.0 but the catalytic GL consumption rate increased with increasing the number of strong acid sites on the catalyst prior to the reaction. The partly (Ta2O5-600) and fully (Ta2O5-700) crystallized samples showed almost no strong Acidity but they exhibited some basicity in the CO2-TPD experiments; their much lower AC selectivity (<40 mol%) as compared with that on Ta2O5-350 (75 mol%) indicated that surface basicity was detrimental to the AC selectivity. The best performing Ta2O5-350 catalyst also showed after activation in the initial hours of the reaction a good catalytic stability in long term reactions, regardless of the reaction temperature (305–340 °C) and GHSVGL (80–400 h−1).
Haopeng Wang - One of the best experts on this subject based on the ideXlab platform.
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sustainable production of acrolein gas phase dehydration of glycerol over nb2o5 catalyst
Journal of Catalysis, 2007Co-Authors: Songhai Chai, Yu Liang, Haopeng Wang, Boqing XuAbstract:Gas-phase dehydration of glycerol to produce acrolein was investigated at 315 °C over Nb2O5 catalysts calcined in the temperature range of 350–700 °C. The catalysts were characterized by nitrogen physisorption, TG-DTA, XRD, and n-butylamine titration using Hammett indicators to gain insight into the effect of calcination temperature on catalyst texture, crystal structure, and Acidity. Calcination at 350 and 400 °C produced amorphous Nb2O5 catalysts that exhibit significantly higher fractions of strong acid sites at −8.2⩽H0⩽−3.0−8.2⩽H0⩽−3.0 (H0H0 being the Hammett Acidity Function) than the crystallized Nb2O5 samples obtained by calcination at or above 500 °C. Glycerol conversion and acrolein selectivity of the Nb2O5 catalysts were dependent of the fraction of strong acid sites (−8.2⩽H0⩽−3.0−8.2⩽H0⩽−3.0). The amorphous catalyst prepared by the calcination at 400 °C, having the highest fraction of acid sites at −8.2⩽H0⩽−3.0−8.2⩽H0⩽−3.0, showed the highest mass specific activity and acrolein selectivity (51 mol%). The other samples, having a higher fraction of either stronger (H0⩽−8.2H0⩽−8.2) or weaker acid sites (−3.0⩽H0⩽6.8−3.0⩽H0⩽6.8), were less effective for glycerol dehydration and formation of the desired acrolein.
