The problem of water and sulfur poisoning in flue gas atmosphere remains a significant obstacle for low-temperature deNO_(x) catalysts.This study investigated the sulfation mechanism of the CoMn_(2)O_(4)/CeTiO_(x)(CMC...The problem of water and sulfur poisoning in flue gas atmosphere remains a significant obstacle for low-temperature deNO_(x) catalysts.This study investigated the sulfation mechanism of the CoMn_(2)O_(4)/CeTiO_(x)(CMCT)catalyst during the selective catalytic reduction of NO_(x) with NH3 under conditions containing H2O and SO_(2) at 150℃.Employing a comprehensive suite of time-resolved analysis and characterization techniques,the evolution of sulfate species was systematically categorized into three stages:initial rapid surface sulfate accumulation,the transformation of surface sulfates to bulk metal sulfates,and partial sulfates decomposition after the removal of H2O and SO_(2).These findings indicate that bulk metal sulfates irreversibly deactivate the catalyst by distorting active component lattices and consuming oxygen vacancies,whereas surface sulfates(including ammonium sulfates and surface-coordinated metal sulfates)cause reversible performance loss through decomposition.Furthermore,the competitive adsorption of H2O and SO_(2) significantly influences the catalytic efficiency,with H2O suppressing SO_(2) adsorption while simultaneously enhancing the formation of Brönsted acid sites.This research underscores the critical role of sulfate dynamics on catalyst performance,revealing the enhanced SO_(2) resistance of the Eley-Rideal mechanism facilitated by the Ce-Ti support relative to the Langmuir-Hinshelwood pathway.Collectively,the study unravels the complex interplay of sulfate dynamics influencing catalyst performance and provides potential approaches to mitigate deactivation in demanding atmospheric conditions.展开更多
Sulfuric acid immobilized on silica gel is designed as a very useful catalyst for synthesis of 2,3-unsaturated glycopyranosides. This handy,metal-free,environment friendly transformation provides high yields andα-ste...Sulfuric acid immobilized on silica gel is designed as a very useful catalyst for synthesis of 2,3-unsaturated glycopyranosides. This handy,metal-free,environment friendly transformation provides high yields andα-stereoselectivities in a very few amount （0.02 eq.） of catalyst and in short reaction times（10 min）.展开更多
A series of SO 2- 4/TiO 2 SiO 2 catalysts with different mass fractions of SiO 2 were prepared by sol gel method. The effect of adding SiO 2 on the crystal structure, specific surface area, oxygen adsorption, and acid...A series of SO 2- 4/TiO 2 SiO 2 catalysts with different mass fractions of SiO 2 were prepared by sol gel method. The effect of adding SiO 2 on the crystal structure, specific surface area, oxygen adsorption, and acidity of SO 2- 4/TiO 2 catalyst and its photocatalytic property for degradation of bromomethane was studied. The results showed that the specific surface area and amount of oxygen adsorption of catalyst were increased by addition of SiO 2, leading to the obvious increase on photocatalytic activity of SO 2- 4/TiO 2 SiO 2 catalysts and mineralization ratio of bromomethane. Comparing with SO 2- 4/TiO 2, the acidic strength and anti moisture ability of SO 2- 4/TiO 2 SiO 2 catalyst were decreased.展开更多
[ Objective] The aim was to study pretreatment of ultrasound enhancing dilute H2SO4 on cellulase activity of corn straw liquid fermentation and explore the pretretment＇ s optimal conditions. [ Method ] By using ortho...[ Objective] The aim was to study pretreatment of ultrasound enhancing dilute H2SO4 on cellulase activity of corn straw liquid fermentation and explore the pretretment＇ s optimal conditions. [ Method ] By using orthogonal test, the pretretment of ultrasound enhancing dilute H2SO4 on corn straw was studied, then straw was fermented as the sole carbon source. Finally, the cellulase activity in extracellular fermentation broth was determined. [Result] The results showed that cellulase activity in extracellular broth was greatest under the conditions of acid bath time 3 h, acid concentration 3.5%, ultrasonic power 150 W, and ultrasonic time 5 h. They were FPA 15.82 U/ml, Cx 39.9 U/ml, 13-Giu 55.94 U/ml respectively. [ Conclusion] Under the above conditions, extracellular cellulase production has a high stability.展开更多
文摘The problem of water and sulfur poisoning in flue gas atmosphere remains a significant obstacle for low-temperature deNO_(x) catalysts.This study investigated the sulfation mechanism of the CoMn_(2)O_(4)/CeTiO_(x)(CMCT)catalyst during the selective catalytic reduction of NO_(x) with NH3 under conditions containing H2O and SO_(2) at 150℃.Employing a comprehensive suite of time-resolved analysis and characterization techniques,the evolution of sulfate species was systematically categorized into three stages:initial rapid surface sulfate accumulation,the transformation of surface sulfates to bulk metal sulfates,and partial sulfates decomposition after the removal of H2O and SO_(2).These findings indicate that bulk metal sulfates irreversibly deactivate the catalyst by distorting active component lattices and consuming oxygen vacancies,whereas surface sulfates(including ammonium sulfates and surface-coordinated metal sulfates)cause reversible performance loss through decomposition.Furthermore,the competitive adsorption of H2O and SO_(2) significantly influences the catalytic efficiency,with H2O suppressing SO_(2) adsorption while simultaneously enhancing the formation of Brönsted acid sites.This research underscores the critical role of sulfate dynamics on catalyst performance,revealing the enhanced SO_(2) resistance of the Eley-Rideal mechanism facilitated by the Ce-Ti support relative to the Langmuir-Hinshelwood pathway.Collectively,the study unravels the complex interplay of sulfate dynamics influencing catalyst performance and provides potential approaches to mitigate deactivation in demanding atmospheric conditions.
基金The project was supported by Shanghai Rising-Star Program(No.06QA14018)University Students Innovative Activities Project of Shanghai Municipal Education Commission(No.KY2008-09S)
文摘Sulfuric acid immobilized on silica gel is designed as a very useful catalyst for synthesis of 2,3-unsaturated glycopyranosides. This handy,metal-free,environment friendly transformation provides high yields andα-stereoselectivities in a very few amount （0.02 eq.） of catalyst and in short reaction times（10 min）.
文摘A series of SO 2- 4/TiO 2 SiO 2 catalysts with different mass fractions of SiO 2 were prepared by sol gel method. The effect of adding SiO 2 on the crystal structure, specific surface area, oxygen adsorption, and acidity of SO 2- 4/TiO 2 catalyst and its photocatalytic property for degradation of bromomethane was studied. The results showed that the specific surface area and amount of oxygen adsorption of catalyst were increased by addition of SiO 2, leading to the obvious increase on photocatalytic activity of SO 2- 4/TiO 2 SiO 2 catalysts and mineralization ratio of bromomethane. Comparing with SO 2- 4/TiO 2, the acidic strength and anti moisture ability of SO 2- 4/TiO 2 SiO 2 catalyst were decreased.
基金Supported by the National Key Technology R&D Program during the11~(th)five-year Plan(2007BAD34B03)the Important Project of Ministryof Education(107127)Scientific Research Foundation ofHefei University of Technology(113-036404)~~
文摘[ Objective] The aim was to study pretreatment of ultrasound enhancing dilute H2SO4 on cellulase activity of corn straw liquid fermentation and explore the pretretment＇ s optimal conditions. [ Method ] By using orthogonal test, the pretretment of ultrasound enhancing dilute H2SO4 on corn straw was studied, then straw was fermented as the sole carbon source. Finally, the cellulase activity in extracellular fermentation broth was determined. [Result] The results showed that cellulase activity in extracellular broth was greatest under the conditions of acid bath time 3 h, acid concentration 3.5%, ultrasonic power 150 W, and ultrasonic time 5 h. They were FPA 15.82 U/ml, Cx 39.9 U/ml, 13-Giu 55.94 U/ml respectively. [ Conclusion] Under the above conditions, extracellular cellulase production has a high stability.
