Bi/Bi_(2)Fe_(4)O_(9)nanocomposites consisting of Bi_(2)Fe_(4)O_(9)nanosheets decorated with Bi nanodots were synthesized by a hydrothermal method.The formation of Bi nanodots on the Bi_(2)Fe_(4)O_(9)nanosheet surfaces...Bi/Bi_(2)Fe_(4)O_(9)nanocomposites consisting of Bi_(2)Fe_(4)O_(9)nanosheets decorated with Bi nanodots were synthesized by a hydrothermal method.The formation of Bi nanodots on the Bi_(2)Fe_(4)O_(9)nanosheet surfaces was attributed to the reducibility of 2-methoxyethanol in the precursor solution.Comparative photocatalytic evaluation reveals that the Bi/Bi_(2)Fe_(4)O_(9)nanocomposites significantly enhance the degradation efficiency(99.0%)of bisphenol A compared with Bi_(2)Fe_(4)O_(9)nanosheets(64.2%)under 120 min simulated solar irradiation.This remarkable enhancement can be attributed to the established Bi/Bi_(2)Fe_(4)O_(9)heterojunction structure,which effectively facilitates the separation of photogenerated electron-hole pairs and accelerates interfacial charge transfer between the metallic Bi nanodots and semiconductor Bi_(2)Fe_(4)O_(9)nanosheets.The synergistic effects arising from this unique architecture ultimately lead to superior photocatalytic performance.展开更多
Zn-based thermal charging devices,utilizing the synergistic effect of ion thermoextraction and thermodiffusion,are able to efficiently convert thermal energy into electrical energy and storage in the devices,making th...Zn-based thermal charging devices,utilizing the synergistic effect of ion thermoextraction and thermodiffusion,are able to efficiently convert thermal energy into electrical energy and storage in the devices,making them a highly promising technology for low-grade heat recovery and utilization.However,the low output power density and energy conversion efficiency resulted by the slow diffusion kinetics of Zn^(2+)hinder their development.Herein,we present a highperformance thermal charging cell design using Zn^(2+)/NH_(4)^(+)hybrid ion electrolyte,which not only maintains the high output voltage of the Zn-based thermoelectric system,but also significantly enhances the output power density due to the fast diffusion kinetics of NH_(4)^(+).Based on this strategy,the thermal charging cell displays a high thermopower of 12.5 mV K^(-1)and an excellent normalized power density of 19.6 mW m^(-2)K^(-2)at a temperature difference of 35 K.The Carnot-relative efficiency is as high as 12.74%.Moreover,it can operate continuously for over 72 h when the temperature difference persists,achieving a balance between thermoelectric conversion and output.This work provides a simple and effective strategy for the design of high-performance thermal charging cells for low-grade heat conversion and utilization.展开更多
Background:Terpinen-4-ol(T4O),a key constituent of tea tree essential oil and various aromatic plants,has shown promising antiproliferative and pro-apoptotic effects in melanoma and other cancer types.However,its effi...Background:Terpinen-4-ol(T4O),a key constituent of tea tree essential oil and various aromatic plants,has shown promising antiproliferative and pro-apoptotic effects in melanoma and other cancer types.However,its efficacy against cutaneous squamous cell carcinoma(cSCC)remains unclear.Thus,in this study,we investigated the in vivo and in vitro effects of T4O on cSCC cell lines and preliminarily explored its impacting pathways.Methods:Using CCK8 and assay colony formation,we assessed the viability of cSCC A431,SCL-1,and COLO-16 cells treated with T40 at varying concentrations(0,1,2,and 4μM).Flow cytometry was employed to evaluate T4O’s effect on cSCC cell’s cycle progression and apoptosis induction.Additionally,western blotting was utilized to examine the expression intensities of N-cadherin and E-cadherin,two indicative markers of the epithelial-mesenchymal transition(EMT)pathway.T4O’s in vivo effect on inhibiting tumor progression was evaluated on an established xenograft tumor model.Then,the molecular mechanisms of T4O’s antitumor effect were explored by an integrated genome-wide transcriptomics and proteomics study on cSCC A431c cells.Finally,calpain-2’s potential mediator role in T4O’s anti-tumor mechanism was investigated in calpain-2 knockdown cell lines prepared via siRNA transfection.Result:It’s demonstrated that T4O treatment inhibited cSCC proliferation,clonogenicity,migration,and invasion while inducing apoptosis and suppressing the EMT pathway.T4O administration also inhibited cSCC tumorigenesis in the xenograft tumor model.RNA-sequencing and iTRAQ analysis detected significant upregulation of calpain-2 expression in T4O-treated cSCC cells.Western blotting confirmed that T4O significantly increased calpain-2 expression and promoted proteolytic cleavage ofβ-catenin and caspase-12,two calpain-2 target proteins.Importantly,siRNA-mediated calpain-2 knockdown relieved T4O’s suppressive effect on cSCC cell proliferation and motility.Mechanistically,T4O upregulates calpain-2 expression and promotes the cleavage ofβ-catenin and caspase-12,with siRNA-mediated calpain-2 knockdown mitigating T4O’s suppressive effects.Conclusion:These findings suggest that T4O’s antitumor activity in cSCC is mediated through the upregulation of calpain-2 expression and subsequent modulation ofβ-catenin and caspase-12.展开更多
To construct high-performance aqueous ammonium-ion full batteries,(NH_(4))_(2)V_(6)O_(16)·1.5H_(2)O(NVO)nanoribbon cathodes were prepared by pH-regulated hydrothermal synthesis.Anodes were prepared by growing the...To construct high-performance aqueous ammonium-ion full batteries,(NH_(4))_(2)V_(6)O_(16)·1.5H_(2)O(NVO)nanoribbon cathodes were prepared by pH-regulated hydrothermal synthesis.Anodes were prepared by growing the active material polyaniline(PANI)on carbon cloth.The assembled NVO//PANI full cells exhibit a reversible capacity of 109.5 mA·h/g at a current density of 1.0 A/g and a high energy density of 23 W·h/kg.The ammonium-ion intercalation/extraction mechanism is primarily governed by the pseudocapacitance behavior.These results indicate that NVO is a potential candidate as a cathode material for aqueous ammonium-ion batteries.展开更多
Peroxymonosulfate(PMS)is commonly used in advanced oxidation processes to degrade organic pollutants in wastewater.In this work,to obtain better PMS activation efficiency,Bi_(4)O_(5)Br_(2)/BCZT(BBT)piezoelectric photo...Peroxymonosulfate(PMS)is commonly used in advanced oxidation processes to degrade organic pollutants in wastewater.In this work,to obtain better PMS activation efficiency,Bi_(4)O_(5)Br_(2)/BCZT(BBT)piezoelectric photocatalyst was designed.Abundant active radicals produced by BBT under visible light irradiation and ultrasonic vibration were used to activate PMS,thereby achieving rapid degradation of high concentration pollutants.With the introduction of BCZT,the catalyst has a strong internal electric field and three-dimensional lamellar structure,which promotes the separation and transfer of electrons and holes.It is worth noting that under optimal reaction conditions,the degradation rate of ARB reached 93%by BBT15 within 10 min.The catalytic experiment combined with the piezoelectric performance test results revealed the key role of piezoelectric photocatalytic reaction in PMS activation.This provides an important prospect for PMS to effectively deal with the degradation of high concentrations of organic pollutants.展开更多
Chemical vapor deposition is the predominant method to prepare MgAl_(2)O_(4)fibers.However,it faces several challenges,including exorbitantly high reaction temperatures,substantial production costs,and relatively low ...Chemical vapor deposition is the predominant method to prepare MgAl_(2)O_(4)fibers.However,it faces several challenges,including exorbitantly high reaction temperatures,substantial production costs,and relatively low yields.In this study,porous MgAl_(2)O_(4)fibers were fabricated through a solid-state reaction method,utilizing MgSO_(4)·5Mg(OH)_(2)·3H_(2)O whiskers as templates,mixed with either aluminum sol orα-Al_(2)O_(3)micropowder.The impact of various parameters on the synthesis of porous MgAl_(2)O_(4)fibres was systematically investigated,including the heat treatment temperature(1000,1100 and 1300℃),the holding time(3 and 10 h)and the aluminum source(aluminum sol orα-Al_(2)O_(3)micropowder).The results reveal that:(1)in comparison with fibers synthesized usingα-Al_(2)O_(3)as the aluminum source,those prepared with aluminum sol exhibit a significantly higher generation amount of MgAl_(2)O_(4);(2)as the heat treatment temperature increases,Al_(2)O_(3)gradually reacts with MgO,continuously increasing the formation amount of porous MgAl_(2)O_(4)with small and uniformly distributed nanopores,and the synthesized porous MgAl_(2)O_(4)fibres have small and uniform nanopores;(3)the optimal synthesis process involves using aluminum sol as the aluminum source and firing at 1300℃ for 3 h.展开更多
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
Nano-MnFe2O4 particles were synthesized by co-precipitation phase inversion method and low-temperature combustion method respectively, using MnCl2, FeCl3, Mn（NO3）2, Fe（NO3）3, NaOH and C6H8O7. X-ray diffraction （...Nano-MnFe2O4 particles were synthesized by co-precipitation phase inversion method and low-temperature combustion method respectively, using MnCl2, FeCl3, Mn（NO3）2, Fe（NO3）3, NaOH and C6H8O7. X-ray diffraction （XRD）, transmission electron microscope （TEM）, Fourier transform infrared spectroscopy （FT-IR）, thermogravim-etry-differential thermal analysis （TG-DTA） and differential scanning calorimetry （DSC） were used to characterize the structure, morphology, thermal stability of MnFe2O4 and its catalytic performance to ammonium perchlorate. Results showed that single-phased and uniform spinel MnFe2O4 was obtained. The average particle size was about 30 and 20 nm. The infrared absorption peaks appeared at about 420 and 574 cm-1, and the particles were stable below 524 ℃. Using the two prepared catalysts, the higher thermal decomposition temperature of ammonium perchlorate was decreased by 77.3 and 84.9 ℃ respectively, while the apparent decomposition heat was increased by 482.5 and 574.3 J？g？1. The catalytic mechanism could be explained by the favorable electron transfer space provided by outer d orbit of transition metal ions and the high specific surface absorption effect of MnFe2O4 particles.展开更多
Chemical looping combustion （CLC） of coal has gained increasing attention as a novel combustion technology for its advantages in CO2 capture. Sulfur evolution from coal causes great harm from either the CLC operatio...Chemical looping combustion （CLC） of coal has gained increasing attention as a novel combustion technology for its advantages in CO2 capture. Sulfur evolution from coal causes great harm from either the CLC operational or environmental perspective. In this research, a combined MnFe2O4 oxygen carrier （OC） was synthesized and its reaction with a typical Chinese high sulfur coal, Liuzhi （LZ） bituminous coal, was performed in a thermogravimetric analyzer （TGA）-Fourier transform infrared （FT-IR） spectrometer. Evolution of sulfur species during reaction of LZ coal with MnFeaO40C was systematically investigated through experimental means combined with thermodynamic simulation. TGA-FTIR analysis of the LZ reaction with MnFe2O4 indicated MnFe2O4 exhibited the desired superior reactivity compared to the single reference oxides Mn304 or Fe203, and SO2 produced was mainly related to oxidization of H2S by MnFe2O4. Experimental analysis of the LZ coal reaction with MnFe2O4, including X-ray diffraction and X-ray photoelectron spectroscopy analysis, verified that the main reduced counterparts of MnFe2O4 were Fe304 and MnO, in good agreement with the related thermodynamic simulation. The obtained MnO was beneficial to stabilize the reduced MnFe2O4 and avoid serious sintering, although the oxygen in MnO was not fully utilized. Meanwhile, most sulfur present in LZ coal was converted to solid MnS during LZ reaction with MnFe2O4, which was further oxidized to MnSO4. Finally, the formation of both MnS and such manganese silicates as Mn2SiO4 and MnSiO3 should be addressed to ensure the full regeneration of the reduced MnFe2O4.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
基金Funded by the National Natural Science Foundation of China(No.50902108)。
文摘Bi/Bi_(2)Fe_(4)O_(9)nanocomposites consisting of Bi_(2)Fe_(4)O_(9)nanosheets decorated with Bi nanodots were synthesized by a hydrothermal method.The formation of Bi nanodots on the Bi_(2)Fe_(4)O_(9)nanosheet surfaces was attributed to the reducibility of 2-methoxyethanol in the precursor solution.Comparative photocatalytic evaluation reveals that the Bi/Bi_(2)Fe_(4)O_(9)nanocomposites significantly enhance the degradation efficiency(99.0%)of bisphenol A compared with Bi_(2)Fe_(4)O_(9)nanosheets(64.2%)under 120 min simulated solar irradiation.This remarkable enhancement can be attributed to the established Bi/Bi_(2)Fe_(4)O_(9)heterojunction structure,which effectively facilitates the separation of photogenerated electron-hole pairs and accelerates interfacial charge transfer between the metallic Bi nanodots and semiconductor Bi_(2)Fe_(4)O_(9)nanosheets.The synergistic effects arising from this unique architecture ultimately lead to superior photocatalytic performance.
基金supported by the Leading Edge Technology of Jiangsu Province(BK20222009-X.Z.,BK20202008-X.Z.)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)National Undergraduate Innovation Training Program of NUAA(202410287179Y).
文摘Zn-based thermal charging devices,utilizing the synergistic effect of ion thermoextraction and thermodiffusion,are able to efficiently convert thermal energy into electrical energy and storage in the devices,making them a highly promising technology for low-grade heat recovery and utilization.However,the low output power density and energy conversion efficiency resulted by the slow diffusion kinetics of Zn^(2+)hinder their development.Herein,we present a highperformance thermal charging cell design using Zn^(2+)/NH_(4)^(+)hybrid ion electrolyte,which not only maintains the high output voltage of the Zn-based thermoelectric system,but also significantly enhances the output power density due to the fast diffusion kinetics of NH_(4)^(+).Based on this strategy,the thermal charging cell displays a high thermopower of 12.5 mV K^(-1)and an excellent normalized power density of 19.6 mW m^(-2)K^(-2)at a temperature difference of 35 K.The Carnot-relative efficiency is as high as 12.74%.Moreover,it can operate continuously for over 72 h when the temperature difference persists,achieving a balance between thermoelectric conversion and output.This work provides a simple and effective strategy for the design of high-performance thermal charging cells for low-grade heat conversion and utilization.
基金supported by the Basic Research Program of the Guizhou Science Cooperation Foundation Project(Grant Number:ZK[2021]466)Guizhou Provincial Health Commission(Grant Number:gzwkj2022-062).
文摘Background:Terpinen-4-ol(T4O),a key constituent of tea tree essential oil and various aromatic plants,has shown promising antiproliferative and pro-apoptotic effects in melanoma and other cancer types.However,its efficacy against cutaneous squamous cell carcinoma(cSCC)remains unclear.Thus,in this study,we investigated the in vivo and in vitro effects of T4O on cSCC cell lines and preliminarily explored its impacting pathways.Methods:Using CCK8 and assay colony formation,we assessed the viability of cSCC A431,SCL-1,and COLO-16 cells treated with T40 at varying concentrations(0,1,2,and 4μM).Flow cytometry was employed to evaluate T4O’s effect on cSCC cell’s cycle progression and apoptosis induction.Additionally,western blotting was utilized to examine the expression intensities of N-cadherin and E-cadherin,two indicative markers of the epithelial-mesenchymal transition(EMT)pathway.T4O’s in vivo effect on inhibiting tumor progression was evaluated on an established xenograft tumor model.Then,the molecular mechanisms of T4O’s antitumor effect were explored by an integrated genome-wide transcriptomics and proteomics study on cSCC A431c cells.Finally,calpain-2’s potential mediator role in T4O’s anti-tumor mechanism was investigated in calpain-2 knockdown cell lines prepared via siRNA transfection.Result:It’s demonstrated that T4O treatment inhibited cSCC proliferation,clonogenicity,migration,and invasion while inducing apoptosis and suppressing the EMT pathway.T4O administration also inhibited cSCC tumorigenesis in the xenograft tumor model.RNA-sequencing and iTRAQ analysis detected significant upregulation of calpain-2 expression in T4O-treated cSCC cells.Western blotting confirmed that T4O significantly increased calpain-2 expression and promoted proteolytic cleavage ofβ-catenin and caspase-12,two calpain-2 target proteins.Importantly,siRNA-mediated calpain-2 knockdown relieved T4O’s suppressive effect on cSCC cell proliferation and motility.Mechanistically,T4O upregulates calpain-2 expression and promotes the cleavage ofβ-catenin and caspase-12,with siRNA-mediated calpain-2 knockdown mitigating T4O’s suppressive effects.Conclusion:These findings suggest that T4O’s antitumor activity in cSCC is mediated through the upregulation of calpain-2 expression and subsequent modulation ofβ-catenin and caspase-12.
基金supported by the National Natural Science Foundation of China(Nos.52171200,52371211)the Changsha Special Project,China(No.kh2301006)。
文摘To construct high-performance aqueous ammonium-ion full batteries,(NH_(4))_(2)V_(6)O_(16)·1.5H_(2)O(NVO)nanoribbon cathodes were prepared by pH-regulated hydrothermal synthesis.Anodes were prepared by growing the active material polyaniline(PANI)on carbon cloth.The assembled NVO//PANI full cells exhibit a reversible capacity of 109.5 mA·h/g at a current density of 1.0 A/g and a high energy density of 23 W·h/kg.The ammonium-ion intercalation/extraction mechanism is primarily governed by the pseudocapacitance behavior.These results indicate that NVO is a potential candidate as a cathode material for aqueous ammonium-ion batteries.
基金financially supported by the National Natural Science Foundation of China(No.51302061)Natural Science Foundation of Hebei Province(No.E2020201021 and E2023201019)+4 种基金Industry-University-Research Cooperation Major Projects of Shijiazhuang(No.241130477A)Research Innovation Team of College of Chemistry and Environmental Science of Hebei University(No.hxkytd2102)Industry-University-research Cooperation Project of Colleges and Universities in Hebei Province(No.CXZX2025016)Hebei Province Innovation Capability Enhancement Plan Project(No.22567620H)Bintuan Science and Technology Program(Nos.2020DB002 and 2022DB009)。
文摘Peroxymonosulfate(PMS)is commonly used in advanced oxidation processes to degrade organic pollutants in wastewater.In this work,to obtain better PMS activation efficiency,Bi_(4)O_(5)Br_(2)/BCZT(BBT)piezoelectric photocatalyst was designed.Abundant active radicals produced by BBT under visible light irradiation and ultrasonic vibration were used to activate PMS,thereby achieving rapid degradation of high concentration pollutants.With the introduction of BCZT,the catalyst has a strong internal electric field and three-dimensional lamellar structure,which promotes the separation and transfer of electrons and holes.It is worth noting that under optimal reaction conditions,the degradation rate of ARB reached 93%by BBT15 within 10 min.The catalytic experiment combined with the piezoelectric performance test results revealed the key role of piezoelectric photocatalytic reaction in PMS activation.This provides an important prospect for PMS to effectively deal with the degradation of high concentrations of organic pollutants.
文摘Chemical vapor deposition is the predominant method to prepare MgAl_(2)O_(4)fibers.However,it faces several challenges,including exorbitantly high reaction temperatures,substantial production costs,and relatively low yields.In this study,porous MgAl_(2)O_(4)fibers were fabricated through a solid-state reaction method,utilizing MgSO_(4)·5Mg(OH)_(2)·3H_(2)O whiskers as templates,mixed with either aluminum sol orα-Al_(2)O_(3)micropowder.The impact of various parameters on the synthesis of porous MgAl_(2)O_(4)fibres was systematically investigated,including the heat treatment temperature(1000,1100 and 1300℃),the holding time(3 and 10 h)and the aluminum source(aluminum sol orα-Al_(2)O_(3)micropowder).The results reveal that:(1)in comparison with fibers synthesized usingα-Al_(2)O_(3)as the aluminum source,those prepared with aluminum sol exhibit a significantly higher generation amount of MgAl_(2)O_(4);(2)as the heat treatment temperature increases,Al_(2)O_(3)gradually reacts with MgO,continuously increasing the formation amount of porous MgAl_(2)O_(4)with small and uniformly distributed nanopores,and the synthesized porous MgAl_(2)O_(4)fibres have small and uniform nanopores;(3)the optimal synthesis process involves using aluminum sol as the aluminum source and firing at 1300℃ for 3 h.
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Supported by the National Natural Science Foundation of China （90305008, 51077072）.
文摘Nano-MnFe2O4 particles were synthesized by co-precipitation phase inversion method and low-temperature combustion method respectively, using MnCl2, FeCl3, Mn（NO3）2, Fe（NO3）3, NaOH and C6H8O7. X-ray diffraction （XRD）, transmission electron microscope （TEM）, Fourier transform infrared spectroscopy （FT-IR）, thermogravim-etry-differential thermal analysis （TG-DTA） and differential scanning calorimetry （DSC） were used to characterize the structure, morphology, thermal stability of MnFe2O4 and its catalytic performance to ammonium perchlorate. Results showed that single-phased and uniform spinel MnFe2O4 was obtained. The average particle size was about 30 and 20 nm. The infrared absorption peaks appeared at about 420 and 574 cm-1, and the particles were stable below 524 ℃. Using the two prepared catalysts, the higher thermal decomposition temperature of ammonium perchlorate was decreased by 77.3 and 84.9 ℃ respectively, while the apparent decomposition heat was increased by 482.5 and 574.3 J？g？1. The catalytic mechanism could be explained by the favorable electron transfer space provided by outer d orbit of transition metal ions and the high specific surface absorption effect of MnFe2O4 particles.
基金supported by the National Natural Science Foundation of China(No.51276210,50906030,50936001)the financial grant of North China University of Water Conservancy and Electric Power(No.201012)the National Basic Research Program(973)of China(No.2011CB707301)
文摘Chemical looping combustion （CLC） of coal has gained increasing attention as a novel combustion technology for its advantages in CO2 capture. Sulfur evolution from coal causes great harm from either the CLC operational or environmental perspective. In this research, a combined MnFe2O4 oxygen carrier （OC） was synthesized and its reaction with a typical Chinese high sulfur coal, Liuzhi （LZ） bituminous coal, was performed in a thermogravimetric analyzer （TGA）-Fourier transform infrared （FT-IR） spectrometer. Evolution of sulfur species during reaction of LZ coal with MnFeaO40C was systematically investigated through experimental means combined with thermodynamic simulation. TGA-FTIR analysis of the LZ reaction with MnFe2O4 indicated MnFe2O4 exhibited the desired superior reactivity compared to the single reference oxides Mn304 or Fe203, and SO2 produced was mainly related to oxidization of H2S by MnFe2O4. Experimental analysis of the LZ coal reaction with MnFe2O4, including X-ray diffraction and X-ray photoelectron spectroscopy analysis, verified that the main reduced counterparts of MnFe2O4 were Fe304 and MnO, in good agreement with the related thermodynamic simulation. The obtained MnO was beneficial to stabilize the reduced MnFe2O4 and avoid serious sintering, although the oxygen in MnO was not fully utilized. Meanwhile, most sulfur present in LZ coal was converted to solid MnS during LZ reaction with MnFe2O4, which was further oxidized to MnSO4. Finally, the formation of both MnS and such manganese silicates as Mn2SiO4 and MnSiO3 should be addressed to ensure the full regeneration of the reduced MnFe2O4.
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.
