K4Ce2Nb10O30 ultrafine powders were prepared by stearic acid method (SAM). The obtained products were analyzed by X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectrometry, scanning ele...K4Ce2Nb10O30 ultrafine powders were prepared by stearic acid method (SAM). The obtained products were analyzed by X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectrometry, scanning electron microscopy and UV-visible absorption spectra. XRD patterns revealed that K4Ce2Nb10O30 powders treated at 900 oC for 2 h presented tetragonal structure without the presence of deleterious phases. Furthermore, the K4Ce2Nb10O30 prepared by SAM had considerable activity under visible light irradiation.展开更多
Pt-HSiW/CeO_(2) catalysts were prepared for chlorobenzene(CB) catalytic combustion by hydrothermal method at different calcination temperatures,and the effects of the surface acidity and chemical valence on the cataly...Pt-HSiW/CeO_(2) catalysts were prepared for chlorobenzene(CB) catalytic combustion by hydrothermal method at different calcination temperatures,and the effects of the surface acidity and chemical valence on the catalytic activity were investigated.The results show that the catalyst calcined at 450℃(Cat-B)exhibits the outstanding catalytic performance,and the Cat-B catalyst possesses 90% conversion of CB at148℃.The excellent catalytic activity of Cat-B is attributed to more Ce^(3+)/(Ce^(3+)+Ce^(4+)),Pt~0/(Pt^(0)+Pt^(2+)),O_(ads)/(O_(latt)+O_(ads)) and Lewis acid sites.The degradation mechanism is proposed based on the analysis of the intermediates with the following reaction pathway:chlorobenzene→phenates/benzoquinone→acetate→maleate→CO_(2)+H_(2)O.展开更多
This work investigates the flow and agglomeration behaviors of battery grade Li_(2)CO_(3)powder and the influence of stearic acid surface modification.The degree of agglomeration is directly related to the uniformity ...This work investigates the flow and agglomeration behaviors of battery grade Li_(2)CO_(3)powder and the influence of stearic acid surface modification.The degree of agglomeration is directly related to the uniformity of Li_(2)CO_(3)and its powder mixtures.According to the Chinese National Nonferrous Metal Industry Standard,battery grade Li_(2)CO_(3)powder has D50 equal to 3–8μm which belongs to a micron-sized superfine powder.Therefore,with the extension of storage time,the serious agglomeration phenomenon occurs due to the large specific surface area and rough and irregular powder particles.The Hausner ratio(HR)of the unmodified sample increases from 1.14 to 1.41,and the corresponding flowability is classified as good to poor.Instead,among samples with doping stearic acid,the optimum amount of it is 0.10 wt%which exhibits an extremely stable HR value from 1.14 to 1.16.Meanwhile,after 156 days,the repose angle(AR)obtained for samples without surface modification and using 0.10 wt%stearic acid are calculated to be 49°and 28°,respectively.Based on the values of HR and AR,the flowability of the unmodified sample is poor while the sample modified with 0.10 wt%of stearic acid still maintain excellent powder flow property.Moreover,The LiMn_(2)O_(4)cathode material synthesized from modified Li_(2)CO_(3)powder with a stearic acid content of 0.10 wt%exhibits good crystallinity and comparable electrochemical performance to that prepared by commercial Li_(2)CO_(3).These results indicate that stearic acid has the potential to be an ideal modifier for battery grade Li_(2)CO_(3)powder that needs to be kept for a long time.展开更多
Cerium‐based catalysts are very attractive for the catalytic abatement of nitrogen oxides(NOx)emitted from stationary sources.However,the main challenge is still achieving satisfactory catalytic activity in the low‐...Cerium‐based catalysts are very attractive for the catalytic abatement of nitrogen oxides(NOx)emitted from stationary sources.However,the main challenge is still achieving satisfactory catalytic activity in the low‐temperature range and tolerance to SO2 poisoning.In the present work,two series of Mo‐modified CeO_(2)catalysts were respectively obtained through a wet impregnation method(Mo‐CeO_(2))and a co‐precipitation method(MoCe‐cp),and the roles of the Mo species were systematically investigated.Activity tests showed that the Mo‐CeO_(2)catalyst displayed much higher NO conversion at low temperature and anti‐SO2 ability than MoCe‐cp.The optimal Mo‐CeO_(2)catalyst displayed over 80%NO elimination efficiency even at 150°C and remarkable SO2 resistance at 250°C(nearly no activity loss after 40 h test).The characterization results indicated that the introduced Mo species were highly dispersed on the Mo‐CeO_(2)catalyst surface,thereby providing more Brønsted acid sites and inhibiting the formation of stable adsorbed NOx species.These factors synergistically promote the selective catalytic reduction(SCR)reaction in accordance with the Eley‐Rideal(E‐R)reaction path on the Mo‐CeO_(2)catalyst.Additionally,the molybdenum surface could protect CeO_(2)from SO2 poisoning;thus,the reducibility of the Mo‐CeO_(2)catalyst declined slightly to an adequate level after sulfation.The results in this work indicate that surface modification with Mo species may be a simple method of developing highly efficient cerium‐based SCR catalysts with superior SO2 durability.展开更多
基金Project supported by the National Natural Science Foundation of China (20872051) "Zijin Star" of NJUST
文摘K4Ce2Nb10O30 ultrafine powders were prepared by stearic acid method (SAM). The obtained products were analyzed by X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectrometry, scanning electron microscopy and UV-visible absorption spectra. XRD patterns revealed that K4Ce2Nb10O30 powders treated at 900 oC for 2 h presented tetragonal structure without the presence of deleterious phases. Furthermore, the K4Ce2Nb10O30 prepared by SAM had considerable activity under visible light irradiation.
基金Project supported by the National Natural Science Foundation of China (21872096)Key Research and Development Project of Henan Province (231111320400)+3 种基金Zhongyuan Yingcai Jihua (ZYYCYU202012183)Academic Leader of Henan Institute of Urban Construction (YCJXSJSDTR202204)College Students'Innovation and Entrepreneurship Training Program of Henan Province(202211765053)Doctoral Research Start-up Project of Henan University of Urban Construction (990/Q2017011)。
文摘Pt-HSiW/CeO_(2) catalysts were prepared for chlorobenzene(CB) catalytic combustion by hydrothermal method at different calcination temperatures,and the effects of the surface acidity and chemical valence on the catalytic activity were investigated.The results show that the catalyst calcined at 450℃(Cat-B)exhibits the outstanding catalytic performance,and the Cat-B catalyst possesses 90% conversion of CB at148℃.The excellent catalytic activity of Cat-B is attributed to more Ce^(3+)/(Ce^(3+)+Ce^(4+)),Pt~0/(Pt^(0)+Pt^(2+)),O_(ads)/(O_(latt)+O_(ads)) and Lewis acid sites.The degradation mechanism is proposed based on the analysis of the intermediates with the following reaction pathway:chlorobenzene→phenates/benzoquinone→acetate→maleate→CO_(2)+H_(2)O.
文摘This work investigates the flow and agglomeration behaviors of battery grade Li_(2)CO_(3)powder and the influence of stearic acid surface modification.The degree of agglomeration is directly related to the uniformity of Li_(2)CO_(3)and its powder mixtures.According to the Chinese National Nonferrous Metal Industry Standard,battery grade Li_(2)CO_(3)powder has D50 equal to 3–8μm which belongs to a micron-sized superfine powder.Therefore,with the extension of storage time,the serious agglomeration phenomenon occurs due to the large specific surface area and rough and irregular powder particles.The Hausner ratio(HR)of the unmodified sample increases from 1.14 to 1.41,and the corresponding flowability is classified as good to poor.Instead,among samples with doping stearic acid,the optimum amount of it is 0.10 wt%which exhibits an extremely stable HR value from 1.14 to 1.16.Meanwhile,after 156 days,the repose angle(AR)obtained for samples without surface modification and using 0.10 wt%stearic acid are calculated to be 49°and 28°,respectively.Based on the values of HR and AR,the flowability of the unmodified sample is poor while the sample modified with 0.10 wt%of stearic acid still maintain excellent powder flow property.Moreover,The LiMn_(2)O_(4)cathode material synthesized from modified Li_(2)CO_(3)powder with a stearic acid content of 0.10 wt%exhibits good crystallinity and comparable electrochemical performance to that prepared by commercial Li_(2)CO_(3).These results indicate that stearic acid has the potential to be an ideal modifier for battery grade Li_(2)CO_(3)powder that needs to be kept for a long time.
文摘Cerium‐based catalysts are very attractive for the catalytic abatement of nitrogen oxides(NOx)emitted from stationary sources.However,the main challenge is still achieving satisfactory catalytic activity in the low‐temperature range and tolerance to SO2 poisoning.In the present work,two series of Mo‐modified CeO_(2)catalysts were respectively obtained through a wet impregnation method(Mo‐CeO_(2))and a co‐precipitation method(MoCe‐cp),and the roles of the Mo species were systematically investigated.Activity tests showed that the Mo‐CeO_(2)catalyst displayed much higher NO conversion at low temperature and anti‐SO2 ability than MoCe‐cp.The optimal Mo‐CeO_(2)catalyst displayed over 80%NO elimination efficiency even at 150°C and remarkable SO2 resistance at 250°C(nearly no activity loss after 40 h test).The characterization results indicated that the introduced Mo species were highly dispersed on the Mo‐CeO_(2)catalyst surface,thereby providing more Brønsted acid sites and inhibiting the formation of stable adsorbed NOx species.These factors synergistically promote the selective catalytic reduction(SCR)reaction in accordance with the Eley‐Rideal(E‐R)reaction path on the Mo‐CeO_(2)catalyst.Additionally,the molybdenum surface could protect CeO_(2)from SO2 poisoning;thus,the reducibility of the Mo‐CeO_(2)catalyst declined slightly to an adequate level after sulfation.The results in this work indicate that surface modification with Mo species may be a simple method of developing highly efficient cerium‐based SCR catalysts with superior SO2 durability.
