A novel type of thermal stabilizer-lanthanum tris (mono- i -octyl phthalate) (LTMP) was synthesized by double-decomposition reaction o f sodium mono- i -octyl phthalate with lanthanum chloride at 60 ℃. Sodium m ono- ...A novel type of thermal stabilizer-lanthanum tris (mono- i -octyl phthalate) (LTMP) was synthesized by double-decomposition reaction o f sodium mono- i -octyl phthalate with lanthanum chloride at 60 ℃. Sodium m ono- i -octyl phthalate was prepared by sodium hydrate and mono- i -octy l phthalate prepared by reaction of isooctyl alcohol and phthalic anhydride in th e presence of sulfuric acid catalyst at 110 ℃. The yield of lanthanum tris (mon o- i -octyl phthalate) is about 84.5%. Its thermal stabilities were measured by heat-ageing oven test when incorporated into PVC. The experimental results show that the heat stability time is about 40min at 190 ℃ when adding 3phr (pe r hundred resin) to PVC. The thermal stability of this product is better than th at of Ca-Zn complex and basic lead salt stabilizers, and equal to that of dibut yltin dilaurate.展开更多
SAPO-34 zeolite membranes show high efficiency for CO2/CH4 separation but suffer from the reduction of separation performance when exposed to humid atmosphere.In this work,n-dodecyltrimethoxysilane(DTMS)was used to mo...SAPO-34 zeolite membranes show high efficiency for CO2/CH4 separation but suffer from the reduction of separation performance when exposed to humid atmosphere.In this work,n-dodecyltrimethoxysilane(DTMS)was used to modify the hollow fibers supported SAPO-34 membranes to increase the external surface hydrophobicity and thus sustain their performance under moisture environment.The modified membranes were fully characterized.Their separation performance was extensively investigated in both dry and wet gaseous systems and compared with the un-modified ones.The un-modified SAPO-34 membrane exhibited a high separation selectivity of 160 and CO2 permeance of 1.18×10-6 mol·m-2·s-1·Pa-1 for separation of dry CO2/CH4 at 298 K.However,its separation selectivity declined to 0.9 and the CO2 permeance was only about 1.7×10-8 mol·m-2·s-1·Pa-1 for wet CO2/CH4 at same temperature.High temperature(e.g.353 K)could reduce the effect of moisture to improve SAPO-34 separation selectivity,but further increasing temperature(e.g.373 K)led to decrease in CO2/CH4 separation selectivity.A significant decrease of selectivity was observed at higher pressure drop.The modified SAPO-34 membrane showed decreased CO2 permeance but increased separation selectivity for dry CO2/CH4 gas mixture,and super performance for wet CO2/CH4 gas mixture due to the improved hydrophobicity of membrane surface.A separation selectivity of 65 and CO2 permeance of 4.73×10-8 mol·m-2·s-1·Pa-1 for wet CO2/CH4 mixture can be observed at 353 K with a pressure drop of 0.4 MPa.Furthermore,the modified membrane exhibited stable separation performance during the 120-hour test for wet CO2/CH4 mixture at 353 K.The hydrophobic modification paves a way for SAPO-34 membranes in real applications.展开更多
Long-term stability test of Mo/HZSM-5-N catalysts（HZSM-5-N stands for nano-sized HZSM-5） in methane dehydroaromatization（MDA）reaction has been performed with periodic CH4-H2 switch at 1033-1073 K for more than 100...Long-term stability test of Mo/HZSM-5-N catalysts（HZSM-5-N stands for nano-sized HZSM-5） in methane dehydroaromatization（MDA）reaction has been performed with periodic CH4-H2 switch at 1033-1073 K for more than 1000 h.During this test,methane conversion ranges from 13% to 16%,and mean yield to aromatics（i.e.benzene and naphthalene） exceeds 10%.N2-physisorption,XRD,NMR and TPO measurements were performed for the used Mo/HZSM-5 catalysts and coke deposition,and the results revealed that the periodic hydrogenation can effectively suppress coke deposition by removing the inert aromatic-type coke,thus ensuring Mo/HZSM-5 partly maintained its activity even in the presence of large amount of coke deposition.The effect of zeolite particle size on the catalytic activity was also explored,and the results showed that the nano-sized zeolite with low diffusion resistance performed better.It is recognized that the size effect was enhanced by reaction time,and it became more remarkable in a long-term MDA reaction even at a low space velocity.展开更多
Pt-CeO2-ZrO2/MgO （Pt-CZ/MgO） catalysts with 0.8 wt% Pt, 3.0 wt% CeO2 and 3.0 wt% ZrO2 were prepared by wet impregnation method. Support MgO was obtained using ion exchange resin method or using commercial MgO. XRD, ...Pt-CeO2-ZrO2/MgO （Pt-CZ/MgO） catalysts with 0.8 wt% Pt, 3.0 wt% CeO2 and 3.0 wt% ZrO2 were prepared by wet impregnation method. Support MgO was obtained using ion exchange resin method or using commercial MgO. XRD, BET, SEM, TEM, DTA-TG and CO2-TPD were used to characterize the catalysts. CH4-CO2 reforming to synthesis gas （syngas） was performed to test the catalytic behavior of the catalysts. The catalyst Pt-CZ/MgO-IE（D） prepared using ion exchange resin exhibits more regular structure, smaller and more unique particle sizes, and stronger basicity than the catalyst Pt-CZ/MgO prepared from commercial MgO. At 1073 K and atmospheric pressure, Pt-CZ/MgO-IE（D） catalyst has a higher activity and greater stability than Pt-CZ/MgO catalyst for CH4-CO2 reforming reaction at high gas hourly space velocity of 36000 mL/（g.h） with a stoichiometric feed of CH4 and C02. Activity measurement and characterization results demonstrate that modification of the support using ion exchange resin method can promote the surface structural property and stability, therefore enhancing the activity and stability for CH4-CO2 reforming reaction.展开更多
The effect of the distribution of organic cations CH3NH3^＋（MA^＋） on the stability,electronic structures and optical properties of CH3NH3 Pb I3 perovskite have been investigated using the plane-wave ultrasoft pseuu...The effect of the distribution of organic cations CH3NH3^＋（MA^＋） on the stability,electronic structures and optical properties of CH3NH3 Pb I3 perovskite have been investigated using the plane-wave ultrasoft pseuudopotentials. Generalized gradient approximation and local density approximation are used to optimize the geometries of six models, which are different in the orientation of organic cations. The results show that model C is more stable than others, and the main contribution to the top of valence band is from I 5p states. In the bottom of conduction bands, the main components are Pb 6s states with an overlapping of I 5p states. When the orientation of organic group is transforming, the Pb I6 octahedra will distort and the band structure will alter with it, which affect the generation and migration of photon-generated carriers and optical properties.展开更多
A double chopper-stabilized analog front-end （DCS-AFE） circuit for a thermopile sensor is presented, which includes a closed-loop front-end amplifier and a 2nd-order 1 bit quantization sigma-delta modulator. The amp...A double chopper-stabilized analog front-end （DCS-AFE） circuit for a thermopile sensor is presented, which includes a closed-loop front-end amplifier and a 2nd-order 1 bit quantization sigma-delta modulator. The amplifier with a closed-loop structure ensures the gain stability against the temperature. Moreover, by adopting the chopper-stabilized technique both for the amplifier and 2nd-order 1-bit quantization sigma-delta modulator, the low-frequency 1/f noise and offset is reduced and high resolution is achieved. The AFE is implemented in the SMIC 0.18 μm 1P6M CMOS process. The measurement results show that in a 3.3 V power supply, 1 Hz input frequency and 3KHz clock frequency, the peak signal-to-noise and distortion ratio （SNDR） is 55.4 dB, the effective number of bits （ENOB） is 8.92 bit, and in the range of -20 to 85 degrees, the detection resolution is 0.2 degree.展开更多
This paper presents a low noise complimentary metal-oxide-semiconductor（CMOS） detection chip for amperometric electrochemical sensors.In order to effectively remove the input offset of the cascaded integrators and t...This paper presents a low noise complimentary metal-oxide-semiconductor（CMOS） detection chip for amperometric electrochemical sensors.In order to effectively remove the input offset of the cascaded integrators and the low frequency noise in the modulator,a novel offset cancellation chopping scheme was proposed in the Incremental AS analog to digital converter（IADC）.A novel low power potentiostat was employed in this chip to provide the biasing voltage for the sensor while mirroring the sensor current out for detection.The chip communicates with FPGA through standard built in I2 C interface and SPI bus.Fabricated in 0.18-μm CMOS process,this chip detects current signal with high accuracy and high linearity.A prototype microsystem was produced to verify the detection chip performance with current input as well as micro-sensors.展开更多
文摘A novel type of thermal stabilizer-lanthanum tris (mono- i -octyl phthalate) (LTMP) was synthesized by double-decomposition reaction o f sodium mono- i -octyl phthalate with lanthanum chloride at 60 ℃. Sodium m ono- i -octyl phthalate was prepared by sodium hydrate and mono- i -octy l phthalate prepared by reaction of isooctyl alcohol and phthalic anhydride in th e presence of sulfuric acid catalyst at 110 ℃. The yield of lanthanum tris (mon o- i -octyl phthalate) is about 84.5%. Its thermal stabilities were measured by heat-ageing oven test when incorporated into PVC. The experimental results show that the heat stability time is about 40min at 190 ℃ when adding 3phr (pe r hundred resin) to PVC. The thermal stability of this product is better than th at of Ca-Zn complex and basic lead salt stabilizers, and equal to that of dibut yltin dilaurate.
基金Supported by the National Natural Science Foundation of China(21490585,21776128)the“Six Top Talents”and“333 Talent Project”of Jiangsu Province,State Key Laboratory of Materials-Oriented Chemical Engineering(ZK201602,ZK201719)Priority Academy Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘SAPO-34 zeolite membranes show high efficiency for CO2/CH4 separation but suffer from the reduction of separation performance when exposed to humid atmosphere.In this work,n-dodecyltrimethoxysilane(DTMS)was used to modify the hollow fibers supported SAPO-34 membranes to increase the external surface hydrophobicity and thus sustain their performance under moisture environment.The modified membranes were fully characterized.Their separation performance was extensively investigated in both dry and wet gaseous systems and compared with the un-modified ones.The un-modified SAPO-34 membrane exhibited a high separation selectivity of 160 and CO2 permeance of 1.18×10-6 mol·m-2·s-1·Pa-1 for separation of dry CO2/CH4 at 298 K.However,its separation selectivity declined to 0.9 and the CO2 permeance was only about 1.7×10-8 mol·m-2·s-1·Pa-1 for wet CO2/CH4 at same temperature.High temperature(e.g.353 K)could reduce the effect of moisture to improve SAPO-34 separation selectivity,but further increasing temperature(e.g.373 K)led to decrease in CO2/CH4 separation selectivity.A significant decrease of selectivity was observed at higher pressure drop.The modified SAPO-34 membrane showed decreased CO2 permeance but increased separation selectivity for dry CO2/CH4 gas mixture,and super performance for wet CO2/CH4 gas mixture due to the improved hydrophobicity of membrane surface.A separation selectivity of 65 and CO2 permeance of 4.73×10-8 mol·m-2·s-1·Pa-1 for wet CO2/CH4 mixture can be observed at 353 K with a pressure drop of 0.4 MPa.Furthermore,the modified membrane exhibited stable separation performance during the 120-hour test for wet CO2/CH4 mixture at 353 K.The hydrophobic modification paves a way for SAPO-34 membranes in real applications.
基金financially supported by the"Strategic Priority Research Program"of Chinese Academy of Sciences(No.XDA09030101)the National Natural Science Foundation of China(No.21103181 and 21473185)+1 种基金DICP Fundamental Research Program for Clean Energy(DICP M201301)Shaanxi Yanchang Petroleum Group Co.Ltd
文摘Long-term stability test of Mo/HZSM-5-N catalysts（HZSM-5-N stands for nano-sized HZSM-5） in methane dehydroaromatization（MDA）reaction has been performed with periodic CH4-H2 switch at 1033-1073 K for more than 1000 h.During this test,methane conversion ranges from 13% to 16%,and mean yield to aromatics（i.e.benzene and naphthalene） exceeds 10%.N2-physisorption,XRD,NMR and TPO measurements were performed for the used Mo/HZSM-5 catalysts and coke deposition,and the results revealed that the periodic hydrogenation can effectively suppress coke deposition by removing the inert aromatic-type coke,thus ensuring Mo/HZSM-5 partly maintained its activity even in the presence of large amount of coke deposition.The effect of zeolite particle size on the catalytic activity was also explored,and the results showed that the nano-sized zeolite with low diffusion resistance performed better.It is recognized that the size effect was enhanced by reaction time,and it became more remarkable in a long-term MDA reaction even at a low space velocity.
基金supported by the National Natural Science Foundation of China (No. 20873013)
文摘Pt-CeO2-ZrO2/MgO （Pt-CZ/MgO） catalysts with 0.8 wt% Pt, 3.0 wt% CeO2 and 3.0 wt% ZrO2 were prepared by wet impregnation method. Support MgO was obtained using ion exchange resin method or using commercial MgO. XRD, BET, SEM, TEM, DTA-TG and CO2-TPD were used to characterize the catalysts. CH4-CO2 reforming to synthesis gas （syngas） was performed to test the catalytic behavior of the catalysts. The catalyst Pt-CZ/MgO-IE（D） prepared using ion exchange resin exhibits more regular structure, smaller and more unique particle sizes, and stronger basicity than the catalyst Pt-CZ/MgO prepared from commercial MgO. At 1073 K and atmospheric pressure, Pt-CZ/MgO-IE（D） catalyst has a higher activity and greater stability than Pt-CZ/MgO catalyst for CH4-CO2 reforming reaction at high gas hourly space velocity of 36000 mL/（g.h） with a stoichiometric feed of CH4 and C02. Activity measurement and characterization results demonstrate that modification of the support using ion exchange resin method can promote the surface structural property and stability, therefore enhancing the activity and stability for CH4-CO2 reforming reaction.
基金Supported by the program for National Natural Science Foundation of China(51102150,51472081)Foundation of Hubei University of Technology for High-level Talents(GCRC13014)Development Founds of Hubei Collaborative Innovation Center(HBSKFZD2014003,HBSKFZD2014011,HBSKFZD2015004)
文摘The effect of the distribution of organic cations CH3NH3^＋（MA^＋） on the stability,electronic structures and optical properties of CH3NH3 Pb I3 perovskite have been investigated using the plane-wave ultrasoft pseuudopotentials. Generalized gradient approximation and local density approximation are used to optimize the geometries of six models, which are different in the orientation of organic cations. The results show that model C is more stable than others, and the main contribution to the top of valence band is from I 5p states. In the bottom of conduction bands, the main components are Pb 6s states with an overlapping of I 5p states. When the orientation of organic group is transforming, the Pb I6 octahedra will distort and the band structure will alter with it, which affect the generation and migration of photon-generated carriers and optical properties.
基金supported by the Research on Information Technology of a New Generation of Strategic Leading Scientific and Technological Special System(No.XDA06020401)
文摘A double chopper-stabilized analog front-end （DCS-AFE） circuit for a thermopile sensor is presented, which includes a closed-loop front-end amplifier and a 2nd-order 1 bit quantization sigma-delta modulator. The amplifier with a closed-loop structure ensures the gain stability against the temperature. Moreover, by adopting the chopper-stabilized technique both for the amplifier and 2nd-order 1-bit quantization sigma-delta modulator, the low-frequency 1/f noise and offset is reduced and high resolution is achieved. The AFE is implemented in the SMIC 0.18 μm 1P6M CMOS process. The measurement results show that in a 3.3 V power supply, 1 Hz input frequency and 3KHz clock frequency, the peak signal-to-noise and distortion ratio （SNDR） is 55.4 dB, the effective number of bits （ENOB） is 8.92 bit, and in the range of -20 to 85 degrees, the detection resolution is 0.2 degree.
基金supported by the State Key Development Program for Basic Research of China(No.2015CB352100)
文摘This paper presents a low noise complimentary metal-oxide-semiconductor（CMOS） detection chip for amperometric electrochemical sensors.In order to effectively remove the input offset of the cascaded integrators and the low frequency noise in the modulator,a novel offset cancellation chopping scheme was proposed in the Incremental AS analog to digital converter（IADC）.A novel low power potentiostat was employed in this chip to provide the biasing voltage for the sensor while mirroring the sensor current out for detection.The chip communicates with FPGA through standard built in I2 C interface and SPI bus.Fabricated in 0.18-μm CMOS process,this chip detects current signal with high accuracy and high linearity.A prototype microsystem was produced to verify the detection chip performance with current input as well as micro-sensors.
