By considering the intrinsic decoherence effect, we investigate the entropy exchange and entanglement in the interacting system of a superconducting charge qubit coupled to a single-mode optical cavity. We found that ...By considering the intrinsic decoherence effect, we investigate the entropy exchange and entanglement in the interacting system of a superconducting charge qubit coupled to a single-mode optical cavity. We found that although the intrinsic decoherence leads to an irreversible evolution of the interacting system due to a suppression of coherent quantum features through the decay of off-diagonal matrix elements of the density operator, and has an apparently influence on the partial entropies of the two-component subsystems, it dose not destroy entropy exchange behavior. In addition, the lower bound of the concurrence, as the measure of entanglement of the coupling system, is calculated. It is shown that the evolution of entanglement is sensitive to the change of the intrinsic decoherence.展开更多
SCN^- from desulphurization waste solution of cocking plant was separated by D241 anion exchange resin. When SCN" concentration of the waste liquid is O.116mg/ml, its dynamic exchange capability is 93.61mg/g resin. T...SCN^- from desulphurization waste solution of cocking plant was separated by D241 anion exchange resin. When SCN" concentration of the waste liquid is O.116mg/ml, its dynamic exchange capability is 93.61mg/g resin. The condition of use KOH as eluted solution to elute SCN^- is KOH concentration 0.5mol/L, flow velocity 60mi/h, with 60ml eluted solution can completely elute SCN" which exchanged from waste solution. Vaporized the eluted solution, obtain the KSCN crystal in which the concentration of SCN^- is 53.34%, converts to KSCN is 89.2%. SCN^- crystal was separate out from Na2SO3/KOH mixed solution. The relationship between the proportion of Na2S2O3/KOH, free liquids in crystal and the saturation solution volume when crystal appear, the content of KSCN in crystal: the ratio of K2S2O3/KSCN show direct ratio with the saturation solution volume when the crystal birth, r^2=0.9964; when the ratio of K2S2O3/KSCN is between 0.15 and 0.25, the content of SCN^- in the crystals grow with K2S2O3 content increases, the content of free liquids in crystal also along with it increase; When the ratio of Na2S2O3/KOH is 0.15, the content of SCN^- is 54.56%; convert to KSCN is 76.2%. When the ratio of K2S2O3/ESCN is 0.25, the content of SCN^- is 65.28%; convert to KSCN is 91.2%. When the ratio of K2S2O3/KSCN exceeds 0.25, the content of SCN^- in the crystals and the content of free liquids in crystal reduce when the ratio of K2S2O3/KSCN increase.展开更多
Al_(x)/HKUST-1(x=1/24,1/12,1/6,1/3),one of the bimetallic copper-based organic framework materials,was successfully prepared by the synthetic exchange method and characterized by X-ray diffraction(XRD),scanning electr...Al_(x)/HKUST-1(x=1/24,1/12,1/6,1/3),one of the bimetallic copper-based organic framework materials,was successfully prepared by the synthetic exchange method and characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),specific surface area(BET),thermogravimetric analysis(TG),infrared spectra(IR),X-ray photoelectron spectroscopy(XPS),and H_(2)-temperature programmed reduction(H_(2)-TPR).The findings indicated that Al_(x)/HKUST-1 maintained the octahedral morphology of its precursor(HKUST-1).The thermal stability and catalytic reduction ability of HKUST-1 skeleton were improved by doping aluminum(Al^(3+)).Al_(1/12)/HKUST-1 showed the best performance among all samples,with a nitric oxide(NO)conversion rate of 100%at 210℃(50℃lower than that of HKUST-1).The valence kind of Al,Cu,and O in Al_(1/12)/HKUST-1 did not change after the catalytic reaction,but the contents of Al,Cu,and O in different forms changed significantly.The catalytic process of the Al_(x)/HKUST-1 followed a Langmuir-Hinshelwood mechanism.展开更多
A carbon-based sulfonated catalyst was prepared by direct sulfonation and carbonization (in moderate conditions:200 °C, 12 h) of red liquor solids, a by-product of paper-making process. The prepared sulfonate...A carbon-based sulfonated catalyst was prepared by direct sulfonation and carbonization (in moderate conditions:200 °C, 12 h) of red liquor solids, a by-product of paper-making process. The prepared sulfonated cata-lyst (SC) had aromatic structure, composed of carbon enriched inner core, and oxygen-containing (SO3H, COOH, OH) groups enriched surface. The SO3H, COOH, OH groups amounted to 0.74 mmol·g^-1, 0.78 mmol·g^-1, 2.18 mmol·g^-1, respectively. The fresh SC showed much higher catalytic activity than that of the traditional solid acid catalysts (strong-acid 732 cation exchange resin, hydrogen type zeolite socony mobile-five (HZSM-5), sulfated zir-conia) in esterification of oleic acid. SC was deactivated during the reactions, through the mechanisms of leaching of sulfonated species and formation of sulfonate esters. Two regeneration methods were developed, and the catalytic activity can be mostly regenerated by regeneration Method 1 and be fully regenerated by regeneration Method 2, respectively.展开更多
Energy recovery device (ERD) is an important part of the seawater reverse osmosis (SWRO) desalination system. There are principally two kinds of ERDs, the centrifugal type and the positive displacement (PD) type...Energy recovery device (ERD) is an important part of the seawater reverse osmosis (SWRO) desalination system. There are principally two kinds of ERDs, the centrifugal type and the positive displacement (PD) type. The PD type is of extensive concern and is preferred in large-scale plants. In this article, an innovative fluid switcher was presented and a two-cylinder hydraulic energy recovery unit with a lab-scale fluid switcher was set up. Tap water was used as the working medium instead of the actual seawater and brine in SWRO desalination plants. Under steady state operating conditions, the experimental results were obtained on the variations of the pressure and flow rate to and from the energy recovery unit. The hydraulic recovery efficiency (En) of the energy recovery unit with the fluid switcher reached up to 76.83%.展开更多
This work is focused on the theoretical investigation of internal leakage of a newly developed pi lotscale fluid switcherenergy recovery device (FSERD) for reverse osmosis (RO) system. For the purpose of in creasi...This work is focused on the theoretical investigation of internal leakage of a newly developed pi lotscale fluid switcherenergy recovery device (FSERD) for reverse osmosis (RO) system. For the purpose of in creasing FSERD efficiency and reducing the operating cost of RO, it is required to control the internal leakage in a low level. In this work, the internal leakage rates at different leakage gaps and retentate brine pressures are investigated by computational fluid dynamics (CFD) method and validating experiments. It is found that the internal leak age has a linear relationship with the retentate brine pressure and a polynomial relationship with the scale of leakage gap. The results of the present work imply that low internal leakage and high retentate brine pressure bring benefits to achieve high FSRD efficiency.展开更多
This paper considers the problem of noise cancellation for the magnetic flux leakage (MFL) data obtained from the inspection of oil pipelines. MFL data is contaminated by various sources of noise, and the noise can co...This paper considers the problem of noise cancellation for the magnetic flux leakage (MFL) data obtained from the inspection of oil pipelines. MFL data is contaminated by various sources of noise, and the noise can considerably reduce the detectability of flaw signals in MFL data. This paper presents a new de-noising approach for removing the system noise contained in the MFL data by using the coefficients de-noising with wavelet transform. Experimental results are presented to demonstrate the advantages of this de-noising approach over the conventional wavelet de-noising method.展开更多
the desalting property of ion-exchange resins in organic solventis reported by using potassium acetate as a model compound. Theexperimental results show that solvability of the solvent, stirringspeed, and temperature ...the desalting property of ion-exchange resins in organic solventis reported by using potassium acetate as a model compound. Theexperimental results show that solvability of the solvent, stirringspeed, and temperature are the factors which influence theion-exchange rate. The increase of solvability, stirring speed andtemperature will speed up the ion-exchange process.展开更多
[Objective] The aims were to construct a new suicide plasmid of Lactobacillus and gene deletion engineering bacteria of Lactobacillus with pUC19 vector. [Methods] pUC19-CM was constructed by inserting a chloramphenico...[Objective] The aims were to construct a new suicide plasmid of Lactobacillus and gene deletion engineering bacteria of Lactobacillus with pUC19 vector. [Methods] pUC19-CM was constructed by inserting a chloramphenicol resistant gene into the multi-cloning site of pUC19,and then two homologous fragments were cloned into each side of the pUC19-CM to construct suicide plasmid pUC19-CM-D. [Results] A replacement mutant strain,whose target gene was replaced by resistant gene,could be obtained by transforming the suicide plasmid pUC19-CM-D into Lactobacillus for resistance screening. [Conclusion] The construction and application of pUC19-CM-D provided a fast and efficient means of construction of gene deletion engineering bacteria of Lactobacillus,and laid a foundation for study of gene function of Lactobacillus.展开更多
An account of recent work on supported single‐atom catalyst design is given here for reactions as diverse as the low‐temperature water‐gas shift,methanol steam reforming,selective ethanol dehydrogenation,and select...An account of recent work on supported single‐atom catalyst design is given here for reactions as diverse as the low‐temperature water‐gas shift,methanol steam reforming,selective ethanol dehydrogenation,and selective hydrogenation of alkynes and dienes.It is of fundamental interest to investigate the intrinsic activity and selectivity of the active metal atom site and compare them to the properties of the corresponding metal nanoparticles and sub‐nm clusters.It is also important to understand what constitutes a stable active metal atom site in the various reaction environments,and maximize their loadings to allow us to design robust catalysts for industrial applications.Combined activity and stability studies,ideally following the evolution of the active site as a function of catalyst treatment in real time are recommended.Advanced characterization methods with atomic resolution will play a key role here and will be used to guide the design of new catalysts.展开更多
N-acetyl-D-methionine, NaAc and the remains of N-acetyl-L-methionine dramatically affect the purification of L-methionine when purified from the mixture of enzymatically deacylated N-acetyl-DL-methionine, leading to a...N-acetyl-D-methionine, NaAc and the remains of N-acetyl-L-methionine dramatically affect the purification of L-methionine when purified from the mixture of enzymatically deacylated N-acetyl-DL-methionine, leading to a low yield conventionally. Here, this paper reports a successful separation and purification of both L-methionine and N-acetyl-D-methionine by an H ion-exchange column. The pH, L-Met concentration and the ratio between the content of sodium cation and the ion-exchange capacity were optimized to obtain the maximum yield. Experimental results indicate that, under the optimized conditions, the yields of L-methionine and N-acetyl-D-methionine can reach as high as 85% and 75%, respectively.展开更多
This paper has investigated the influence of gasoline sulfur content on durability of catalytic converter for vehicle exhaust gas. Two gasoline samples with different sulfur contents (equating to 150 μg/g and 50 μg/...This paper has investigated the influence of gasoline sulfur content on durability of catalytic converter for vehicle exhaust gas. Two gasoline samples with different sulfur contents (equating to 150 μg/g and 50 μg/g of sulfur, respectively) were used to examine the durability and performance of catalytic converter on the bench test. The test results have revealed that in comparison to the influence of sulfur on ageing of catalytic converter the thermal ageing had a more remarkable impact on the performance of catalytic converter, and the performance of catalytic converter could be restored by high-temperature desulfurization process after ageing by the high-sulfur gasoline sample (containing 150 μg/g of sulfur) .展开更多
The TiO2-densified cellulose composite beads were activated by epichlorohydrin and coupled with diethylamine, to function as an anion exchanger for expanded bed chromatography. The adsorbent exhibited a favorable perf...The TiO2-densified cellulose composite beads were activated by epichlorohydrin and coupled with diethylamine, to function as an anion exchanger for expanded bed chromatography. The adsorbent exhibited a favorable performance of expanded bed adsorption for proteins, and therefore was applied to the expanded bed recovery of D-2-chloropropionic acid dehalogenase directly from the unclarified homogenate of Pseudomonas sp. NT21. The binding capacity of the dehalogenase was found to be 8.54U·ml^-1 adsorbent, and two active peaks were eluted respectively at 0.15mol·L^-1 and 0.3mol·L^-1 (NH4)2SO4. The result indicated that the overall enzyme yield was 68%, with a purification factor of 22. In comparison to other recovery processes, the yield of the expanded bed process rises at least 70%, simultaneously saving a great deal of operation time and costs.展开更多
ITQ-2 zeolites were prepared by sequential alkali-swelling and ultrasonic-delamination of precursor MCM-22 and characterized by X-ray powder diffraction, scanning electron microscopy, nitrogen adsorption-desorption, a...ITQ-2 zeolites were prepared by sequential alkali-swelling and ultrasonic-delamination of precursor MCM-22 and characterized by X-ray powder diffraction, scanning electron microscopy, nitrogen adsorption-desorption, ammonia temperature-programmed desorption and in-situ Fourier-transform infrared spectroscopy. The delamination induced a change in the morphology of ITQ-2 zeolites from aggregated thin platelets to scattered platelets, together with a significant increase in external specific surface area, which reached a plateau at the ultrasonic treatment time of 3 h. The catalytic cracking of n-dodecane over ITQ-2 zeolites was evaluated with ITQ-2 coated on the inside wall of a tubular reactor at 550 ℃ and 4 MPa. The sample obtained by ultrasonic treatment of 3 h (ITQ-2-3) gave the highest initial conversion of n-dodecane, whereas those of 5 h and I h gave the conversion even lower than MCM-22, which was in agreement with the trend of the ratio of strong Lewis acid to the total acid amount. Although the amount of cokes deposited on ITQ-2-3 was larger than that on MCM-22, the former deactivated slowly, suggesting that a large external specific surface area benefits the stability of zeolite coatings,展开更多
基金National Natural Science Foundation of China under Grant No.10374007
文摘By considering the intrinsic decoherence effect, we investigate the entropy exchange and entanglement in the interacting system of a superconducting charge qubit coupled to a single-mode optical cavity. We found that although the intrinsic decoherence leads to an irreversible evolution of the interacting system due to a suppression of coherent quantum features through the decay of off-diagonal matrix elements of the density operator, and has an apparently influence on the partial entropies of the two-component subsystems, it dose not destroy entropy exchange behavior. In addition, the lower bound of the concurrence, as the measure of entanglement of the coupling system, is calculated. It is shown that the evolution of entanglement is sensitive to the change of the intrinsic decoherence.
文摘SCN^- from desulphurization waste solution of cocking plant was separated by D241 anion exchange resin. When SCN" concentration of the waste liquid is O.116mg/ml, its dynamic exchange capability is 93.61mg/g resin. The condition of use KOH as eluted solution to elute SCN^- is KOH concentration 0.5mol/L, flow velocity 60mi/h, with 60ml eluted solution can completely elute SCN" which exchanged from waste solution. Vaporized the eluted solution, obtain the KSCN crystal in which the concentration of SCN^- is 53.34%, converts to KSCN is 89.2%. SCN^- crystal was separate out from Na2SO3/KOH mixed solution. The relationship between the proportion of Na2S2O3/KOH, free liquids in crystal and the saturation solution volume when crystal appear, the content of KSCN in crystal: the ratio of K2S2O3/KSCN show direct ratio with the saturation solution volume when the crystal birth, r^2=0.9964; when the ratio of K2S2O3/KSCN is between 0.15 and 0.25, the content of SCN^- in the crystals grow with K2S2O3 content increases, the content of free liquids in crystal also along with it increase; When the ratio of Na2S2O3/KOH is 0.15, the content of SCN^- is 54.56%; convert to KSCN is 76.2%. When the ratio of K2S2O3/ESCN is 0.25, the content of SCN^- is 65.28%; convert to KSCN is 91.2%. When the ratio of K2S2O3/KSCN exceeds 0.25, the content of SCN^- in the crystals and the content of free liquids in crystal reduce when the ratio of K2S2O3/KSCN increase.
基金financial supports from the Natural Science Foundation of Hunan Province,China(No.2020JJ4685)the Open Fund for Key Laboratory of Metallurgical Emission Reduction and Resources Utilization of Ministry of Education in Anhui University of Technology,China(No.JKF20-02)+2 种基金the Natural Science Foundation of Hunan Province,China(No.2019JJ40378)the Open Fund for State Environmental Protection Key Laboratory of Mineral Metallurgical Resources Utilization and Pollution Control in Wuhan University of Science and Technology,China(No.HB201908)the Scientific Technology Project of Strategic Emerging Industries and Major Achievement Transformation of Hunan Province,China(No.2017GK4010)。
文摘Al_(x)/HKUST-1(x=1/24,1/12,1/6,1/3),one of the bimetallic copper-based organic framework materials,was successfully prepared by the synthetic exchange method and characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),specific surface area(BET),thermogravimetric analysis(TG),infrared spectra(IR),X-ray photoelectron spectroscopy(XPS),and H_(2)-temperature programmed reduction(H_(2)-TPR).The findings indicated that Al_(x)/HKUST-1 maintained the octahedral morphology of its precursor(HKUST-1).The thermal stability and catalytic reduction ability of HKUST-1 skeleton were improved by doping aluminum(Al^(3+)).Al_(1/12)/HKUST-1 showed the best performance among all samples,with a nitric oxide(NO)conversion rate of 100%at 210℃(50℃lower than that of HKUST-1).The valence kind of Al,Cu,and O in Al_(1/12)/HKUST-1 did not change after the catalytic reaction,but the contents of Al,Cu,and O in different forms changed significantly.The catalytic process of the Al_(x)/HKUST-1 followed a Langmuir-Hinshelwood mechanism.
基金Supported by the National Natural Science Foundation of China(21276076)the Fundamental Research Funds for the Central Universities of China(WA1014003)State Key Laboratory of Chemical Engineering(SKL-ChE-10C06)
文摘A carbon-based sulfonated catalyst was prepared by direct sulfonation and carbonization (in moderate conditions:200 °C, 12 h) of red liquor solids, a by-product of paper-making process. The prepared sulfonated cata-lyst (SC) had aromatic structure, composed of carbon enriched inner core, and oxygen-containing (SO3H, COOH, OH) groups enriched surface. The SO3H, COOH, OH groups amounted to 0.74 mmol·g^-1, 0.78 mmol·g^-1, 2.18 mmol·g^-1, respectively. The fresh SC showed much higher catalytic activity than that of the traditional solid acid catalysts (strong-acid 732 cation exchange resin, hydrogen type zeolite socony mobile-five (HZSM-5), sulfated zir-conia) in esterification of oleic acid. SC was deactivated during the reactions, through the mechanisms of leaching of sulfonated species and formation of sulfonate esters. Two regeneration methods were developed, and the catalytic activity can be mostly regenerated by regeneration Method 1 and be fully regenerated by regeneration Method 2, respectively.
基金the Seawater Desalination Research Programs of Tianjin(043185211-4)
文摘Energy recovery device (ERD) is an important part of the seawater reverse osmosis (SWRO) desalination system. There are principally two kinds of ERDs, the centrifugal type and the positive displacement (PD) type. The PD type is of extensive concern and is preferred in large-scale plants. In this article, an innovative fluid switcher was presented and a two-cylinder hydraulic energy recovery unit with a lab-scale fluid switcher was set up. Tap water was used as the working medium instead of the actual seawater and brine in SWRO desalination plants. Under steady state operating conditions, the experimental results were obtained on the variations of the pressure and flow rate to and from the energy recovery unit. The hydraulic recovery efficiency (En) of the energy recovery unit with the fluid switcher reached up to 76.83%.
基金Supported by the Research and Development Programs of Tianjin(10JCYBJC04700,10ZCKFSH02100)
文摘This work is focused on the theoretical investigation of internal leakage of a newly developed pi lotscale fluid switcherenergy recovery device (FSERD) for reverse osmosis (RO) system. For the purpose of in creasing FSERD efficiency and reducing the operating cost of RO, it is required to control the internal leakage in a low level. In this work, the internal leakage rates at different leakage gaps and retentate brine pressures are investigated by computational fluid dynamics (CFD) method and validating experiments. It is found that the internal leak age has a linear relationship with the retentate brine pressure and a polynomial relationship with the scale of leakage gap. The results of the present work imply that low internal leakage and high retentate brine pressure bring benefits to achieve high FSRD efficiency.
文摘This paper considers the problem of noise cancellation for the magnetic flux leakage (MFL) data obtained from the inspection of oil pipelines. MFL data is contaminated by various sources of noise, and the noise can considerably reduce the detectability of flaw signals in MFL data. This paper presents a new de-noising approach for removing the system noise contained in the MFL data by using the coefficients de-noising with wavelet transform. Experimental results are presented to demonstrate the advantages of this de-noising approach over the conventional wavelet de-noising method.
文摘the desalting property of ion-exchange resins in organic solventis reported by using potassium acetate as a model compound. Theexperimental results show that solvability of the solvent, stirringspeed, and temperature are the factors which influence theion-exchange rate. The increase of solvability, stirring speed andtemperature will speed up the ion-exchange process.
基金Supported by National Science &Technology Pillar Program in the Eleventh Five-year Plan Period (2007BAD75B06)Guangxi Sci-ence Foundation (0782003-4)~~
文摘[Objective] The aims were to construct a new suicide plasmid of Lactobacillus and gene deletion engineering bacteria of Lactobacillus with pUC19 vector. [Methods] pUC19-CM was constructed by inserting a chloramphenicol resistant gene into the multi-cloning site of pUC19,and then two homologous fragments were cloned into each side of the pUC19-CM to construct suicide plasmid pUC19-CM-D. [Results] A replacement mutant strain,whose target gene was replaced by resistant gene,could be obtained by transforming the suicide plasmid pUC19-CM-D into Lactobacillus for resistance screening. [Conclusion] The construction and application of pUC19-CM-D provided a fast and efficient means of construction of gene deletion engineering bacteria of Lactobacillus,and laid a foundation for study of gene function of Lactobacillus.
基金financial support of the work by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), under Awards Grant Number DE-FG02-05ER15730
文摘An account of recent work on supported single‐atom catalyst design is given here for reactions as diverse as the low‐temperature water‐gas shift,methanol steam reforming,selective ethanol dehydrogenation,and selective hydrogenation of alkynes and dienes.It is of fundamental interest to investigate the intrinsic activity and selectivity of the active metal atom site and compare them to the properties of the corresponding metal nanoparticles and sub‐nm clusters.It is also important to understand what constitutes a stable active metal atom site in the various reaction environments,and maximize their loadings to allow us to design robust catalysts for industrial applications.Combined activity and stability studies,ideally following the evolution of the active site as a function of catalyst treatment in real time are recommended.Advanced characterization methods with atomic resolution will play a key role here and will be used to guide the design of new catalysts.
文摘N-acetyl-D-methionine, NaAc and the remains of N-acetyl-L-methionine dramatically affect the purification of L-methionine when purified from the mixture of enzymatically deacylated N-acetyl-DL-methionine, leading to a low yield conventionally. Here, this paper reports a successful separation and purification of both L-methionine and N-acetyl-D-methionine by an H ion-exchange column. The pH, L-Met concentration and the ratio between the content of sodium cation and the ion-exchange capacity were optimized to obtain the maximum yield. Experimental results indicate that, under the optimized conditions, the yields of L-methionine and N-acetyl-D-methionine can reach as high as 85% and 75%, respectively.
文摘This paper has investigated the influence of gasoline sulfur content on durability of catalytic converter for vehicle exhaust gas. Two gasoline samples with different sulfur contents (equating to 150 μg/g and 50 μg/g of sulfur, respectively) were used to examine the durability and performance of catalytic converter on the bench test. The test results have revealed that in comparison to the influence of sulfur on ageing of catalytic converter the thermal ageing had a more remarkable impact on the performance of catalytic converter, and the performance of catalytic converter could be restored by high-temperature desulfurization process after ageing by the high-sulfur gasoline sample (containing 150 μg/g of sulfur) .
基金the Natural Science Foundation of Ningbo (No.2005A610018).ACKN0WLEDGEMENTS The authors would like to thank Mr. Qi Nan for taking part in this study, and for financial support by the Natural Science Foundation of Ningbo. Discussion with Dr. Lin Dong-Qiang has been helpful and is appreciated.
文摘The TiO2-densified cellulose composite beads were activated by epichlorohydrin and coupled with diethylamine, to function as an anion exchanger for expanded bed chromatography. The adsorbent exhibited a favorable performance of expanded bed adsorption for proteins, and therefore was applied to the expanded bed recovery of D-2-chloropropionic acid dehalogenase directly from the unclarified homogenate of Pseudomonas sp. NT21. The binding capacity of the dehalogenase was found to be 8.54U·ml^-1 adsorbent, and two active peaks were eluted respectively at 0.15mol·L^-1 and 0.3mol·L^-1 (NH4)2SO4. The result indicated that the overall enzyme yield was 68%, with a purification factor of 22. In comparison to other recovery processes, the yield of the expanded bed process rises at least 70%, simultaneously saving a great deal of operation time and costs.
文摘ITQ-2 zeolites were prepared by sequential alkali-swelling and ultrasonic-delamination of precursor MCM-22 and characterized by X-ray powder diffraction, scanning electron microscopy, nitrogen adsorption-desorption, ammonia temperature-programmed desorption and in-situ Fourier-transform infrared spectroscopy. The delamination induced a change in the morphology of ITQ-2 zeolites from aggregated thin platelets to scattered platelets, together with a significant increase in external specific surface area, which reached a plateau at the ultrasonic treatment time of 3 h. The catalytic cracking of n-dodecane over ITQ-2 zeolites was evaluated with ITQ-2 coated on the inside wall of a tubular reactor at 550 ℃ and 4 MPa. The sample obtained by ultrasonic treatment of 3 h (ITQ-2-3) gave the highest initial conversion of n-dodecane, whereas those of 5 h and I h gave the conversion even lower than MCM-22, which was in agreement with the trend of the ratio of strong Lewis acid to the total acid amount. Although the amount of cokes deposited on ITQ-2-3 was larger than that on MCM-22, the former deactivated slowly, suggesting that a large external specific surface area benefits the stability of zeolite coatings,