Flue gas and coal bed methane are two important sources of greenhouse gases.Pressure swing adsorption process has a wide range of application in the field of gas separation,and the selection of adsorbent is crucial.In...Flue gas and coal bed methane are two important sources of greenhouse gases.Pressure swing adsorption process has a wide range of application in the field of gas separation,and the selection of adsorbent is crucial.In this regard,in order to assess the better adsorbent for separating CO_(2) from flue gas and CH_(4) from coal bed methane,adsorption isotherms of CO_(2),CH_(4) and N_(2) on activated carbon and carbon molecular sieve are measured at 303.15,318.15 and 333.15 K,and up to 250 kPa.The experimental data fit better with Langmuir 2 compared to Langmuir 3 and Langmuir-Freundlich models,and Clausius-Clapeyron equation was used to calculate the isosteric heat.Both the order of the adsorbed amount and the adsorption heat on the two adsorbents are CO_(2)>CH_(4)>N_(2).The adsorption kinetics are calculated by the pseudo-first kinetic model,and the order of adsorption rates on activated carbon is N_(2)-CH_(4)>CO_(2),while on carbon molecular sieve,it is CO_(2)-N_(2)>CH_(4).It is shown that relative molecular mass and adsorption heat are the primary effect on kinetics for activated carbon,while kinetic diameter is the main resistance factor for carbon molecular sieve.Moreover,the adsorption selectivity of CH_(4)/N_(2) and CO_(2)/N_(2) were estimated with the ideal adsorption solution theory,and carbon molecular sieve performed best at 318.15 K for both CO_(2) and CH_(4) separation.The study suggested that activated carbon is a better choice for separating flue gas and carbon molecular sieve can be a strong candidate for separating coal bed methane.展开更多
In order to comprehend the applicability of microwave irradiation for recovering coalbed methane,it is necessary to evaluate the microwave irradiation-induced alterations in coals with varying levels of metamorphism.I...In order to comprehend the applicability of microwave irradiation for recovering coalbed methane,it is necessary to evaluate the microwave irradiation-induced alterations in coals with varying levels of metamorphism.In this work,the carbon molecular sieve combined with KMnO_(4)oxidation was selected to fabricate carbon molecular sieve with diverse oxidation degrees,which can serve as model substances toward coals.Afterwards,the microwave irradiation dependences of pores,functional groups,and highpressure methane adsorption characteristics of model substances were studied.The results indicated that microwave irradiation causes rearrangement of oxygen-containing functional groups,which could block the micropores with a size of 0.40-0.60 nm in carbon molecular sieve;meanwhile,naphthalene and phenanthrene generated by macro-molecular structure pyrolysis due to microwave irradiation could block the micropores with a size of 0.70-0.90 nm.These alterations in micropore structure weaken the saturated methane adsorption capacity of oxidized carbon molecular sieve by 2.91%-23.28%,suggesting that microwave irradiation could promote methane desorption.Moreover,the increased mesopores found for oxidized carbon molecular sieve after microwave irradiation could benefit CH4 diffusion.In summary,the oxidized carbon molecular sieve can act as model substances toward coals with different ranks.Additionally,microwave irradiation is a promising technology to enhance coalbed methane recovery.展开更多
The activation effect of boric acid as an activator is good,and we investigate the best activation conditions for the boric acid impregnation method.To represent the structural characteristics and adsorption performan...The activation effect of boric acid as an activator is good,and we investigate the best activation conditions for the boric acid impregnation method.To represent the structural characteristics and adsorption performance of the Stellera Chamaejasme based carbon molecular sieves,we use Brunner-Emmet-Teller(BET)measurements,scan-ning electron microscope(SEM),Raman spectra(Raman),X-ray diffraction(XRD),and adsorption property measurement.When the loading ratio was 0.68:1,the specific surface area was 532.21 m^(2)/g,the total pore volume was 0.24 cm 3/g,the average pore size was 1.81 nm,the adsorption value of methylene blue was 145.28 mg/g,and the adsorption value of iodine was 713.33 mg/g,the results showed that boric acid had better activation effect.The carbon molecular sieves made from Stellera Chamaejasme and activated with boric acid produce two peaks on the aperture distribution graph that are densely distributed in the micropore range.This indicates that boric acid’s pore-forming tendency is primarily micropore.展开更多
Hydrogen is a green clean fuel and chemical feedstock. Its separation and purification from hydrogencontaining mixtures is the key step in the production of hydrogen with high purity(>99.99%). In this work, carbon ...Hydrogen is a green clean fuel and chemical feedstock. Its separation and purification from hydrogencontaining mixtures is the key step in the production of hydrogen with high purity(>99.99%). In this work, carbon molecular sieve(CMS) membranes with ultrahigh permselectivity for hydrogen purification were fabricated by high-temperature(700–900 ℃) pyrolysis of polymeric precursor of phenolphthaleinbased cardo poly(arylene ether ketone)(PEK-C). The evolution of the microstructural texture and ultramicroporous structure and gas separation performance of the CMS membrane were characterized via TG-MS, FT-IR, XRD, TEM, CO2 sorption analysis and gas permeation measurements. CMS membranes prepared at 700 ℃ exhibited amorphous turbostratic carbon structures and high H2 permeability of 5260 Barrer with H2/CH4, H2/N2 and H2/CO selectivities of 311, 142, 75, respectively. When carbonized at900 ℃, the CMS membrane with ultrahigh H2/CH4 selectivity of 1859 was derived owing to the formation of the dense and ordered carbon structure. CMS membranes with ultrahigh permselectivity exhibit an attractive application prospect in hydrogen purification.展开更多
Photochemical oxidation of thiophene in n-octane/water extraction system using O2 as oxidant was studied. The reaction mechanism ofthiophene oxidation was proposed. Results obtained here can be used as the reference f...Photochemical oxidation of thiophene in n-octane/water extraction system using O2 as oxidant was studied. The reaction mechanism ofthiophene oxidation was proposed. Results obtained here can be used as the reference for the oxidative desulfurization of gasoline because thiophene is one of the main components containing sulfur in fluid catalytic cracking gasoline. Thiophene dissolved in n-octane was photodecomposed and removed into the water phase at ambient temperature and atmospheric pressure. A 500 W high-pressure mercury lamp (main wave length 365 nm, 0.22 kW/m) was used as light source for irradiation, and air was introduced by a gas pump to supply O2. Thiophene can be photo-oxidized to sulfone, oxalic acid, SO4^2-, and CO2. The desulfurization yield of thiophene in n-octane is 58.9% under photo-irradiation for 5 h under the conditions of air flow at 150 mL/min and V(water):V(n-octane)=1:1. It can be improved to 92.3% by adding 0.15 g zeoliteartificial into 100 mL reaction system, which is the adsorbent for O2 and thiophene. And under such conditions, the photo-oxidation kinetics of thiophene with O2/zeoliteartificial is first-order with an apparent rate constant of 0.5047 h^-1 and a half-time of 1.37 h. The sulfur content can be depressed from 800 μL/L to less than 62 μL/L.展开更多
A series of Cr-containing MCM-41 molecular sieves crystallized at room temperature with a hexagonal and well-ordered structure were synthesized. XRD, FT-IR and DRS UV-Vis techniques were used to characterize the sampl...A series of Cr-containing MCM-41 molecular sieves crystallized at room temperature with a hexagonal and well-ordered structure were synthesized. XRD, FT-IR and DRS UV-Vis techniques were used to characterize the samples. The results indicate incorporation of Cr into the MCM-41 framework, and dispersion of some CrsO3 on the surface or/and in the bulk of the MCM-41. Test of catalytic properties of the series of samples for the topic reaction was carried out using a continuous-flow fixed-bed quartz reactor. Factors influencing the catalytic performance for this title reaction, such as Cr/Si ratio in MCM- 41 and reaction temperature were investigated. The experimental results indicate that over the 5%CrMCM-41 a 43.27% conversion of ethane and a 86.70% selectivity for ethylene were achieved in the ethane dehydrogenation with COs to ethylene at 973 K. It is suggested that both Cr^6+ and Cr^3+ are the catalytic activity center.展开更多
Thermally stable mesoporous silica and Ti-containing molecular sieves have been synthesized at mild temperature using low-cost and biodegradable --- amphoteric tetradecyl betaine as template. The physicochemical chara...Thermally stable mesoporous silica and Ti-containing molecular sieves have been synthesized at mild temperature using low-cost and biodegradable --- amphoteric tetradecyl betaine as template. The physicochemical characterizations proved that Ti(IV) could be incorporated in the mesoporous struture.展开更多
Research and development of efficient, economical and resource-based flue gas desulfurization technology has always been a hot spot in the field of air pollution control. Molecular sieve materials have been paid atten...Research and development of efficient, economical and resource-based flue gas desulfurization technology has always been a hot spot in the field of air pollution control. Molecular sieve materials have been paid attention to by SO<sub>2</sub> adsorbent researchers due to their huge specific surface area. In this paper, 13X zeolite was modified with Cu(NO<sub>3</sub>) <sub>2</sub>·3H<sub>2</sub>O to obtain 13x-Xwt %CuO (calculated by the amount of CuO loaded). The adsorption time and capacity of SO<sub>2</sub> penetration sorbent and the isothermal curve of N<sub>2</sub> adsorption-desorption were studied. The results are as follows: 13X-3wt%CuO has the best adsorption effect, the penetration adsorption time is 110 min, the penetration adsorption capacity is 43.41 mg·g<sup>-1</sup>, the saturation adsorption capacity is 49.27 mg·g<sup>-1</sup>;The amount of CuO loading has a great influence on the adsorption effect of modified 13X molecular sieve on SO<sub>2</sub>. SEM and BET characterization showed that CuO modification did not change the external morphology of 13X molecular sieve, changed the pore size, but did not block the original channel of the molecular sieve, before and after modification belong to the type I adsorption isothermal curve. The pore size distribution and type of molecular sieve, as well as the content and type of alkali metal cations jointly control the adsorption process of SO<sub>2</sub> by 13X-xwt %CuO. XPS characterization showed that Cu(NO<sub>3</sub>) <sub>2</sub> decomposed into CuO and Cu<sub>2</sub>O during roasting at 450°C, CuO/Cu<sub>2</sub>O ≈ 1.5. The R<sup>2</sup> values of the quasi-second-order kinetic models obtained from the 13X-Xwt %CuO particle diffusion kinetic models were all above 0.99, indicating that the quasi-second-order kinetic equations were more relevant. Particle diffusion dynamics model in fitting results show that the adsorption process can be divided into two stages, the first phase of surface adsorption and diffusion rate in the granules common control process, more accurate dynamics model of the secondary in the second phase particle diffusion rate control stage, mainly for the micropore adsorption or chemical adsorption, quasi level 2 dynamic model conformity of variation;C is a constant not equal to 0, indicating that the adsorption of SO<sub>2</sub> is not completely through the form of intra-particle diffusion, and a small amount of chemisorption exists. And it is the compound effect of multiple adsorption mechanisms.展开更多
A TAPO-11 molecular sieve with the space group lcm2 was synthesized successfully. The samples with different space group were controlled simply only by adjusting the crystallization temperature (CT) in the hydrother...A TAPO-11 molecular sieve with the space group lcm2 was synthesized successfully. The samples with different space group were controlled simply only by adjusting the crystallization temperature (CT) in the hydrothermal system. In the system of gel with a molar composition of 0.7R- xTiO2: P2O5: Al2O3: 30H2O, where x is 0.01-0.10 and the R is a mixture of di-n-propylamine and diisopropylamine as templates. When CT was between 150-160℃, the calcined sample showed the space group of Icm^2, while it showed Pna21 at CT larger than 190℃. The characterizations of UV-Vis and FT-IR confirmed that Ti was incorporated into the AEL framework successfully.展开更多
In order to study the donor ability of ferrocenylimines as directing ortho metalation group(DMG) to lithium alkylide to prepare planar chiral ferrocene, a series of ferrocenyl schiff bases were synthesized by new me...In order to study the donor ability of ferrocenylimines as directing ortho metalation group(DMG) to lithium alkylide to prepare planar chiral ferrocene, a series of ferrocenyl schiff bases were synthesized by new methods using molecular sieves(0.4nm) and AlCl3 as catalysts. The reaction periods were reduced using these two catalysts in contrast with Al2O3, which was a traditional method used in the literature. In addition, as an important feature of these schiff bases, we found that they were unstable as oils in air or when filtrated through silica gel, but were stable as solids. The structures of the new compounds were confirmed by IR, ^1H NMR and HRMS.展开更多
The large pore molecular sieves VPI-5 and Si VPI-5 were synthesized by using three organic amines (dipropylamine, diisopropylamine and dipentylamine) as the structure-directing agents. Compared with general alumlnopho...The large pore molecular sieves VPI-5 and Si VPI-5 were synthesized by using three organic amines (dipropylamine, diisopropylamine and dipentylamine) as the structure-directing agents. Compared with general alumlnophosphate molecular sieves, the synthesis of the molecular sieves of VPI-5 type ls of many unique features. Both VPI-5 and Si-VPI-5 were characterized by XRD, IR, TG-DTA, and MAS-NMR.展开更多
The molecular sieve VPI-5 was synthesized by using various organic amines (DEA, Di-PA, DBA, DPenA, TBA, DEOA and TEOA) as the structure-directing agent. The use of DPA enlarged the range of the crystallization tempera...The molecular sieve VPI-5 was synthesized by using various organic amines (DEA, Di-PA, DBA, DPenA, TBA, DEOA and TEOA) as the structure-directing agent. The use of DPA enlarged the range of the crystallization temperature from 110℃ to 190℃ in the synthesis of VPI-5, while the use of TEOA changed the composition of the reactants in a broad variety. Diamines are the typical amines in the synthesis of VPI-5. Among them DBA and DPA are the most favorite structure-directing agents for the synthesis of VPI-5 molecular sieve.展开更多
Single crystals of the molecular sieve, MnAPO-5, were synthesized by hydrothermal synthesis in the presence of fluoride ions. It was shown by X-ray diffraction, infrared spectroscopy, electron paramagnetic resonance s...Single crystals of the molecular sieve, MnAPO-5, were synthesized by hydrothermal synthesis in the presence of fluoride ions. It was shown by X-ray diffraction, infrared spectroscopy, electron paramagnetic resonance spectroscopy, electron probe analysis and chemical composition analysis that the structure of MnAPO-5 is of the A1PO-5 type, and manganese(Ⅱ) is incorporated into the framework. Adsorption properties, thermal stability and surface acidity were also investigated.展开更多
A large single crystal of TPAF-AlPO4-5 molecular sieve was synthesized by hydrothermal crystallization in the presence of ammonium fluoride. Starting material composition was · 1 P2O5 · 1 Al2O3 · 2. 2 T...A large single crystal of TPAF-AlPO4-5 molecular sieve was synthesized by hydrothermal crystallization in the presence of ammonium fluoride. Starting material composition was · 1 P2O5 · 1 Al2O3 · 2. 2 TPAOH · 1. 7 NH4F ·318 H2O. The crystal size has a hexagonal prism with 80μm across and 500μm length.The structure of tetrapropylarnmonium fluoride - aluminium phosphate type-5 was investigated with X-ray diffraction. The unit cell composition is 12AlPO4 · TPAF, space group P6cc (a= 13. 740(5), c= 8. 474(4) A ). Average bond distances are: P-O 1. 564A and Al-O 1. 640A ,which may be due to the partial disorder of the arrangement of P, Al in the framework. The angles of O-T-O and T-O-T (T?P, Al) are 102-116° and 148-176°, respectively. Residue electron density was not well enough defined to give a precise position for tetrapropylammonium fluoride (TPAF). The template agent, TPA+ cations, situate in the 12-ring channels and F- anions locate in double 4-rings near the 12-ring channels. Fixing atomic positions for the TPAF reduced the unweighted and weighted R, R, from 0. 063 and 0. 082 to 0. 046 and 0. 042,respectively.展开更多
The nanostrutured mesoporous silica materials MCM-41 with different pore sizes were synthesized by adding 1,3,5-trimethylbenzene (TMB) as assistant agent in the reactant mixture. The obtained samples were investigated...The nanostrutured mesoporous silica materials MCM-41 with different pore sizes were synthesized by adding 1,3,5-trimethylbenzene (TMB) as assistant agent in the reactant mixture. The obtained samples were investigated by XRD, HRTEM, FTIR and N_2 adsorptions. It is shown that the pore sizes, ordered degree and specific surface area increase effectively with the incremental addition of TMB in an appropriate range, but the (100) peak intensity of XRD pattern becomes weakened and the ordered degree decreases when the additive quantity continued to increase. With the addition of TMB in an appropriate range, the effective surfactant ion pair packing parameter, g=V/a_0l, is mediated in the range of 1/3-1/2 with the increment of V and l, indicating that mesoporous silica is a well-ordered hexagonal structure. However, when the addition of TMB increases, g value becomes larger, which leads to a less long-range ordered structure for the uneven condissolution of TMB.展开更多
基金supported by the renewable energy and hydrogen projects in National Key Research and Development Plan of China(2019YFB1505000).
文摘Flue gas and coal bed methane are two important sources of greenhouse gases.Pressure swing adsorption process has a wide range of application in the field of gas separation,and the selection of adsorbent is crucial.In this regard,in order to assess the better adsorbent for separating CO_(2) from flue gas and CH_(4) from coal bed methane,adsorption isotherms of CO_(2),CH_(4) and N_(2) on activated carbon and carbon molecular sieve are measured at 303.15,318.15 and 333.15 K,and up to 250 kPa.The experimental data fit better with Langmuir 2 compared to Langmuir 3 and Langmuir-Freundlich models,and Clausius-Clapeyron equation was used to calculate the isosteric heat.Both the order of the adsorbed amount and the adsorption heat on the two adsorbents are CO_(2)>CH_(4)>N_(2).The adsorption kinetics are calculated by the pseudo-first kinetic model,and the order of adsorption rates on activated carbon is N_(2)-CH_(4)>CO_(2),while on carbon molecular sieve,it is CO_(2)-N_(2)>CH_(4).It is shown that relative molecular mass and adsorption heat are the primary effect on kinetics for activated carbon,while kinetic diameter is the main resistance factor for carbon molecular sieve.Moreover,the adsorption selectivity of CH_(4)/N_(2) and CO_(2)/N_(2) were estimated with the ideal adsorption solution theory,and carbon molecular sieve performed best at 318.15 K for both CO_(2) and CH_(4) separation.The study suggested that activated carbon is a better choice for separating flue gas and carbon molecular sieve can be a strong candidate for separating coal bed methane.
基金supported by the National Natural Science Foundation of China(42272202 and 52264001)the Yunnan Fundamental Research Projects(202201AT070144)+1 种基金the Yunnan Ten Thousand Talents Plan Young&Elite Talents Project(YNWRQNBJ-2019-164)Training Programmes of Innovation and Entrepreneurship for Undergraduates of Yunnan Province(S202210674128).
文摘In order to comprehend the applicability of microwave irradiation for recovering coalbed methane,it is necessary to evaluate the microwave irradiation-induced alterations in coals with varying levels of metamorphism.In this work,the carbon molecular sieve combined with KMnO_(4)oxidation was selected to fabricate carbon molecular sieve with diverse oxidation degrees,which can serve as model substances toward coals.Afterwards,the microwave irradiation dependences of pores,functional groups,and highpressure methane adsorption characteristics of model substances were studied.The results indicated that microwave irradiation causes rearrangement of oxygen-containing functional groups,which could block the micropores with a size of 0.40-0.60 nm in carbon molecular sieve;meanwhile,naphthalene and phenanthrene generated by macro-molecular structure pyrolysis due to microwave irradiation could block the micropores with a size of 0.70-0.90 nm.These alterations in micropore structure weaken the saturated methane adsorption capacity of oxidized carbon molecular sieve by 2.91%-23.28%,suggesting that microwave irradiation could promote methane desorption.Moreover,the increased mesopores found for oxidized carbon molecular sieve after microwave irradiation could benefit CH4 diffusion.In summary,the oxidized carbon molecular sieve can act as model substances toward coals with different ranks.Additionally,microwave irradiation is a promising technology to enhance coalbed methane recovery.
基金Graduate Innovation Project of Qinghai University for Nationalities(2021XJXS12)Graduate Innovation Project of Qinghai University for Nationalities(12M2021018).
文摘The activation effect of boric acid as an activator is good,and we investigate the best activation conditions for the boric acid impregnation method.To represent the structural characteristics and adsorption performance of the Stellera Chamaejasme based carbon molecular sieves,we use Brunner-Emmet-Teller(BET)measurements,scan-ning electron microscope(SEM),Raman spectra(Raman),X-ray diffraction(XRD),and adsorption property measurement.When the loading ratio was 0.68:1,the specific surface area was 532.21 m^(2)/g,the total pore volume was 0.24 cm 3/g,the average pore size was 1.81 nm,the adsorption value of methylene blue was 145.28 mg/g,and the adsorption value of iodine was 713.33 mg/g,the results showed that boric acid had better activation effect.The carbon molecular sieves made from Stellera Chamaejasme and activated with boric acid produce two peaks on the aperture distribution graph that are densely distributed in the micropore range.This indicates that boric acid’s pore-forming tendency is primarily micropore.
基金the National Key R&D Program of China(2017YFB0603403)National Natural Science Foundation of China(21676044,21878033,21978034)+1 种基金High Level Innovation Team of Liaoning Province(XLYC1908033)Fundamental Research Funds for the Central Universities(DUT19ZD211,DUT 2018TB02)for the financial support。
文摘Hydrogen is a green clean fuel and chemical feedstock. Its separation and purification from hydrogencontaining mixtures is the key step in the production of hydrogen with high purity(>99.99%). In this work, carbon molecular sieve(CMS) membranes with ultrahigh permselectivity for hydrogen purification were fabricated by high-temperature(700–900 ℃) pyrolysis of polymeric precursor of phenolphthaleinbased cardo poly(arylene ether ketone)(PEK-C). The evolution of the microstructural texture and ultramicroporous structure and gas separation performance of the CMS membrane were characterized via TG-MS, FT-IR, XRD, TEM, CO2 sorption analysis and gas permeation measurements. CMS membranes prepared at 700 ℃ exhibited amorphous turbostratic carbon structures and high H2 permeability of 5260 Barrer with H2/CH4, H2/N2 and H2/CO selectivities of 311, 142, 75, respectively. When carbonized at900 ℃, the CMS membrane with ultrahigh H2/CH4 selectivity of 1859 was derived owing to the formation of the dense and ordered carbon structure. CMS membranes with ultrahigh permselectivity exhibit an attractive application prospect in hydrogen purification.
基金Science and Technology Development Planning Foundation of Jilin Province, China(No.20030405)
文摘Photochemical oxidation of thiophene in n-octane/water extraction system using O2 as oxidant was studied. The reaction mechanism ofthiophene oxidation was proposed. Results obtained here can be used as the reference for the oxidative desulfurization of gasoline because thiophene is one of the main components containing sulfur in fluid catalytic cracking gasoline. Thiophene dissolved in n-octane was photodecomposed and removed into the water phase at ambient temperature and atmospheric pressure. A 500 W high-pressure mercury lamp (main wave length 365 nm, 0.22 kW/m) was used as light source for irradiation, and air was introduced by a gas pump to supply O2. Thiophene can be photo-oxidized to sulfone, oxalic acid, SO4^2-, and CO2. The desulfurization yield of thiophene in n-octane is 58.9% under photo-irradiation for 5 h under the conditions of air flow at 150 mL/min and V(water):V(n-octane)=1:1. It can be improved to 92.3% by adding 0.15 g zeoliteartificial into 100 mL reaction system, which is the adsorbent for O2 and thiophene. And under such conditions, the photo-oxidation kinetics of thiophene with O2/zeoliteartificial is first-order with an apparent rate constant of 0.5047 h^-1 and a half-time of 1.37 h. The sulfur content can be depressed from 800 μL/L to less than 62 μL/L.
基金This work was financially supported by the Sci—ence and Technology Department of Jilin Province,China(20040703—2)and the sub·Program of the Sci—ence and Technology Cooperation Project between China and Spain.
文摘A series of Cr-containing MCM-41 molecular sieves crystallized at room temperature with a hexagonal and well-ordered structure were synthesized. XRD, FT-IR and DRS UV-Vis techniques were used to characterize the samples. The results indicate incorporation of Cr into the MCM-41 framework, and dispersion of some CrsO3 on the surface or/and in the bulk of the MCM-41. Test of catalytic properties of the series of samples for the topic reaction was carried out using a continuous-flow fixed-bed quartz reactor. Factors influencing the catalytic performance for this title reaction, such as Cr/Si ratio in MCM- 41 and reaction temperature were investigated. The experimental results indicate that over the 5%CrMCM-41 a 43.27% conversion of ethane and a 86.70% selectivity for ethylene were achieved in the ethane dehydrogenation with COs to ethylene at 973 K. It is suggested that both Cr^6+ and Cr^3+ are the catalytic activity center.
文摘Thermally stable mesoporous silica and Ti-containing molecular sieves have been synthesized at mild temperature using low-cost and biodegradable --- amphoteric tetradecyl betaine as template. The physicochemical characterizations proved that Ti(IV) could be incorporated in the mesoporous struture.
文摘Research and development of efficient, economical and resource-based flue gas desulfurization technology has always been a hot spot in the field of air pollution control. Molecular sieve materials have been paid attention to by SO<sub>2</sub> adsorbent researchers due to their huge specific surface area. In this paper, 13X zeolite was modified with Cu(NO<sub>3</sub>) <sub>2</sub>·3H<sub>2</sub>O to obtain 13x-Xwt %CuO (calculated by the amount of CuO loaded). The adsorption time and capacity of SO<sub>2</sub> penetration sorbent and the isothermal curve of N<sub>2</sub> adsorption-desorption were studied. The results are as follows: 13X-3wt%CuO has the best adsorption effect, the penetration adsorption time is 110 min, the penetration adsorption capacity is 43.41 mg·g<sup>-1</sup>, the saturation adsorption capacity is 49.27 mg·g<sup>-1</sup>;The amount of CuO loading has a great influence on the adsorption effect of modified 13X molecular sieve on SO<sub>2</sub>. SEM and BET characterization showed that CuO modification did not change the external morphology of 13X molecular sieve, changed the pore size, but did not block the original channel of the molecular sieve, before and after modification belong to the type I adsorption isothermal curve. The pore size distribution and type of molecular sieve, as well as the content and type of alkali metal cations jointly control the adsorption process of SO<sub>2</sub> by 13X-xwt %CuO. XPS characterization showed that Cu(NO<sub>3</sub>) <sub>2</sub> decomposed into CuO and Cu<sub>2</sub>O during roasting at 450°C, CuO/Cu<sub>2</sub>O ≈ 1.5. The R<sup>2</sup> values of the quasi-second-order kinetic models obtained from the 13X-Xwt %CuO particle diffusion kinetic models were all above 0.99, indicating that the quasi-second-order kinetic equations were more relevant. Particle diffusion dynamics model in fitting results show that the adsorption process can be divided into two stages, the first phase of surface adsorption and diffusion rate in the granules common control process, more accurate dynamics model of the secondary in the second phase particle diffusion rate control stage, mainly for the micropore adsorption or chemical adsorption, quasi level 2 dynamic model conformity of variation;C is a constant not equal to 0, indicating that the adsorption of SO<sub>2</sub> is not completely through the form of intra-particle diffusion, and a small amount of chemisorption exists. And it is the compound effect of multiple adsorption mechanisms.
基金This work was supported by the National Natural Science Foundation of China (No. 20473027) Science and Technology Commission of Shanghai Municipality (No. 05dz22306)Pujiang project (No. 05PJ14041).
文摘A TAPO-11 molecular sieve with the space group lcm2 was synthesized successfully. The samples with different space group were controlled simply only by adjusting the crystallization temperature (CT) in the hydrothermal system. In the system of gel with a molar composition of 0.7R- xTiO2: P2O5: Al2O3: 30H2O, where x is 0.01-0.10 and the R is a mixture of di-n-propylamine and diisopropylamine as templates. When CT was between 150-160℃, the calcined sample showed the space group of Icm^2, while it showed Pna21 at CT larger than 190℃. The characterizations of UV-Vis and FT-IR confirmed that Ti was incorporated into the AEL framework successfully.
文摘In order to study the donor ability of ferrocenylimines as directing ortho metalation group(DMG) to lithium alkylide to prepare planar chiral ferrocene, a series of ferrocenyl schiff bases were synthesized by new methods using molecular sieves(0.4nm) and AlCl3 as catalysts. The reaction periods were reduced using these two catalysts in contrast with Al2O3, which was a traditional method used in the literature. In addition, as an important feature of these schiff bases, we found that they were unstable as oils in air or when filtrated through silica gel, but were stable as solids. The structures of the new compounds were confirmed by IR, ^1H NMR and HRMS.
基金Supported by the National Natural Science Foundation of China
文摘The large pore molecular sieves VPI-5 and Si VPI-5 were synthesized by using three organic amines (dipropylamine, diisopropylamine and dipentylamine) as the structure-directing agents. Compared with general alumlnophosphate molecular sieves, the synthesis of the molecular sieves of VPI-5 type ls of many unique features. Both VPI-5 and Si-VPI-5 were characterized by XRD, IR, TG-DTA, and MAS-NMR.
基金Supported by the National Natural Science Foundation of China
文摘The molecular sieve VPI-5 was synthesized by using various organic amines (DEA, Di-PA, DBA, DPenA, TBA, DEOA and TEOA) as the structure-directing agent. The use of DPA enlarged the range of the crystallization temperature from 110℃ to 190℃ in the synthesis of VPI-5, while the use of TEOA changed the composition of the reactants in a broad variety. Diamines are the typical amines in the synthesis of VPI-5. Among them DBA and DPA are the most favorite structure-directing agents for the synthesis of VPI-5 molecular sieve.
文摘Single crystals of the molecular sieve, MnAPO-5, were synthesized by hydrothermal synthesis in the presence of fluoride ions. It was shown by X-ray diffraction, infrared spectroscopy, electron paramagnetic resonance spectroscopy, electron probe analysis and chemical composition analysis that the structure of MnAPO-5 is of the A1PO-5 type, and manganese(Ⅱ) is incorporated into the framework. Adsorption properties, thermal stability and surface acidity were also investigated.
文摘A large single crystal of TPAF-AlPO4-5 molecular sieve was synthesized by hydrothermal crystallization in the presence of ammonium fluoride. Starting material composition was · 1 P2O5 · 1 Al2O3 · 2. 2 TPAOH · 1. 7 NH4F ·318 H2O. The crystal size has a hexagonal prism with 80μm across and 500μm length.The structure of tetrapropylarnmonium fluoride - aluminium phosphate type-5 was investigated with X-ray diffraction. The unit cell composition is 12AlPO4 · TPAF, space group P6cc (a= 13. 740(5), c= 8. 474(4) A ). Average bond distances are: P-O 1. 564A and Al-O 1. 640A ,which may be due to the partial disorder of the arrangement of P, Al in the framework. The angles of O-T-O and T-O-T (T?P, Al) are 102-116° and 148-176°, respectively. Residue electron density was not well enough defined to give a precise position for tetrapropylammonium fluoride (TPAF). The template agent, TPA+ cations, situate in the 12-ring channels and F- anions locate in double 4-rings near the 12-ring channels. Fixing atomic positions for the TPAF reduced the unweighted and weighted R, R, from 0. 063 and 0. 082 to 0. 046 and 0. 042,respectively.
文摘The nanostrutured mesoporous silica materials MCM-41 with different pore sizes were synthesized by adding 1,3,5-trimethylbenzene (TMB) as assistant agent in the reactant mixture. The obtained samples were investigated by XRD, HRTEM, FTIR and N_2 adsorptions. It is shown that the pore sizes, ordered degree and specific surface area increase effectively with the incremental addition of TMB in an appropriate range, but the (100) peak intensity of XRD pattern becomes weakened and the ordered degree decreases when the additive quantity continued to increase. With the addition of TMB in an appropriate range, the effective surfactant ion pair packing parameter, g=V/a_0l, is mediated in the range of 1/3-1/2 with the increment of V and l, indicating that mesoporous silica is a well-ordered hexagonal structure. However, when the addition of TMB increases, g value becomes larger, which leads to a less long-range ordered structure for the uneven condissolution of TMB.