The aromatic compounds,including o-xylene,m-xylene,p-xylene,and ethylbenzene,primarily originate from the catalytic reforming of crude oil,and have a wide variety of applications.However,because of similar physical an...The aromatic compounds,including o-xylene,m-xylene,p-xylene,and ethylbenzene,primarily originate from the catalytic reforming of crude oil,and have a wide variety of applications.However,because of similar physical and chemical properties,these compounds are difficult to be identified by gas chromatography(GC)without standard samples.With the development of modern nuclear magnetic resonance(NMR)techniques,NMR has emerged as a powerful and efficient tool for the rapid analysis of complex and crude mixtures without purification.In this study,the parameters of one-dimensional(1D)total correlation spectroscopy(TOCSY)NMR techniques,including 1D selective gradient TOCSY and 1D chemicalshift-selective filtration(CSSF)with TOCSY,were optimized to obtain comprehensive molecular structure information.The results indicate that the overlapped signals in NMR spectra of nonpolar aromatic compounds(including o-xylene,m-xylene,p-xylene and ethylbenzene),polar aromatic compounds(benzyl alcohol,benzaldehyde,benzoic acid),and aromatic compounds with additional conjugated bonds(styrene)can be resolved in 1D TOCSY.More importantly,full molecular structures can be clearly distinguished by setting appropriate mixing time in 1D TOCSY.This approach simplifies the NMR spectra,provides structural information of entire molecules,and can be applied for the analysis of other structural isomers.展开更多
The synthesis of a continuous IMF zeolite membrane was fabricated on tubular substrates by seeded growth for the first time. The straight channels of IMF zeolite with diameters of 0.53–0.59 nm are distinguishable for...The synthesis of a continuous IMF zeolite membrane was fabricated on tubular substrates by seeded growth for the first time. The straight channels of IMF zeolite with diameters of 0.53–0.59 nm are distinguishable for p-xylene from o-xylene molecules. Pure IMF-phase high-silica IM-5 zeolite seeds with uniform and fine crystal size were fabricated by a new sonication-assisted aging process. The seeds were coated on the support by dipcoating and induced the formation of continuous membrane. Separation performance in p-/o-xylene mixture was investigated at various temperature and pressure. The typical IM-5zeolite membrane had p-/o-xylene separation factor of 3.7. Our results suggest that IM-5 zeolite is a potentially good membrane material for the separation of xylene mixtures.展开更多
To obtain high yields of monocyclic aromatic hydrocarbons with methyl side chains,such as toluene and xylene,methane(CH_(4))can be introduced into the hydrocracking of polycyclic aromatic hydrocarbons.CH_(4)can partic...To obtain high yields of monocyclic aromatic hydrocarbons with methyl side chains,such as toluene and xylene,methane(CH_(4))can be introduced into the hydrocracking of polycyclic aromatic hydrocarbons.CH_(4)can participate in the reaction,supply methyl side chains to the product,and improve product distribution.In this study,the hydrogenation reaction of polycyclic aromatic hydrocarbons over a carbonized NiMo/Hβcatalyst in a CH_(4)and hydrogen(H_(2))environment was investigated to study the promotional effect of CH_(4)on the hydrocracking of polycyclic aromatics.Under conditions of 3.5 MPa,380℃,volume air velocity of 4 h^(-1),gas-oil volume ratio of 800,and H_(2):CH_(4)molar ratio of 1:1,the conversion rate of naphthalene was 99.97%,the liquid phase yield was 93.62%,and the selectivity of BTX were 17.76%,25.17%,and 20.47%,respectively.In comparison to the use of a H_(2)atmosphere,the selectivity of benzene was significantly decreased,whereas the selectivity of toluene and xylene were increased.It was shown that CH_(4)can participate in the hydrocracking of naphthalene and improve the selectivity of toluene and xylene in the liquid product.The carbonized NiMo/Hβcatalyst was characterized by a range of analytical methods(such as X-ray diffraction(XRD),ammonia-temperature-programmed desorption(NH3-TPD),hydrogen-temperature-programmed reduction(H_(2)-TPR),and X-ray photoelectron spectroscopy(XPS)).The results indicated that Ni and Mo carbides were the major species in the carbonized NiMo/Hβcatalyst and were considered to be active sites for the activation of CH_(4)and H_(2).After loading the metal components,the catalyst displayed prominent weak acidic sites,which may be suitable locations for cracking,alkylation,and other related reactions.Therefore,the carbonized NiMo/Hβcatalyst displayed multiple functions during the hydrocracking of polycyclic aromatic hydrocarbons in a CH_(4)and H_(2)environment.These results could be used to develop a new way to efficiently utilize polycyclic aromatic hydrocarbons and natural gas resources.展开更多
Catalytic methylation of toluene with methanol is an important alternative pathway for xylene production.Previous studies have indicated that methanol always undergoes several side reactions on acidic zeolites,resulti...Catalytic methylation of toluene with methanol is an important alternative pathway for xylene production.Previous studies have indicated that methanol always undergoes several side reactions on acidic zeolites,resulting in oxygencontaining byproducts such as dimethyl ethers,ketones,and carboxylic acids.Herein,the presence and distribution of the oxygenated compounds formed during toluene methylation were firstly examined by systematic chromatographic analysis.Plausible formation mechanisms for the various oxygenates are discussed.The most problematic byproduct is found to be acetic acid,which can lead to inferior product quality and damage downstream units.A feasible solution is presented for oxygenate removal after toluene methylation,in which acetic acid is eliminated by catalytic decomposition into low-boilingpoint acetone over a MgO catalyst.This process allows for all of the low-boiling-point oxygenates,including methanol,dimethyl ether,acetone,and butanone,to be removed from the aromatics phase,taking advantage of the temperature of the reaction effluent and standard distillation equipment.X-ray diffraction was used to characterize the crystal phase of the fresh and used MgO decarbonylation catalysts,while thermogravimetry/mass spectrometry and Fourier-transform infrared spectroscopy were applied to investigate the transformation mechanism of acetic acid over the decarbonylation catalyst.CO insertion and ketonization of acetic acid accounted for the formation and elimination of acetic acid,respectively.The combined methylation/decarbonylation process should enable the production of high-quality xylenes,an important industrial feedstock,by overcoming the main technical obstacles associated with the toluene methylation process.展开更多
Metal ions doping is a typical approach for tuning sensing properties of metal oxide semiconductors based gas sensors.Herein,hierarchical flower-like pure and In-doped Co_(3)O_(4) nanostructures assembled by porous tw...Metal ions doping is a typical approach for tuning sensing properties of metal oxide semiconductors based gas sensors.Herein,hierarchical flower-like pure and In-doped Co_(3)O_(4) nanostructures assembled by porous two-dimensional(2D)nanosheets are synthesized via a solvothermal method and annealing process.The sensing measurements display that the In@Co_(3)O_(4)-4 based sensor possesses high response value of 55.9 toward 100 ppm xylene at 150 ℃,which is nearly 3.8times larger than that of pure Co_(3)O_(4) sensor.Furthermore,it possesses good selectivity and anti-humidity properties.Combined with the results of DFT calculations,the mechanism of enhanced gas sensing performance is analyzed systematically.展开更多
A bimetal-exchanged NaY zeolite(Cu(Ⅰ)-Y(Ⅲ)-Y)with a desirable adsorptive desulfurization(ADS)performance was prepared and characterized by means of X-ray diffraction,specific surface area measurements,X-ray fluoresc...A bimetal-exchanged NaY zeolite(Cu(Ⅰ)-Y(Ⅲ)-Y)with a desirable adsorptive desulfurization(ADS)performance was prepared and characterized by means of X-ray diffraction,specific surface area measurements,X-ray fluorescence spectrometer,X-ray photoelectron spectroscopy,thermal gravity analysis and Fourier transform infrared spectroscopy.The effect of Y(Ⅲ)ions on ADS in the presence of the xylenes was investigated.Results indicated that the ADS performance of Y(Ⅲ)-Y is higher than that of most reported CeY.The Y(Ⅲ)-based Cu(Ⅰ)-Y(Ⅲ)-Y demonstrated the higher breakthrough loading than those of reported Ce(Ⅲ)/Ce(Ⅳ)-based transition metal Y zeolites,showing that Y(Ⅲ)ions play a promoting role in improving the ADS selectivity.For Cu(Ⅰ)-Y(Ⅲ)-Y,a new strong S-M interaction(S stands for sulfur,while M stands for metal)active site was formed,which might be caused by the synergistic effect between Cu(Ⅰ)and Y(Ⅲ).The Cu(Ⅰ)-Y(Ⅲ)-Y,which combined the advantages of Cu(I)-Y and Y(Ⅲ)-Y,is a kind of promising adsorbent.The breakthrough loading decreased in the order of Cu(Ⅰ)-Y(Ⅲ)-Y>Y(Ⅲ)-Y>Cu(Ⅰ)-Y,and the effect of xylene isomers on the sulfur removal was in the order of ortho-xylene>meta-xylene>para-xylene,which exhibited the same trend with the bond order of xylenes.展开更多
The acidity and acid distribution of hierarchical porous ZSM-5 were tailored via phosphate modification. The catalytic results showed that both benzene conversion and selectivity of toluene and xylene increased with t...The acidity and acid distribution of hierarchical porous ZSM-5 were tailored via phosphate modification. The catalytic results showed that both benzene conversion and selectivity of toluene and xylene increased with the presence of appropriate amount of phosphorus. Meanwhile, side reactions such as methanol to olefins related with the formation of by-product ethylbenzene formation and isomerization of xylene to meta-xylene were suppressed efficiently. The acid strength and sites amount of Br?nsted acid of the catalyst were crucial for improving benzene conversion and yield of xylene, whereas passivation of external surface acid sites played an important role in breaking thermodynamic equilibrium distribution of xylene isomers.展开更多
Objective This study was designed to conduct a retrospective and systematic occupational health risk assessment(OHRA)of enterprises that used benzene,toluene,and xylene(BTX)in Shanghai,China.Methods All data for the s...Objective This study was designed to conduct a retrospective and systematic occupational health risk assessment(OHRA)of enterprises that used benzene,toluene,and xylene(BTX)in Shanghai,China.Methods All data for the study were obtained from 1,705 occupational health examination and evaluation reports from 2013 to 2017,and a semiquantitative model following Chinese OHRA guidelines(GBZ/T 298-2017)was applied for the assessment.Results The selected enterprises using BTX were mainly involved in manufacturing of products.Using the exposure level method,health risk levels associated with exposure to BTX were classified as medium,negligible,or low.However,the risk levels associated with benzene and toluene were significantly different according to job types,with gluers and inkers exhibiting greater health risks.For the same job type,the health risk levels assessed using the comprehensive index method were higher than those using the exposure level method.Conclusion Our OHRA reveals that workers who are exposed to BTX still face excessive health risk.Additionally,the risk level varied depending on job categories and exposure to specific chemicals.Therefore,additional control measures recommended by OHRA guidelines are essential to reduce worker exposure levels.展开更多
The emerging FCC-based technologies are applied in an attempt to shift to the production of designated light olefins(including mainly ethylene and propylene) as well as light aromatics(including benzene, toluene, and ...The emerging FCC-based technologies are applied in an attempt to shift to the production of designated light olefins(including mainly ethylene and propylene) as well as light aromatics(including benzene, toluene, and xylene)developed by the Research Institute of Petroleum Processing(RIPP), SINOPEC. The RIPP's proprietary technologies covering the Deep Catalytic Cracking(DCC), the Enhanced Deep Catalytic Cracking(DCC-PLUS), and the Maximizing Catalytic Propylene(MCP) have been playing decisive roles in the processing of crude aimed at closer integration of petroleum refining and petrochemical production both inside and outside of China since 1990. Three cases of commercial applications in five refineries, including Case Ⅰ— the closer integration between the steam cracker and the DCC/DCC-PLUS unit, Case Ⅱ— the petrochemical refinery provided with a DCC-PLUS unit, and Case Ⅲ— the integrated petrochemical/fuels refinery provided with a MCP unit, have highlighted their far-reaching effects on global petrochemicals production.展开更多
A plug‐flow reactor coated with carbon‐doped TiO2 (C‐TiO2 ) powder was investigated for the control of vaporous aromatics (benzene, toluene, ethylbenzene, and o‐xylene (BTEX)) under a range of experimental conditi...A plug‐flow reactor coated with carbon‐doped TiO2 (C‐TiO2 ) powder was investigated for the control of vaporous aromatics (benzene, toluene, ethylbenzene, and o‐xylene (BTEX)) under a range of experimental conditions. The characteristics of the as‐prepared C‐TiO2 and a reference Degussa P25 TiO2 powder were examined using X‐ray diffraction, scanning electron microscopy, diffuse‐reflectance ultraviolet‐visible‐near infrared spectroscopy, and Fourier transform infrared spectroscopy. The experimental conditions for the photocatalytic performance of the as‐prepared C‐TiO2 photocatalyst were controlled using three operational parameters, relative humidity, flow rate, and input concentration. Unlike other target compounds, very little benzene was removed by the C‐TiO2 photocatalyst under visible‐light irradiation. In contrast, the C‐TiO2 exhibited higher removal efficiencies for the other three target compounds (toluene, ethylbenzene, and xylene) compared with those achieved using unmodified TiO2 under visible‐light irradiation. The highest removal efficiency was obtained at a relative humidity value of 45%. Specifically, the toluene removal efficiency determined at a relative humidity of 45% was 78%, whereas it was close to 0%, 7.2%, and 5.5% for relative humidity values of 20%, 70%, and 95%, respectively. In addition, the removal efficiencies for the three target compounds decreased as the flow rate or input concentration increased. These findings indicate that the as‐prepared C‐TiO2 photocatalyst could be used for the removal of toxic vaporous aromatics under optimized operating conditions.展开更多
This study aims to compare iso-rank vitrinite-rich and inertinite-rich coal samples to understand the impact of coal-forming processes on pyrolysis chemistry.A medium rank C bituminous coal was density-fractionated to...This study aims to compare iso-rank vitrinite-rich and inertinite-rich coal samples to understand the impact of coal-forming processes on pyrolysis chemistry.A medium rank C bituminous coal was density-fractionated to create a vitrinite-rich and an inertinite-rich sub-sample.The vitrinite-rich sample has 83 vol% total vitrinite (mineral-matter-free basis),whereas the inertinite-rich counterpart has 66 vol% total inertinite.The vitrinite-rich sample is dominated by collotelinite and collodetrinite.Fusinite,semifusinite,and inertodetrinite are the main macerals of the inertinite-rich sample.Molecular chemistry was assessed using a pyrolysis gas chromatograph (py-GC) equipped with a thermal desorption unit coupled to a time of flight mass spectrometer (MS) (py-GC/MS) and solid-state nuclear magnetic resonance (13C CP-MAS SS NMR).The pyrolysis products of the coal samples are generally similar,comprised of low and high molecular weight alkanes,alkylbenzenes,alkylphenols,and alkyl-subtituted polycyclic aromatic hydrocarbons,although the vitrinite-rich sample is chemically more diverse.The lack of diversity exhibited by the inertinite-rich sample upon pyrolysis may be interpreted to suggest that major components were heated in their geologic history.Based on the 13C CP-MAS SS NMR analysis,the inertinite-rich sample has a greater fraction of phenolics,reflected in the py-GC/MS results as substituted and unsubstituted derivatives.The greater abundance of phenolics for the inertinite-rich sample may suggest a fire-related origin for the dominant macerals of this sample.The C2-alkylbenzene isomers (p-xylene and o-xylene) were detected in the pyrolysis products for the vitrinite-rich and inertinite-rich samples,though more abundant in the former.The presence of these in both samples likely reflects common source vegetation for the dominant vitrinite and inertinite rnacerals.展开更多
Aromatic polybenzothiazolamides were prepared by low temperature solution method by condensing the 2, 2’-diarnino-6, 6’-bibenzothiazole with four different acid chlorides in quantitative yield. These polymers were c...Aromatic polybenzothiazolamides were prepared by low temperature solution method by condensing the 2, 2’-diarnino-6, 6’-bibenzothiazole with four different acid chlorides in quantitative yield. These polymers were characterized by IR and NMR. Viscosities of these polyamides range from 0.42 to 1 dl/gm. All these polymers were stable upto 300℃in air.展开更多
Instead of 2-(aroylmethylene)benzimidazolines 3 or 2-(aroyl-methyl)benzimidazoles 4, 4-aryl-2, 3-dihydro-1H-1, 5-benzodiazepin-2-ones 5 were obtained exclusively from the reaction of o-phenylenediamine (1) and ethyl a...Instead of 2-(aroylmethylene)benzimidazolines 3 or 2-(aroyl-methyl)benzimidazoles 4, 4-aryl-2, 3-dihydro-1H-1, 5-benzodiazepin-2-ones 5 were obtained exclusively from the reaction of o-phenylenediamine (1) and ethyl aroylacetates 2 in the presence of a catalytic amount of potassium hydroxide.展开更多
Surface species resulting from the decomposition of methanol on Na—、K—、Rb—、Cs—、BCs—、KCs— and KBCs—X zeolite at 420℃,and the relationship between sur-face species and the side chain alkylation selectivity ...Surface species resulting from the decomposition of methanol on Na—、K—、Rb—、Cs—、BCs—、KCs— and KBCs—X zeolite at 420℃,and the relationship between sur-face species and the side chain alkylation selectivity from toluene with methanol have beenstudied by infrared and gas chromatographic methods.展开更多
This paper reports the phase separation behavior of ABS filmscast on the surfaces of homopelymers or random copolymers.It is foundthat phase separation of ABS films was induced by the surfaces of thesubstrate polymers...This paper reports the phase separation behavior of ABS filmscast on the surfaces of homopelymers or random copolymers.It is foundthat phase separation of ABS films was induced by the surfaces of thesubstrate polymers.The relationship between the miscibility of the sub-strate polymers and the phase separation behavior of ABS films was alsoexamined.展开更多
High-performance liquid chromatographic systems for the separation of buckminsterfullerene(C<sub>60</sub>) and related fullerene C<sub>70</sub> were investigated with methanol/benzene or methan...High-performance liquid chromatographic systems for the separation of buckminsterfullerene(C<sub>60</sub>) and related fullerene C<sub>70</sub> were investigated with methanol/benzene or methanol/toluene (35/65-60/40 in Ⅴ/Ⅴ) as eluant in C18 reversed phase column. The system is suitable for fast analysis of fullerenes at lower percentage of methanol, and repeatly large scale perparation at higher percentage of methanol.展开更多
The reaction between 2,5-Dimethylpyrrole (1) and R<sub>F</sub>I (2)(R<sub>F</sub>: a, Cl(CF<sub>2</sub>)<sub>4</sub>; b, Cl(CF<sub>2</sub>)<sub>...The reaction between 2,5-Dimethylpyrrole (1) and R<sub>F</sub>I (2)(R<sub>F</sub>: a, Cl(CF<sub>2</sub>)<sub>4</sub>; b, Cl(CF<sub>2</sub>)<sub>6</sub>; c, Cl(CF<sub>2</sub>)<sub>8</sub>; d, n-C<sub>6</sub>F<sub>13</sub>; e, n-C<sub>8</sub>F<sub>17</sub>) in the presence of Na<sub>2</sub>S<sub>2</sub>O<sub>4</sub>-NaHCO<sub>3</sub> in acetonitrile resulted in the formation of 2-perfluoroalkyl-2,5-dimethyl-2H-pyrrole (3) as a major product in good yield.展开更多
The composite ZSM—5 zeolite/vermiculite catalyst,in which tiny ZSM—5 zeolite parti-cles embedded in the vermiculite substrate,has been synthesized by hydrothermal method with vermiculite assilicon source.The catalyt...The composite ZSM—5 zeolite/vermiculite catalyst,in which tiny ZSM—5 zeolite parti-cles embedded in the vermiculite substrate,has been synthesized by hydrothermal method with vermiculite assilicon source.The catalytic behavior of resulting catalyst for xylene isomerization,propylene aromatizationand toluene disproportionation is better than that of HZSM—5 zeolite.展开更多
基金We thank the Natural Science Foundation of Shanxi Province(202103021224439)National Natural Science Foundation of China(22075308)for financial support.
文摘The aromatic compounds,including o-xylene,m-xylene,p-xylene,and ethylbenzene,primarily originate from the catalytic reforming of crude oil,and have a wide variety of applications.However,because of similar physical and chemical properties,these compounds are difficult to be identified by gas chromatography(GC)without standard samples.With the development of modern nuclear magnetic resonance(NMR)techniques,NMR has emerged as a powerful and efficient tool for the rapid analysis of complex and crude mixtures without purification.In this study,the parameters of one-dimensional(1D)total correlation spectroscopy(TOCSY)NMR techniques,including 1D selective gradient TOCSY and 1D chemicalshift-selective filtration(CSSF)with TOCSY,were optimized to obtain comprehensive molecular structure information.The results indicate that the overlapped signals in NMR spectra of nonpolar aromatic compounds(including o-xylene,m-xylene,p-xylene and ethylbenzene),polar aromatic compounds(benzyl alcohol,benzaldehyde,benzoic acid),and aromatic compounds with additional conjugated bonds(styrene)can be resolved in 1D TOCSY.More importantly,full molecular structures can be clearly distinguished by setting appropriate mixing time in 1D TOCSY.This approach simplifies the NMR spectra,provides structural information of entire molecules,and can be applied for the analysis of other structural isomers.
基金the financial supports that are from the National Natural Science Foundation of China (21921006, U22A20414 and 21938007)the Natural Science Foundation of Jiangsu Province (BK20220002)the open project of the State Key Laboratory of China (KL21-04 and D2021FK055)。
文摘The synthesis of a continuous IMF zeolite membrane was fabricated on tubular substrates by seeded growth for the first time. The straight channels of IMF zeolite with diameters of 0.53–0.59 nm are distinguishable for p-xylene from o-xylene molecules. Pure IMF-phase high-silica IM-5 zeolite seeds with uniform and fine crystal size were fabricated by a new sonication-assisted aging process. The seeds were coated on the support by dipcoating and induced the formation of continuous membrane. Separation performance in p-/o-xylene mixture was investigated at various temperature and pressure. The typical IM-5zeolite membrane had p-/o-xylene separation factor of 3.7. Our results suggest that IM-5 zeolite is a potentially good membrane material for the separation of xylene mixtures.
基金the financial support from the Graduate Student Innovation and Practical Ability Training Program of Xi’an Shiyou University (No. YCS21212111)Open Fund Project of the State Key Laboratory of Heavy Oil, China (SKLHOP201703)+3 种基金National Natural Science Foundation of China (No. 52274039)Natural Science Foundation of Shaanxi Provincial Department of Education (Grant 2023-JC-YB-414)Natural Science Foundation of Shaanxi Province in China (No. 2022JZ-28)the Open Fund Project of the National Oil Shale Exploitation Research and Development Center, China (No. 33550022-ZC0613-0255)
文摘To obtain high yields of monocyclic aromatic hydrocarbons with methyl side chains,such as toluene and xylene,methane(CH_(4))can be introduced into the hydrocracking of polycyclic aromatic hydrocarbons.CH_(4)can participate in the reaction,supply methyl side chains to the product,and improve product distribution.In this study,the hydrogenation reaction of polycyclic aromatic hydrocarbons over a carbonized NiMo/Hβcatalyst in a CH_(4)and hydrogen(H_(2))environment was investigated to study the promotional effect of CH_(4)on the hydrocracking of polycyclic aromatics.Under conditions of 3.5 MPa,380℃,volume air velocity of 4 h^(-1),gas-oil volume ratio of 800,and H_(2):CH_(4)molar ratio of 1:1,the conversion rate of naphthalene was 99.97%,the liquid phase yield was 93.62%,and the selectivity of BTX were 17.76%,25.17%,and 20.47%,respectively.In comparison to the use of a H_(2)atmosphere,the selectivity of benzene was significantly decreased,whereas the selectivity of toluene and xylene were increased.It was shown that CH_(4)can participate in the hydrocracking of naphthalene and improve the selectivity of toluene and xylene in the liquid product.The carbonized NiMo/Hβcatalyst was characterized by a range of analytical methods(such as X-ray diffraction(XRD),ammonia-temperature-programmed desorption(NH3-TPD),hydrogen-temperature-programmed reduction(H_(2)-TPR),and X-ray photoelectron spectroscopy(XPS)).The results indicated that Ni and Mo carbides were the major species in the carbonized NiMo/Hβcatalyst and were considered to be active sites for the activation of CH_(4)and H_(2).After loading the metal components,the catalyst displayed prominent weak acidic sites,which may be suitable locations for cracking,alkylation,and other related reactions.Therefore,the carbonized NiMo/Hβcatalyst displayed multiple functions during the hydrocracking of polycyclic aromatic hydrocarbons in a CH_(4)and H_(2)environment.These results could be used to develop a new way to efficiently utilize polycyclic aromatic hydrocarbons and natural gas resources.
基金We gratefully acknowledge the support from the National 973 Program of China(Grant No.2003CB615800).
文摘Catalytic methylation of toluene with methanol is an important alternative pathway for xylene production.Previous studies have indicated that methanol always undergoes several side reactions on acidic zeolites,resulting in oxygencontaining byproducts such as dimethyl ethers,ketones,and carboxylic acids.Herein,the presence and distribution of the oxygenated compounds formed during toluene methylation were firstly examined by systematic chromatographic analysis.Plausible formation mechanisms for the various oxygenates are discussed.The most problematic byproduct is found to be acetic acid,which can lead to inferior product quality and damage downstream units.A feasible solution is presented for oxygenate removal after toluene methylation,in which acetic acid is eliminated by catalytic decomposition into low-boilingpoint acetone over a MgO catalyst.This process allows for all of the low-boiling-point oxygenates,including methanol,dimethyl ether,acetone,and butanone,to be removed from the aromatics phase,taking advantage of the temperature of the reaction effluent and standard distillation equipment.X-ray diffraction was used to characterize the crystal phase of the fresh and used MgO decarbonylation catalysts,while thermogravimetry/mass spectrometry and Fourier-transform infrared spectroscopy were applied to investigate the transformation mechanism of acetic acid over the decarbonylation catalyst.CO insertion and ketonization of acetic acid accounted for the formation and elimination of acetic acid,respectively.The combined methylation/decarbonylation process should enable the production of high-quality xylenes,an important industrial feedstock,by overcoming the main technical obstacles associated with the toluene methylation process.
文摘Metal ions doping is a typical approach for tuning sensing properties of metal oxide semiconductors based gas sensors.Herein,hierarchical flower-like pure and In-doped Co_(3)O_(4) nanostructures assembled by porous two-dimensional(2D)nanosheets are synthesized via a solvothermal method and annealing process.The sensing measurements display that the In@Co_(3)O_(4)-4 based sensor possesses high response value of 55.9 toward 100 ppm xylene at 150 ℃,which is nearly 3.8times larger than that of pure Co_(3)O_(4) sensor.Furthermore,it possesses good selectivity and anti-humidity properties.Combined with the results of DFT calculations,the mechanism of enhanced gas sensing performance is analyzed systematically.
基金the financial supports from the National Natural Science Foundation of China(81172204)。
文摘A bimetal-exchanged NaY zeolite(Cu(Ⅰ)-Y(Ⅲ)-Y)with a desirable adsorptive desulfurization(ADS)performance was prepared and characterized by means of X-ray diffraction,specific surface area measurements,X-ray fluorescence spectrometer,X-ray photoelectron spectroscopy,thermal gravity analysis and Fourier transform infrared spectroscopy.The effect of Y(Ⅲ)ions on ADS in the presence of the xylenes was investigated.Results indicated that the ADS performance of Y(Ⅲ)-Y is higher than that of most reported CeY.The Y(Ⅲ)-based Cu(Ⅰ)-Y(Ⅲ)-Y demonstrated the higher breakthrough loading than those of reported Ce(Ⅲ)/Ce(Ⅳ)-based transition metal Y zeolites,showing that Y(Ⅲ)ions play a promoting role in improving the ADS selectivity.For Cu(Ⅰ)-Y(Ⅲ)-Y,a new strong S-M interaction(S stands for sulfur,while M stands for metal)active site was formed,which might be caused by the synergistic effect between Cu(Ⅰ)and Y(Ⅲ).The Cu(Ⅰ)-Y(Ⅲ)-Y,which combined the advantages of Cu(I)-Y and Y(Ⅲ)-Y,is a kind of promising adsorbent.The breakthrough loading decreased in the order of Cu(Ⅰ)-Y(Ⅲ)-Y>Y(Ⅲ)-Y>Cu(Ⅰ)-Y,and the effect of xylene isomers on the sulfur removal was in the order of ortho-xylene>meta-xylene>para-xylene,which exhibited the same trend with the bond order of xylenes.
基金Supported by the National Natural Science Foundation of China(21476207,21506189)Zhejiang Postdoctoral Research Funded Projects(BSH1502147)
文摘The acidity and acid distribution of hierarchical porous ZSM-5 were tailored via phosphate modification. The catalytic results showed that both benzene conversion and selectivity of toluene and xylene increased with the presence of appropriate amount of phosphorus. Meanwhile, side reactions such as methanol to olefins related with the formation of by-product ethylbenzene formation and isomerization of xylene to meta-xylene were suppressed efficiently. The acid strength and sites amount of Br?nsted acid of the catalyst were crucial for improving benzene conversion and yield of xylene, whereas passivation of external surface acid sites played an important role in breaking thermodynamic equilibrium distribution of xylene isomers.
基金supported by research grants from the National Natural Science Foundation of China[No.81474929]。
文摘Objective This study was designed to conduct a retrospective and systematic occupational health risk assessment(OHRA)of enterprises that used benzene,toluene,and xylene(BTX)in Shanghai,China.Methods All data for the study were obtained from 1,705 occupational health examination and evaluation reports from 2013 to 2017,and a semiquantitative model following Chinese OHRA guidelines(GBZ/T 298-2017)was applied for the assessment.Results The selected enterprises using BTX were mainly involved in manufacturing of products.Using the exposure level method,health risk levels associated with exposure to BTX were classified as medium,negligible,or low.However,the risk levels associated with benzene and toluene were significantly different according to job types,with gluers and inkers exhibiting greater health risks.For the same job type,the health risk levels assessed using the comprehensive index method were higher than those using the exposure level method.Conclusion Our OHRA reveals that workers who are exposed to BTX still face excessive health risk.Additionally,the risk level varied depending on job categories and exposure to specific chemicals.Therefore,additional control measures recommended by OHRA guidelines are essential to reduce worker exposure levels.
基金Financial supports from the SINOPEC Research program (S111088, S105086, and S193046)
文摘The emerging FCC-based technologies are applied in an attempt to shift to the production of designated light olefins(including mainly ethylene and propylene) as well as light aromatics(including benzene, toluene, and xylene)developed by the Research Institute of Petroleum Processing(RIPP), SINOPEC. The RIPP's proprietary technologies covering the Deep Catalytic Cracking(DCC), the Enhanced Deep Catalytic Cracking(DCC-PLUS), and the Maximizing Catalytic Propylene(MCP) have been playing decisive roles in the processing of crude aimed at closer integration of petroleum refining and petrochemical production both inside and outside of China since 1990. Three cases of commercial applications in five refineries, including Case Ⅰ— the closer integration between the steam cracker and the DCC/DCC-PLUS unit, Case Ⅱ— the petrochemical refinery provided with a DCC-PLUS unit, and Case Ⅲ— the integrated petrochemical/fuels refinery provided with a MCP unit, have highlighted their far-reaching effects on global petrochemicals production.
基金supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MEST) (2011‐0027916)the Korea government (MEST) through GCRC‐SOP (2011‐0030658)Kyungpook National University Research Fund,2012
文摘A plug‐flow reactor coated with carbon‐doped TiO2 (C‐TiO2 ) powder was investigated for the control of vaporous aromatics (benzene, toluene, ethylbenzene, and o‐xylene (BTEX)) under a range of experimental conditions. The characteristics of the as‐prepared C‐TiO2 and a reference Degussa P25 TiO2 powder were examined using X‐ray diffraction, scanning electron microscopy, diffuse‐reflectance ultraviolet‐visible‐near infrared spectroscopy, and Fourier transform infrared spectroscopy. The experimental conditions for the photocatalytic performance of the as‐prepared C‐TiO2 photocatalyst were controlled using three operational parameters, relative humidity, flow rate, and input concentration. Unlike other target compounds, very little benzene was removed by the C‐TiO2 photocatalyst under visible‐light irradiation. In contrast, the C‐TiO2 exhibited higher removal efficiencies for the other three target compounds (toluene, ethylbenzene, and xylene) compared with those achieved using unmodified TiO2 under visible‐light irradiation. The highest removal efficiency was obtained at a relative humidity value of 45%. Specifically, the toluene removal efficiency determined at a relative humidity of 45% was 78%, whereas it was close to 0%, 7.2%, and 5.5% for relative humidity values of 20%, 70%, and 95%, respectively. In addition, the removal efficiencies for the three target compounds decreased as the flow rate or input concentration increased. These findings indicate that the as‐prepared C‐TiO2 photocatalyst could be used for the removal of toxic vaporous aromatics under optimized operating conditions.
基金The lead author acknowledges the Research,Education and Investment(REI)Fund of the Geological Society of South Africa(GSSA),National Research Foundation of South Africa(NRF),and the University of Johannesburg’s(UJ)Centre of Excellence for Integrated Mineral and Energy Resource Analysis(CIMERA)for funding.
文摘This study aims to compare iso-rank vitrinite-rich and inertinite-rich coal samples to understand the impact of coal-forming processes on pyrolysis chemistry.A medium rank C bituminous coal was density-fractionated to create a vitrinite-rich and an inertinite-rich sub-sample.The vitrinite-rich sample has 83 vol% total vitrinite (mineral-matter-free basis),whereas the inertinite-rich counterpart has 66 vol% total inertinite.The vitrinite-rich sample is dominated by collotelinite and collodetrinite.Fusinite,semifusinite,and inertodetrinite are the main macerals of the inertinite-rich sample.Molecular chemistry was assessed using a pyrolysis gas chromatograph (py-GC) equipped with a thermal desorption unit coupled to a time of flight mass spectrometer (MS) (py-GC/MS) and solid-state nuclear magnetic resonance (13C CP-MAS SS NMR).The pyrolysis products of the coal samples are generally similar,comprised of low and high molecular weight alkanes,alkylbenzenes,alkylphenols,and alkyl-subtituted polycyclic aromatic hydrocarbons,although the vitrinite-rich sample is chemically more diverse.The lack of diversity exhibited by the inertinite-rich sample upon pyrolysis may be interpreted to suggest that major components were heated in their geologic history.Based on the 13C CP-MAS SS NMR analysis,the inertinite-rich sample has a greater fraction of phenolics,reflected in the py-GC/MS results as substituted and unsubstituted derivatives.The greater abundance of phenolics for the inertinite-rich sample may suggest a fire-related origin for the dominant macerals of this sample.The C2-alkylbenzene isomers (p-xylene and o-xylene) were detected in the pyrolysis products for the vitrinite-rich and inertinite-rich samples,though more abundant in the former.The presence of these in both samples likely reflects common source vegetation for the dominant vitrinite and inertinite rnacerals.
文摘Aromatic polybenzothiazolamides were prepared by low temperature solution method by condensing the 2, 2’-diarnino-6, 6’-bibenzothiazole with four different acid chlorides in quantitative yield. These polymers were characterized by IR and NMR. Viscosities of these polyamides range from 0.42 to 1 dl/gm. All these polymers were stable upto 300℃in air.
基金This work was supported by the National Natural Science Foundation of China.
文摘Instead of 2-(aroylmethylene)benzimidazolines 3 or 2-(aroyl-methyl)benzimidazoles 4, 4-aryl-2, 3-dihydro-1H-1, 5-benzodiazepin-2-ones 5 were obtained exclusively from the reaction of o-phenylenediamine (1) and ethyl aroylacetates 2 in the presence of a catalytic amount of potassium hydroxide.
文摘Surface species resulting from the decomposition of methanol on Na—、K—、Rb—、Cs—、BCs—、KCs— and KBCs—X zeolite at 420℃,and the relationship between sur-face species and the side chain alkylation selectivity from toluene with methanol have beenstudied by infrared and gas chromatographic methods.
文摘This paper reports the phase separation behavior of ABS filmscast on the surfaces of homopelymers or random copolymers.It is foundthat phase separation of ABS films was induced by the surfaces of thesubstrate polymers.The relationship between the miscibility of the sub-strate polymers and the phase separation behavior of ABS films was alsoexamined.
文摘High-performance liquid chromatographic systems for the separation of buckminsterfullerene(C<sub>60</sub>) and related fullerene C<sub>70</sub> were investigated with methanol/benzene or methanol/toluene (35/65-60/40 in Ⅴ/Ⅴ) as eluant in C18 reversed phase column. The system is suitable for fast analysis of fullerenes at lower percentage of methanol, and repeatly large scale perparation at higher percentage of methanol.
文摘The reaction between 2,5-Dimethylpyrrole (1) and R<sub>F</sub>I (2)(R<sub>F</sub>: a, Cl(CF<sub>2</sub>)<sub>4</sub>; b, Cl(CF<sub>2</sub>)<sub>6</sub>; c, Cl(CF<sub>2</sub>)<sub>8</sub>; d, n-C<sub>6</sub>F<sub>13</sub>; e, n-C<sub>8</sub>F<sub>17</sub>) in the presence of Na<sub>2</sub>S<sub>2</sub>O<sub>4</sub>-NaHCO<sub>3</sub> in acetonitrile resulted in the formation of 2-perfluoroalkyl-2,5-dimethyl-2H-pyrrole (3) as a major product in good yield.
文摘The composite ZSM—5 zeolite/vermiculite catalyst,in which tiny ZSM—5 zeolite parti-cles embedded in the vermiculite substrate,has been synthesized by hydrothermal method with vermiculite assilicon source.The catalytic behavior of resulting catalyst for xylene isomerization,propylene aromatizationand toluene disproportionation is better than that of HZSM—5 zeolite.