The bimetallic NiCu/SAPO-11 catalysts were prepared by co-impregnation, sequential impregnation, coprecipitation, and mechanical mixing methods. Powder X-ray diffraction, nitrogen adsorption-desorption,temperature-pro...The bimetallic NiCu/SAPO-11 catalysts were prepared by co-impregnation, sequential impregnation, coprecipitation, and mechanical mixing methods. Powder X-ray diffraction, nitrogen adsorption-desorption,temperature-programmed desorption of ammonia, transmission electron microscopy, temperatureprogrammed reduction of hydrogen, and X-ray photoelectron spectroscopy were used to characterize the physicochemical properties of the catalysts. The catalytic performance of the catalysts was assessed by the hydroisomerization of n-octane. Results indicated that the conversion of n-octane and selectivity to n-octane isomers were related to the preparation methods of the catalysts. The catalysts with Ni-Cu alloy effectively restrained the hydrogenolysis reaction that decreases the selectivity of isomerization. The catalyst prepared by the mechanical mixing of NiO and CuO hardly formed Ni-Cu alloy, showing obvious hydrogenolysis and low selectivity to n-octane isomers. The unbalance between the metal and acid sites resulted in the low conversion of n-octane and selectivity to n-octane isomers. Among all the catalysts,the catalyst prepared by the co-impregnation method exhibited high catalytic activity and selectivity to n-octane isomers.展开更多
SAPO-11 molecular sieves were synthesized using silica sol, hydrophilic fumed silica, and tetraethyl orthosilicate（TEOS） as silicon precursors. Their physicochemical properties were characterized using XRD,SEM, nitr...SAPO-11 molecular sieves were synthesized using silica sol, hydrophilic fumed silica, and tetraethyl orthosilicate（TEOS） as silicon precursors. Their physicochemical properties were characterized using XRD,SEM, nitrogen adsorption-desorption, Py-IR, NH;-TPD, EDS, and;Al,;P,;Si MAS NMR techniques. The catalytic performance was assessed in the hydroisomerization of n-octane. The results showed that the silicon precursors influenced the physicochemical properties and catalytic performance of SAPO-11. SAPO-11 synthesized using hydrophilic fumed silica as silicon precursor showed higher silicon distribution and had more medium acid sites. SAPO-11 synthesized using TEOS as silicon precursor had more silicon content, but more silicon islands formed in its framework. The depolymerization of silicon precursors might affect the silicon content and distribution in SAPO-11. In the hydroisomerization of n-octane, the catalytic activity strongly depended on the number of medium acid sites instead of the number of total acid sites.SAPO-11 synthesized using hydrophilic fumed silica as silicon precursor exhibited higher catalytic activity than the other samples because it has more medium acid sites.展开更多
The catalyst NiW/HSAPO-11 was prepared by impregnating Ni and W onto HSAPO-11 zeolite with two different methods. The isomerization and aromatization properties were investigated with an microreactor using n-octane ...The catalyst NiW/HSAPO-11 was prepared by impregnating Ni and W onto HSAPO-11 zeolite with two different methods. The isomerization and aromatization properties were investigated with an microreactor using n-octane as a feedstock. NiW/HSAPO-11 shows a high hydroconversion activity of n-octane, and the optimum operating parameters for the catalyst to produce high octane number products were: 400℃, 2.0MPa, VH2:Vn-octane= 400:1, liquid hourly space velocity LHSV=1.0h-1. Under the optimum reaction condition, the conversion efficiency, C5 liquid + product selectivity, isomerization and aromatization product selectivity were 69.80%, 56.95%, 79.73% and 1.29% respectively. The catalyst (S1) impregnated with Ni and W after the HSAPO-11 zeolite was combined with Al2O3 matrix, performed better than the catalyst (S2) impregnated with Ni and W before combining with the Al2O3 matrix.展开更多
A bifunctional catalyst Pt/HY-β was prepared from a bimicroporous composite zeolite Y-β. Characterization results showed that the specific surface area, pore volume, and acid amount of the catalyst Pt/HY-β all decr...A bifunctional catalyst Pt/HY-β was prepared from a bimicroporous composite zeolite Y-β. Characterization results showed that the specific surface area, pore volume, and acid amount of the catalyst Pt/HY-β all decreased compared to the original zeolite. The catalytic performance of this catalyst in n-octane hydroisomerization was investigated in a fixed bed stainless steel tubular reactor. The results showed that at a hydrogen/n-octane volume ratio of 1000, pressure of 0.6 MPa, temperature of 230 ℃ and LHSV of 3 h^-1, the conversion of n-octane, yield of liquid, hydrocracking rate and yield of iso-octane were 52.32%, 88.66%, 12.60%, 39.51%, respectively.展开更多
（R）-2-hydroxy-3-phenylpropionic acid （PIP,） is an ideal antimicrobial compound with broad-spectrum activity against a wide range of Gram-positive bacteria, some Gram-negative bacteria, and fungi. We studied the bi...（R）-2-hydroxy-3-phenylpropionic acid （PIP,） is an ideal antimicrobial compound with broad-spectrum activity against a wide range of Gram-positive bacteria, some Gram-negative bacteria, and fungi. We studied the bioconversion of phenylpyruvate （PPA） to PLA using whole recombinant Escherichia coli cells in a series of buffer/organic solvent systems. Octane was found to be the best organic solvent. The optimum volume ratio of the water phase to the n-octane phase, conversion temperature, substrate concentration, and cell concentration were 6：4, 40 ℃, 12.5 g/L, and 30 g/L wet cells, respectively. Under the optimized conditions, the average PLA productivity in the aqueous/ n-octane system was 30.69% higher than that in the aqueous system, and 32.31 g/L PLA was obtained with the use of a stirred reactor （2-L scale）. Taken together, our findings indicated that PLA biosynthesis was more efficient in an aqueous/n-octane biphasic system than in a monophasic aqueous system. The proposed biphasic system is an effective strategy for enhancing PLA yield and the biosynthesis of its analogues.展开更多
A seed-directed approach to synthesizing Fe ZSM-22 zeolite without organic structure directing agent(OSDA)was developed by using Fe-rich diatomite as all aluminum and iron sources.The Fe ZSM-22zeolite with optimal cry...A seed-directed approach to synthesizing Fe ZSM-22 zeolite without organic structure directing agent(OSDA)was developed by using Fe-rich diatomite as all aluminum and iron sources.The Fe ZSM-22zeolite with optimal crystallinity and purity can be obtained by systematically adjusting feed composition and synthesis conditions.Characterizations show that Fe ZSM-22 zeolite synthesized with OSDA-free owns high crystallinity,obvious thin needle-shaped morphology and high Bronsted/Lewis acid ratio.Significantly,when used for n-octane hydroisomerization reaction,its derived catalyst exhibits the best catalytic performance reflected by the highest selectivity to C_(8)isomers compared to the two reference catalysts prepared based on a Fe-containing and a Fe-free ZSM-22 synthesized through an OSDA-directed route from natural diatomite and conventional chemicals,respectively.This work provides an alternative route to sustainably synthesizing heteroatomic zeolites with high performance.展开更多
Zn-modified ZSM-5 catalysts are widely used in alkane aromatization.Self-pillared ZSM-5 zeolites are ideal supports to anchor metals due to their high specific surface areas and abundant Si-OH defects,facilitating the...Zn-modified ZSM-5 catalysts are widely used in alkane aromatization.Self-pillared ZSM-5 zeolites are ideal supports to anchor metals due to their high specific surface areas and abundant Si-OH defects,facilitating the dispersion of metal precursors in the zeolite.In this work,with self-pillared ZSM-5 zeolite nanosheets as the support,Zn_(x)/SPZSM-5 catalysts were prepared by the incipient wet impregnation method,and the evolution in structure,acidity,and Zn species distribution was studied.Their catalytic performance for n-octane aromatization was also evaluated.NH_(3)-temperature-programmed desorption,pyridine adsorption infrared spectra,X-ray photoelectron spectroscopy,and X-ray absorption spectroscopy results indicated that[ZnOH]^(+)species are formed by introducing zinc into ZSM-5 zeolite,at the expense of the silanol hydroxyl and proton acid sites.The distribution of acid sites,the nature of zinc species,and the subsequent catalytic performance of Zn_(x)/SPZSM-5 catalysts in n-octane aromatization are significantly influenced by the zinc contents.A linear correlation exists between the amount of[ZnOH]^(x)species and the selectivity of aromatics for n-octane aromatization over the Zn_(x)/SPZSM-5 catalysts.This could be attributed to the[ZnOH]^(x)species being a critical species for promoting BTX(benzene,toluene,and xylene)formation,which can enhance the alkanes dehydrogenation and olefins aromatization,thus improving BTX selectivity.展开更多
This paper introduces the terahertz time- domain spectroscopy （THz-TDS） used for the quantitative detection of n-heptane volume ratios in 41 n-heptane and n-octane mixtures with the concentration range of 0-100% at ...This paper introduces the terahertz time- domain spectroscopy （THz-TDS） used for the quantitative detection of n-heptane volume ratios in 41 n-heptane and n-octane mixtures with the concentration range of 0-100% at the intervals of 2.5%. Among 41 samples, 33 were used for calibration and the remaining 8 tbr validation. Models of chemometrics methods, including partial least squares （PLS） and back propagation-artificial neural network （BP-ANN）, were built between the THz- TDS and the n-heptane percentage. To evaluate the quality of the built models, we calculated the correlation coefficient （R） and root-mean-square errors （RMSE） of calibration and validation models. R and RMSE of two methods were close to 1 and 0 within acceptable levels, respectively, demonstrating that the combination of THz- TDS and chemometrics methods is a potential and promising tool for further quantitative detection of n- alkanes.展开更多
Zinc-modified Pt/SAPO-11 catalysts were prepared by incipient wetness impregnation and assessed in the hydroisomerization of n-octane.Their physicochemical properties were investigated using powder X-ray diffraction,s...Zinc-modified Pt/SAPO-11 catalysts were prepared by incipient wetness impregnation and assessed in the hydroisomerization of n-octane.Their physicochemical properties were investigated using powder X-ray diffraction,scanning electron microscopy,nitrogen adsorption-desorption,pyridine-adsorbed infrared spectroscopy,temperature-programmed desorption of NH3,temperature-programmed reduction of hydrogen,temperature-programmed desorption of hydrogen,transmission electron microscopy,and X-ray photoelectron spectroscopy.The addition of zinc resulted in high dispersion of platinum.Zinc acted as a competitive adsorbent,changed the location of platinum.The catalyst with a zinc loading of 0.5%gave the highest selectivity to dimethylhexanes,but the conversion was lower than those achieved with the other catalysts.Dimethylhexanes have large molecular diameters,and therefore their diffusion may be difficult.This weakens the catalytic activity of the zinc-modified catalysts and lowers the n-octane conversion.展开更多
Two solvent mixtures: n-pentane/n-hexane and n-heptane/n-octane at ten different percentage ratios were used to dissolve 2.5 g of vacuum distilled Anthan crude oil residue (500°C). The crude oil/n-alkane mixture ...Two solvent mixtures: n-pentane/n-hexane and n-heptane/n-octane at ten different percentage ratios were used to dissolve 2.5 g of vacuum distilled Anthan crude oil residue (500°C). The crude oil/n-alkane mixture in different conical flasks was stoppered, shaked mechanically and allowed to stand overnight. The resultant solution was subsequently filtered using a vacuum pump to afford the different weights of the residue (asphaltenes). The result of the weights of asphaltenes obtained at the different ratios of solvent mixtures showed that the highest amount of precipitate was obtained at 100% n-pentane solvent. Also there was a sharp increase in the amount of asphaltenes precipitated when the percentage ratio of n-pentane to n-hexane precipitant was 40:60 and when the ratio of n-heptane to n-octane precipitant was 30:70. A good understanding of the contribution of the different n-alkane solvents in the precipitation of asphaltenes is very necessary to flow assurance of crude oils in terms of solid precipitation.展开更多
基金supported by the National Natural Science Foundation of China (No. 21676300)
文摘The bimetallic NiCu/SAPO-11 catalysts were prepared by co-impregnation, sequential impregnation, coprecipitation, and mechanical mixing methods. Powder X-ray diffraction, nitrogen adsorption-desorption,temperature-programmed desorption of ammonia, transmission electron microscopy, temperatureprogrammed reduction of hydrogen, and X-ray photoelectron spectroscopy were used to characterize the physicochemical properties of the catalysts. The catalytic performance of the catalysts was assessed by the hydroisomerization of n-octane. Results indicated that the conversion of n-octane and selectivity to n-octane isomers were related to the preparation methods of the catalysts. The catalysts with Ni-Cu alloy effectively restrained the hydrogenolysis reaction that decreases the selectivity of isomerization. The catalyst prepared by the mechanical mixing of NiO and CuO hardly formed Ni-Cu alloy, showing obvious hydrogenolysis and low selectivity to n-octane isomers. The unbalance between the metal and acid sites resulted in the low conversion of n-octane and selectivity to n-octane isomers. Among all the catalysts,the catalyst prepared by the co-impregnation method exhibited high catalytic activity and selectivity to n-octane isomers.
基金supported by the National Natural Science Foundation,China(no.21676300)
文摘SAPO-11 molecular sieves were synthesized using silica sol, hydrophilic fumed silica, and tetraethyl orthosilicate（TEOS） as silicon precursors. Their physicochemical properties were characterized using XRD,SEM, nitrogen adsorption-desorption, Py-IR, NH;-TPD, EDS, and;Al,;P,;Si MAS NMR techniques. The catalytic performance was assessed in the hydroisomerization of n-octane. The results showed that the silicon precursors influenced the physicochemical properties and catalytic performance of SAPO-11. SAPO-11 synthesized using hydrophilic fumed silica as silicon precursor showed higher silicon distribution and had more medium acid sites. SAPO-11 synthesized using TEOS as silicon precursor had more silicon content, but more silicon islands formed in its framework. The depolymerization of silicon precursors might affect the silicon content and distribution in SAPO-11. In the hydroisomerization of n-octane, the catalytic activity strongly depended on the number of medium acid sites instead of the number of total acid sites.SAPO-11 synthesized using hydrophilic fumed silica as silicon precursor exhibited higher catalytic activity than the other samples because it has more medium acid sites.
文摘The catalyst NiW/HSAPO-11 was prepared by impregnating Ni and W onto HSAPO-11 zeolite with two different methods. The isomerization and aromatization properties were investigated with an microreactor using n-octane as a feedstock. NiW/HSAPO-11 shows a high hydroconversion activity of n-octane, and the optimum operating parameters for the catalyst to produce high octane number products were: 400℃, 2.0MPa, VH2:Vn-octane= 400:1, liquid hourly space velocity LHSV=1.0h-1. Under the optimum reaction condition, the conversion efficiency, C5 liquid + product selectivity, isomerization and aromatization product selectivity were 69.80%, 56.95%, 79.73% and 1.29% respectively. The catalyst (S1) impregnated with Ni and W after the HSAPO-11 zeolite was combined with Al2O3 matrix, performed better than the catalyst (S2) impregnated with Ni and W before combining with the Al2O3 matrix.
基金sponsored by China Petroleumand Chemical Corporation(No.:090701)
文摘A bifunctional catalyst Pt/HY-β was prepared from a bimicroporous composite zeolite Y-β. Characterization results showed that the specific surface area, pore volume, and acid amount of the catalyst Pt/HY-β all decreased compared to the original zeolite. The catalytic performance of this catalyst in n-octane hydroisomerization was investigated in a fixed bed stainless steel tubular reactor. The results showed that at a hydrogen/n-octane volume ratio of 1000, pressure of 0.6 MPa, temperature of 230 ℃ and LHSV of 3 h^-1, the conversion of n-octane, yield of liquid, hydrocracking rate and yield of iso-octane were 52.32%, 88.66%, 12.60%, 39.51%, respectively.
基金Project supported by the National Natural Science Foundation of China(Nos.31470092 and 31501459)the Natural Science Youth Foundation of Jiangsu Province(No.BK20130380)China
文摘（R）-2-hydroxy-3-phenylpropionic acid （PIP,） is an ideal antimicrobial compound with broad-spectrum activity against a wide range of Gram-positive bacteria, some Gram-negative bacteria, and fungi. We studied the bioconversion of phenylpyruvate （PPA） to PLA using whole recombinant Escherichia coli cells in a series of buffer/organic solvent systems. Octane was found to be the best organic solvent. The optimum volume ratio of the water phase to the n-octane phase, conversion temperature, substrate concentration, and cell concentration were 6：4, 40 ℃, 12.5 g/L, and 30 g/L wet cells, respectively. Under the optimized conditions, the average PLA productivity in the aqueous/ n-octane system was 30.69% higher than that in the aqueous system, and 32.31 g/L PLA was obtained with the use of a stirred reactor （2-L scale）. Taken together, our findings indicated that PLA biosynthesis was more efficient in an aqueous/n-octane biphasic system than in a monophasic aqueous system. The proposed biphasic system is an effective strategy for enhancing PLA yield and the biosynthesis of its analogues.
基金the financial supports from the National Natural Science Foundation of China(22322803,22178059,22208054,22221005,22072019)Key Technologies Innovation and Industrialization Projects of Fujian Province(2022G031)Qingyuan Innovation Laboratory(00121002,00523005)。
文摘A seed-directed approach to synthesizing Fe ZSM-22 zeolite without organic structure directing agent(OSDA)was developed by using Fe-rich diatomite as all aluminum and iron sources.The Fe ZSM-22zeolite with optimal crystallinity and purity can be obtained by systematically adjusting feed composition and synthesis conditions.Characterizations show that Fe ZSM-22 zeolite synthesized with OSDA-free owns high crystallinity,obvious thin needle-shaped morphology and high Bronsted/Lewis acid ratio.Significantly,when used for n-octane hydroisomerization reaction,its derived catalyst exhibits the best catalytic performance reflected by the highest selectivity to C_(8)isomers compared to the two reference catalysts prepared based on a Fe-containing and a Fe-free ZSM-22 synthesized through an OSDA-directed route from natural diatomite and conventional chemicals,respectively.This work provides an alternative route to sustainably synthesizing heteroatomic zeolites with high performance.
基金supported by the Scientific Research Funding Project of Liaoning Province(2024-MS-110,LJKQZ20221476)the Guangxi Science and Technology Major Program(GUIKEAA24206022)+3 种基金the Joint Special Open Innovation Foundation of Liaoning Binhai Laboratory(LBLG-2024-03)the Liaoning Province International Science and Technology Cooperation Program Project(2024JH2/102100004)the Shenyang Young and Middle-aged Scientific and Technological Innovation Talents Support Plan(RC220357)the Postgraduate Education Reform Project of Liaoning Province(LNYJG2022400)。
文摘Zn-modified ZSM-5 catalysts are widely used in alkane aromatization.Self-pillared ZSM-5 zeolites are ideal supports to anchor metals due to their high specific surface areas and abundant Si-OH defects,facilitating the dispersion of metal precursors in the zeolite.In this work,with self-pillared ZSM-5 zeolite nanosheets as the support,Zn_(x)/SPZSM-5 catalysts were prepared by the incipient wet impregnation method,and the evolution in structure,acidity,and Zn species distribution was studied.Their catalytic performance for n-octane aromatization was also evaluated.NH_(3)-temperature-programmed desorption,pyridine adsorption infrared spectra,X-ray photoelectron spectroscopy,and X-ray absorption spectroscopy results indicated that[ZnOH]^(+)species are formed by introducing zinc into ZSM-5 zeolite,at the expense of the silanol hydroxyl and proton acid sites.The distribution of acid sites,the nature of zinc species,and the subsequent catalytic performance of Zn_(x)/SPZSM-5 catalysts in n-octane aromatization are significantly influenced by the zinc contents.A linear correlation exists between the amount of[ZnOH]^(x)species and the selectivity of aromatics for n-octane aromatization over the Zn_(x)/SPZSM-5 catalysts.This could be attributed to the[ZnOH]^(x)species being a critical species for promoting BTX(benzene,toluene,and xylene)formation,which can enhance the alkanes dehydrogenation and olefins aromatization,thus improving BTX selectivity.
文摘This paper introduces the terahertz time- domain spectroscopy （THz-TDS） used for the quantitative detection of n-heptane volume ratios in 41 n-heptane and n-octane mixtures with the concentration range of 0-100% at the intervals of 2.5%. Among 41 samples, 33 were used for calibration and the remaining 8 tbr validation. Models of chemometrics methods, including partial least squares （PLS） and back propagation-artificial neural network （BP-ANN）, were built between the THz- TDS and the n-heptane percentage. To evaluate the quality of the built models, we calculated the correlation coefficient （R） and root-mean-square errors （RMSE） of calibration and validation models. R and RMSE of two methods were close to 1 and 0 within acceptable levels, respectively, demonstrating that the combination of THz- TDS and chemometrics methods is a potential and promising tool for further quantitative detection of n- alkanes.
基金supported by the National Natural Science Foundation of China(21676300)~~
文摘Zinc-modified Pt/SAPO-11 catalysts were prepared by incipient wetness impregnation and assessed in the hydroisomerization of n-octane.Their physicochemical properties were investigated using powder X-ray diffraction,scanning electron microscopy,nitrogen adsorption-desorption,pyridine-adsorbed infrared spectroscopy,temperature-programmed desorption of NH3,temperature-programmed reduction of hydrogen,temperature-programmed desorption of hydrogen,transmission electron microscopy,and X-ray photoelectron spectroscopy.The addition of zinc resulted in high dispersion of platinum.Zinc acted as a competitive adsorbent,changed the location of platinum.The catalyst with a zinc loading of 0.5%gave the highest selectivity to dimethylhexanes,but the conversion was lower than those achieved with the other catalysts.Dimethylhexanes have large molecular diameters,and therefore their diffusion may be difficult.This weakens the catalytic activity of the zinc-modified catalysts and lowers the n-octane conversion.
文摘Two solvent mixtures: n-pentane/n-hexane and n-heptane/n-octane at ten different percentage ratios were used to dissolve 2.5 g of vacuum distilled Anthan crude oil residue (500°C). The crude oil/n-alkane mixture in different conical flasks was stoppered, shaked mechanically and allowed to stand overnight. The resultant solution was subsequently filtered using a vacuum pump to afford the different weights of the residue (asphaltenes). The result of the weights of asphaltenes obtained at the different ratios of solvent mixtures showed that the highest amount of precipitate was obtained at 100% n-pentane solvent. Also there was a sharp increase in the amount of asphaltenes precipitated when the percentage ratio of n-pentane to n-hexane precipitant was 40:60 and when the ratio of n-heptane to n-octane precipitant was 30:70. A good understanding of the contribution of the different n-alkane solvents in the precipitation of asphaltenes is very necessary to flow assurance of crude oils in terms of solid precipitation.
