A series of bifunctional catalysts composed of a component for higher alcohol synthesis (Cu-CoMn oxides, CCM) and an acidic zeolite (SAPO-34, ZSM-5, Y, MCM-41) were prepared for production of liquid hydrocarbon di...A series of bifunctional catalysts composed of a component for higher alcohol synthesis (Cu-CoMn oxides, CCM) and an acidic zeolite (SAPO-34, ZSM-5, Y, MCM-41) were prepared for production of liquid hydrocarbon directly from a bio-syngas through a one-stage pro-cess. The effects of zeolite type, zeolite content, Si/Al ratio and preparation method on catalyst texture and its reaction performance were investigated. Higher selectivities and yields of liquid products were obtained by using bifunctional catalysts. The yields of liquid hydrocarbons decreased in the order CCM-ZSM-5〉CCM-SAPO-34〉CCM-Y〉CCM-MCM-41. CCM-ZSM-5 (20wt%, Si/Al=100) prepared by coprecipitation method displayed the optimal catalytic performance with the highest CO conversion (76%) and yield of liquid products (30%). The catalysts were characterized by N2 adsorption/desorption, NH3-TPD, XRD, and H2-TPR analysis. The results showed that higher speci c surface areas and pore volumes of bifunctional catalysts were achieved by adding zeolites into CuCoMn precursors. Medium pore dimension and moderate acidity in CCM-ZSM-5 were observed, which proba-bly resulted in its excellent reaction performance. Additionally, a higher number of weaker acid sites (weak and/or medium acid sites) were formed by increasing ZSM-5 content in CCM-ZSM-5 or decreasing Si/Al ratio in ZSM-5. It was also seen that metal dispersion was higher and reducibility of metal ions was easier on the CCM-ZSM-5 catalyst prepared by coprecipitation. The higher alcohols-to-hydrocarbon process provides a promising route to hydrocarbon fuels via higher alcohols from syngas or biobased feedstocks.展开更多
A numerical investigation on the co-pyrolysis of 1,3-butadiene and propyne is performed to explore the synergistic effect between fuel components on aromatic hydrocarbon formation. A detailed kinetic model of 1,3-buta...A numerical investigation on the co-pyrolysis of 1,3-butadiene and propyne is performed to explore the synergistic effect between fuel components on aromatic hydrocarbon formation. A detailed kinetic model of 1,3-butadiene/propyne co-pyrolysis with the sub-mechanism of aromatic hydrocarbon formation is developed and validated on previous 1,3-butadiene and propyne pyrolysis experiments. The model is able to reproduce both the single component pyrolysis and the co-pyrolysis experiments, as well as the synergistic effect between 1,3- butadiene and propyne on the formation of a series of aromatic hydrocarbons. Based on the rate of production and sensitivity analyses, key reaction pathways in the fuel decomposition and aromatic hydrocarbon formation processes are revealed and insight into the synergistic effect on aromatic hydrocarbon formation is also achieved. The synergistic effect results from the interaction between 1,3-butadiene and propyne. The easily happened chain initiation in the 1,3-butadiene decomposition provides an abundant radical pool for propyne to undergo the H-atom abstraction and produce propargyl radical which plays key roles in the formation of aromatic hydrocarbons. Besides, the 1,3-butadiene/propyne co-pyrolysis includes high concentration levels of C3 and C4 precursors simultaneously, which stimulates the formation of key aromatic hydrocarbons such as toluene and naphthalene.展开更多
In recent years, production of engine fuels and energy from biomass has drawn much interest. In this work, we conducted a novel integrated process for the preparation of bio-hydrogen and bio-fuels using lignocellulosi...In recent years, production of engine fuels and energy from biomass has drawn much interest. In this work, we conducted a novel integrated process for the preparation of bio-hydrogen and bio-fuels using lignocellulosic biomass pyrolysis-oil (bio-oil). The process includes (i) the production of bio-hydrogen or bio-syngas by the catalytic cracking of bio-oil, (ii) the adjustment of bio-syngas, and (iii) the production of bio-fuels by ole nic polymerization (OP) together with Fischer-Tropsch synthesis (FTS). Under the optimal conditions, the yield of bio-hydrogen was 120.9 g H2/(kg bio-oil). The yield of hydrocarbon bio-fuels reached 526.1 g/(kg bio-syngas) by the coupling of OP and FTS. The main reaction pathways (or chemical processes) were discussed based on the products observed and the catalyst property.展开更多
The interaction potential index IPI(X) of 16 Br, C1, I, NO2, CN, CHO, COOH, CH3, CH: kinds of substituents X (X---OH, SH, NH2, :CH2, C-CH, Ph, COCH3, COOCH3) were proposed, which are derived from the experimenta...The interaction potential index IPI(X) of 16 Br, C1, I, NO2, CN, CHO, COOH, CH3, CH: kinds of substituents X (X---OH, SH, NH2, :CH2, C-CH, Ph, COCH3, COOCH3) were proposed, which are derived from the experimental enthalpies of formation △fHФ (g) values of monosubstituted straight-chain alkanes. Based on the IPI(X) and polarizability effect index, a simple and effective model was constructed to estimate the △fHФ (g) values of monosubstituted alkanes RX (including the branched derivatives). The present model takes into account not only the contributions of the alkyl R and the substituent X, but also the contribution of the interaction between R and X. Its stability and prediction ability was confirmed by the results of leave-one-out method. Compared with previous reported studies, the obtained equation can be used to estimate enthalpies of formation for much more kinds of monosubstituted alkanes with less parameters. Thus, it is recommended for the calculation of the △fHФ(g) for the RX.展开更多
Much attention is devoted to fluorescent dyes especially those with potential in versatile applications.Reactions under "click" conditions between nonfluorescent 3-azidocoumarins and terminal alkynes produce...Much attention is devoted to fluorescent dyes especially those with potential in versatile applications.Reactions under "click" conditions between nonfluorescent 3-azidocoumarins and terminal alkynes produced 3-(1,2,3-triazol-1-yl)coumarins,a novel type of fluorescent dyes with intense fluorescence.The structures of the new coumarins were characterized by 1H NMR,MS,and IR spectra.Fluorescence spectra measurement demonstrated excellent fluorescence performance of the triazolylcoumarins and this click reaction is a promising candidate for bioconjugation and bioimaging applications since both azide and alkynes are quite inert to biological systems.展开更多
Hydrazinolysis ofethylthiopyrimidine derivative 2 gave 2-hydrazinopyrimidine 3 which used as a convenient precursor for the synthesis of pyrazolylpyrimidines, hydrazones and pyrimidotriazines. Also, treatment of 2 wit...Hydrazinolysis ofethylthiopyrimidine derivative 2 gave 2-hydrazinopyrimidine 3 which used as a convenient precursor for the synthesis of pyrazolylpyrimidines, hydrazones and pyrimidotriazines. Also, treatment of 2 with ethyl chloroacetate yielded N^-carbethoxymethyl-2-ethylthio-pyrimidine 15, which on reaction with ethyl carbazate and hydrazine hydrate afforded pyrimidotriazine and imidazopyrimidine, respectively. Chlorination of 2 using phosphorous oxycbloride yielded 4-chloropyrimidine 18, which reacted with some heterocyclic compounds having vicinal amino cyano groups to give some new polynuclear heterocyclic system. Also, the effect of some active methylene compounds on 18 was also studied. Some of the newly synthesized compounds were tested as mollucicidal agents against Biomphlaria alexandrina snails that caused intestinal bilharzias, the national problem in Egypt.展开更多
Many studies have observed that leaf wax δDn-alkane values differed significantly between woods and grasses in modern plants, with grasses D-depleted by 40 %0-70 ‰. The reasons for the differences in leaf wax δDn-a...Many studies have observed that leaf wax δDn-alkane values differed significantly between woods and grasses in modern plants, with grasses D-depleted by 40 %0-70 ‰. The reasons for the differences in leaf wax δDn-alkane values between woods and grasses, however, remain unclear. In this study, we measured the δD values of soil water (δDsw), leaf water (δDlw), and leaf wax n-alkane (δDn-alkane) for woods and grasses. We found no significant differences in the δD values of soil water (P = 0.82) and leaf water (P= 0.74) between the two life forms of plants. Therefore, the differences in leaf wax δDn-alkane values between woods and grasses may correlate with inherent properties of different plant life forms, such as leaf structures, biosynthetic processes, and leaf morphologies. Moreover, it is also possible that soil water with different 6Dsw at different depths utilized by woods and grasses may be responsible for some of the differences in leaf wax δDn-alkane values between the two life forms of plants, if woods mainly use soil water from the 〉100 cm depth, whereas grasses mainly use soil water from the 〈100 cm depth. The results of this work allow us to better understand the leaf wax δDn-alkane values of different plant life forms in a region.展开更多
The thiamine-dependent enzyme (1R, 2S, 5S, 6S)-2-succinyl-5-enolpyruvyl-6-hydroxyl-3-cyclohexene-l-carboxylate (SEPHCHC) synthase, also known as MenD, catalyzes a Stetter-like reaction in the biosynthesis of vitam...The thiamine-dependent enzyme (1R, 2S, 5S, 6S)-2-succinyl-5-enolpyruvyl-6-hydroxyl-3-cyclohexene-l-carboxylate (SEPHCHC) synthase, also known as MenD, catalyzes a Stetter-like reaction in the biosynthesis of vitamin K. It is found to catalyze a novel reductive C-N bond ligation reaction between nitroarenes and et-ketoacids to form N-hydroxamates. This reaction likely pro- ceeds through an enzyme-mediated, slow two-electron reduction of the nitroalkanes to form a nitroso intermediate, which serves as the electrophilic acceptor of the ketoacid-derived acyl anion. The involvement of the nitroso intermediate is support- ed by the fact that similar N-hydroxamates are readily formed at a much higher rate when nitroso compounds replace the nitro substrates in the chemoenzymatic reactions. These results demonstrate that the thiamine-dependent enzyme is able to catalyze novel, nonnative reactions that may find new chemoenzymatic applications.展开更多
文摘A series of bifunctional catalysts composed of a component for higher alcohol synthesis (Cu-CoMn oxides, CCM) and an acidic zeolite (SAPO-34, ZSM-5, Y, MCM-41) were prepared for production of liquid hydrocarbon directly from a bio-syngas through a one-stage pro-cess. The effects of zeolite type, zeolite content, Si/Al ratio and preparation method on catalyst texture and its reaction performance were investigated. Higher selectivities and yields of liquid products were obtained by using bifunctional catalysts. The yields of liquid hydrocarbons decreased in the order CCM-ZSM-5〉CCM-SAPO-34〉CCM-Y〉CCM-MCM-41. CCM-ZSM-5 (20wt%, Si/Al=100) prepared by coprecipitation method displayed the optimal catalytic performance with the highest CO conversion (76%) and yield of liquid products (30%). The catalysts were characterized by N2 adsorption/desorption, NH3-TPD, XRD, and H2-TPR analysis. The results showed that higher speci c surface areas and pore volumes of bifunctional catalysts were achieved by adding zeolites into CuCoMn precursors. Medium pore dimension and moderate acidity in CCM-ZSM-5 were observed, which proba-bly resulted in its excellent reaction performance. Additionally, a higher number of weaker acid sites (weak and/or medium acid sites) were formed by increasing ZSM-5 content in CCM-ZSM-5 or decreasing Si/Al ratio in ZSM-5. It was also seen that metal dispersion was higher and reducibility of metal ions was easier on the CCM-ZSM-5 catalyst prepared by coprecipitation. The higher alcohols-to-hydrocarbon process provides a promising route to hydrocarbon fuels via higher alcohols from syngas or biobased feedstocks.
基金This work is supported by the National Natural Science Foundation of China (No.51476155, No.51622605, No.91541201), the National Key Sci- entific Instruments and Equipment Development Program of China (No.2012YQ22011305), the National Postdoctoral Program for Innovative Talents (No.BX201600100), and China Postdoctoral Science Foundation (No.2016M600312).
文摘A numerical investigation on the co-pyrolysis of 1,3-butadiene and propyne is performed to explore the synergistic effect between fuel components on aromatic hydrocarbon formation. A detailed kinetic model of 1,3-butadiene/propyne co-pyrolysis with the sub-mechanism of aromatic hydrocarbon formation is developed and validated on previous 1,3-butadiene and propyne pyrolysis experiments. The model is able to reproduce both the single component pyrolysis and the co-pyrolysis experiments, as well as the synergistic effect between 1,3- butadiene and propyne on the formation of a series of aromatic hydrocarbons. Based on the rate of production and sensitivity analyses, key reaction pathways in the fuel decomposition and aromatic hydrocarbon formation processes are revealed and insight into the synergistic effect on aromatic hydrocarbon formation is also achieved. The synergistic effect results from the interaction between 1,3-butadiene and propyne. The easily happened chain initiation in the 1,3-butadiene decomposition provides an abundant radical pool for propyne to undergo the H-atom abstraction and produce propargyl radical which plays key roles in the formation of aromatic hydrocarbons. Besides, the 1,3-butadiene/propyne co-pyrolysis includes high concentration levels of C3 and C4 precursors simultaneously, which stimulates the formation of key aromatic hydrocarbons such as toluene and naphthalene.
文摘In recent years, production of engine fuels and energy from biomass has drawn much interest. In this work, we conducted a novel integrated process for the preparation of bio-hydrogen and bio-fuels using lignocellulosic biomass pyrolysis-oil (bio-oil). The process includes (i) the production of bio-hydrogen or bio-syngas by the catalytic cracking of bio-oil, (ii) the adjustment of bio-syngas, and (iii) the production of bio-fuels by ole nic polymerization (OP) together with Fischer-Tropsch synthesis (FTS). Under the optimal conditions, the yield of bio-hydrogen was 120.9 g H2/(kg bio-oil). The yield of hydrocarbon bio-fuels reached 526.1 g/(kg bio-syngas) by the coupling of OP and FTS. The main reaction pathways (or chemical processes) were discussed based on the products observed and the catalyst property.
基金This work was supported by the National Natural Science Foundation of China (No.21072053 and No.20772028) and the Scientific Research Fund of Hunan Provincial Education Department (No.10K025 and No.09C386).
文摘The interaction potential index IPI(X) of 16 Br, C1, I, NO2, CN, CHO, COOH, CH3, CH: kinds of substituents X (X---OH, SH, NH2, :CH2, C-CH, Ph, COCH3, COOCH3) were proposed, which are derived from the experimental enthalpies of formation △fHФ (g) values of monosubstituted straight-chain alkanes. Based on the IPI(X) and polarizability effect index, a simple and effective model was constructed to estimate the △fHФ (g) values of monosubstituted alkanes RX (including the branched derivatives). The present model takes into account not only the contributions of the alkyl R and the substituent X, but also the contribution of the interaction between R and X. Its stability and prediction ability was confirmed by the results of leave-one-out method. Compared with previous reported studies, the obtained equation can be used to estimate enthalpies of formation for much more kinds of monosubstituted alkanes with less parameters. Thus, it is recommended for the calculation of the △fHФ(g) for the RX.
基金the Program for Changjiang Scholars and Innovative Research Teamin University(No.IRT0526)Shanghai Municipal Natural Science Foundation (No.06ZR14001)
文摘Much attention is devoted to fluorescent dyes especially those with potential in versatile applications.Reactions under "click" conditions between nonfluorescent 3-azidocoumarins and terminal alkynes produced 3-(1,2,3-triazol-1-yl)coumarins,a novel type of fluorescent dyes with intense fluorescence.The structures of the new coumarins were characterized by 1H NMR,MS,and IR spectra.Fluorescence spectra measurement demonstrated excellent fluorescence performance of the triazolylcoumarins and this click reaction is a promising candidate for bioconjugation and bioimaging applications since both azide and alkynes are quite inert to biological systems.
文摘Hydrazinolysis ofethylthiopyrimidine derivative 2 gave 2-hydrazinopyrimidine 3 which used as a convenient precursor for the synthesis of pyrazolylpyrimidines, hydrazones and pyrimidotriazines. Also, treatment of 2 with ethyl chloroacetate yielded N^-carbethoxymethyl-2-ethylthio-pyrimidine 15, which on reaction with ethyl carbazate and hydrazine hydrate afforded pyrimidotriazine and imidazopyrimidine, respectively. Chlorination of 2 using phosphorous oxycbloride yielded 4-chloropyrimidine 18, which reacted with some heterocyclic compounds having vicinal amino cyano groups to give some new polynuclear heterocyclic system. Also, the effect of some active methylene compounds on 18 was also studied. Some of the newly synthesized compounds were tested as mollucicidal agents against Biomphlaria alexandrina snails that caused intestinal bilharzias, the national problem in Egypt.
文摘Many studies have observed that leaf wax δDn-alkane values differed significantly between woods and grasses in modern plants, with grasses D-depleted by 40 %0-70 ‰. The reasons for the differences in leaf wax δDn-alkane values between woods and grasses, however, remain unclear. In this study, we measured the δD values of soil water (δDsw), leaf water (δDlw), and leaf wax n-alkane (δDn-alkane) for woods and grasses. We found no significant differences in the δD values of soil water (P = 0.82) and leaf water (P= 0.74) between the two life forms of plants. Therefore, the differences in leaf wax δDn-alkane values between woods and grasses may correlate with inherent properties of different plant life forms, such as leaf structures, biosynthetic processes, and leaf morphologies. Moreover, it is also possible that soil water with different 6Dsw at different depths utilized by woods and grasses may be responsible for some of the differences in leaf wax δDn-alkane values between the two life forms of plants, if woods mainly use soil water from the 〉100 cm depth, whereas grasses mainly use soil water from the 〈100 cm depth. The results of this work allow us to better understand the leaf wax δDn-alkane values of different plant life forms in a region.
文摘The thiamine-dependent enzyme (1R, 2S, 5S, 6S)-2-succinyl-5-enolpyruvyl-6-hydroxyl-3-cyclohexene-l-carboxylate (SEPHCHC) synthase, also known as MenD, catalyzes a Stetter-like reaction in the biosynthesis of vitamin K. It is found to catalyze a novel reductive C-N bond ligation reaction between nitroarenes and et-ketoacids to form N-hydroxamates. This reaction likely pro- ceeds through an enzyme-mediated, slow two-electron reduction of the nitroalkanes to form a nitroso intermediate, which serves as the electrophilic acceptor of the ketoacid-derived acyl anion. The involvement of the nitroso intermediate is support- ed by the fact that similar N-hydroxamates are readily formed at a much higher rate when nitroso compounds replace the nitro substrates in the chemoenzymatic reactions. These results demonstrate that the thiamine-dependent enzyme is able to catalyze novel, nonnative reactions that may find new chemoenzymatic applications.