Starch,as a typical polysaccharide with natural spherical morphology,is not only a preferred precursor for preparing carbon materials but also a model polymer for investigating thermochemical evolution mechanisms.Howe...Starch,as a typical polysaccharide with natural spherical morphology,is not only a preferred precursor for preparing carbon materials but also a model polymer for investigating thermochemical evolution mechanisms.However,starch usually suffers from severe foaming and low carbon yield during direct pyrolysis.Herein,we report a simple and eco-friendly dry strategy,by maleic anhydride initiating the esterification of starch,to design carbon microspheres against the starch foaming.Moreover,the infuence of ester grafting on the pyrolytic behavior of starch is also focused.The formation of ester groups in precursor guarantees the structural stability of starch-based intermediate because it can promote the accumulation of unsaturated species and accelerate the water elimination during pyrolysis.Meanwhile,the esterification and dehydration reactions greatly deplete the primary hydroxyl groups in the starch molecules and thus the rapid levoglucosan release is inhibited,which well keeps the spherical morphology of starch and ensures the high carbon yield.In further exploration as anode materials for Lithium-ion batteries,the obtained carbon microspheres exhibit good cyclability and rate performance with a reversible capacity of 444 m Ah g^(-1)at 50 m A g^(-1).This work provides theoretical fundamentals for the controllable thermal transformation of biomass towards wide applications.展开更多
In this work, the hydrogenation of maleic anhydride to succinic anhydride in the presence of 5 m%Ni/clay catalysts was investigated. These catalysts were characterized by X-ray diffraction （XRD）, H2 temperature prog...In this work, the hydrogenation of maleic anhydride to succinic anhydride in the presence of 5 m%Ni/clay catalysts was investigated. These catalysts were characterized by X-ray diffraction （XRD）, H2 temperature programmed reduction （TPR） and thermogravimetric analysis （TGA） techniques. The XRD and TPR studies showed that Ni was present as Ni2＋ on the support, which indicated that there were no elemental nickel （Ni^0） and Ni203 species in the unreduced samples. Increasing of calcination temperature to 650 ℃ leads to destruction of the support structure observed in TGA, while the catalyst sample calcined at 550 ℃ exhibits better performances than other samples. The ideal conversion of maleic anhydride （97.14%） and selectivity of succinic anhydride （99.55%） were realized at a reaction temperature of 180 ℃ and a weight hourly space velocity of 4 h^-1 under a reaction pressure of 1 MPa.展开更多
The colloidal carbon microspheres(CMS)were prepared by the hydrothermal method.The nickel catalysts supported on carbon microspheres(Ni/CMS)were further prepared and were characterized by the Fourier transform infrare...The colloidal carbon microspheres(CMS)were prepared by the hydrothermal method.The nickel catalysts supported on carbon microspheres(Ni/CMS)were further prepared and were characterized by the Fourier transform infrared spectroscopy(FTIR),the X-ray diffraction(XRD),the scanning electron microscopy(SEM),the transmission electron microscopy(TEM),and the N_(2)adsorption technique.The selective hydrogenation of maleic anhydride(MA)to succinic anhydride(SA)over the Ni/CMS catalysts was investigated.The results indicated that the Ni/CMS catalyst,which was prepared with glucose as carbon source and calcined at 500℃,exhibited the best performance.The hydrogen pressure,reaction temperature,and reaction time could significantly affect the conversion of maleic anhydride during the hydrogenation reaction.A 98.4%conversion of MA and an 100%selectivity to SA were achieved over the Ni/CMS catalyst in acetic anhydride solvent under mild conditions covering a temperature of 90℃,a H2 pressure of 1.0 MPa,and a reaction time of 3 h.展开更多
A decorated ruthenium catalyst was prepared by the coprecipitation method and used for the selective hydrogenation of maleic anhydride(MA) to γ-butyrolactone(GBL). The as-prepared catalyst was characterized by XRD, T...A decorated ruthenium catalyst was prepared by the coprecipitation method and used for the selective hydrogenation of maleic anhydride(MA) to γ-butyrolactone(GBL). The as-prepared catalyst was characterized by XRD, TGDTG and N2 adsorption techniques. The characterization tests revealed that the catalyst carrier was composed of monoclinic zirconia(m-ZrO2) and hydroxyl cobalt oxide(CoO(OH)). The hydrogenation results showed that the content of CoO(OH), the reaction temperature, the hydrogen pressure and the reaction time significantly affected the catalytic selectivity to GBL. The promotional effect of CoO(OH) was remarkable, which led to an obvious increase in GBL selectivity. An 100% MA conversion and 92.0% selectivity to GBL were achieved over the Ru/ZrO2-CoO(OH)(35%) catalyst in water solvent under the conditions involving a reaction temperature of 180 ℃, a hydrogen pressure of 3.0 MPa, and a reaction time of 6 h.展开更多
Plasma polymerized maleic anhydride （MA） was carried out by using maleic anhydride supersaturated ethanol solution as a precursor in a dielectric barrier discharge （DBD）. The film properties were characterized by ...Plasma polymerized maleic anhydride （MA） was carried out by using maleic anhydride supersaturated ethanol solution as a precursor in a dielectric barrier discharge （DBD）. The film properties were characterized by water contact angle （WCA）, Fourier transfer infrared （FTIR）, X-ray photoelectron spectroscopy （XPS）, atomic force microscope （AFM） analysis, and a thickness profilometer. The influence of the processing parameters on the film properties such as tile power frequency and polymerization zone was investigated. The results show that anhydride group incorporated into the growing films is favorable at the frequency of 80 kHz and working pressure of 50 Pa. The poly （maleic anhydride） film is uniform and compact at an average deposition rate of 8 nm/min.展开更多
In this study, Cr and Co promoted, as well as unpromoted vanadium phosphate （VPO） catalysts were synthesized by the reaction of V2O5 and o-H3PO4 in organic medium followed by calcination in n-butane/air environment ...In this study, Cr and Co promoted, as well as unpromoted vanadium phosphate （VPO） catalysts were synthesized by the reaction of V2O5 and o-H3PO4 in organic medium followed by calcination in n-butane/air environment at 673 K. The physico-chemical properties and the catalytic behavior were affected by the addition of Cr and Co dopants. H2-TPR was used to investigate the nature of oxidants in the unpromoted and promoted catalysts. The results showed that both the Cr and Co promoters remarkably lowered the temperature of the reduction peak associated with V^5＋. The amount of oxygen species originated from the active phase, V^4＋, removed was significantly increased for Co and Cr-promoted catalysts. Both Cr and Co dopants improve strongly the n-butane conversion without sacrificing the MA selectivity. A good correlation was observed between the amount of oxygen species removed from V^4＋ phase and the activity for n-butane oxidation to maleic anhydride. This suggested that V^4＋-O was the center for the activation of n-butane.展开更多
Four vanadium phosphate catalysts supported on γ-A1203 （20 wt%） were synthesized via wetness impregnation of VOHPO4.0.5H2O precursor and calcined for different durations （6, 10, 30 and 75 h） at 673 K in a reactio...Four vanadium phosphate catalysts supported on γ-A1203 （20 wt%） were synthesized via wetness impregnation of VOHPO4.0.5H2O precursor and calcined for different durations （6, 10, 30 and 75 h） at 673 K in a reaction flow of n-butane/air mixture. The samples calcined for 6 and 10 h produced only a single phase of （VO）2P2O7. However, the VOPO4 phase （β-VOPO4） was detected and became more prominent with only a minor pyrophosphate peaks were found after 30 h of calcination. All these pyrophosphate peaks disappeared after 75 h of calcination. The formation of V^5＋ phase was also observed in the SEM micrographs. The redox properties and the nature of oxidants of the catalysts employed in this study were investigated by H2-TPR analysis. Selective oxidation of n-butane to maleic anhydride （MA） over these catalysts shows that the percentage of n-butane conversion decreases with the transformation of the catalysts from V^4＋ to V^5＋ phases. An appropriate ratio of V^5＋/V^4＋ can enhance the performance of the VPO catalyst. However, a higher amount of V^5＋ and its associated oxygen species are responsible to promote the MA selectivity.展开更多
The modified petroleum resin emulsion prepared from the C9petroleum resin was modified with maleic anhydride.The effects of maleic rosin and maleic anhydride addition level,the modification time and the alkali liquor ...The modified petroleum resin emulsion prepared from the C9petroleum resin was modified with maleic anhydride.The effects of maleic rosin and maleic anhydride addition level,the modification time and the alkali liquor on the properties of the emulsion were discussed.The results showed that the optimum process conditions covered:a maleic anhydride mass fraction of 1.5%,a maleic rosin mass fraction of 10%,a KOH mass fraction of 1%,a petroleum resin modification temperature of 200℃,a petroleum resin modification duration of 3 h,and a modified petroleum resin emulsion/wax emulsion mixing ratio of 1:1.The particle size of modified petroleum resin emulsion prepared under these conditions was equal to 104.166μm.展开更多
This study focuses on the effects of reducing solvents used in the preparation of vanadyl pyrophosphate （VPO）, and ZrO2 and （ZrO）2P2O7 promoters on the structure and catalytic performance of VPO catalysts. The VPO...This study focuses on the effects of reducing solvents used in the preparation of vanadyl pyrophosphate （VPO）, and ZrO2 and （ZrO）2P2O7 promoters on the structure and catalytic performance of VPO catalysts. The VPO catalysts were prepared by the following steps： 1） Formation of vanadium phosphate by the reaction of V2O5 and H3PO4, 2） Synthesis of VPO precursor through the reduction of vanadium phosphate by reducing solvents, and 3） Activation of the precursor. For Zr promoted VPO, Zr was added to the precursor before activation. The P/V atomic ratios of different VPO catalysts, which were prepared by using different reducing solvents, were different. The precursor prepared by using isobutanol or isobutanol-benzyl alcohol contained VO（H2PO4）2 and VOHPO4·0.5H2O. The precursor prepared by using hexanol also contained VO（H2PO4）2 and VOHPO4·0.5H2O crystal phases, but the amount of VOHPO4·0.5H2O was much less than that of VO（H2PO4）2. After activation, all the VPO catalysts, prepared by using different reducing solvents, contained only the （VO）2P2O7 crystal phase. The VPO prepared by using isobutanol-petroleum ether as reducing solvent was the most active, while the VPO prepared by using hexanol had the lowest activity. Nevertheless, their total selectivity to phthalic and maleic anhydrides was almost the same. Both ZrO2 and （ZrO）2P2O7 promoters increased the activity and selectivity of VPO, but ZrO2 promoter increased the activity of VPO more drastically than （ZrO）2P2O7 promoter.展开更多
A bipolymer maleic anhydride-methyl acrylate （MAMA） was synthesized from maleic anhydride and methyl acrylate based on molecular design.MAMA further reacted with oleylamine or octadecyl alcohol to generate two comb ...A bipolymer maleic anhydride-methyl acrylate （MAMA） was synthesized from maleic anhydride and methyl acrylate based on molecular design.MAMA further reacted with oleylamine or octadecyl alcohol to generate two comb polymers called Oleamide-MAMA （NMAMA） and OctadecanolMAMA （OMAMA）,respectively.The structure of both the polymers was confirmed by their infrared spectral analysis （IR）,gel permeation chromatography analysis （GPC） and differential scanning calorimeter （DSC）.Moreover,the pour point depressing （PPD） properties of these comb polymers were examined experimentally.Experimental results showed that besides the molecular weight and concentration of the polymers,the length of side chains and the number of functional groups also had great influence on the pour point depressing performance.The π bonds and hydrogen bonds between depressants were the key factors for improving the pour point depressing properties.These results suggest that both OMAMA and NMAMA are potential pour point depressants for industry.展开更多
A series of vanadyl pyrophosphate catalyst （VPO） modified by different additives have been prepared with the aim to study the performance for selective conversion of n-butane to maleic anhydride（MA）. The addition ...A series of vanadyl pyrophosphate catalyst （VPO） modified by different additives have been prepared with the aim to study the performance for selective conversion of n-butane to maleic anhydride（MA）. The addition of various promoters improved the catalytic performance remarkably on both activity and selectivity. The correlation of activity and selectivity of the catalysts with their structure has been discussed. The increase in BET surface areas and surface redox sites leads to an enhanced activity. However, good selectivity can only be obtained on those surfaces with suitable surface acid sites.展开更多
基金supported by the National Science Foundation for Excellent Young Scholars of China(21922815)the Key Research and Development(R&D)Projects of Shanxi Province(201903D121180)the National Key Research and Development(R&D)Program of China。
文摘Starch,as a typical polysaccharide with natural spherical morphology,is not only a preferred precursor for preparing carbon materials but also a model polymer for investigating thermochemical evolution mechanisms.However,starch usually suffers from severe foaming and low carbon yield during direct pyrolysis.Herein,we report a simple and eco-friendly dry strategy,by maleic anhydride initiating the esterification of starch,to design carbon microspheres against the starch foaming.Moreover,the infuence of ester grafting on the pyrolytic behavior of starch is also focused.The formation of ester groups in precursor guarantees the structural stability of starch-based intermediate because it can promote the accumulation of unsaturated species and accelerate the water elimination during pyrolysis.Meanwhile,the esterification and dehydration reactions greatly deplete the primary hydroxyl groups in the starch molecules and thus the rapid levoglucosan release is inhibited,which well keeps the spherical morphology of starch and ensures the high carbon yield.In further exploration as anode materials for Lithium-ion batteries,the obtained carbon microspheres exhibit good cyclability and rate performance with a reversible capacity of 444 m Ah g^(-1)at 50 m A g^(-1).This work provides theoretical fundamentals for the controllable thermal transformation of biomass towards wide applications.
文摘In this work, the hydrogenation of maleic anhydride to succinic anhydride in the presence of 5 m%Ni/clay catalysts was investigated. These catalysts were characterized by X-ray diffraction （XRD）, H2 temperature programmed reduction （TPR） and thermogravimetric analysis （TGA） techniques. The XRD and TPR studies showed that Ni was present as Ni2＋ on the support, which indicated that there were no elemental nickel （Ni^0） and Ni203 species in the unreduced samples. Increasing of calcination temperature to 650 ℃ leads to destruction of the support structure observed in TGA, while the catalyst sample calcined at 550 ℃ exhibits better performances than other samples. The ideal conversion of maleic anhydride （97.14%） and selectivity of succinic anhydride （99.55%） were realized at a reaction temperature of 180 ℃ and a weight hourly space velocity of 4 h^-1 under a reaction pressure of 1 MPa.
基金The authors are grateful for the financial supports of the Project of Research and Development Fund of Nanchong City(19YFZJ0107,18YFZJ0041)the Meritocracy Research Funds of China West Normal University(17YC041)the Undergraduate Training Program for Innovation of China West Normal University.(cxcy2020186).
文摘The colloidal carbon microspheres(CMS)were prepared by the hydrothermal method.The nickel catalysts supported on carbon microspheres(Ni/CMS)were further prepared and were characterized by the Fourier transform infrared spectroscopy(FTIR),the X-ray diffraction(XRD),the scanning electron microscopy(SEM),the transmission electron microscopy(TEM),and the N_(2)adsorption technique.The selective hydrogenation of maleic anhydride(MA)to succinic anhydride(SA)over the Ni/CMS catalysts was investigated.The results indicated that the Ni/CMS catalyst,which was prepared with glucose as carbon source and calcined at 500℃,exhibited the best performance.The hydrogen pressure,reaction temperature,and reaction time could significantly affect the conversion of maleic anhydride during the hydrogenation reaction.A 98.4%conversion of MA and an 100%selectivity to SA were achieved over the Ni/CMS catalyst in acetic anhydride solvent under mild conditions covering a temperature of 90℃,a H2 pressure of 1.0 MPa,and a reaction time of 3 h.
基金the financial support from the Natural Science Foundation of China(No.21303139)the Key Fund Project of Educational Department of Sichuan Province(No.14ZA0126)the Open Project of Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province(No.CSPC2013-1)
文摘A decorated ruthenium catalyst was prepared by the coprecipitation method and used for the selective hydrogenation of maleic anhydride(MA) to γ-butyrolactone(GBL). The as-prepared catalyst was characterized by XRD, TGDTG and N2 adsorption techniques. The characterization tests revealed that the catalyst carrier was composed of monoclinic zirconia(m-ZrO2) and hydroxyl cobalt oxide(CoO(OH)). The hydrogenation results showed that the content of CoO(OH), the reaction temperature, the hydrogen pressure and the reaction time significantly affected the catalytic selectivity to GBL. The promotional effect of CoO(OH) was remarkable, which led to an obvious increase in GBL selectivity. An 100% MA conversion and 92.0% selectivity to GBL were achieved over the Ru/ZrO2-CoO(OH)(35%) catalyst in water solvent under the conditions involving a reaction temperature of 180 ℃, a hydrogen pressure of 3.0 MPa, and a reaction time of 6 h.
基金National Natural Science Foundation of China(No.10475010)
文摘Plasma polymerized maleic anhydride （MA） was carried out by using maleic anhydride supersaturated ethanol solution as a precursor in a dielectric barrier discharge （DBD）. The film properties were characterized by water contact angle （WCA）, Fourier transfer infrared （FTIR）, X-ray photoelectron spectroscopy （XPS）, atomic force microscope （AFM） analysis, and a thickness profilometer. The influence of the processing parameters on the film properties such as tile power frequency and polymerization zone was investigated. The results show that anhydride group incorporated into the growing films is favorable at the frequency of 80 kHz and working pressure of 50 Pa. The poly （maleic anhydride） film is uniform and compact at an average deposition rate of 8 nm/min.
文摘In this study, Cr and Co promoted, as well as unpromoted vanadium phosphate （VPO） catalysts were synthesized by the reaction of V2O5 and o-H3PO4 in organic medium followed by calcination in n-butane/air environment at 673 K. The physico-chemical properties and the catalytic behavior were affected by the addition of Cr and Co dopants. H2-TPR was used to investigate the nature of oxidants in the unpromoted and promoted catalysts. The results showed that both the Cr and Co promoters remarkably lowered the temperature of the reduction peak associated with V^5＋. The amount of oxygen species originated from the active phase, V^4＋, removed was significantly increased for Co and Cr-promoted catalysts. Both Cr and Co dopants improve strongly the n-butane conversion without sacrificing the MA selectivity. A good correlation was observed between the amount of oxygen species removed from V^4＋ phase and the activity for n-butane oxidation to maleic anhydride. This suggested that V^4＋-O was the center for the activation of n-butane.
文摘Four vanadium phosphate catalysts supported on γ-A1203 （20 wt%） were synthesized via wetness impregnation of VOHPO4.0.5H2O precursor and calcined for different durations （6, 10, 30 and 75 h） at 673 K in a reaction flow of n-butane/air mixture. The samples calcined for 6 and 10 h produced only a single phase of （VO）2P2O7. However, the VOPO4 phase （β-VOPO4） was detected and became more prominent with only a minor pyrophosphate peaks were found after 30 h of calcination. All these pyrophosphate peaks disappeared after 75 h of calcination. The formation of V^5＋ phase was also observed in the SEM micrographs. The redox properties and the nature of oxidants of the catalysts employed in this study were investigated by H2-TPR analysis. Selective oxidation of n-butane to maleic anhydride （MA） over these catalysts shows that the percentage of n-butane conversion decreases with the transformation of the catalysts from V^4＋ to V^5＋ phases. An appropriate ratio of V^5＋/V^4＋ can enhance the performance of the VPO catalyst. However, a higher amount of V^5＋ and its associated oxygen species are responsible to promote the MA selectivity.
文摘The modified petroleum resin emulsion prepared from the C9petroleum resin was modified with maleic anhydride.The effects of maleic rosin and maleic anhydride addition level,the modification time and the alkali liquor on the properties of the emulsion were discussed.The results showed that the optimum process conditions covered:a maleic anhydride mass fraction of 1.5%,a maleic rosin mass fraction of 10%,a KOH mass fraction of 1%,a petroleum resin modification temperature of 200℃,a petroleum resin modification duration of 3 h,and a modified petroleum resin emulsion/wax emulsion mixing ratio of 1:1.The particle size of modified petroleum resin emulsion prepared under these conditions was equal to 104.166μm.
文摘This study focuses on the effects of reducing solvents used in the preparation of vanadyl pyrophosphate （VPO）, and ZrO2 and （ZrO）2P2O7 promoters on the structure and catalytic performance of VPO catalysts. The VPO catalysts were prepared by the following steps： 1） Formation of vanadium phosphate by the reaction of V2O5 and H3PO4, 2） Synthesis of VPO precursor through the reduction of vanadium phosphate by reducing solvents, and 3） Activation of the precursor. For Zr promoted VPO, Zr was added to the precursor before activation. The P/V atomic ratios of different VPO catalysts, which were prepared by using different reducing solvents, were different. The precursor prepared by using isobutanol or isobutanol-benzyl alcohol contained VO（H2PO4）2 and VOHPO4·0.5H2O. The precursor prepared by using hexanol also contained VO（H2PO4）2 and VOHPO4·0.5H2O crystal phases, but the amount of VOHPO4·0.5H2O was much less than that of VO（H2PO4）2. After activation, all the VPO catalysts, prepared by using different reducing solvents, contained only the （VO）2P2O7 crystal phase. The VPO prepared by using isobutanol-petroleum ether as reducing solvent was the most active, while the VPO prepared by using hexanol had the lowest activity. Nevertheless, their total selectivity to phthalic and maleic anhydrides was almost the same. Both ZrO2 and （ZrO）2P2O7 promoters increased the activity and selectivity of VPO, but ZrO2 promoter increased the activity of VPO more drastically than （ZrO）2P2O7 promoter.
文摘A bipolymer maleic anhydride-methyl acrylate （MAMA） was synthesized from maleic anhydride and methyl acrylate based on molecular design.MAMA further reacted with oleylamine or octadecyl alcohol to generate two comb polymers called Oleamide-MAMA （NMAMA） and OctadecanolMAMA （OMAMA）,respectively.The structure of both the polymers was confirmed by their infrared spectral analysis （IR）,gel permeation chromatography analysis （GPC） and differential scanning calorimeter （DSC）.Moreover,the pour point depressing （PPD） properties of these comb polymers were examined experimentally.Experimental results showed that besides the molecular weight and concentration of the polymers,the length of side chains and the number of functional groups also had great influence on the pour point depressing performance.The π bonds and hydrogen bonds between depressants were the key factors for improving the pour point depressing properties.These results suggest that both OMAMA and NMAMA are potential pour point depressants for industry.
基金Partially Supported by National Education Commission of China.
文摘A series of vanadyl pyrophosphate catalyst （VPO） modified by different additives have been prepared with the aim to study the performance for selective conversion of n-butane to maleic anhydride（MA）. The addition of various promoters improved the catalytic performance remarkably on both activity and selectivity. The correlation of activity and selectivity of the catalysts with their structure has been discussed. The increase in BET surface areas and surface redox sites leads to an enhanced activity. However, good selectivity can only be obtained on those surfaces with suitable surface acid sites.
