CuO-CoO-MnO/SiO2 nanocomposite aerogels were prepared by using tetraethyl orthosilicate （TEOS） as Si source, and aqueous solution of Cu, Co and Mn acetates as transition metal sources via sol-gel process and supercr...CuO-CoO-MnO/SiO2 nanocomposite aerogels were prepared by using tetraethyl orthosilicate （TEOS） as Si source, and aqueous solution of Cu, Co and Mn acetates as transition metal sources via sol-gel process and supercritical drying （SCD） technique. The effect of synthesis conditions on gelation was investigated. Moreover, the composition of the CuO-CoO-MnO/SiO2 nanocomposite aerogels was characterized by electron dispersive spectroscopy （EDS） and X-ray photoelectron spectroscopy （XPS）, and the specific surface area of the nanocomposite aerogels was determined by the Brunauer-Emmett-Teller （BET） method. Diphenyl carbonate （DPC） as the product was analyzed by gas chromatography （GC）. The experimental results show that the range of optimal temperature for gelation is 30-45 ℃, and the pH is 3.0-4.5. CuO-CoO-MnO/SiO2 nanocomposite aerogels are porous with a specific surface area of 384.9-700.6 m2/g. Compared to CO2 SCD, ethanol SCD is even favorable to the formation of aerogel with high specific surface area. The transition metals content in the nanocomposite aerogels can be controlled to be 0.71at%-13.77at%. With CuO-CoO-MnO/SiO2 nanocomposite aerogels as catalyst carrier, the yield of DPC is in direct proportion to the atomic fraction of transition metals in the nanocomposite aerogels, and it is up to 26.31 mass%, which is much higher than that via other porous carriers.展开更多
An alumina-supported cobalt aerogel catalyst prepared from a sol-gel and a supercritical drying method was used in the catalytic decomposition of methane. The physical-chemical properties of the catalyst were characte...An alumina-supported cobalt aerogel catalyst prepared from a sol-gel and a supercritical drying method was used in the catalytic decomposition of methane. The physical-chemical properties of the catalyst were characterized and its activity for methane decomposition was investigated. The effects of calcination and reaction temperatures on the activity of the catalyst and the morphology of the carbon nanotubes produced were discussed. A CoAl2O4 spinel structure formed in the calcined catalyst. The quantity of the nanotubes produced in the reaction increases with the amount of cobalt in the reduced catalyst. A higher reaction temperature leads to a higher reaction rate, though faster deactivation of the catalyst occurs with the change. The carbon nanotubes grown on the catalyst have smooth walls and uniform di-ameter distribution.展开更多
Carbon aerogels (CAG) were synthesized by the pyrolysis of resorcinol-furfural based organic aerogels, derived from sol-gel polymerization of resorcinol and furfural using different catalysts followed by supercritical...Carbon aerogels (CAG) were synthesized by the pyrolysis of resorcinol-furfural based organic aerogels, derived from sol-gel polymerization of resorcinol and furfural using different catalysts followed by supercritical drying of as-prepared gels. Different catalysts viz. hydrochloric acid (HA), acetic acid (AcH) and hexamethylenetetramine (HMTA) of different concentrations were used for this purpose in order to study the role of different catalysts and the effect of R/C ratio (reactant to catalyst molar ratio) on the formation of organic gel monolith and their physical properties were investigated. Aerogels were thoroughly characterized by using CHN, FTIR, TG-DSC, XRD and SEM. A considerable reduction of gelation time and the formation of relatively denser organic gel were observed in the case of HMTA, which indicated the dual role (catalyst & cross-linking agent) of HMTA during the polymerization/polycondensation of resorcinol and furfural. Carbon aerogels obtained by using different catalysts showed BET surface area, average pore size, total pore volumes in the range of 438 496 m2/g, 17.9 22.4 ? and 0.20 0.27 cm3/g, respectively. The SEM images and results revealed the presence of different morphologies of carbon aerogels, obtained by using different catalysts. The HMTA catalyzed samples were found to have highest surface area with particles in smaller in size and well interconnected 3D carbon network.展开更多
利用可再生能源将CO_(2)转化成高附加值的燃料或化学品,是一项实现“碳中和,碳达峰”的新资源化技术,但目前高性能电催化CO_(2)转化的催化剂研发,仍然是一项热点问题。设计具有“类珊瑚状”结构的多级孔氮掺杂碳气凝胶(N-CA)作为优化气...利用可再生能源将CO_(2)转化成高附加值的燃料或化学品,是一项实现“碳中和,碳达峰”的新资源化技术,但目前高性能电催化CO_(2)转化的催化剂研发,仍然是一项热点问题。设计具有“类珊瑚状”结构的多级孔氮掺杂碳气凝胶(N-CA)作为优化气体传质的碳载体,利用非共价固定技术,将酞菁钴(CoPc)稳定于气凝胶骨架的表面,以实现活性位点和导电碳骨架稳定结合。CoPc@N-CA展现出优异的电催化CO_(2)还原(CO_(2)RR)活性,在较宽的电势窗口-0.5~-1.0 V vs.RHE下,对CO的选择性>80%,最高为99.05%;在-0.85 V vs.RHE电位下,CoPc@N-CA对CO的部分电流密度达到14.40 mA·cm^(-2),约是以商业碳黑(CB)为基底设计的CoPc@CB(3.66·mA cm^(-2))催化剂的4倍。内在活性分析发现,CoPc@N-CA优异的活性可归因于N-CA独特的多孔结构,这不仅促进了CO_(2)分子的传质,有利于CO_(2)RR反应动力学,而且有利于暴露Co活性位点,从而促进CO_(2)RR。展开更多
A series of NiO/SiO2 aerogel catalysts were prepared by sol gel method. The effects of the nickel content on the structure and existing forms of NiO/SiO2 aerogel catalysts were investigated by using XRD, TPR and FT IR...A series of NiO/SiO2 aerogel catalysts were prepared by sol gel method. The effects of the nickel content on the structure and existing forms of NiO/SiO2 aerogel catalysts were investigated by using XRD, TPR and FT IR. The results showed that there were interactions between NiO and SiO2. But as nickel content increased, the interaction decreased. The nickel oxide in the catalysts appeared in different forms as nickel content was changed. When the content was less than 13%, Ni? entered into the SiO2 structure completely and it became clusters after calcining. If the content altered from 20% to 50%, NiO existed as both microcrystal and clusters, the later spices was dominating. However, when the content increased to 70%, microcrystal became the primary components.展开更多
基金Funded by the Hebei Natural Science Foundation(No.E2011209003)the Science and Technology Development Foundation of Hebei (No. 10215606D)the Ph D Programs Foundation of Hebei United University
文摘CuO-CoO-MnO/SiO2 nanocomposite aerogels were prepared by using tetraethyl orthosilicate （TEOS） as Si source, and aqueous solution of Cu, Co and Mn acetates as transition metal sources via sol-gel process and supercritical drying （SCD） technique. The effect of synthesis conditions on gelation was investigated. Moreover, the composition of the CuO-CoO-MnO/SiO2 nanocomposite aerogels was characterized by electron dispersive spectroscopy （EDS） and X-ray photoelectron spectroscopy （XPS）, and the specific surface area of the nanocomposite aerogels was determined by the Brunauer-Emmett-Teller （BET） method. Diphenyl carbonate （DPC） as the product was analyzed by gas chromatography （GC）. The experimental results show that the range of optimal temperature for gelation is 30-45 ℃, and the pH is 3.0-4.5. CuO-CoO-MnO/SiO2 nanocomposite aerogels are porous with a specific surface area of 384.9-700.6 m2/g. Compared to CO2 SCD, ethanol SCD is even favorable to the formation of aerogel with high specific surface area. The transition metals content in the nanocomposite aerogels can be controlled to be 0.71at%-13.77at%. With CuO-CoO-MnO/SiO2 nanocomposite aerogels as catalyst carrier, the yield of DPC is in direct proportion to the atomic fraction of transition metals in the nanocomposite aerogels, and it is up to 26.31 mass%, which is much higher than that via other porous carriers.
基金supports from a 973 Program of the Chinese Ministry of Science and Technology under contract number G199902240National Natural Science Foundation of China under contract numbers 20006072,29792079-2 and 29876032 are gratefully acknowledged.
文摘An alumina-supported cobalt aerogel catalyst prepared from a sol-gel and a supercritical drying method was used in the catalytic decomposition of methane. The physical-chemical properties of the catalyst were characterized and its activity for methane decomposition was investigated. The effects of calcination and reaction temperatures on the activity of the catalyst and the morphology of the carbon nanotubes produced were discussed. A CoAl2O4 spinel structure formed in the calcined catalyst. The quantity of the nanotubes produced in the reaction increases with the amount of cobalt in the reduced catalyst. A higher reaction temperature leads to a higher reaction rate, though faster deactivation of the catalyst occurs with the change. The carbon nanotubes grown on the catalyst have smooth walls and uniform di-ameter distribution.
文摘Carbon aerogels (CAG) were synthesized by the pyrolysis of resorcinol-furfural based organic aerogels, derived from sol-gel polymerization of resorcinol and furfural using different catalysts followed by supercritical drying of as-prepared gels. Different catalysts viz. hydrochloric acid (HA), acetic acid (AcH) and hexamethylenetetramine (HMTA) of different concentrations were used for this purpose in order to study the role of different catalysts and the effect of R/C ratio (reactant to catalyst molar ratio) on the formation of organic gel monolith and their physical properties were investigated. Aerogels were thoroughly characterized by using CHN, FTIR, TG-DSC, XRD and SEM. A considerable reduction of gelation time and the formation of relatively denser organic gel were observed in the case of HMTA, which indicated the dual role (catalyst & cross-linking agent) of HMTA during the polymerization/polycondensation of resorcinol and furfural. Carbon aerogels obtained by using different catalysts showed BET surface area, average pore size, total pore volumes in the range of 438 496 m2/g, 17.9 22.4 ? and 0.20 0.27 cm3/g, respectively. The SEM images and results revealed the presence of different morphologies of carbon aerogels, obtained by using different catalysts. The HMTA catalyzed samples were found to have highest surface area with particles in smaller in size and well interconnected 3D carbon network.
文摘利用可再生能源将CO_(2)转化成高附加值的燃料或化学品,是一项实现“碳中和,碳达峰”的新资源化技术,但目前高性能电催化CO_(2)转化的催化剂研发,仍然是一项热点问题。设计具有“类珊瑚状”结构的多级孔氮掺杂碳气凝胶(N-CA)作为优化气体传质的碳载体,利用非共价固定技术,将酞菁钴(CoPc)稳定于气凝胶骨架的表面,以实现活性位点和导电碳骨架稳定结合。CoPc@N-CA展现出优异的电催化CO_(2)还原(CO_(2)RR)活性,在较宽的电势窗口-0.5~-1.0 V vs.RHE下,对CO的选择性>80%,最高为99.05%;在-0.85 V vs.RHE电位下,CoPc@N-CA对CO的部分电流密度达到14.40 mA·cm^(-2),约是以商业碳黑(CB)为基底设计的CoPc@CB(3.66·mA cm^(-2))催化剂的4倍。内在活性分析发现,CoPc@N-CA优异的活性可归因于N-CA独特的多孔结构,这不仅促进了CO_(2)分子的传质,有利于CO_(2)RR反应动力学,而且有利于暴露Co活性位点,从而促进CO_(2)RR。
文摘A series of NiO/SiO2 aerogel catalysts were prepared by sol gel method. The effects of the nickel content on the structure and existing forms of NiO/SiO2 aerogel catalysts were investigated by using XRD, TPR and FT IR. The results showed that there were interactions between NiO and SiO2. But as nickel content increased, the interaction decreased. The nickel oxide in the catalysts appeared in different forms as nickel content was changed. When the content was less than 13%, Ni? entered into the SiO2 structure completely and it became clusters after calcining. If the content altered from 20% to 50%, NiO existed as both microcrystal and clusters, the later spices was dominating. However, when the content increased to 70%, microcrystal became the primary components.
