Red mud was investigated in triglyceride transesterification with a view to determine its viability as a basic catalyst for use in biodiesel synthesis. The effect of calcination temperature on the structure and activi...Red mud was investigated in triglyceride transesterification with a view to determine its viability as a basic catalyst for use in biodiesel synthesis. The effect of calcination temperature on the structure and activity of red mud catalysts was investigated. It was found that highly active catalyst was obtained by simply drying red mud at 200℃. Utilization of red mud as a catalyst for biodiesel production not only provides a cost-effective and environmentally friendly way of recycling this solid red mud waste, significantly reducing its environmental effects, but also reduces the price of biodiesel to make biodiesel competitive with petroleum diesel.展开更多
A new method for the fabrication of carbon aerogels is reported in this paper. Resorcinol and furfural were gelated in isopropanol with basic catalysts and then dried directly under isopropanol supercritical condition...A new method for the fabrication of carbon aerogels is reported in this paper. Resorcinol and furfural were gelated in isopropanol with basic catalysts and then dried directly under isopropanol supercritical condition, followed by carbonization under nitrogen atmosphere. The bulk densities of carbon aerogels obtained are in the range of 0.21g/cm3~0.27g/cm3 and the sizes of the interconnected carbon nano-particles are in the range of 20nm^30nm. All of the aerogel samples exhibit high BET surface areas in the range of 730m2/g^900m2/g. The bulk density, micro-pore volume, meso-pore volume and meso-pore diameter can be controlled by gelation conditions such as R/I ratio and R/C ratio.展开更多
A basic ionic liquid, namely 1,1＇-（butane-1,4-diyl）bis（1,4-diazabicyclo [2.2.2]octan-1-ium） hydrox-ide, was prepared and characterized using Fourier-transform infrared spectroscopy, XH nuclear magnetic...A basic ionic liquid, namely 1,1＇-（butane-1,4-diyl）bis（1,4-diazabicyclo [2.2.2]octan-1-ium） hydrox-ide, was prepared and characterized using Fourier-transform infrared spectroscopy, XH nuclear magnetic resonance spectroscopy, and pH measurements. The ionic liquid was used for efficient promotion of the synthesis of pyrano[2,3-d]pyrimidinone and pyrido[2,3-d]pyrimidine derivatives at room temperature under grinding conditions. A simple procedure, short reaction time, high yields, non-column chromatographic separation, commercial availability of the starting materials, and recyclability of the catalyst are attractive features of this process.展开更多
One-pot synthesis of dimethyl carbonate (DMC) from methanol, propylene oxide (PO) and carbon dioxide has been investigated using the basic zeolites as catalysts. Among the zeolites studied, Beta showed the best cataly...One-pot synthesis of dimethyl carbonate (DMC) from methanol, propylene oxide (PO) and carbon dioxide has been investigated using the basic zeolites as catalysts. Among the zeolites studied, Beta showed the best catalytic performance for DMC production. That the desilication of zeolite structure resulted in a hierarchical porosity of Beta, leading to more amount of KOH can be loaded on the surface of zeolite and therefore enhancing the base strength of the catalyst was proposed to be the reason for improved catalytic performance.展开更多
In solid basic catalysis field,how to achieve optimized activity and desired stability through elaborate control over basic site properties remains a challenge.In this work,taking advantage of the structure memory eff...In solid basic catalysis field,how to achieve optimized activity and desired stability through elaborate control over basic site properties remains a challenge.In this work,taking advantage of the structure memory effect of layered double hydroxides(LDHs),rehydrated Ca4 Al1-x Gax-LDHs and Ca4 Al1-x Inx-LDHs catalysts were prepared and applied in aldol condensation reaction that isobutyraldehyde(IBD)reacts with formaldehyde(FA)to obtain hydroxypivalaldehyde(HPA).Notably,the resulting re-Ca4 Al0.90Ga0.10-LDHs exhibits an extraordinarily-high catalytic activity(HPA yield:72%),which is to our best knowledge the highest level in this reaction.The weak Br?nsted basic site,7-coordinated Ca-OH group,which serves as an active site,catalyzes the condensation process and promotes the product desorption.Studies on structure-property correlations demonstrate that Ga as a structural promoter induces a moderate expansion of the laminate lattice,which results in a significant increase in the concentration of weak basic sites in re-Ca4Al0.90Ga0.10-LDHs,accounting for its high catalytic activity.This work illuminates that geometric structure of basic active sites can be tuned via introducing catalyst additive,which leads to a largely improved performance of hydrotalcite solid basic catalysts towards aldol condensation reaction.展开更多
A series of Ni/SBA-15 catalysts with Ni contents from 5 wt%–20 wt%and CaO-12.5%Ni/SBA-15 catalysts with CaO contents from 1.4 wt%– 9.8 wt%have been prepared.The structure of the catalysts was characterized using X-r...A series of Ni/SBA-15 catalysts with Ni contents from 5 wt%–20 wt%and CaO-12.5%Ni/SBA-15 catalysts with CaO contents from 1.4 wt%– 9.8 wt%have been prepared.The structure of the catalysts was characterized using X-ray diffraction（XRD）,N2 adsorption-desorption,transmission electron microscopy（TEM）and X-ray photoelectron spectroscopy（XPS）.The performance of catalytic steam reforming of the poplar leaves to the hydrogen-rich syngas was tested in a fixed-bed reactor.The results indicate that the 7.0wt%CaO-12.5wt%Ni/SBA-15 catalyst exhibits the best performance for the catalytic steam reforming of poplar leaves to hydrogen-rich syngas.The ratio of H2：CO can reach ca 5：1 in the hydrogen-rich syngas.The yield of H2 can reach 273.30 mL/g（poplar leaves）.In the CaO-Ni/SBA-15 catalyst,Ni active component mainly fills the role of catalytic steam reforming of the poplar leaves,and CaO active component mainly plays the role as water-gas shift and CO2 sorbent.展开更多
Surface properties （viz. surface area, basicity/base strength distribution, and crystal phases） of alkali metal doped CaO （alkali metal/Ca= 0.1 and 0.4） catalysts and their catalytic activity/selectivity in oxidat...Surface properties （viz. surface area, basicity/base strength distribution, and crystal phases） of alkali metal doped CaO （alkali metal/Ca= 0.1 and 0.4） catalysts and their catalytic activity/selectivity in oxidative coupling of methane （OCM） to higher hydrocarbons at different reaction conditions （viz. temperature, 700 and 750 ℃; CH4/O2 ratio, 4.0 and 8.0 and space velocity, 5140-20550 cm^3 ·g^-1·h^-1） have been investigated. The influence of catalyst calcination temperature on the activity/selectivity has also been investigated. The surface properties （viz. surface area, basicity/base strength distribution） and catalytic activity/selectivity of the alkali metal doped CaO catalysts are strongly influenced by the alkali metal promoter and its concentration in the alkali metal doped CaO catalysts. An addition of alkali metal promoter to CaO results in a large decrease in the surface area but a large increase in the surface basicity （strong basic sites） and the C2＋ selectivity and yield of the catalysts in the OCM process. The activity and selectivity are strongly influenced by the catalyst calcination temperature. No direct relationship between surface basicity and catalytic activity/selectivity has been observed. Among the alkali metal doped CaO catalysts, Na-CaO （Na/Ca = 0.1, before calcination） catalyst （calcined at 750 ℃）, showed best performance （C2＋ selectivity of 68.8% with 24.7% methane conversion）, whereas the poorest performance was shown by the Rb-CaO catalyst in the OCM process.展开更多
The oxidative coupling of methane to C2 hydrocarbons has been studied over a series of La-promoted CaO （La/Ca = 0.05） catalysts, prepared using different precursor salts for CaO and La2O3 （viz. acetates, carbonates...The oxidative coupling of methane to C2 hydrocarbons has been studied over a series of La-promoted CaO （La/Ca = 0.05） catalysts, prepared using different precursor salts for CaO and La2O3 （viz. acetates, carbonates, nitrates and hydroxides） and catalyst preparation methods （viz. physical mixing of precursors, co-precipitation using ammonium carbonate/sodium carbonate as a precipitating agent）, under different reaction conditions （temperature： 700-850 ℃, CH4/O2 ratio： 4.0 and 8.0, and GHSV： 51360 cm^3·g^-1·h^- 1）. The surface area and surface basicity/base strength distribution of the catalysts have also been investigated. The surface properties and catalytic activity/selectivity of the La-promoted CaO catalysts vary from catalyst to catalyst depending on the catalyst precursors used and catalyst preparation method. The basicity/base strength distribution is strongly influenced by the precursors （for CaO and La2O3） and catalyst preparation method. Basicity （total and strong basic sites measured in terms of CO2 chemisorbed at 50℃ and 500 ℃, respectively） observed for the catalyst prepared by co-precipitation method is higher than that of the catalysts prepared by physical mixing method. The catalysts prepared by the nitrates of La- and Ca- and co- precipitated by the solution of sodium carbonate and ammonium carbonate exhibit different catalytic performance in OCM. The finding that no direct relationship between the surface basicity and catalytic activity/selectivity in OCM exists indicates that basicity is not solely responsible for obtaining high selectivity to C2 hydrocarbons.展开更多
The Co3O4 and Zr-,Ce-,and La-Co3O4 catalysts were prepared,characterized,and applied to produce CH4 from CO_(2) catalytic hydrogenation in low temperature as 140–220℃.The results indicated that the addition of Zr,Ce...The Co3O4 and Zr-,Ce-,and La-Co3O4 catalysts were prepared,characterized,and applied to produce CH4 from CO_(2) catalytic hydrogenation in low temperature as 140–220℃.The results indicated that the addition of Zr,Ce,or La to the Co3O4 decreased the crystallite sizes of Co and the outer-shell electron density of Co^3+,and increased the specific surface area,which would provide more active sites for the CO_(2) methanation.Especially,the addition of Zr also changed the reducing state of Co3O4 via an obvious change in the interaction between Co3O4 and ZrO2.Furthermore,Zr doped into the Co3O4 increased the basic intensity of the weak and medium basic sites,as well as the amount of Lewis acid sites,and Bronsted acid sites were also found on the Zr-Co3O4 surface.The introduction of Zr,Ce,or La favored the production of CH4,and the Zr-Co3O4catalyst exhibited the highest CO_(2) conversion(58.2%)and CH4 selectivity(100%)at 200℃,and 0.5 MPa with a gaseous hourly space velocity of 18,000 ml·g^-1(cat)·h^-1,and the catalytic activity of CO_(2) methanation for the Zr-,Ce-,and La-Co3O4 exhibited more stable than Co3O4 in a 20-h reaction.展开更多
In this work, a novel alkaline catalyst was synthesized by an economical and effective method of roasting waste banana peel. From XRD, FTIR, SEM, EDS, TGA and CO2-TPD characterization, it was proved that the calcined ...In this work, a novel alkaline catalyst was synthesized by an economical and effective method of roasting waste banana peel. From XRD, FTIR, SEM, EDS, TGA and CO2-TPD characterization, it was proved that the calcined banana peel catalyst showed the strong alkalinity and well dispersity in microstructure, and K2O-KCl as the main active contents. The calcined banana peel catalyst showed better catalytic performance than the catalysts by physical mixing of K2O and KCl, which was due to good dispersibility of K2O-KCl formed during decomposing of carbon fiber by calcination of banana peel. Furthermore, the calcined banana peel catalyst also performed well in both water-resistant ability and recyclability, indicating their potential for biodiesel production from an efficient, robust, and low-cost catalyst.展开更多
The transesterification of cottonseed oil in the presence of methanol to fatty acid methyl ester (FAME) using flax-based fibres catalyst modified with an alkaline moiety was studied. The catalyst was prepared by radia...The transesterification of cottonseed oil in the presence of methanol to fatty acid methyl ester (FAME) using flax-based fibres catalyst modified with an alkaline moiety was studied. The catalyst was prepared by radiation induced grafting (RIG) of glycidyl methacrylate (GMA) onto dignified flax fibres followed by amination with diethylamine (DEA) and treatment with NaOH solution. A maximum FAME conversion of 88.6% was obtained at 60°;C with a catalyst dosage of 2.5 wt%, an oil/methanol ratio of 1:33 and a time of 2 h. The biodiesel quality was verified by nuclear magnetic resonance (1H NMR). Kinetic analysis showed a reaction activation energy of 69.33 kJ·molˉ1 and a rate constant of 0.00349 minˉ1 indicating that the catalytic reaction was kinetically controlled. Thermodynamic analyses revealed that the reaction was reversible, non-spontaneous and endothermic with an enthalpy of 66.62 kJ·molˉ1. The obtained biodiesel showed physical and chemical characteristics complying with ASTM D6751. It can be concluded that the alkaline biopolymer catalyst prepared in the present study is a promising green candidate for biodiesel production.展开更多
基金supported by the Natural Science Basic Research Plan in Shaanxi Province of China (No.2010JM2003)the Fundamental Research Funds for the Central Universities (No. GK200902006)
文摘Red mud was investigated in triglyceride transesterification with a view to determine its viability as a basic catalyst for use in biodiesel synthesis. The effect of calcination temperature on the structure and activity of red mud catalysts was investigated. It was found that highly active catalyst was obtained by simply drying red mud at 200℃. Utilization of red mud as a catalyst for biodiesel production not only provides a cost-effective and environmentally friendly way of recycling this solid red mud waste, significantly reducing its environmental effects, but also reduces the price of biodiesel to make biodiesel competitive with petroleum diesel.
基金The National Natural Science Foundation of China (No. 59973028), The Team Project of the Natural Science Foundation of Guangdong (No.[( )(20003038)]), and The Talent Training Program Foundation of the Higher Education Departmen
文摘A new method for the fabrication of carbon aerogels is reported in this paper. Resorcinol and furfural were gelated in isopropanol with basic catalysts and then dried directly under isopropanol supercritical condition, followed by carbonization under nitrogen atmosphere. The bulk densities of carbon aerogels obtained are in the range of 0.21g/cm3~0.27g/cm3 and the sizes of the interconnected carbon nano-particles are in the range of 20nm^30nm. All of the aerogel samples exhibit high BET surface areas in the range of 730m2/g^900m2/g. The bulk density, micro-pore volume, meso-pore volume and meso-pore diameter can be controlled by gelation conditions such as R/I ratio and R/C ratio.
基金the University of Guilan Research Council for the partial support of this work
文摘A basic ionic liquid, namely 1,1＇-（butane-1,4-diyl）bis（1,4-diazabicyclo [2.2.2]octan-1-ium） hydrox-ide, was prepared and characterized using Fourier-transform infrared spectroscopy, XH nuclear magnetic resonance spectroscopy, and pH measurements. The ionic liquid was used for efficient promotion of the synthesis of pyrano[2,3-d]pyrimidinone and pyrido[2,3-d]pyrimidine derivatives at room temperature under grinding conditions. A simple procedure, short reaction time, high yields, non-column chromatographic separation, commercial availability of the starting materials, and recyclability of the catalyst are attractive features of this process.
文摘One-pot synthesis of dimethyl carbonate (DMC) from methanol, propylene oxide (PO) and carbon dioxide has been investigated using the basic zeolites as catalysts. Among the zeolites studied, Beta showed the best catalytic performance for DMC production. That the desilication of zeolite structure resulted in a hierarchical porosity of Beta, leading to more amount of KOH can be loaded on the surface of zeolite and therefore enhancing the base strength of the catalyst was proposed to be the reason for improved catalytic performance.
文摘In solid basic catalysis field,how to achieve optimized activity and desired stability through elaborate control over basic site properties remains a challenge.In this work,taking advantage of the structure memory effect of layered double hydroxides(LDHs),rehydrated Ca4 Al1-x Gax-LDHs and Ca4 Al1-x Inx-LDHs catalysts were prepared and applied in aldol condensation reaction that isobutyraldehyde(IBD)reacts with formaldehyde(FA)to obtain hydroxypivalaldehyde(HPA).Notably,the resulting re-Ca4 Al0.90Ga0.10-LDHs exhibits an extraordinarily-high catalytic activity(HPA yield:72%),which is to our best knowledge the highest level in this reaction.The weak Br?nsted basic site,7-coordinated Ca-OH group,which serves as an active site,catalyzes the condensation process and promotes the product desorption.Studies on structure-property correlations demonstrate that Ga as a structural promoter induces a moderate expansion of the laminate lattice,which results in a significant increase in the concentration of weak basic sites in re-Ca4Al0.90Ga0.10-LDHs,accounting for its high catalytic activity.This work illuminates that geometric structure of basic active sites can be tuned via introducing catalyst additive,which leads to a largely improved performance of hydrotalcite solid basic catalysts towards aldol condensation reaction.
基金supported by the National Basic Research Program of China(No.2005CB221405)the National"863"Project of China(No.2006AA10Z425)
文摘A series of Ni/SBA-15 catalysts with Ni contents from 5 wt%–20 wt%and CaO-12.5%Ni/SBA-15 catalysts with CaO contents from 1.4 wt%– 9.8 wt%have been prepared.The structure of the catalysts was characterized using X-ray diffraction（XRD）,N2 adsorption-desorption,transmission electron microscopy（TEM）and X-ray photoelectron spectroscopy（XPS）.The performance of catalytic steam reforming of the poplar leaves to the hydrogen-rich syngas was tested in a fixed-bed reactor.The results indicate that the 7.0wt%CaO-12.5wt%Ni/SBA-15 catalyst exhibits the best performance for the catalytic steam reforming of poplar leaves to hydrogen-rich syngas.The ratio of H2：CO can reach ca 5：1 in the hydrogen-rich syngas.The yield of H2 can reach 273.30 mL/g（poplar leaves）.In the CaO-Ni/SBA-15 catalyst,Ni active component mainly fills the role of catalytic steam reforming of the poplar leaves,and CaO active component mainly plays the role as water-gas shift and CO2 sorbent.
文摘Surface properties （viz. surface area, basicity/base strength distribution, and crystal phases） of alkali metal doped CaO （alkali metal/Ca= 0.1 and 0.4） catalysts and their catalytic activity/selectivity in oxidative coupling of methane （OCM） to higher hydrocarbons at different reaction conditions （viz. temperature, 700 and 750 ℃; CH4/O2 ratio, 4.0 and 8.0 and space velocity, 5140-20550 cm^3 ·g^-1·h^-1） have been investigated. The influence of catalyst calcination temperature on the activity/selectivity has also been investigated. The surface properties （viz. surface area, basicity/base strength distribution） and catalytic activity/selectivity of the alkali metal doped CaO catalysts are strongly influenced by the alkali metal promoter and its concentration in the alkali metal doped CaO catalysts. An addition of alkali metal promoter to CaO results in a large decrease in the surface area but a large increase in the surface basicity （strong basic sites） and the C2＋ selectivity and yield of the catalysts in the OCM process. The activity and selectivity are strongly influenced by the catalyst calcination temperature. No direct relationship between surface basicity and catalytic activity/selectivity has been observed. Among the alkali metal doped CaO catalysts, Na-CaO （Na/Ca = 0.1, before calcination） catalyst （calcined at 750 ℃）, showed best performance （C2＋ selectivity of 68.8% with 24.7% methane conversion）, whereas the poorest performance was shown by the Rb-CaO catalyst in the OCM process.
文摘The oxidative coupling of methane to C2 hydrocarbons has been studied over a series of La-promoted CaO （La/Ca = 0.05） catalysts, prepared using different precursor salts for CaO and La2O3 （viz. acetates, carbonates, nitrates and hydroxides） and catalyst preparation methods （viz. physical mixing of precursors, co-precipitation using ammonium carbonate/sodium carbonate as a precipitating agent）, under different reaction conditions （temperature： 700-850 ℃, CH4/O2 ratio： 4.0 and 8.0, and GHSV： 51360 cm^3·g^-1·h^- 1）. The surface area and surface basicity/base strength distribution of the catalysts have also been investigated. The surface properties and catalytic activity/selectivity of the La-promoted CaO catalysts vary from catalyst to catalyst depending on the catalyst precursors used and catalyst preparation method. The basicity/base strength distribution is strongly influenced by the precursors （for CaO and La2O3） and catalyst preparation method. Basicity （total and strong basic sites measured in terms of CO2 chemisorbed at 50℃ and 500 ℃, respectively） observed for the catalyst prepared by co-precipitation method is higher than that of the catalysts prepared by physical mixing method. The catalysts prepared by the nitrates of La- and Ca- and co- precipitated by the solution of sodium carbonate and ammonium carbonate exhibit different catalytic performance in OCM. The finding that no direct relationship between the surface basicity and catalytic activity/selectivity in OCM exists indicates that basicity is not solely responsible for obtaining high selectivity to C2 hydrocarbons.
基金Supported by the National Natural Science Foundation of China(21366004)Guangxi Natural Science Foundation(2016GXNSFFA380015)the Dean Project of Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology(2016Z003)
文摘The Co3O4 and Zr-,Ce-,and La-Co3O4 catalysts were prepared,characterized,and applied to produce CH4 from CO_(2) catalytic hydrogenation in low temperature as 140–220℃.The results indicated that the addition of Zr,Ce,or La to the Co3O4 decreased the crystallite sizes of Co and the outer-shell electron density of Co^3+,and increased the specific surface area,which would provide more active sites for the CO_(2) methanation.Especially,the addition of Zr also changed the reducing state of Co3O4 via an obvious change in the interaction between Co3O4 and ZrO2.Furthermore,Zr doped into the Co3O4 increased the basic intensity of the weak and medium basic sites,as well as the amount of Lewis acid sites,and Bronsted acid sites were also found on the Zr-Co3O4 surface.The introduction of Zr,Ce,or La favored the production of CH4,and the Zr-Co3O4catalyst exhibited the highest CO_(2) conversion(58.2%)and CH4 selectivity(100%)at 200℃,and 0.5 MPa with a gaseous hourly space velocity of 18,000 ml·g^-1(cat)·h^-1,and the catalytic activity of CO_(2) methanation for the Zr-,Ce-,and La-Co3O4 exhibited more stable than Co3O4 in a 20-h reaction.
基金The financial supports from the National Natural Science Foundation of China (NSFC) (No. 21306063)the Fundamental Research Funds for the Central Universities (JUSRP51623A)+2 种基金the Key Research and Development Program of Jiangsu Province (Industry Outlook and Common Key Technologies) (BE2015204)the Fundamental Research Funds for the Central Universities (JUSRP51507)MOE & SAFEA for the 111 Project (B13025)
文摘In this work, a novel alkaline catalyst was synthesized by an economical and effective method of roasting waste banana peel. From XRD, FTIR, SEM, EDS, TGA and CO2-TPD characterization, it was proved that the calcined banana peel catalyst showed the strong alkalinity and well dispersity in microstructure, and K2O-KCl as the main active contents. The calcined banana peel catalyst showed better catalytic performance than the catalysts by physical mixing of K2O and KCl, which was due to good dispersibility of K2O-KCl formed during decomposing of carbon fiber by calcination of banana peel. Furthermore, the calcined banana peel catalyst also performed well in both water-resistant ability and recyclability, indicating their potential for biodiesel production from an efficient, robust, and low-cost catalyst.
文摘The transesterification of cottonseed oil in the presence of methanol to fatty acid methyl ester (FAME) using flax-based fibres catalyst modified with an alkaline moiety was studied. The catalyst was prepared by radiation induced grafting (RIG) of glycidyl methacrylate (GMA) onto dignified flax fibres followed by amination with diethylamine (DEA) and treatment with NaOH solution. A maximum FAME conversion of 88.6% was obtained at 60°;C with a catalyst dosage of 2.5 wt%, an oil/methanol ratio of 1:33 and a time of 2 h. The biodiesel quality was verified by nuclear magnetic resonance (1H NMR). Kinetic analysis showed a reaction activation energy of 69.33 kJ·molˉ1 and a rate constant of 0.00349 minˉ1 indicating that the catalytic reaction was kinetically controlled. Thermodynamic analyses revealed that the reaction was reversible, non-spontaneous and endothermic with an enthalpy of 66.62 kJ·molˉ1. The obtained biodiesel showed physical and chemical characteristics complying with ASTM D6751. It can be concluded that the alkaline biopolymer catalyst prepared in the present study is a promising green candidate for biodiesel production.
