The role of NH4^+ ion confinement in the catalytic etherification of HMF(5-hydroxymethylfurfural) with ethanol to biodiesel additives was evidenced by studying the catalytic behavior of NH4^+-Beta zeolites with SiO2/A...The role of NH4^+ ion confinement in the catalytic etherification of HMF(5-hydroxymethylfurfural) with ethanol to biodiesel additives was evidenced by studying the catalytic behavior of NH4^+-Beta zeolites with SiO2/Al2O3 ratios of 25 and 75.In order to affect the strength and distribution of the acidic sites, as well as the mobility of NH4^+ ions in the zeolites cages, a secondary level of porosity was introduced in the NH4^+-Beta, presenting a different stability versus alkaline treatment, by using a thermal or an ultrasound assisted method.By analyzing the catalytic behavior in these two series of samples with respect to the changes in porosity by nonlocal density functional theory, structure by XRD, amount of acid sites by FT-IR and mobility of NH4^+ cations by measurements of reversible NH4^+ exchange capacity, was evidenced a decrease in catalytic performances both in terms of rate of HMF depletion and productivity to the main products, when confinement of the ammonium ions is lost due to the introduction of mesoporosity.The high capability of ammonium ions release, associated to the mono-dentate configuration,and the minor confinement effect inside the zeolite pore system, due to the more opened pores structure of mesoporous zeolites, hinders both the direct etherification of HMF to EMF [5-(ethoxymethyl)furan-2-carbaldehyde] and the parallel reaction pathway via acetalization, favoring the rapid desorption of the HMFDEA [5-(hydroxymethyl)furfural diethyl acetal] product out of the crystal and the consequent inhibition of the consecutive reactions to EMFDEA [5-(ethoxymethyl)furfural diethyl acetal] and EMF.展开更多
Attempts had been made to synthesize Al2O3-2SiO2 nanopowders by sol-gel method with tetraethoxysilane（TEOS） and aluminum nitrate（ANN） as the starting materials.DTS,TEM,SEM and BET were employed to study the effect...Attempts had been made to synthesize Al2O3-2SiO2 nanopowders by sol-gel method with tetraethoxysilane（TEOS） and aluminum nitrate（ANN） as the starting materials.DTS,TEM,SEM and BET were employed to study the effects of process parameters on the size,specific surface area and structure（morphology） of powders.The alkali-activation reactivity of the powders was tested for manufacturing geopolymers and their hydrothermal reactions were performed for fabricating zeolites.The results show that the optimum process parameters and drying method for preparing Al2O3-2SiO2 nanopowders are as follows：the molar ratio of water and ethanol to TEOS are 0：1 and 12：1 respectively at synthetic temperature of 50 ℃ and the drying method is azeotropic distillation with microwave drying.The average particle diameters of the powders were about 70 nm and the largest BET specific surface area was up to 669 m^2·g^-1.The compressive strength of the geopolymer and the calcium exchange capacity（by CaCO3） of NaA zeolite prepared with the powders reached to 29 MPa and 366 m^2·g^-1 respectively.展开更多
We substituted several environmentally friendly catalysts which included HY and H- β zeolites, various cation-exchanged β zeolites, and solid-supported ferric chloride for conventional catalysts for the synth...We substituted several environmentally friendly catalysts which included HY and H- β zeolites, various cation-exchanged β zeolites, and solid-supported ferric chloride for conventional catalysts for the synthesis of 3-(1-cyclohexenyl)-2-butanone from the reaction of ethylidenecyclohexane with acetic anhydride at room temperature. HY zeolite was found to be the most effective for this reaction, and gave the acylated product in a 72% yield under the conditions of n (ethylidenecyclohexane)/ n (acetic anhydride)/ m (HY zeolite)=1 mmol/10 mmol/0 100 g, reaction temperature 25 ℃ and reaction time 2 h. The used HY zeolite can be recovered, regenerated and gave almost the same yield as the fresh one. The lifetime of the HY zeolite is over 80 h. The effect of different factors on the reaction has also been investigated.展开更多
A novel route to comprehensive utilization of valuable elements such as Ti, A1, Si and Mg in Ti-bearing electric arc furnace molten slag （Ti-bearing EAF slag） was proposed. The route can be expressed as a three-step...A novel route to comprehensive utilization of valuable elements such as Ti, A1, Si and Mg in Ti-bearing electric arc furnace molten slag （Ti-bearing EAF slag） was proposed. The route can be expressed as a three-step process including alkali fusion, water leaching and acidolysis. Following these processes under the optimum conditions, the recovery ratios of TiO2, Al2O3, SiO2 and MgO were about 97.5, 93.5, 27.9 and 53.5%, respectively. Meanwhile, nanostructured TiO2, NaA zeolite and Mg（OH）2 fire retardant were synthesized simultaneously by using Ti-bearing EAF slag as raw materials. In addition, the photocatalytic activity of prepared nanostructured TiO2 and the adsorption property of obtained NaA zeolite were investigated. The results showed that the photodegradation efficiency of as-prepared TiO2 was 80% for rhodamine B and the adsorption efficiency of NaA zeolite was 61% for Cu2＋ under the optimum conditions.展开更多
文摘The role of NH4^+ ion confinement in the catalytic etherification of HMF(5-hydroxymethylfurfural) with ethanol to biodiesel additives was evidenced by studying the catalytic behavior of NH4^+-Beta zeolites with SiO2/Al2O3 ratios of 25 and 75.In order to affect the strength and distribution of the acidic sites, as well as the mobility of NH4^+ ions in the zeolites cages, a secondary level of porosity was introduced in the NH4^+-Beta, presenting a different stability versus alkaline treatment, by using a thermal or an ultrasound assisted method.By analyzing the catalytic behavior in these two series of samples with respect to the changes in porosity by nonlocal density functional theory, structure by XRD, amount of acid sites by FT-IR and mobility of NH4^+ cations by measurements of reversible NH4^+ exchange capacity, was evidenced a decrease in catalytic performances both in terms of rate of HMF depletion and productivity to the main products, when confinement of the ammonium ions is lost due to the introduction of mesoporosity.The high capability of ammonium ions release, associated to the mono-dentate configuration,and the minor confinement effect inside the zeolite pore system, due to the more opened pores structure of mesoporous zeolites, hinders both the direct etherification of HMF to EMF [5-(ethoxymethyl)furan-2-carbaldehyde] and the parallel reaction pathway via acetalization, favoring the rapid desorption of the HMFDEA [5-(hydroxymethyl)furfural diethyl acetal] product out of the crystal and the consequent inhibition of the consecutive reactions to EMFDEA [5-(ethoxymethyl)furfural diethyl acetal] and EMF.
基金Supported by the National Natural Science Foundation of China (50962002,50602006)Opening Funds of State Key Laboratory of Chemical Resource Engineering of Beijing University of Chemical Technology (201008)
文摘Attempts had been made to synthesize Al2O3-2SiO2 nanopowders by sol-gel method with tetraethoxysilane（TEOS） and aluminum nitrate（ANN） as the starting materials.DTS,TEM,SEM and BET were employed to study the effects of process parameters on the size,specific surface area and structure（morphology） of powders.The alkali-activation reactivity of the powders was tested for manufacturing geopolymers and their hydrothermal reactions were performed for fabricating zeolites.The results show that the optimum process parameters and drying method for preparing Al2O3-2SiO2 nanopowders are as follows：the molar ratio of water and ethanol to TEOS are 0：1 and 12：1 respectively at synthetic temperature of 50 ℃ and the drying method is azeotropic distillation with microwave drying.The average particle diameters of the powders were about 70 nm and the largest BET specific surface area was up to 669 m^2·g^-1.The compressive strength of the geopolymer and the calcium exchange capacity（by CaCO3） of NaA zeolite prepared with the powders reached to 29 MPa and 366 m^2·g^-1 respectively.
基金Supported by the National Natural Science Foundation of China( No.2 0 1730 14 )
文摘We substituted several environmentally friendly catalysts which included HY and H- β zeolites, various cation-exchanged β zeolites, and solid-supported ferric chloride for conventional catalysts for the synthesis of 3-(1-cyclohexenyl)-2-butanone from the reaction of ethylidenecyclohexane with acetic anhydride at room temperature. HY zeolite was found to be the most effective for this reaction, and gave the acylated product in a 72% yield under the conditions of n (ethylidenecyclohexane)/ n (acetic anhydride)/ m (HY zeolite)=1 mmol/10 mmol/0 100 g, reaction temperature 25 ℃ and reaction time 2 h. The used HY zeolite can be recovered, regenerated and gave almost the same yield as the fresh one. The lifetime of the HY zeolite is over 80 h. The effect of different factors on the reaction has also been investigated.
基金This study was supported by the National Natural Science Foundation of China （Nos. 51471122 and 51604202）, the China Postdoctoral Science Foundation （No. 2016M592397） and the Science and Technology Project of Guangdong Province （No. 2013B090600025）.
文摘A novel route to comprehensive utilization of valuable elements such as Ti, A1, Si and Mg in Ti-bearing electric arc furnace molten slag （Ti-bearing EAF slag） was proposed. The route can be expressed as a three-step process including alkali fusion, water leaching and acidolysis. Following these processes under the optimum conditions, the recovery ratios of TiO2, Al2O3, SiO2 and MgO were about 97.5, 93.5, 27.9 and 53.5%, respectively. Meanwhile, nanostructured TiO2, NaA zeolite and Mg（OH）2 fire retardant were synthesized simultaneously by using Ti-bearing EAF slag as raw materials. In addition, the photocatalytic activity of prepared nanostructured TiO2 and the adsorption property of obtained NaA zeolite were investigated. The results showed that the photodegradation efficiency of as-prepared TiO2 was 80% for rhodamine B and the adsorption efficiency of NaA zeolite was 61% for Cu2＋ under the optimum conditions.
