A series of Pt catalysts supported on the Hβ-zeolite that is ion-exchanged with the rare earth metal ions of Ce(III) and La(III),are prepared by impregnation,characterized by inductively coupled plasma (ICP),X-...A series of Pt catalysts supported on the Hβ-zeolite that is ion-exchanged with the rare earth metal ions of Ce(III) and La(III),are prepared by impregnation,characterized by inductively coupled plasma (ICP),X-ray diffraction (XRD),BET,temperature-programmed desorption of ammonia (NH3-TPD),temperature-programmed reduction of hydrogen (H2-TPR) and H2-chemisorption techniques,and evaluated in the hydroisomerization of n-heptane with an atmospheric fixed-bed reactor.The reaction temperature,time on stream,space velocity,and the ratio of H2/n-heptane are changed to get the optimal conditions.The Ce(III) and La(III)-exchanged Hβ-zeolites exhibit higher selectivity for isomerized products than the neat Hβ-zeolite.Moreover,the Ce(III)-exchanged catalysts give higher conversions of n-heptane,whereas the La(III)-exchanged ones do not show any improvement in con-version.Under optimal conditions,the catalyst with 0.4% (by mass) Pt and 0.5% (by mass) Ce loading presents very high selectivity of isomerized products of 95.1% coupled with high n-heptane conversion of 68.7%.Effects of the ion-exchange of Ce(III) and La(III) on the catalytic performance are discussed in relation with the physico-chemical properties of catalysts.展开更多
A new type of composite adsorbents was synthesized by incorporating monoethanol amine (MEA) into β-zeolite. The parent and MEA- functionalized β-zeolites were characterized by X-ray diffraction (XRD), N2 adsorpt...A new type of composite adsorbents was synthesized by incorporating monoethanol amine (MEA) into β-zeolite. The parent and MEA- functionalized β-zeolites were characterized by X-ray diffraction (XRD), N2 adsorption, and thermogravimetric analysis (TGA). The adsorption behavior of carbon dioxide (CO2), methane (CH4), and nitrogen (N2) on these adsorbents was investigated at 303 K. The results show that the structure of zeolite was well preserved after MEA modification. In comparison with CH4 and N2, CO2 was preferentially adsorbed on the adsorbents investigated. The introduction of MEA significantly improved the selectivity of both CO2/CH4 and CO2/N2, the optimal selectivity of CO2/CH4 can reach 7.70 on 40 wt% of MEA-functionalized β-zeolite (MEA(40)-β) at 1 atm. It is worth noticing that a very high selectivity of CO2/N2 of 25.67 was obtained on MEA(40)-β. Steric effect and chemical adsorbate-adsorbent interaction were responsible for such high adsorption selectivity of CO2. The present MEA-functionalized β-zeolite adsorbents may be a good candidate for applications in flue gas separation, as well as natural gas and landfill gas purifications.展开更多
zeolite was synthesized by using tetraethyl ammonium hydroxide as the template reagent andmicrowave radiation as the heat source. The effect of the sol composition and the radiation temperature onzeolite crystallinity...zeolite was synthesized by using tetraethyl ammonium hydroxide as the template reagent andmicrowave radiation as the heat source. The effect of the sol composition and the radiation temperature onzeolite crystallinity was investigated. The zeolite was tested and compared with the commercial product, whichwas produced by conventional hydrothermal synthesis method. The physico-chemical properties of the syn-thesized samples, the specific surface area of the samples synthesized under microwave irradiation and porevolume measured by X-ray diffraction apparatus, were better than the conventional samples. The etherificationexperiment on FCC light naphtha in the presence of transition metals modified Hβ-zeolite, which was synthe-sized firstly under microwave irradiation, was studied in a fixed-bed reactor. The effect of catalyst preparationconditions on its activity, stability and the effect of reaction temperature, methanol/tertiary-carbon olefin molarratio and liquid hourly space velocity on the etherification reaction were discussed. The experimental resultsshowed that the different metals modified Hβ-zeolite had different etherification performances. And theconversion of tertiary carbon-olefins of the molybdenum modified Hβzeolite, which was loaded at a concen-tration of 3 percents, was higher than that on 6.0 percent of Hβzeolite. The modified Hβzeolite catalystspossessed favorable prospects for its higher stability.展开更多
The presence of naphthenic acids in oil sand products and process streams is the cause of toxicity to aquatic life and corrosion. The removal of organic acids from tailings pond water reduces the negative impact on ma...The presence of naphthenic acids in oil sand products and process streams is the cause of toxicity to aquatic life and corrosion. The removal of organic acids from tailings pond water reduces the negative impact on marine life. The ultra-violet (UV) photocatalytic reduction of commercial naphthenic acid in water using TiO2-zeolitecomposites showed a significant decrease in the concentration of naphthenic acid, accompanied by an increase in carbon dioxide formation;the presence of carbon dioxide signifies degradation of the naphthenic acids. Mixtures of the acid and photocatalyst kept in the dark did not show any concentration changes. The extent of naphthenic acid reduction by UV light was verified by the reduction in total acidity. The total acidity values of mixtures of the acid and TiO2-zeoliteexposed to UV decreased by 31% compared to mixtures kept in the dark. A reduction in total acidity may lead to a decrease in the toxicity of naphthenic acid contaminated water.展开更多
The biosorptive interaction of Ag++ with resting cell of %Lactobacillus sp.% strain A09 has been further studied on a molecular level by means of XPS, EDX, UV-Vis and FTIR techniques. The X-ray photoelectron spectrosc...The biosorptive interaction of Ag++ with resting cell of %Lactobacillus sp.% strain A09 has been further studied on a molecular level by means of XPS, EDX, UV-Vis and FTIR techniques. The X-ray photoelectron spectroscopy(XPS) shows that the reductive ratio of the Ag++ to Ag+0 by the A09 biomass reaches to about 54^5% for 3 d. The contain of amino acid residues in dry powder of the biomass such as cysteine, methionine, arginine and lysine, being capable of reducing the Ag++ to Ag+0, are very small in quantity both cysteine and methionine are far less than 0^18%, and both arginine and lysine far less than 0^336%, %via% the analysis with quantitative energy-dispersive X-ray(EDX). The amount of the reducing sugars in the biomass is far larger than 2^71% analyzed by ultraviolet-visible spectrophotometry(UV-Vis). The chemical functional group on cell wass of the biomass such as the carboxylate anion of amino-acid residues seems to be the site for the Ag++ binding and the free aldehyde group of the hemiacetalic hydroxyl from reducing sugars, %i.e.% the hydrolysates of the polysaccharides from the cell wass, plays a protagonist in serving as the electron donor for reducing the Ag++ to Ag+0, characterized by fourier transform infrared(FTIR) spectrophotometry.展开更多
基金Supported by the Jiangsu Provincial Key Natural Science Foundation for Universities(06KJA53012) the National Natural Science Foundation of China(20476046 20976084)
文摘A series of Pt catalysts supported on the Hβ-zeolite that is ion-exchanged with the rare earth metal ions of Ce(III) and La(III),are prepared by impregnation,characterized by inductively coupled plasma (ICP),X-ray diffraction (XRD),BET,temperature-programmed desorption of ammonia (NH3-TPD),temperature-programmed reduction of hydrogen (H2-TPR) and H2-chemisorption techniques,and evaluated in the hydroisomerization of n-heptane with an atmospheric fixed-bed reactor.The reaction temperature,time on stream,space velocity,and the ratio of H2/n-heptane are changed to get the optimal conditions.The Ce(III) and La(III)-exchanged Hβ-zeolites exhibit higher selectivity for isomerized products than the neat Hβ-zeolite.Moreover,the Ce(III)-exchanged catalysts give higher conversions of n-heptane,whereas the La(III)-exchanged ones do not show any improvement in con-version.Under optimal conditions,the catalyst with 0.4% (by mass) Pt and 0.5% (by mass) Ce loading presents very high selectivity of isomerized products of 95.1% coupled with high n-heptane conversion of 68.7%.Effects of the ion-exchange of Ce(III) and La(III) on the catalytic performance are discussed in relation with the physico-chemical properties of catalysts.
基金supported by the Major Basic Research Project of Natural Science Foundation of Jiangsu Province Colleges (No. 08 kJA530001)the Program for Changjiang Scholars and Innovative Research Team in University (No. IRT0732)
文摘A new type of composite adsorbents was synthesized by incorporating monoethanol amine (MEA) into β-zeolite. The parent and MEA- functionalized β-zeolites were characterized by X-ray diffraction (XRD), N2 adsorption, and thermogravimetric analysis (TGA). The adsorption behavior of carbon dioxide (CO2), methane (CH4), and nitrogen (N2) on these adsorbents was investigated at 303 K. The results show that the structure of zeolite was well preserved after MEA modification. In comparison with CH4 and N2, CO2 was preferentially adsorbed on the adsorbents investigated. The introduction of MEA significantly improved the selectivity of both CO2/CH4 and CO2/N2, the optimal selectivity of CO2/CH4 can reach 7.70 on 40 wt% of MEA-functionalized β-zeolite (MEA(40)-β) at 1 atm. It is worth noticing that a very high selectivity of CO2/N2 of 25.67 was obtained on MEA(40)-β. Steric effect and chemical adsorbate-adsorbent interaction were responsible for such high adsorption selectivity of CO2. The present MEA-functionalized β-zeolite adsorbents may be a good candidate for applications in flue gas separation, as well as natural gas and landfill gas purifications.
文摘zeolite was synthesized by using tetraethyl ammonium hydroxide as the template reagent andmicrowave radiation as the heat source. The effect of the sol composition and the radiation temperature onzeolite crystallinity was investigated. The zeolite was tested and compared with the commercial product, whichwas produced by conventional hydrothermal synthesis method. The physico-chemical properties of the syn-thesized samples, the specific surface area of the samples synthesized under microwave irradiation and porevolume measured by X-ray diffraction apparatus, were better than the conventional samples. The etherificationexperiment on FCC light naphtha in the presence of transition metals modified Hβ-zeolite, which was synthe-sized firstly under microwave irradiation, was studied in a fixed-bed reactor. The effect of catalyst preparationconditions on its activity, stability and the effect of reaction temperature, methanol/tertiary-carbon olefin molarratio and liquid hourly space velocity on the etherification reaction were discussed. The experimental resultsshowed that the different metals modified Hβ-zeolite had different etherification performances. And theconversion of tertiary carbon-olefins of the molybdenum modified Hβzeolite, which was loaded at a concen-tration of 3 percents, was higher than that on 6.0 percent of Hβzeolite. The modified Hβzeolite catalystspossessed favorable prospects for its higher stability.
文摘The presence of naphthenic acids in oil sand products and process streams is the cause of toxicity to aquatic life and corrosion. The removal of organic acids from tailings pond water reduces the negative impact on marine life. The ultra-violet (UV) photocatalytic reduction of commercial naphthenic acid in water using TiO2-zeolitecomposites showed a significant decrease in the concentration of naphthenic acid, accompanied by an increase in carbon dioxide formation;the presence of carbon dioxide signifies degradation of the naphthenic acids. Mixtures of the acid and photocatalyst kept in the dark did not show any concentration changes. The extent of naphthenic acid reduction by UV light was verified by the reduction in total acidity. The total acidity values of mixtures of the acid and TiO2-zeoliteexposed to UV decreased by 31% compared to mixtures kept in the dark. A reduction in total acidity may lead to a decrease in the toxicity of naphthenic acid contaminated water.
文摘The biosorptive interaction of Ag++ with resting cell of %Lactobacillus sp.% strain A09 has been further studied on a molecular level by means of XPS, EDX, UV-Vis and FTIR techniques. The X-ray photoelectron spectroscopy(XPS) shows that the reductive ratio of the Ag++ to Ag+0 by the A09 biomass reaches to about 54^5% for 3 d. The contain of amino acid residues in dry powder of the biomass such as cysteine, methionine, arginine and lysine, being capable of reducing the Ag++ to Ag+0, are very small in quantity both cysteine and methionine are far less than 0^18%, and both arginine and lysine far less than 0^336%, %via% the analysis with quantitative energy-dispersive X-ray(EDX). The amount of the reducing sugars in the biomass is far larger than 2^71% analyzed by ultraviolet-visible spectrophotometry(UV-Vis). The chemical functional group on cell wass of the biomass such as the carboxylate anion of amino-acid residues seems to be the site for the Ag++ binding and the free aldehyde group of the hemiacetalic hydroxyl from reducing sugars, %i.e.% the hydrolysates of the polysaccharides from the cell wass, plays a protagonist in serving as the electron donor for reducing the Ag++ to Ag+0, characterized by fourier transform infrared(FTIR) spectrophotometry.