Preparation and Characterization of Three-dimensional Photocatalyst-TiO2 Particulate Film Immobilized on Activated Carbon Fibers

A novel three-dimensional photocatalyst, TiO2 particulate film immobilized on activated carbon fibers (TiO2/ACFs), was prepared by liquid phase deposition. The photocatalyst was characterized by SEM, XRD, BET surface area and photodegradation of methylene blue solution. TiO2 particulate film, with a thickness of nearly 200 nm and grain sizes of 30~50 nm, was deposited on almost each carbon fiber. The inner space between adjacent fibers remained as unmodified ACFs, therefore, both UV illumination and polluted solutions were allowed to pass through the felt-form photocatalyst to form a three-dimensional environment for photocatalytic reactions. With BET surface areas of 400~600 m2/g, the TiO2/ACFs exhibited an enhanced adsorption of pollutants for photocatalysis. Comparative degradations indicated that photocatalytic activity of the TiO2/ACFs was slightly higher than that of Degussa P-25 TiO2. Two special properties, the three-dimensional structure and combined effects of ACFs' adsorption and titania's photodegradation, made contribution to high photocatalytic activity. Additionally, the TiO2/ACFs exhibited high stability and potentially application for practical usage.     

以类水滑石为前体的Ni催化剂及其催化甲烷水蒸气重整制氢:催化活性和动力学(英文)

Ni/Mg–Al catalysts derived from hydrotalcite-type precursors were prepared by a co-precipitation technique and applied to steam reforming of methane. By comparison with Ni/γ-Al2O3 and Ni/α-Al2O3 catalysts prepared by in-cipient wetness impregnation, the Ni/Mg–Al catalyst presented much higher activity as a result of higher specific surface area and better Ni dispersion. The Ni/Mg–Al catalyst with a Ni/Mg/Al molar ratio of 0.5:2.5:1 exhibited the highest activity for steam methane reforming and was selected for kinetic investigation. With external and inter-nal diffusion limitations eliminated, kinetic experiments were carried out at atmospheric pressure and over a temperature range of 823–973 K. The results demonstrated that the overal conversion of CH4 and the conversion of CH4 to CO2 were strongly influenced by reaction temperature, residence time of reactants as wel as molar ratio of steam to methane. A classical Langmuir–Hinshelwood kinetic model proposed by Xu and Froment (1989) fitted the experimental data with excellent agreement. The estimated adsorption parameters were consistent thermodynamical y.     

WP/γ-Al2O3催化剂的制备、表征及加氢脱硫和加氢脱氮活性

Two series of WP/Al2O3 catalyst precursors with WP mass loading in the range 18.5%-37.1% were prepared using the impregnation method and mixing method, respectively, and the catalysts were then obtained by temperature-programmed reduction of supported tungsten phosphate (precursor of WP/Al2O3 catatlysts) in H2 at 650℃ for 4h. The catalysts were characterized by XRD, BET, TG/DTA, XPS and 31p MAS-NMR. The activities of these catalysts were tested in the hydrodenitrogenation (HDN) of pyridine and hydrodesulfurization (HDS) of thiophene at 340℃ and 3.0MPa. The results showed that owing to the stronger interaction of the support with the active species, the precursor of WP/Al2O3 catalyst was more difficultly phosphided and a greater amount of W species was in a high valence state W6 on the surface of the catalyst prepared by the impregnation method than that by the mixing method. 31p MAS-NMR results indicated that 31p shift from 85% H3PO4 of 2.55 × 10-4 for WP and 2.57 × 10-4 for WP/γ-Al2O3 catalysts prepared by mixing method. Such WP/Al2O3 catalysts showed higher HDN activities and lower HDS activities than those prepared by the impregnation method under the same loading of WP.WP/γ-Al2O3 catalysts with weak interaction between support and active species were favorable for HDN reaction while the WP/γ-Al2O3 catalysts with strong interaction were favorable for HDS reaction.     

Catalytic Wet Air Oxidation of oChlorophenol in Wastewater

Catalytic wet air oxidation (CWAO) was investigated in laboratory-scale experiments for the treatment of o-chlorophenol in wastewater. Experimental results showed that wet air oxidation (WAO) process in the absence of catalyst was also effective for o-chlorophenol in wastewater treatment. Up to 80% of the initial CODcr was removed by wet air oxidation at 270℃ with twice amount of the required stoichiometric oxygen supply. At temperature of 150℃, the removal rate of CODCr was only 30%. Fe2(SO4)3, CuSO4, Cu(NO3)2 and MnSO4 exhibited high catalytic activity. Higher removal rate of CODcr was obtained by CWAO. More than 96% of the initial CODcr was removed at 270℃ and 84.6%-93.6% of the initial COD Cr was removed at 150℃. Mixed catalysts had better catalytic activity for the degradation of o-chlorophenol in wastewater.     

Effects of Precursors for Preparing Intermediate Layer on the Performance of Ti/SnO2+Sb2O3/PbO2 Anode

The Ti/SnO2+Sb2O3/PbO2 anode with SnO2+Sb2O3 intermediate layer obtained by the polymeric precursor method (PPM) and with the conventional route was studied. The morphology and microstructure of SnO2+Sb2O3 intermediate layer derived from different precursors and the top PbO2 active layer were examined by means of ESEM and XRD. The lifetime and electrocatalytic activity of the anode were also assessed by the cyclic voltammetry and accelerated lifetime test in 1.0 mol/L H2SO4 solution. It was found that precursor solvents affected lifetime, microstructure and morphology of the anode, and had little influence on electrocatalysis activity of the electrodes. The accelerated lifetime of Ti/SnO2+Sb2O3/PbO2 anode with intermediate layer prepared by PPM was 29.5 h in 1.0 mol/L H2SO4 solution, which was respectively about four times and twice that of the anode prepared with ethylene glycol and ethanol. After the anode was subjected to thermal corrosion, the lifetime still reached 27 h in contrast to the others.     

Controlled release and enhanced antibacterial activity of salicylic acid by hydrogen bonding with chitosan☆

Microcapsules of salicylic acid(SA)with chitosan were prepared by spray drying method.Various analytical methods were used to characterize the nature of microcapsules.Fourier-transform infrared spectroscopy(FTIR)confirmed the presence of intermolecular interactions between chitosan and SA.Particle size analysis showed that the average size of microcapsules ranged from 2 to 20 μm.Scanning electron microscopy(SEM)studies indicated that the microspheres were spherical and had a relatively smooth surface.Microbiological assay of antibacterial activity for SA and its microcapsules was measured using different bacterial strains.It was found that the antibacterial activity of SA was improved after the formation of microcapsules.The in vitro release profile showed that the microcapsules could control SA release from 1 h to 4 h.Kinetic studies revealed that the release pattern follows Korsmeyer–Peppas mechanism.Enhanced antibacterial activity of the SA microcapsules was attributed to the synergistic effects of intermolecular hydrogen-bonding interactions N–H?O and O–H?O_C between SA and chitosan.It was also confirmed by quantum chemical calculation.     

铁酸镍负载TiO2的可磁分离光催化剂的制备及性能

A magnetically separable photocatalyst TiO2/SiO2/NiFe2O4 （TSN） with a typical ferromagnetic hysteresis was prepared by a liquid catalytic phase transfer method. When the intensity of applied magnetic field weakened to zero, the remnant magnetism of the prepared photocatalyst faded to zero. The photocatalytst can be separated from water when an external magnetic field is added and redispersed into aqueous solution after the external magnetic field is eliminated, that makes the photocatalysts promising for wastewater treatment. Transmission electron microscope （TEM） and X-ray diffractometer （XRD） were used to characterize the structure of the photocatalyst indicating that the magnetic SiOffNiFe204 （SN） particle was compactly enveloped by P-25 titania and Tit2 shell was formed. The magnetic composite showed high photocatalytic activity for the degradation of methyl orange in water. A thin SiO2 layer between NiFe2O4 and TiO2 shell prevented effectively the leakage of charges from TiO2 particles to NiFe2O4, which gave rise to the increase in photocatalytic activity. Moreover, the experiment on recycled use of TSN demonstrated a good repeatability of the photocatalytic activity.     

相对湿度对不同载体的负载Cu催化剂催化燃烧甲苯的影响

The copper based catalysts, CuO/γ-Al2O3, CuO/γ-Al2O3-cordierite (Cord) and CuO/Cord, were prepared by impregnation method. The catalytic activity of the catalysts was tested in absence and presence of water vapor, and the catalysts were characterized. Temperature program desorption (TPD) experiments of toluene and water on the catalysts were carried out. The influence of water vapor on the activity of the catalysts was discussed. Results showed that addition of the water vapor has a significant negative effect on the catalytic activity of the catalysts. The higher the concentration of the water vapor in feed steam was, the lower the catalytic activity of the copper based catalysts became, which could be mainly ascribed to the competition of water molecules with toluene molecules for adsorption on the catalyst surfaces. TPD experiments showed that the strength of the interaction between water mole-cules and three catalysts followed the order: CuO/γ-Al2O3>CuO/γ-Al2O3-Cord>CuO/Cord. As a consequence of that, the degree of degradation in the catalytic activity of these three catalysts by the water vapor followed the order: CuO/γ-Al2O3>CuO/γ-Al2O3-Cord>CuO/Cord. However, the negative effect of the water vapor was reversible.     

Pt-Sn/SBA-15催化剂的制备、表征和长链烷烃脱氢催化性能

A series of the Pt-Sn/SBA-15 catalysts were prepared and their properties characterized by using X-ray powder diffraction （XRD）, N2 adsorption-desorption, high resolution transmission electron microscope, X-ray photoelectron spectroscopy （XPS） and H2-temperature programmed reduction. Their performances in long chain alkane dehydrogenation were evaluated in a fixed-bed microreactor with dodecane as a model alkane. The results indicated that SBA-15 maintained the well-order mesoporous structure during the reaction. The performance of the catalyst was found not dominated by its textural properties, but by the molar ratio of Sn to Pt which governed the degree of Sn reduction. Owing to the highest degree of Sn reduction, 1% （by mass） Pt-1.8% （by mass） Sn/SBA-15 showed the best catalytic activity. At 0.1 MPa and 470℃, the molar ratio of hydrogen to alkane at 4, and liquid hourly space velocity （LHSV） 20 h^-1, the dodecane conversion is 10%, and the dodecene selectivity is about 70%.     

Effects of Supports and Promoter Ag on Pd Catalysts for Selective Hydrogenation of Acetylene

SiO2, a-Al2O3, g-Al2O3, ZrO2 and CeO2 were used as supports and Ag as promoter to study their effects on Pd catalysts for selective hydrogenation of acetylene. The catalysts were prepared by impregnated synthesis and characterized by XRD, BET and TEM. The catalytic reaction was carried out in a fixed-bed reactor. Overall, the low specific surface area supports were better to increase the ethylene selectivity at high conversion rate of acetylene. Among the four Pd catalysts on low specific surface area supports, the catalyst on low specific surface area SiO2 (LSA-SiO2) retained a high ethylene selectivity even at complete conversion, while the other catalysts showed significant decrease in the selectivity at complete conversion. The performance of Pd/LSA-SiO2 was important to decrease the loss of ethylene in selective hydrogenation of trace acetylene in ethylene. Addition of Ag to Pd/LSA-SiO2 significantly decreased the formation of ethane, C4 alkenes and green oil, and improved the ethylene selectivity to 90% when Pd:Ag=1:1 and 1:3(w). When the ratio of Pd to Ag was above 1, the activity of Pd-Ag bimetallic catalyst was similar to that of Pd monometallic catalyst, and the selectivity of ethylene increased with increasing of amount of Ag. When the ratio of Pd to Ag was below 1, the activity of bimetallic catalyst decreased with increasing of amount of Ag, while the selectivity of ethylene was kept unchanged. The optimum temperature was 200~230℃ for 0.02%(w)Pd-0.02%(w)Ag/LSA-SiO2 to give a high ethylene selectivity and low formation of green oil.     

Influence of CO-evolving groups on the activity of activated carbon fiber for SO2 removal

An investigation was made into the influence of CO-evolving and CO₂-evolving groups on the activities of activated carbon fibers (ACFs) for the oxidative conversion of SO₂ into aq. H₂SO₄ in the presence of O₂ and H₂O. The results indicated that the amount of evolved CO determined the SO₂ removal activity of ACFs, whereas, the amount of evolved CO₂ did not correlate with the ACFs activity for SO₂ removal. A direct proportionality between the amount of evolved CO and the enhanced activity of SO₂ removal was confirmed by using different oxidizing agents for changing the types and amount of oxygen functional groups in ACFs.     

固体超强酸SO42-/ZrO2/SBA-15的合成及其催化活性

水热合成了介孔材料SBA-15,并以其为载体负载固体超强酸SO42-/ZrO2,通过XRD和N2吸附/脱附对制备的SO42-/ZrO2/SBA-15催化剂进行了表征。在固定床反应器中,以丙烯和乙酸为原料,研究了该催化剂合成乙酸异丙酯的活性。结果表明实验制备的催化剂具有较好的介孔结构,并在乙酸异丙酯的合成中表现出了良好的活性。     

SO2在球状活性炭上的吸附转化研究

研究了不同比表面积的沥青基球状活性炭（ＰＳＡＣ）在Ｏ２和Ｈ２Ｏ存在下脱除ＳＯ２的能力．结果表明,比表面积较大的ＰＳＡＣ具有较强的脱除ＳＯ２能力．在本实验条件下,三种不同比表面积的ＰＳＡＣ对ＳＯ２及ＳＯ２＋Ｏ２的吸附量无明显区别,但对Ｈ２Ｏ的吸附量随比表面积增大而增大,与样品的脱硫活性随比表面积增大的变化规律相一致,表明较多的水有利于ＳＯ２的脱除．这可归因于水既有利于样品活性部位上的ＳＯｘ转化成Ｈ２ＳＯ４,又能洗脱所生成的Ｈ２ＳＯ４,减少活性位上的Ｈ２ＳＯ４量,使ＳＯ２的吸附转化过程连续不断地进行     

粘结剂对蜂窝状V2O5/ACH同时脱硫脱硝活性的影响

在以硅酸盐和酚醛树脂为粘结剂的蜂窝状活性炭(ACH)载体上担载V2O5,制备了系列V2O5/ACH催化剂,考察了粘结剂对其同时脱硫脱硝活性的影响. 结果表明,以硅酸盐为粘结剂的催化剂中碳和碱金属含量改变,影响脱硫脱硝活性,碳含量高、碱金属含量低的载体适合用于制备脱硫脱硝催化剂. 以酚醛树脂为粘结剂的催化剂具有较高的碳含量和微孔孔容,脱硫活性较高,但脱硝活性低. 添加硅酸盐所制催化剂因其具有较高的氧/碳比例,导致脱硝活性较高,但载体的微孔数量减少,从而降低了比表面积和微孔孔容,进而降低其脱硫活性. 在添加30%硅酸盐或酚醛树脂(碳化温度为900℃)的最佳条件下,硅酸盐为粘结剂所制催化剂的脱硝率达90%以上,酚醛树脂为粘结剂所制催化剂的硫容为7.3%(w).     

浸渍法制备SO42-/TiO2-La2O3及其光催化氧化性能

不同硫酸浓度条件下,利用浸渍法处理TiO₂-La₂O₃,制得系列固体超强酸SO₄^2-/TiO₂-La₂O₃。通过XRD、FT-IR、TG-DTA和UV-Vis表征,揭示SO₄^2-/TiO₂-La₂O₃的微观结构和内在规律性。以邻硝基苯酚为探针反应,考察SO₄^2-/TiO₂-La₂O₃光催化性能。结果表明,SO₄^2-/TiO₂-La₂O₃的光催化活性明显高于TiO₂-La₂O₃,SO₄^2-/TiO₂-La₂O₃的催化活性取决于H₂SO₄浓度,浸渍液中H₂SO₄的合适浓度为0.5 mol·L^-1,掺杂La₂O₃适宜的物质的量分数为0.5%,最佳焙烧温度为500 ℃。     

Enhancement of electrosorption capacity of activated carbon fibers by grafting with carbon nanofibers

The composite films of activated carbon fibers (ACFs) and carbon nanofibers (CNFs) are prepared via chemical vapor deposition of CNFs onto ACFs in different times from 0.5 to 2 h and their electrosorption behaviors in NaCl solution are investigated. The morphology, structure, porous and electrochemical properties are characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, N₂ adsorption at 77 K, contact angle goniometer and electrochemical workstation, respectively. The results show that CNFs have been hierarchically grown on the surface of ACFs and the as grown ACF/CNF composite films have less defects, higher specific capacitances, more suitable mesoporous structure and more hydrophilic surface than the pristine ACFs, which is beneficial to their electrosorption performance. The ACFs/CNFs with CNFs deposited in 1 h exhibit an optimized NaCl removal ratio of 80%, 55% higher than that of ACFs and the NaCl electrosorption follows a Langmuir isotherm with a maximum electrosorption capacity of 17.19 mg/g.     

粉煤灰改性脱硫脱硝特性实验研究

以粉煤灰、石灰、添加剂为原料,通过湿法/干法制备了"富氧型"粉煤灰改性吸收剂.通过固定床实验,筛选出添加业氯酸钠(NaClO2)粉煤灰改性吸收剂,具有较好的脱硫脱硝效果;正交实验表明,Ca/(S+N)、温度是影响湿法制备的改性吸收剂脱硫脱硝的主要因素,且在实验条件下,脱硫率可以达到100%,脱硝率最高达到90%;而干法...     

H2O和SO2对Mn-Fe/MPS催化剂用于NH3低温还原NO的影响

研究了H2O和SO2对Mn-Fe/MPS催化剂低温下选择性催化NH3还原(SCR)NO的影响. 结果表明,Mn-Fe/MPS催化剂具有良好的催化活性,在空速为20000 h-1、反应温度433 K时,NO的SCR转化率达99.1%. 在反应温度低于413 K时,水蒸汽(10%, j)在一定程度上降低了催化活性;超过433 K时,这种影响可完全消除,NO的SCR转化率达到97.8%以上. 低浓度SO2(100′10-6)存在条件下,443 K时催化效率仍可稳定在97.2%. 在水和SO2共存的情况下,生成的硫酸盐和亚硫酸盐沉积在催化剂表面导致催化剂逐渐失活,FT-IR测试也表明伴随SCR反应生成了硫酸铵. 提高反应温度可以延缓催化剂的失活. 此外还研究了不同活化温度对催化剂活性恢复的影响,结果表明,当活化温度达到773 K时,催化剂活性可以完全恢复. 本研究中的催化剂的综合性能优于目前文献报道的其他催化剂.     

固体酸S_2O_8~(2-)/Fe_2O_3-SiO_2催化制备马来酸二己酯

在铁氧化物中引入硅的氧化物 ,并用S2 O82 -浸渍铁硅复合氧化物 ,制得固体酸催化剂S2 O82 -/Fe2 O3 SiO2 (Ⅰ )。用马来酸酐与正己醇的酯化反应考察了催化剂的活性。通过XRD和TEM分析 ,对催化剂的结构进行了表征。结果表明 ,Ⅰ的最佳制备条件为 :n(Fe)∶n(Si)为 5∶1、70℃陈化 3h ,2 0 0℃焙烧 2h、用 0 2 5mol/L的 (NH4) 2 S2 O8浸渍 3h、在 5 5 0℃下煅烧 6h ;Ⅰ的催化活性比S2 O2 -8/Fe2 O3 和SO2 -4/Fe2 O3 SiO2 更强 ,S2 O2 -8对Fe2 O3 SiO2 的促进作用明显高于SO2 -4;SiO2 的引入提高了催化剂的分散效果 ;有较好的使用重复性 ;它代替硫酸、对甲苯磺酸用于催化马来酸酐和正己醇的酯化反应可得无色透明的酯化产物     

钛基修饰氧化物电极降解敌百虫的研究

采用高温热氧化法制备了具有较高的电催化活性和良好稳定性的钛基锡锑铅氧化物电极,以有机磷农药敌百虫为目标有机物,考察了电压、电解质加入量、pH值、电解时间等因素对敌百虫降解率和溶液COD的影响.在外加电压为9 V,电解质硫酸钠的质量浓度0.1 mol/L,pH=6,电解100 mg/L的敌百虫模拟废水,2.0 h降解率为87.54%,3.0 h降解率为95.60%,此时溶液的COD去除率达72.58%.