Characteristics of titania supported copper oxide catalysts for wet air oxidation of phenol

Various techniques have been used to characterize the CuO(x)/TiO(2) catalysts with different copper loading. Surface area, pore volume and pore size distribution of the prepared catalysts were estimated from nitrogen adsorption isotherm. Temperature programmed reduction (TPR), X-ray diffraction (XRD), electron spin resonance (ESR), X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES) experiments were performed to investigate the chemical state of the copper species. The chemical state of copper in the CuO(x)/TiO(2) catalysts varied with copper loading (1-25wt.%): highly dispersed Cu(2+) cluster for 1 and 5wt.%, and bulk CuO for 7-25wt.%. The activity and mineralization selectivity of the CuO(x)/TiO(2) catalysts increased with copper loading up to 20wt.%, and remained almost constant for higher copper loading. The optimum copper loading was 20wt.% for the wet air oxidation of phenol over the CuO(x)/TiO(2) catalysts in this work. The stability of the CuO(x)/TiO(2) catalysts with different copper loading was also studied with respect to carbonaceous deposits and copper leaching.     

气相色谱法测定茶色素中的乙酸乙酯残留量

本文建立了一个气相色谱法测定茶色素中的乙酸乙酯残留量的方法。方法的回收率为100.1％～101.1％,相对标准偏差为2.0％,检测限为2ng(S/N≥3).测定结果表明:方法具有简单、可靠、快速、准确等特点。     

Catalytic combustion of benzene over copper oxide supported on SBA-15 using chelating method

The catalytic combustion of benzene over copper oxide supported on SBA-15 was investigated. The catalysts were prepared by the using chelating method and characterized. It is clear that the loading of CuO on the silica matrix drastically decreases the surface area and pore volume of the catalysts, as would be expected for the incorporation of CuO. The catalytic activity increased with an increase of CuO loading ratio. When CuO loading reached 5.8 wt%, the total conversion temperature was lowered to 350 degrees C.     

Catalytic wet air oxidation of chlorophenols over supported ruthenium catalysts

A series of noble metal (Pt, Pd, Ru) loaded zirconia catalysts were evaluated in the catalytic wet air oxidation (CWAO) of mono-chlorophenols (2-CP, 3-CP, 4-CP) under relatively mild reaction conditions. Among the investigated noble metals, Ru appeared to be the best to promote the CWAO of CPs as far as incipient-wetness impregnation was used to prepare all the catalysts. The position of the chlorine substitution on the aromatic ring was also shown to have a significant effect on the CP reactivity in the CWAO over 3wt.% Ru/ZrO(2). 2-CP was relatively easier to degradate compared to 3-CP and 4-CP. One reason could be the higher adsorption of 2-CP on the catalyst surface. Further investigations suggested that 3wt.% Ru/ZrO(2) is a very efficient catalyst in the CWAO of 2-CP as far as high 2-CP conversion and TOC abatement could still be reached at even lower temperature (393K) and lower total pressure (3MPa). Additionally, the conversion of 2-CP was demonstrated to increase with the initial pH of the 2-CP solution. The dechlorination reaction is promoted at higher pH. In all cases, the adsorption of the reactants and the reaction intermediates was shown to play a major role. All parameters that would control the molecule speciation in solution or the catalyst surface properties would have a key effect.     

Catalytic combustion of chlorobenzene over Mn-Ce-La-O mixed oxide catalysts

A series of Mn(x)-CeLa mixed oxide catalysts with different compositions prepared by sol-gel method were tested for the catalytic combustion of chlorobenzene (CB), as a model of chlorinated aromatics. Mn(x)-CeLa catalysts with the ratios of Mn/(Mn + Ce + La) in the range from 0.69 to 0.8 were found to possess high catalytic activity in the catalytic combustion of CB. The stability and deactivation of Mn(x)-CeLa catalysts were studied by other assistant experiments. Mn(x)-CeLa catalysts can deactivate below 330 °C, due to the strong adsorption of Cl species produced during the decomposition of CB. Nevertheless, the increase in oxygen concentration can enhance the resistance to Cl poisoning through the reaction of surface oxygen species with residual chlorine. At 350 °C, high activity, good selectivity and desired stability were observed over Mn(x)-CeLa catalysts.     

铟-锡复合氧化物粉末的制备及甲烷催化燃烧性能研究

采用共沉淀法制备In2O3-SnO2复合粉末,以TEM、XRD、BET等实验手段对催化剂粉体的形貌和结构进行了表征.结果表明制备的催化剂样品颗粒均匀,粒径范围在10～40nm.该复合氧化物对甲烷的催化燃烧表现出了良好的催化活性.最佳制备条件为铟离子摩尔分数为40%,焙烧温度为600℃.     

Synthesis of copper oxalate in ether-water bilayer refluxing system and their conversion to copper oxide nanowires

Copper oxalate nanowires with a mean diameter of 100 nm and a length of 10 µm were synthesized via the reaction of copper acetate and dimethyl oxalate in ether-water bilayer refluxing system. The volume ratio of ether to water and the concentration of copper acetate were used to examine the effects on forming copper oxalate nanowires. Copper oxalate nanowires were obtained only in the case of the greater volume ratio of ether to water and the lower concentration of copper acetate. Copper oxalate nanowires with a dense structure (enclosed by a smooth surface) can be further transformed into highly porous copper oxide nanowires by the decomposition of copper oxalate nanowires at 350 °C.     

锰基催化剂的制备及其对气相邻二氯苯的催化燃烧性能

二噁英类含氯挥发性有机物（Cl-VOC）是毒性很强的环境污染物,为了筛选用于催化燃烧Cl-VOC的高效、稳定的催化剂,采用共沉淀法制备了（Fe、Co、Cu、V）-Mn催化剂,并负载于堇青石载体上,用邻二氯苯作为模型化合物对其催化性能进行评价,结果发现Cu-Mn/堇青石催化剂对气相邻二氯苯的催化燃烧性能最好。XRD结果显示Cu-Mn/堇青石催化剂煅烧之后有新的尖晶石CuMn2O4晶相出现;SEM结果表明Cu-Mn/堇青石催化剂颗粒分散均匀;反应前后EDS对比结果表明,反应后催化剂表面残留有少量氯,但是,寿命测试表明持续反应20h,邻二氯苯的降解率能稳定在65%,说明Cu-Mn/堇青石催化剂用于催化燃烧含氯有机挥发物具有较好的应用前景。     

Investigation of structural,optical, antibacterial,and dielectric properties of V-doped copper oxide thin films: Comparison with undoped copper oxide thin films

Vanadium doped Copper oxide (CO) thin films were prepared by the sol-gel dip-coating method. The properties of thin films were examined by X-Ray Diffractometer (XRD), UV–Visible-NIR spectrophotometry, and dielectric properties analyzer. The antibacterial and photocatalytic properties were also determined. XRD spectra revealed the dual-phase of copper oxide (cuprite and tenorite) for all percentages of V with no other impurity peak. Tauc's relation is used to probe the optical band gap which is reduced from 1.96 to 1.64 eV with an increase in vanadium doping percentage. The impurity band coalesces with the conduction band of copper oxide to decrease the band gap. Dielectric constant measurements reveal that the Ac conductivity of thin films increases with an increase in V doping percentage.     

Catalytic combustion of toluene over platinum supported on Ce–Zr–O solid solution modified by Y and Mn

A series of CeO₂–ZrO₂ mixed oxides were prepared using coprecipitation method and characterized by BET, oxygen storage capacity (OSC), X-ray diffraction (XRD) and H₂-temperature-programmed reduction (H₂-TPR). The catalytic activities toward toluene combustion were investigated in a micro-reactor. The results demonstrate that the catalytic activity of Pt/γ-Al₂O₃/Ce_0.50Zr_0.50O₂ monolithic catalyst can be greatly improved by doping metal into Ce_0.50Zr_0.50O₂. When doping Y and Mn into Ce_0.50Zr_0.50O₂ simultaneously, the catalyst Pt/γ-Al₂O₃/Ce_0.40Zr_0.40Y_0.10Mn_0.10O_X shows the highest activity. The T₁₀ (the temperature of 10% toluene conversion) and the complete conversion temperature (the temperature of 90% toluene conversion) of toluene are 443 and 489 K, respectively. Gas hourly space velocity (GHSV) results show that the prepared catalyst can be applied in a wide range of GHSV (from 12,000 to 20,000 h⁻¹). The catalyst prepared shows great potential for practical application.     

Characterization and mechanical properties of electrospun cellulose acetate/graphene oxide composite nanofibers

Graphene oxide incorporated cellulose acetate composite nanofibers were prepared via an electrospinning technique. The weight percentage of graphene oxide varied from 0.05 to 1.5 wt.% in the polymer solution. The morphologies and crystal structures of the resultant composite nanofibers were investigated by scanning electron microscopy and X-ray diffraction. The specific interaction was demonstrated by Fourier-transform infrared spectroscopy. Tensile test was performed to measure the mechanical properties of the prepared cellulose acetate/graphene oxide composite nanofibers. 1.5 wt.% cellulose acetate/graphene oxide composite nanofibers showed the highest tensile strength and Young's modulus.     

Characterization of copper oxide nanolayers deposited by direct current magnetron sputtering

Direct current reactive magnetron sputtering was used to deposit the thin layers of copper oxide (Cu₂O) on glass substrates. A solid disc of pure copper as the target was sputtered in an argon gas under sputtering pressures varying from 0.133 to 4 Pa. The effects of the sputtering power and pressure on the structural and optical properties of Cu₂O thin films were systematically studied. The deposited layers were characterized using X-ray diffraction, atomic force microscopy, profilometry and spectrophotometry. The optical transmission of the films was measured in the visible region. The increase in pressure resulted in a higher growth rate than increasing sputtering power. The increase in power produced Cu₂O thin films that were detrimental to the optical transmission of the films.     

H2还原预处理CuO/γ-Al2O3催化剂对其催化燃烧甲苯活性的影响

用浸渍法和H2还原预处理法制备两种CuO/γ-Al2O3催化剂,并用N2吸附脱附、XRD、TPR和CO化学吸附对经H2还原处理前后的催化剂进行表征,比较两种催化剂催化氧化(燃烧)甲苯的活性。研究结果表明,与浸渍法制备的CuO/γ-Al2O3催化剂相比,经H2还原预处理,再次焙烧后得到的CuO/γ-Al2O3/HR催化剂对甲苯催化燃烧活性明显提高。XRD和TPR分析表明,H2还原预处理提高了催化剂表面活性组分CuO的分散度、还原能力,同时,还降低了CuO的晶体尺寸,从而提高了催化剂催化氧化甲苯的活性。     

乙二醇法制备负载型钴基-堇青石催化剂及其催化燃烧甲苯的活性

用乙二醇法和浸渍法制备两种负载在堇青石上的钴基负载催化剂,并用XRD、XPS、TPR和TPD对制备的催化剂进行表征,比较两种催化剂催化氧化(燃烧)甲苯的活性。研究结果表明,与浸渍法制备的Co/cord催化剂相比,乙二醇法制备的催化剂Co/cord-EG对甲苯催化燃烧活性明显提高。应用乙二醇法制备Co/cord-EG负载型催化剂,Co元素主要以Co2+存在于载体表面;而传统浸渍法制备的Co/cord催化剂,Co元素是以Co2+与Co3+的两种化学状态存在于载体表面。应用乙二醇法制备Co/cord-EG负载型催化剂,有助于在载体表面形成比较均匀的吸附活性位。应用乙二醇法制备的Co/cord-EG催化剂,催化活性组分能在载体表面上以更小颗粒而且更高的分散度存在,从而能明显提高其催化活性。     

焙烧温度对醋酸盐体系液相燃烧合成尖晶石型LiMn2O4的影响

以醋酸锂、醋酸锰为原料，尿素为燃料，用液相燃烧合成方法制备尖晶石型LiMn2O4物质，考察了焙烧温度（300-800℃焙烧5h）对产物的组成结构、晶粒大小及电化学性能的影响。实验结果表明，未焙烧产物中主晶相为LiMn2O4及少量Mn2O3，但在300-800℃焙烧5h后都可得到单相的LiMn2O4粉体材料，焙烧温度为900℃时，LiMn2O4部分分解为Mn3O4；产物颗粒随焙烧温度升高而长大，≤600℃时，产物颗粒〈100nm，≥700℃时产物颗粒〉100nm，可观察到LiMn2O4的特征八面体结构；在焙烧温度800℃以下，产物的电化学性能随焙烧温度的升高而增加。当电流密度为C/3时，焙烧温度为800℃的首次放电容量为105mAh／g，但循环性能较差，30次循环后仅剩83％。     

The microwave irradiation effect on copper leaching from sulfide/oxide ores

Increasing the rate and ultimate copper recovery from low-grade copper sources may be the most important problem affecting the economy of copper mining. This present research work is a study on microwave-irradiation application for copper recovery from two main types of copper ores (i.e., oxide and sulfide) was investigated. The results of rolling bottle tests showed that H₂SO₄ consumptions were lower in the pretreated ores in comparison with the conventional leaching tests. Leaching tests in shaking flasks by using the two types of ores showed a significant increase (up to 26% in some cases) in copper recoveries from pretreated ores. Main effective parameters such as irradiation power, ore states in the microwave chamber, and irradiation times were completely studied. To explain the behavior according to the enhanced copper recoveries, some possible mechanisms were discussed.     

Physicochemical properties and operational stability of Taguchi design-optimized Candida rugosa lipase supported on biogenic silica/magnetite/graphene oxide for ethyl valerate synthesis

Biobased ternary nanocomposites can stabilize enzymes for greater stability, catalytic activity and easy recovery. This study aimed to optimize biogenic silica/magnetite/graphene oxide nanocomposite supported Candida rugosa lipase (CRL/SiO₂/Fe₃O₄/GO) for ethyl valerate (EV) synthesis and characterize the biocatalysts’ physicochemical properties and operational stability. CRL conjugated-oil palm leaves-derived biogenic SiO₂/Fe₃O₄/GO nanocomposite showed a maximum immobilized protein of 44.13 ± 2.1 mg/g with a specific activity (534.87 ± 9.5 U/mg), than free CRL (≥700 U/mg). GL-A-SiO₂/Fe₃O₄/GO exhibited the highest surface area (260.87 m²/g) alongside superior thermal stability in TGA/DTG. XRD revealed an amorphous SiO₂ (crystallinity = 26.7%), while Fe₃O₄ existed as cubic spinel crystal (crystallinity = 90.2%). Taguchi Design-optimization found that CRL/SiO₂/Fe₃O₄/GO best catalyzed the EV synthesis (90.4% in 3 h) at 40 ℃ using 3 mg/mL of biocatalyst, valeric acid/ethanol molar ratio of 1:2, in 10% (m/v) molecular sieves with stirring in heptane at 200 rpm. EV production was confirmed by FTIR- (C=O: 1738 cm^?1 and C–O–C: 1174 cm^?1) and GC–MS ([M]⁺ m/z = 130, C₇H₁₄O₂). CRL/SiO₂/Fe₃O₄/GO’s reusability for 11 successive esterification cycles demonstrated the SiO₂/Fe₃O₄/GO’s exceptional hyperactivation and stabilization properties on immobilized CRL. These findings conveyed the SiO₂/Fe₃O₄/GO’s efficacy to alter CRL's physicochemical properties and operational stability for catalyzing higher yields EV.     

Green strategy of scaleably synthesizing copper nanocomposites with remarkable catalytic activity for wastewater treatment

The functional copper nanocomposites (Cu NCs) have received increasing attention in the environmen-tal catalysis application for wastewater treatment due to their superior catalytic activity and reactivity.However,overcoming the pH limitations towards the neutral and alkaline wastewater remains a tricky challenge.In this work,we demonstrate a green strategy to synthesize Cu NCs with coexistence of active Cu,Cu2O and ZrO2 by self-propagating combustion of metallic glassy ribbons,which exhibit the extremely superior catalytic performance for degradation reaction,providing full conversion of organic dyes com-pletely to the environmental friendly small species (efficiency ＞ 99％) under acidic,neutral and alkaline conditions.Compared with all other catalysts developed thus far,the novel Cu NCs catalysts with more active sites present much enhanced catalytic capability of degradation efficiency without the use of any chemical reagents for neutral and alkaline organic dye solutions.The possible decomposition pathways of organic dyes for different pH systems were systematically investigated.More importantly,the two kinds of catalytic mechanism related to high reactivity of nanoscale Cu/Cu2O and strong oxidizing capability of activated.OH/·O2-radicals can also be successfully confirmed under different pH conditions.The green synthetic approach can be extended to design the various M-based nanocomposites (M =Fe,Co,Ni,Ag,Pd) as efficient catalysts for the functional applications of many chemical reactions.     

燃烧法合成花状、四针状氧化锌及其气敏性能研究

研究了以锌粉为原料,活性炭为催化剂,高温气相氧化反应制备花状、四针状和无定形氧化锌的合成条件及形貌.X射线衍射结果表明该晶体属六方晶系纤锌矿结构.扫描电镜研究结果表明活性炭催化剂用量、反应温度对产物氧化锌晶须的形态影响很大,对所有样品的气敏元件在浓度范围为5×10(-6)～2×10(-4)的甲醇、乙醇、丙酮和正丙醇气体...