纳米孔炭负载 MnOx 催化剂上苯甲醇氧化反应性能

 以纳米孔炭 (NC) 为载体, 采用浸渍法制备了一系列 MnOx/NC 催化剂, 并用于以空气为氧源的苯甲醇液相氧化反应. 通过 X 射线衍射、X 射线光电子能谱、N2 吸附-脱附和 H2-程序升温还原等手段对催化剂进行了表征, 考察了催化剂中 Mn 负载量和焙烧温度, 以及反应条件等对反应性能的影响. 结果表明, 10%MnOx/NC 催化剂的活性较高, 反应 4 h 后苯甲醇转化率可达 80.4%; 明显高于活性炭负载的 MnOx 催化剂. 这主要归因于其表面存在大量高分散、且易于还原的 Mn 物种.     

Generation of sulfate radicals by supported ruthenium catalyst for phenol oxidation in water

In this study we report the preparation of RuO₂/Fe₃O₄@nSiO₂@mSiO₂ core–shell powder mesoporous catalyst for heterogeneous oxidation of phenol by peroxymonosulfate (PMS) as oxidant. The properties of this supported catalyst were characterized by SEM–EDS (scanning electron microscopy–energy dispersive X-ray spectroscopy), XRD (powder X-ray diffraction), TEM (transmission electron microscopy), and nitrogen adsorption–desorption. It is found that using ruthenium oxide-based catalyst is highly effective in activating PMS for related sulfate radicals. The effects of catalyst loading, phenol concentration, PMS concentration, reaction temperature, and reusability of the as-prepared catalyst on phenol degradation were investigated. In RuO₂/Fe₃O₄@nSiO₂@mSiO₂ mesoporous catalyst, Oxone (PMS) was effectively activated and 100 % phenol degradation occurred in 40 min. The magnetic RuO₂/Fe₃O₄@nSiO₂@mSiO₂ catalyst was facility separated from the solution by an external magnetic field. To regenerate the deactivated catalyst and improve its catalytic properties, three different methods involving annealing in air, washing with water, and applying ultrasonics were used. The catalyst was recovered thoroughly by heat treatment.     

Hydrogen storage and delivery: immobilization of a highly active homogeneous catalyst for the decomposition of formic acid to hydrogen and carbon dioxide

The homogeneous catalytic system, based on water-soluble ruthenium(II)–TPPTS catalyst (TPPTS = meta-trisulfonated triphenylphosphine), selectively decomposes HCOOH into H₂ and CO₂ in aqueous solution. Although this reaction results in only two gas products, heterogeneous catalysts could be advantageous for recycling, especially for dilute formic acid solutions, or for mobile, portable applications. Several approaches have been used to immobilize/solidify the homogeneous ruthenium–TPPTS catalyst based on ion exchange, coordination and physical absorption. The activity of the various heterogeneous catalysts for the decomposition of formic acid has been determined. These heterogenized catalysts offer the advantage of easy catalyst separation/recycling in dilute formic acid, or for mobile, portable applications.     

Catalytic Combustion of Methane over MnOx／ZrO2-Al2O3 Catalysts

MnOx/Al2O3 and MnOx/ZrO2-Al2O3 catalysts were prepared by incipient wetness impregnation of Mn(CH3COO)2 on the corresponding supports, followed by the characterization using X-ray diffraction (XRD). temperature programmed reduction (TPR) and BET surface area techniques. The result shows the BET surface area of ZrO2-Al2O3 is lower than that of Al2O3 due to the loading of ZrO2.However tile resulted MnOx/ZrO2-Al2O3 catalyst exhibits higher activity for methane combustion than MnOx/Al2O3, because the addition of ZrO2 onto Al2O3 is beneficial for the dispersion of Mn species and the improvement of the lattice oxygen activity in MnOx. subsequently the activation of methane during combustion. The optimum loading of Zr in MnOx/ZrO2-Al2O3 is in the range of 5%-10% correlated with the calcination temperatures of catalyst supports.     

Oxidative carbonylation of phenol to diphenyl carbonate catalyzed by palladium complexes bridged with N,N‐ligands over functionalized silica

Heterogeneous palladium catalysts anchored on functionalized silica were prepared by sol–gel methods and their catalytic properties for the oxidative carbonylation of phenol to diphenyl carbonate (DPC) were investigated. The catalysts were characterized by means of IR, XPS, EA and BET. The Pd loading in the heterogeneous catalysts and leaching in solution were detected by atomic absorption. The effects of different reaction parameters such as temperature, solvent and inorganic cocatalyst on the yield of DPC and Pd leaching were also studied. It was found that Cu₂O and tetrahydrofuran (THF) were the best partners with these heterogeneous catalysts. In the presence of 3 Å molecular sieves as dehydrating agent, the heterogeneous palladium catalyst prepared from 2‐acylpyridine revealed excellent catalytic performance and stability at 110 °C for 5 h, giving 13.7% yield of DPC based on phenol and 4.0% Pd loss in solution. The heterogeneous catalyst was more active and stable compared with traditional supported Pd? C catalyst under the same reaction conditions. Copyright © 2005 John Wiley & Sons, Ltd.     

表面修饰多壁碳纳米管负载二氧化钛的制备及催化碳酸二甲酯与苯酚酯交换反应的性能

制备了表面修饰多壁碳纳米管负载TiO₂的催化剂,并将其应用于碳酸二甲酯与苯酚的酯交换反应. 采用X射线电子能谱、透射电子显微镜、低温N₂吸附-脱附和X射线衍射等对催化剂进行了表征. 结果表明,以低浓度的氨水（0.4%）代替去离子水作为沉淀剂时,制备的催化剂显示出更好的催化活性、分离性与重复使用性. 考察了TiO₂负载量、催化剂用量及反应时间对反应性能的影响. 在最佳反应条件下,苯酚转化率为42.5%,碳酸甲苯酯与碳酸二苯酯的总选择性达到99.9%以上. 经过4次重复使用后,催化剂的活性略有下降.     

印染污泥的活性炭负载过渡金属化合物非均相催化臭氧化

采用湿式浸渍法,将6种含过渡金属(Cu,Fe,Zn,Ni,Mn,Ce)元素的化合物负载在活性炭（AC）上,制得6种催化剂AC/M(M=Cu,Fe,Zn,Ni,Mn,Ce),在室温条件下,催化臭氧化处理苯酚溶液和印染污泥。 催化剂AC/M通过Boehm滴定、XRD和BET分析进行表征。 苯酚的3种降解方法中,AC/M催化剂的臭氧催化最好,AC/M吸附处理次之,单独臭氧处理的效果最差。 在苯酚的降解处理过程中,AC/M催化臭氧化处理苯酚溶液的效率依次为：AC/Fe＞AC/Zn＞AC/Ni＞AC/Ce＞AC/Cu＞AC/Mn。 AC/M催化剂催化臭氧化效果随溶液pH值的增大而增强。 AC/M催化剂处理印染污泥的效率依次为：AC/Fe＞AC/Zn＞AC/Ce=AC/Ni＞AC/Cu＞AC/Mn,AC/Fe催化臭氧化处理印染污泥可使污泥中有机质含量降低8.17%。     

Structure and oxidation state of silica-supported manganese oxide catalysts and reactivity for acetone oxidation with ozone

Silica-supported manganese oxide catalysts with loadings of 3, 10, 15, and 20 wt % (as MnO2) were characterized with use of X-ray absorption spectroscopy and X-ray diffraction (XRD). The edge positions in the X-ray absorption spectra indicated that the oxidation state for the manganese decreased with increasing metal oxide loading from a value close to that of Mn2O3 (+3) to a value close to that of Mn3O4 (+2(2)/3). The XRD was consistent with these results as the diffractograms for the supported catalysts of higher manganese oxide loading matched those of a Mn3O4 reference. The reactivity of the silica-supported manganese oxide catalysts in acetone oxidation with ozone as an oxidant was studied over the temperature range of 300 to 600 K. Both oxygen and ozone produced mainly CO2 as the product of oxidation, but in the case of ozone the reaction temperature and activation energy were significantly reduced. The effect of metal oxide loading was investigated, and the activity for acetone oxidation was greater for a 10 wt % MnOx/SiO2 catalyst sample compared to a 3 wt % MnOx/SiO2 sample.     

石墨烯氢氧化钴复合催化剂的一步合成及其对酸性橙的催化降解(英文)

用一步合成自组装法制备出了氢氧化钴与还原氧化石墨烯(Co(OH)2/rGO)的复合催化剂,并将其用于水中染料的催化降解实验.通过X射线衍射(XRD),激光拉曼(Raman)光谱,透射电镜(TEM),X射线能量色散谱(EDS)以及X射线光电子能谱(XPS)等一系列分析手段对催化剂的结构形貌进行了详细的表征,表征结果证实氢氧化钴很好地附着在还原石墨烯的表面.最后初步考察了催化剂催化单过硫酸钾(PMS)降解酸性橙(AO7)的性能.结果表明,催化剂显示出了高效的催化性能,酸性橙的色度可在12 min内完全去除,总有机碳(TOC)实验也表明染料降解的同时也可获得较高的矿化度.循环稳定性实验表明在进行到第三次实验时,催化剂仍能保持高的催化活性,将酸性橙在16 min内降解完毕.     

Novel Ni−Fe-oxide systems for catalytic oxidation of cyanide in an aqueous phase

Catalytic activity of mixed Ni?Fe oxide systems with respect to air oxidation of aqueous cyanide solution at 308 K was investigated. The catalysts employed were prepared by an oxidation-precipitation method at room temperature and were characterized by powder X-ray diffraction (XRD), Mössbauer spectroscopy, and chemical analysis. The cyanide oxidation rate was found to be dependent on the catalyst's calcination temperature, pH of the medium, and catalyst loading. Results revealed that the catalyst calcined at 120°C is the most active where up to 90% of free cyanide (4 mM) was removed after oxidation for 30 minutes in the presence of 2.5 g/L catalyst at pH 9.5. The cyanide conversion becomes less favorable as the pH of the solution increases (with other constant parameters). The selectivity data showed that carbon dioxide is the main oxidation product, regardless of pH of the solution.     

Fe2O3/CNT催化湿法H2O2氧化苯酚

通过化学沉积法和热处理得到多壁碳纳米管负载Fe2O3催化剂 Fe2O3/CNT, Fe2O3的负载质量分数约为15.1%,XRD表征显示,负载的Fe2O3存在α和γ这2种晶型。考察了Fe2O3/CNT催化湿式H2O2氧化去除废水中苯酚催化性能,通过苯酚的去除率及反应过程中催化剂活性组分的溶出总量,研究了催化剂制备过程中添加聚乙烯醇对催化剂性能的影响。在苯酚和H2O2初始浓度分别为350和1 500 mg/L、催化剂投加量为1.0 g/L、温度80 ℃条件下,经过240 min的反应,苯酚去除率达100％,COD去除率为86.1％。     

石墨烯氢氧化钴复合催化剂的一步合成及其对酸性橙的催化降解

用一步合成自组装法制备出了氢氧化钴与还原氧化石墨烯（Co（OH）₂/rGO）的复合催化剂,并将其用于水中染料的催化降解实验. 通过X射线衍射（XRD）,激光拉曼（Raman）光谱,透射电镜（TEM）,X射线能量色散谱（EDS）以及X射线光电子能谱（XPS）等一系列分析手段对催化剂的结构形貌进行了详细的表征,表征结果证实氢氧化钴很好地附着在还原石墨烯的表面. 最后初步考察了催化剂催化单过硫酸钾（PMS）降解酸性橙（AO7）的性能. 结果表明,催化剂显示出了高效的催化性能,酸性橙的色度可在12 min内完全去除,总有机碳（TOC）实验也表明染料降解的同时也可获得较高的矿化度. 循环稳定性实验表明在进行到第三次实验时,催化剂仍能保持高的催化活性,将酸性橙在16 min内降解完毕.     

Low Pt content Pt–Ru–Ir–Sn quaternary catalysts for anodic methanol oxidation in DMFC

In this communication we report our research work on low Pt content Pt–Ru–Ir–Sn quaternary catalysts for use in DMFC anodes. The carbon-supported quaternary metal alloy catalyst was synthesized according to the solution reduction method and was deposited onto a carbon fiber paper or a carbon aerogel nanofoam to form the anode for direct methanol fuel cells. The Pt loading of the electrode is 0.1 mg/cm². The testing results from a three-electrode electrochemical cell show that the simultaneous use of higher Ir (25–35 wt.%) and Sn (10 wt.%) content gives satisfactory stability and higher activity for methanol oxidation than the commercially available E-TEK anode (80%[0.5Pt 0.5Ru]/C on carbon cloth). Energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), scanning electron microscope (SEM), and Bruner–Emmett–Teller method (BET) measurements were carried out to characterize the composition, structure, morphology, and surface area of the developed catalysts.     

亚微米级Cu0/Fe3O4复合物多相催化过一硫酸盐降解有机污染物

过一硫酸盐催化活化技术因其可产生强氧化性活性氧化物种,可快速氧化降解并矿化有机污染物的优异性能而备受关注.本文成功制备了亚微米级Cu0/Fe3O4复合物,发现其能多相催化过一硫酸盐产生单线态氧降解有机污染物.首先,以CuCl2·2H2O,FeCl2·4H2O和FeCl3·6H2O为铜源和铁源,水合肼为还原剂,采用水热法在180oC反应24 h制备了亚微米级磁性Cu0/Fe3O4复合物.表征结果显示,所制材料为Cu0和Fe3O4的复合物,颗粒大小约为220 nm;单一相Cu0和Fe3O4晶体粒径分别为33.8和106.2 nm,而Cu0/Fe3O4复合物中Cu0和Fe3O4晶体粒径分别减为20.8和31.9 nm.这表明Cu0和Fe3O4复合降低了Cu0和Fe3O4晶体粒径,有利于Cu0和Fe3O4的分散.BET测试结果表明,Cu0/Fe3O4复合物比表面积为4.6 m2/g,与Cu0颗粒的(4.2 m2/g)相当,但远小于Fe3O4的(15.6 m2/g).制备的Cu0/Fe3O4复合物可有效催化过一硫酸盐产生单线态氧降解罗丹明B、亚甲基蓝、金橙II、苯酚和对氯酚.当Cu0/Fe3O4复合物的用量为0.1 g/L,过一硫酸盐浓度为0.5 mmol/L和初始pH为7时,Cu0/Fe3O4复合物可在30 min内完全降解20μmol/L的罗丹明B、亚甲基蓝、金橙II以及0.1 mmol/L的苯酚和对氯酚.对比试验显示,在相同条件下,Cu0和Fe3O4颗粒分别可以降解28%和20%的罗丹明B.这表明Cu0/Fe3O4复合物中的Cu0和Fe3O4晶体在催化过一硫酸盐降解污染物的反应中具有协同作用,这主要来源于Cu0/Fe3O4复合物中Cu0和Fe3O4的晶体粒径变小和更好的分散.采用分光光度法测定了降解反应液中铜和铁离子的溶出量.当Cu0/Fe3O4复合物的用量为0.1 g/L,过一硫酸盐浓度为0.5 mmol/L和初始pH为7时,反应60 min后,降解液中铜和铁离子的浓度分别为0.22和0.1 mg/L,仅占复合物中总铜和总铁量的1.1%和0.2%,表明Cu0/Fe3O4复合物具有较强的化学稳定性.所制Cu0/Fe3O4复合物具有超顺磁性,借助磁场实现快速分离回收,可循环利用五次,表明其优越的催化稳定性.通过加入乙醇和叠氮化钠,考察了Cu0/Fe3O4复合物催化活化过一硫酸盐体系中的活性氧化物种.发现100 mmol/L乙醇的加入对污染物的降解无明显影响,而加入同等量的叠氮化钠可完全抑制污染物的降解,表明Cu0/Fe3O4复合物催化活化过一硫酸盐产生的主要活性氧物种为单线态氧.采用电子顺磁共振谱进一步证实了单线态氧的生成.基于以上研究,Cu0/Fe3O4复合物催化活化过一硫酸盐的机理为Cu0/Fe3O4作为一个电子媒介加速过一硫酸盐和污染物之间的电子转移,从而导致污染物被快速降解.该反应机理不同于常见的金属催化过一硫酸盐产生硫酸根和羟自由基的反应机理.我们推测,电导性优良的Cu0在此催化反应中起着关键性作用.本催化方法可作为一种绿色的氧化技术用于环境污染物的氧化降解处理.     

新型钴-聚吡咯-碳载Pt燃料电池催化剂的制备与表征

采用脉冲微波辅助化学还原法制备了钴-聚吡咯-碳（Co-PPy-C）载Pt 催化剂（Pt/Co-PPy-C）,其中Pt 的总质量占20%. 利用透射电镜（TEM）、光电子射线能谱分析（XPS）和X射线衍射（XRD）研究了催化剂的结构,用循环伏安（CV）、线性扫描伏安（LSV）等方法考察了其电化学活性及氧还原反应（ORR）动力学特性及耐久性. Pt/Co-PPy-C电催化剂的金属颗粒直径约1.8 nm,略小于商用催化剂Pt/C（JM）颗粒尺寸（约2.5 nm）;催化剂在载体上分散均匀,粒径分布范围较窄. Pt/Co-PPy-C的电化学活性比表面积（ECSA）（75.1 m²·g^-1）高于商用催化剂的ECSA（51.3 m²·g^-1）. XPS测试表明,自制催化剂表面的Pt 主要以零价形式存在. 而XRD结果显示,自制催化剂中Pt（111）峰最强,Pt 主要为面心立方晶格. Pt/Co-PPy-C具有与Pt/C（JM）相同的半波电位;在0.9 V下,Pt/Co-PPy-C的比活性（1.21 mA·cm^-2）高于商用催化剂的比活性（1.04 mA·cm^-2）,表现出更好的ORR催化活性.动力学性能测试表明催化剂的ORR反应以四电子路线进行. CV测试1000 圈后,Pt/Co-PPy-C和Pt/C（JM）的ECSA 分别衰减了13.0%和24.0%,可见自制催化剂的耐久性高于商用Pt/C（JM）,在质子交换膜燃料电池（PEMFC）领域有一定的应用前景.     

焙烧温度对非负载Ni-Mo-Al_2O_3催化剂加氢脱氧性能的影响

采用热分解硝酸镍和钼酸铵的方法制备了Ni-Mo-Al2O3非负载催化剂。分别以乙酸、苯酚为探针分子,在连续流动固定床反应器上评价了催化剂的加氢脱氧活性,并采用XRD、BET、XRD、EDS等技术对催化剂进行了表征,着重考察了焙烧温度对催化剂的晶态结构、表面元素相对含量及催化性能的影响。结果表明,随着焙烧温度的升高,催化剂的比表面积增大,晶化程度提高,焙烧温度550℃时,催化剂表面Ni、Mo、Al的比例达到最优,并具有最好的加氢脱氧活性。在250℃、0.4 MPa条件下,乙酸的脱氧率达到96.0%;在200℃、0.3 MPa条件下,苯酚的脱氧率达到96.8%。     

高效组合型Pt-Fe/C 催化剂用于肉桂醛选择性加氢反应

采用有机金属化合物Pt2(dba)3(dba为二亚苄基丙酮)还原分解法制得均匀分布的Pt纳米颗粒(粒径在2.0nm左右),直接吸附到经预处理的Fe/C载体上,即得到了组合型Pt-Fe/C催化剂.采用透射电子显微镜(TEM)、X射线光电子能谱(XPS)和能量散射X射线谱(EDS)等技术表征了催化剂表面Pt颗粒大小分布,Pt、Fe化学态和催化剂表面元素等.将该组合型催化剂用于肉桂醛(CAL)选择性加氢反应,获得了良好的效果,其催化活性比浸渍法制备的Pt/C催化剂高1倍以上.在60°C、2.5h、4.0MPaH2反应条件下,1%(w,质量分数)Pt-1.5%(w)Fe/C催化剂肉桂醛加氢转化率为99.2%,肉桂醇(COL)选择性达到85.0%.     

Low temperature preparation of anatase TiO2-coated activated carbon

Anatase titania sols were synthesized at low temperature (i.e. 75 °C) by hydrolysis of titaniumn-butoxide in abundant acidic aqueous solution. The prepared TiO₂ nanoparticles were loaded on activated carbon in a rotatory evaporator under vacuum, and then the composite photocatalyst was employed for the removal of phenol from water. The apparent rate constant and quantum yield of the composite photocatalyst enhanced 5 and 2.5 times, respectively, compared to single phase titania. The activated carbon with strong adsorbent activity provided sites for the adsorption of phenol, and the adsorbed phenol migrated continuously onto the surface of TiO₂ particles which were located mainly at the exterior surface of the activated carbon. Some phenol remained adsorbed on the catalyst when no traces of phenol were detected in the water. This adsorbed phenol could be degraded by illuminated titania while maintaining UV-irradiation. The photocatalyst was used for six cycles with degraded rate of phenol still higher than 80%.     

COx-Free Hydrogen and Carbon Nanofibers Produced from Direct Decomposition of Methane on Nickel-Based Catalysts

Direct decomposition of methane was carried out using a fixed-bed reactor at 700℃for the production of COx-free hydrogen and carbon nanofibers. The catalytic performance of NiO-M/SiO2 catalysts (where M=AgO, CoO, CuO, FeO, MnOx and MoO) in methane decomposition was investigated. The experimental results indicate that among the tested catalysts, NiO/SiO2 promoted with CuO give the highest hydrogen yield. In addition, the examination of the most suitable catalyst support, including Al2O3, CeO2, La2O3, SiO2, and TiO2, shows that the decomposition of methane over NiO-CuO favors SiO2 support. Furthermore, the optimum ratio of NiO to CuO on SiO2 support for methane decomposition was determined. The experimental results show that the optimum weight ratio of NiO to CuO fell at 8:2 (w/w) since the highest yield of hydrogen was obtained over this catalyst.     

新型钴-聚吡咯-碳载Pt燃料电池催化剂的制备与表征

采用脉冲微波辅助化学还原法制备了钴-聚吡咯-碳(Co-PPy-C)载Pt催化剂(Pt/Co-PPy-C),其中Pt的总质量占20%.利用透射电镜(TEM)、光电子射线能谱分析(XPS)和X射线衍射(XRD)研究了催化剂的结构,用循环伏安(CV)、线性扫描伏安(LSV)等方法考察了其电化学活性及氧还原反应(ORR)动力学特性及耐久性.Pt/Co-PPy-C电催化剂的金属颗粒直径约1.8 nm,略小于商用催化剂Pt/C(JM)颗粒尺寸(约2.5 nm);催化剂在载体上分散均匀,粒径分布范围较窄.Pt/Co-PPy-C的电化学活性比表面积(ECSA)(75.1 m2·g-1)高于商用催化剂的ECSA(51.3 m2·g-1).XPS测试表明,自制催化剂表面的Pt主要以零价形式存在.而XRD结果显示,自制催化剂中Pt(111)峰最强,Pt主要为面心立方晶格.Pt/Co-PPy-C具有与Pt/C(JM)相同的半波电位;在0.9 V下,Pt/Co-PPy-C的比活性(1.21 mA·cm-2)高于商用催化剂的比活性(1.04 mA·cm-2),表现出更好的ORR催化活性.动力学性能测试表明催化剂的ORR反应以四电子路线进行.CV测试1000圈后,Pt/Co-PPy-C和Pt/C(JM)的ECSA分别衰减了13.0%和24.0%,可见自制催化剂的耐久性高于商用Pt/C(JM),在质子交换膜燃料电池(PEMFC)领域有一定的应用前景.