Sr掺杂强化LaCo0.5Cu0.5O3型钙钛矿活化过一硫酸盐的性能

采用溶胶-凝胶法制备A位掺Sr的La_xSr_1-xCo_0.5Cu_0.5O₃钙钛矿增强传统B位掺杂钙钛矿活化过一硫酸盐（PMS）的能力。本文选取效果最好的La_0.7Sr_0.3Co_0.5Cu_0.5O₃型钙钛矿为研究对象,以偶氮染料AO7为目标污染物,考察了钙钛矿投加量、PMS浓度、pH和染料废水中常见Cl^-对La_0.7Sr_0.3Co_0.5Cu_0.5O₃/PMS体系降解AO7的影响,并测试了材料的重复利用性和矿化能力。结果表明,La_0.7Sr_0.3Co_0.5Cu_0.5O₃/PMS降解AO7的速度随着材料投加量和PMS浓度的增加而加快,在中性条件下反应速度最快且矿化率良好。该体系主要活性物种之一为·OH,但Sr掺杂后钙钛矿的O空位增多使得¹O₂也参与到降解过程之中。     

可见光激发Bi2MoO6活化PMS降解盐酸四环素

为了利用半导体光催化和硫酸根自由基高级氧化技术协同作用处理抗生素废水,采用溶剂热法制备三维结构的钼酸铋(Bi₂MoO₆)微球,并在可见光照射下激发Bi₂MoO₆进而活化过一硫酸氢盐(PMS)处理含盐酸四环素(TC)废水。利用扫描电子显微镜(SEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)、紫外-可见漫反射光谱(UV-Vis DRS)等对样品形貌特征、晶格结构、光学性能进行表征。结果表明,Bi₂MoO₆纳米片组成的三维微球具有良好的吸附和可见光催化降解TC能力,活化PMS协同作用可以进一步提高系统降解TC的效率。通过静态实验,考察催化剂使用量、PMS初始浓度、环境共存阴离子(Cl^-、CO^2-₃、NO^-₃)和腐殖酸(HA)对可见光激发Bi₂MoO₆活化PMS降解TC性能的影响。自由基捕获实验表明,·OH、SO^-₄·、O^-₂·和h⁺等活性基团在可见光激发Bi₂MoO₆活化PMS催化降解TC过程中都做出了贡献。     

不同形貌氧化钴活化过一硫酸盐降解硝基酚

通过控制形貌制备具有高活性晶面的金属氧化物可提高硝基酚的降解效果,以硝酸钴和乙酸钴为原料,制备了八面体、立方块和棒状Co₃O₄,通过X射线衍射（XRD）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）对催化剂进行表征,表明合成的Co₃O₄粒径均匀、纯度较高。以3种不同形貌的Co₃O₄为催化剂,在pH值为8.0条件下活化过一硫酸盐（PMS）降解不同种类的硝基酚,采用高效液相色谱和总有机碳分析仪测定反应前后硝基酚和总有机碳含量（TOC）变化。3种Co₃O₄在Co₃O₄/PMS体系降解硝基酚时表现出不同的催化活性：棒状Co₃O₄ > 立方块Co₃O₄ > 八面体Co₃O₄,并且对不同硝基酚的降解效率存在显著的差异性。3种Co₃O₄在pH值为8.0下活化PMS所析出的Co²⁺含量较低,且均表现出良好的循环利用性。自由基淬灭实验和电子自旋共振（ESR）测试表明Co₃O₄/PMS体系降解硝基酚是通过自由基和非自由基机制共同协作完成的,起作用的活性氧化物种主要为羟基自由基（·OH）、硫酸根自由基（SO₄^·-）和单线态氧（¹O₂）。     

La0.8Ce0.2Fe0.9Ru0.1O3/TiO2催化湿式氧化降解草甘膦废水

草甘膦是种广谱除草剂,草甘膦废水产量大、可生化性差。以钙钛矿型La_0.8Ce_0.2Fe_0.9Ru_0.1O₃/TiO₂为催化剂,采用湿式氧化(WAO)和催化湿式氧化(CWAO)法对草甘膦废水进行高效降解,并对草甘膦降解机制进行研究。应用XRD和XRF对催化剂进行表征,结果表明,合成的催化剂具有钙钛矿结构,但由于Ru原子半径太大可能没有完全进入钙钛矿骨架,导致CWAO反应后有微量Ru溶出。考察反应温度对草甘膦降解的影响,并对反应过程中C、N、P产物的选择性进行分析,结果表明,提高反应温度和加入催化剂有利于提高草甘膦转化率及对CO₂和P^3-₄的选择性,但反应温度过高不利于生成N₂,因为高温下NH₃-N更容易被氧化成N^-₂和N^-₃。在实验条件下,合适的反应温度为200 ℃,反应180 min草甘膦转化率大于95%,同时对CO₂和N₂有较高的选择性,分别为54.59%和19.40%。应用计算量子化学计算草甘膦分子的净电荷分布,结果表明,WAO和CWAO中草甘膦反应的断键部位为C—C键、C—P键和C—N键,而后中间产物再进一步被氧化为CO₂、N₂、 N^-₂、N^-₃、P^3-₄等。     

Stabilisation of active nickel catalysts in partial oxidation of methane to synthesis gas by iron addition

Mixed LaNi_xFe_(1−x)O₃ perovskite oxides (0≤x≤1) have been prepared by a sol–gel related method, characterised by X-ray diffraction (XRD), specific surface area measurements, transmission electron microscopy (TEM) coupled to an energy dispersive X-ray spectrometer (EDS). These systems are the precursors of highly efficient catalysts in partial oxidation of methane to synthesis gas. Studies on the state of these systems after test show the stabilisation of active nickel by increasing the amount of iron. These systems permit to control the reversible migration of nickel from the structure to the surface. The best mixed perovskite for the partial oxidation of methane is LaNi_0.3Fe_0.7O₃.     

Simultaneous utilization of electro-generated O2 and H2 for H2O2 production: An upgrade of the Pd-catalytic electro-Fenton process for pollutants degradation

The Electro-Fenton (EF) process is one of the promising advanced oxidation processes (AOPs) for environmental remediation. The H₂O₂ yield of EF process largely determines its performance on organic pollutants degradation. Conventional Pd-catalytic EF process generates H₂O₂ via the combination reaction of anodic O₂ and cathodic H₂. However, the relatively expensive catalyst limits its application. Herein, a hybrid Pd/activated carbon (Pd/AC)-stainless steel mesh (SS) cathode (PACSS) was proposed, which enables more efficient H₂O₂ generation. It utilizes AC, the support of Pd catalyst, as part of cathode for H₂O₂ generation via 2-electron anodic O₂ reduction, and SS serve as a current distributor. Moreover, H₂O₂ could be catalytically decomposed upon AC to generate highly reactive ·OH, which avoids the use of Fe²⁺. Compared with conventional Pd catalyst, H₂O₂ concentration obtained by PACSS cathode is 248.2% higher, the O₂ utilization efficiency was also increased from 3.2% to 10.8%. Within 50 min, 26.3%, 72.5%, and 94.0% H₂O₂ was decomposed by Pd, AC, and Pd/AC. Fluorescence detection results implied that Pd/AC is effective upon H₂O₂ activation for OH generation. Finally, iron-free EF process enabled by PACSS cathode was examined to be effective for reactive blue 19 (RB19) degradation. After continuous running for 10 cycles (500 min), the PACSS cathode was still stable for H₂O₂ generation, H₂O₂ activation, and RB19 degradation, showing its potential application for organic pollutants degradation without increase in the running cost.     

Degradation of bisphenol A by peroxymonosulfate activated by MnFe2O4 prepared by salt-assisted solution combustion synthesis

Magnetic manganese ferrite (MnFe₂O₄) prepared by the salt-assisted solution combustion synthesis was used to activate peroxymonosulfate(PMS) to oxidize bisphenol A in aqueous solution. The prepared MnFe₂O₄ catalyst was characterized by XRD and BET. The effects of MnFe₂O₄ dosage, PMS dosage, initial pH of the solution, quencher, and co-existing ions on the degradation of bisphenol A were investigated. The reusability of the MnFe₂O₄ catalyst was evaluated through cycling experiments. The results showed that the best dosages of MnFe₂O₄ and PMS were 0.3 g/L and 0.3 mmol/L, respectively. When the initial pH was 11.0, the degradation rate of bisphenol A was 99.3% in 60 min. When putting some quenchers into the MnFe₂O₄/PMS catalytic system, all of them showed depression effects on degradation of bisphenol A, and the ¹O₂ was the main active species. The co-existing ions such as Cl^-, HCO₃^-, and HPO₄^2- in solution affected the degradation of bisphenol A. The TOC removal rate of bisphenol A within 60 min was 34.9%, the rupture and opening of benzene ring are the main reaction pathways. After the MnFe₂O₄ catalyst was recycled three times, the degradation rate of bisphenol A remained at about 90.0%.     

盐助溶液燃烧法制备MnFe2O4催化过一硫酸盐降解双酚A

采用盐助溶液燃烧法制备磁性铁酸锰（MnFe₂O₄）,催化过一硫酸氢盐（PMS）氧化降解水溶液中的双酚A。通过XRD、BET等手段对制备的铁酸锰催化剂进行了表征。探究了MnFe₂O₄投加量、PMS投加量、溶液初始pH、淬灭剂、共存离子等因素对双酚A降解效果的影响,评估了MnFe₂O₄催化剂的循环利用性能。结果表明,MnFe₂O₄和PMS的最合理投加量分别为 0.3 g/L、0.3 mmol/L,初始pH为11.0时双酚A降解效果最好,60 min内的降解率可达99.3%。淬灭实验表明,催化体系中同时存在多种活性物质,¹O₂是主要活性物种。溶液中Cl^-、HCO₃^-和HPO₄^2-等共存离子的存在影响双酚A的降解。双酚A在60 min内的TOC去除率为34.9%,苯环断裂和开环反应是其主要降解路径。MnFe₂O₄催化剂循环使用三次后,双酚A的降解率仍保持在90.0%左右。     

Magnéli phases TinO2n−1 as novel ozonation catalysts for effective mineralization of phenol

Magnéli phases Ti_nO_2n-1 have been demonstrated as promising environmentally friendly materials in advanced oxidation processes. In this study, Magnéli phases Ti_nO_2n-1 have been used as catalysts for the ozonation of phenol in aqueous solution for the first time. The materials exhibited excellent catalytic ozonation activities both in phenol degradation and mineralization. When Ti₄O₇ was added, the reaction rate was six-fold higher than that of with ozone alone, while the total organic carbon removal rate was substantially elevated from around 19.2% to 92%. By virtue of the good chemical stability of the materials, a low metal leaching of less than 0.15 mg·L^-1 could effectively avoid the secondary pollution by metal ions. Radical quenching tests revealed ·O₂^- and ¹O₂ to be active oxygen species for phenol degradation at pH 5. As semiconductor catalysts, Ti_nO_2n-1 materials show electronic transfer capability. Ozone adsorbed at B-acid sites of the catalyst surface can capture an electron from the conversion of Ti(Ⅲ) to Ti(IV), and is thereby broken into the active oxygen species. It was interesting to observe that Ti_nO_2n-1 exhibit better catalytic activity for phenol degradation and mineralization with lower n value. The difference in electrical conductivity can be considered as a major factor for the catalytic performances. More highly conductive catalysts show a faster electron-transfer rate and better catalytic activity. Thus, significant evidences have been obtained for a single-electron-transfer mechanism of catalytic ozonation with Magnéli phases Ti_nO_2n-1.     

碱/碱土金属修饰Ni基催化剂的CO2吸附与甲烷化性能

采用分步浸渍法制备了碱/碱土金属修饰Ni基催化剂Ni-M/Al₂O₃ (M=K₂CO₃, Na₂CO₃, MgO, CaO)。探究了碱/碱土金属的添加对改性Ni基催化剂CO₂吸附和甲烷化性能的影响。研究发现,碱/碱土金属的添加提高了Ni/Al₂O₃催化剂表面的碱性活性位点密度,强化了其CO₂吸附性能。碱/碱土金属类型影响Ni-M/Al₂O₃催化剂碱性活性位点的分布、NiO物相的转化及Ni的分散度,进而影响其甲烷化性能。MgO添加使NiO物相转化为与载体呈强相互作用的β型和γ型NiO,降低了催化剂表面的强碱性活性位点比例,有利于CO₂吸附活化。Ni-MgO/Al₂O₃的CO₂吸附容量最高为0.68mmolCO₂/g,其CO₂转化率和CH₄选择性分别高达58.4%和95.4%,其在烟气CO₂捕集与原位甲烷化中极具应用前景。     

火焰喷雾合成法制备La0.8Sr0.2Mn1-xCuxO3催化氧化CO性能研究

采用火焰喷雾合成法制备了Sr²⁺、Cu²⁺分别取代A、B位的La_0.8Sr_0.2Mn_1-xCu_xO₃ （x=0,0.1,0.2,0.3,0.4）钙钛矿催化剂,并用于CO催化氧化实验,研究了水蒸气和CO₂对催化剂CO氧化活性的影响。对不同取代量La_0.8Sr_0.2Mn_1-xCu_xO₃ 催化剂进行了XRD、SEM、EDS、BET、XPS、H₂-TPR和O₂-TPD等表征测试。结果表明,火焰喷雾合成法制备的钙钛矿催化剂具有良好的钙钛矿相、疏松多孔结构和催化氧化活性。其中,La_0.8Sr_0.2Mn_0.9Cu_0.1O₃分别在119.4℃和133.3℃实现50%和90%的CO转化率。掺杂水蒸气和CO₂会与CO在催化剂表面形成竞争吸附,导致5种催化剂性能衰减,但La_0.8Sr_0.2Mn_0.9Cu_0.1O₃仍能在150.2℃实现90%的CO催化转化,在连续稳定性催化氧化测试中,5种催化剂性能衰减不超过10%。结合上述CO催化氧化实验,火焰喷雾合成法制备的催化剂具有良好的稳定性和催化活性,适合制备高CO催化氧化活性的钙钛矿催化剂。     

Reduction of CeO2 in composites with transition metal complex oxides under hydrogen containing atmosphere and its correlation with catalytic activity

Reduction behavior of pure and doped CeO₂, the multi-phase La_0.6Sr_0.4CoO₃?xCeO₂, La_0.8Sr_0.2MnO₃ ?xCeO₂, and La_0.95Ni_0.6Fe_0.4O₃?xCeO₂ composites, was studied under hydrogen containing atmosphere to address issues related to the improvement of electrochemical and catalytic performance of electrodes in fuel cells. The enhanced reduction of cerium oxide was observed initially at 800°C in all composites in spite of the presence of highly reducible transition metal cations that could lead to the increase in surface concentration of oxygen vacancies and generation of the electron enriched surface. Due to continuous reduction of cerium oxide in La_0.6Sr_0.4CoO₃?xCeO₂ and La_0.8Sr_0.2MnO₃?xCeO₂ (up to 10 h) composites the redox activity of the Ce⁴⁺/Ce³⁺ pair could be suppressed and additional measures are required for reversible spontaneous regeneration of Ce⁴⁺. After 3 h exposure to H₂-Ar at 800°C the reduction of cerium oxides and perovskite phases in La_0.95Ni_0.6Fe_0.4O₃?xCeO₂ composites was diminished. The extent of cerium oxide involvement in the reduction process varies with time, and depends on its initial deviation from oxygen stoichiometry (that results in the larger lattice parameter and the longer pathway for O^2- transport through the fluorite lattice), chemical origin of transition metal cations in the perovskite, and phase diversity in multi-phase composites.     

低温等离子体协同Mn基催化剂降解氯苯研究

以氯代挥发性有机物（CVOCs）中的典型代表氯苯为研究对象,分别采用硝酸锰（MN）和乙酸锰（MA）为前体,通过浸渍法制备Mn基催化剂,考察了低温等离子体协同Mn基催化剂降解氯苯性能以及抑制反应副产物臭氧生成的影响。研究发现对于不同反应系统,提升电压可以提高氯苯降解效率;催化剂引入能够大幅度提高氯苯降解性能,与MnO _x （MN）/γ-Al₂O₃相比,MnO _x （MA）/γ-Al₂O₃引入对氯苯降解效果更好,对臭氧生成的抑制性能更高。利用N₂吸附-脱附、扫描电镜（SEM）、X射线衍射（XRD）、傅里叶红外光谱（FT-IR）和X射线光电子能谱（XPS）等手段对反应前后催化剂进行表征分析,发现放电并未对催化剂的孔径及晶相结构产生影响;通过无机氯选择性和尾气质谱结果分析氯苯降解过程中氯元素变化;与MnO _x （MN）/γ-Al₂O₃催化剂相比,MnO _x （MA）/γ-Al₂O₃催化剂的比表面积相对较大,活性组分分散性更高、更均匀,从而导致反应系统内更多的臭氧在催化剂表面分解为活性氧原子,提高了氯苯的降解性能并抑制了反应系统内臭氧的生成。     

铈掺杂强化碳纳米管活化过一硫酸盐实验研究

采用浸渍-煅烧法制备了高效稳定的CeO₂/CNT复合材料。利用X射线衍射、X射线光电子能谱和Raman光谱等手段对材料结构进行表征,并研究了复合材料活化过一硫酸盐（PMS）对磺胺异唑的降解性能。结果表明,在材料投加量为75 mg·L^-1、PMS投加量为0.3 mmol·L^-1、初始pH为5.36时,30 min降解率可达90%以上,50 min内可完全去除,反应过程符合伪一级反应动力学模型,活化剂使用5次后仍有77%的去除率。电子顺磁共振实验表明,SO₄?^-、?OH和¹O₂均参与了反应,碳纳米管表面缺陷可能与¹O₂的形成有关。CeO₂的掺杂提高了碳纳米管中缺陷碳的含量,同时Ce³⁺/Ce⁴⁺为反应提供了更多活性位点,从而有效提升了碳纳米管活化PMS的性能,为铈基碳纳米管复合材料应用于过硫酸盐高级氧化技术提供了借鉴。     

Production of aryl oxygen-containing compounds from catalytic pyrolysis of bagasse lignin over LaTixFe1−xO3

A new approach, named production of aryl oxygen-containing compounds from the catalytic pyrolysis of bagasse lignin (BL) over perovskite oxide, was proposed. A series of LaTi_xFe_1-xO₃ (LTF-x) samples were prepared by the solid state reaction method. The crystal phase and morphology of LTF-x were characterized by XRD and SEM respectively. Catalytic pyrolysis performance of LTF-x was performed by TG-DTG and the distribution patterns of gaseous, liquid and solid products from BL was investigated using a fixed-bed micro-reactor. The optimal reaction conditions were determined:the pyrolysis temperature was 600℃, the mass ratio of m_BL:m_LTF-0.2 was 3:1, the velocity of carrier gas was 100 ml·min^-1. The gaseous products were mainly composed of CO₂, CO, CH₄ and C_nH_m (n=2-4, m=2n + 2 or m=2n). The main aryl oxygen-containing compounds in liquid products were phenolics, guaiacols, syringols and phenylates, the rest were benzenes, furans, esters and carboxylic acid. The total contents of aryl oxygencontaining compounds were from 62% up to more than 72% under the action of the perovskite. Moreover, the LTF-0.2 sample had nice regenerability.     

Location and size regulation of manganese oxides within mesoporous silica for enhanced antibiotic degradation

Refractory antibiotics in domestic wastewater are hard to be completely eliminated by conventional methods, and then lead to severe environmental contamination and adverse effects on public health. In present work, advanced oxidation processes (AOPs) are adopted to remove the antibiotic of sulfachloropyridazine (SCP). Nanosized Mn₂O₃ was fabricated on the SBA-15 material to catalytically activate potassium peroxydisulfate (PDS) to generate reactive oxygen radicals of ?OH and SO₄^- for SCP degradation. The effects of location and size of Mn₂O₃ were explored through choosing either the as-made or template-free SBA-15 as the precursor of substrate. Great influences from the site and size of Mn₂O₃ on the oxidation activity were discovered. It was found that Mn₂O₃ with a large size at the exterior of SBA-15 (Mn-tfSBA) was slightly easier to degrade SCP at a low manganese loading of 1.0–2.0?mmol?g^?1; however, complete SCP removal could only be achieved on the catalyst of Mn₂O₃ with a refined size at the interior of SBA-15 (Mn-asSBA). Moreover, the SO₄^- species were revealed to be the decisive radicals in the SCP degradation processes. Exploring the as-made mesoporous silica as a support provides a new idea for the further development of environmentally friendly catalysts.     

Concentration-induced structural diversity and catalytic activity of BF3/n-BuOH complexes for n-decene polymerization

The BF₃/n-BuOH complexes were investigated as active species in catalyzing n-decene polymerization reaction. The structures of BF₃/n-BuOH complexes were characterized not only by modern spectrum but also by calculation at theoretical level. The results confirmed that BF₃/n-BuOH complexes changed from BF₃·(n-BuOH)₂ complexes to BF₃·n-BuOH complexes with the mass fraction of BF₃ increasing. These two complexes have different catalytic activity, but BF₃·n-BuOH was superior. The highest n-decene conversion could reach 99% and the most excellent selectivity of n-decene trimer and tetramer could reach up to 80% yield by a series of controlled conditions. This work can help to understand the catalytic active species of n-decene polymerization and provide support for industrialization of poly-alpha-olefins (PAOs).     

Ga掺杂FeNb11O29材料的制备及其电化学性能

FeNb₁₁O₂₉由于其高的理论充电容量(400 mAh·g^-1),作为锂离子电池(LIBs)负极材料具有很大的应用前景。然而,目前报道的FeNb₁₁O₂₉实际容量仅有168~273 mAh·g^-1。因此,有必要进一步提高其电化学性能。本文介绍了一种制备Ga掺杂FeNb₁₁O₂₉材料的方法,成功合成了Ga_xFe_1-xNb₁₁O₂₉(x=0.1,0.2)。结果表明,Ga_0.2Fe_0.8Nb₁₁O₂₉的电导率比FeNb₁₁O₂₉提高了两个数量级。X射线衍射结果显示,Ga掺杂不会改变FeNb₁₁O₂₉的正交剪切ReO₃晶体结构。扫描电镜结果显示,材料的微观形貌没有发生明显改变。电化学实验表明,Ga_0.2Fe_0.8Nb₁₁O₂₉具有较好的电化学性能,在电流密度为0.1 C时,Ga_0.2Fe_0.8Nb₁₁O₂₉充电容量为290 mAh·g^-1,当电流密度达到5 C时容量仍能保持145 mAh·g^-1,此外,Ga_0.2Fe_0.8Nb₁₁O₂₉具有良好的循环稳定性,在电流密度为5 C时循环1 000圈之后,容量保持率为91.0%,而不掺杂的FeNb₁₁O₂₉的充电容量仅有107 mAh·g^-1,容量保持率仅为55.9%。利用Ga掺杂改善FeNb₁₁O₂₉负极材料的电化学性能在锂离子电池中具有广阔的应用前景。     

Mechanism of the cathode process in the electrolytic boriding in molten salts

The mechanism of the cathode process in the electrolytic deposition of boron on a platinum electrode has been investigated in the systems LiF---KF---KBF₄ and LiF---KF---B₂O₃ by means of the voltametric and chronopotentiometric methods. It was found that in the system LiF---KF---KBF₄ boron is reduced directly from the tetrafluoroborate complex anion by a simple 3-electron process. In the system LiF---KF---B₂O₃ boron oxide reacts with the basic fluoride electrolyte under formation of the BF⁻₄ anion and of unspecified oxofluoro complex(es) with a mean oxygen to boron ratio of 1.66. The ratio of boron concentrations in the BF⁻₄ anion and in the oxofluoro complex(es) is about 0.1. The difference between the deposition potential of boron from those two electrochemically active species is about 0.47 V in favour of BF⁻₄. The value of the diffusion coefficient of the BF⁻₄ anion was found to be 4.4 × 10⁻⁹ m² s⁻¹ (700°C).     

钼酸铋半导体光催化剂的研究新进展

钼酸铋拥有典型的Aurivillius型结构,主要由(Bi_2O_2)~(2+)层及MoO_6钙钛片层状结构组成,显示出良好的光催化性能,广泛用于有机污染物的降解,成为近年来最受关注的一类可见光催化材料。综述钼酸铋半导体光催化剂的制备方法,以及通过构建异质结、掺杂、固溶体、金属沉积、量子点等改性措施提高其光催化活性,归纳和总结钼酸铋光催化剂在催化氧化反应、降解有机废水、电化学储能和CO_2的还原、气体传感器等方面的应用,并对钼酸铋光催化剂发展进行展望。