不同方法制备碳载金催化剂对臭氧的催化分解

采用浸渍法和溶胶负载法制备以改性活性碳为载体以纳米金为活性组分的催化剂,通过BET,SEM和XPS表征制备方法对催化剂比表面积、孔隙结构、表面形貌及表面元素组成的影响,测试催化剂在室温下对低浓度臭氧的催化分解性能.结果显示,在室温,相对湿度为45±5%,空速为96000h(-1).臭氧初始浓度为50mg/m3,气体与催化剂的接触时间为0.04s的条件下,在1200min时采用浸渍法制备的催化剂对臭氧的分解率为85%,而溶胶负载法制备的催化剂此时对臭氧的分解效率仍在94%以上.采用溶胶负载法制备的催化剂纳米金颗粒粒径更小、更均匀,在催化剂表面的覆盖率更大是其催化活性更高的主要原因.     

纳米TiO2/凹凸棒土复合体的制备及其表征

以凹凸棒土（ATP）为载体，采用溶胶-凝胶法制备纳米TiO₂/ATP复合型催化剂.利用扫描电镜（SEM）、热重-差热分析（TG-DSC）、X射线衍射分析（XRD）等分析测试手段对其组成、结构、尺寸进行分析和表征.结果表明，该复合材料由ATP和锐钛矿型的纳米TiO₂组成，其中TiO₂ 纳米粒子尺寸在20～30 nm之间，比相同工艺条件下的无负载的TiO₂纳米粒子尺寸小；在该纳米复合材料中，纳米TiO₂颗粒间不发生团聚，并且与ATP间结合牢固.     

用于臭氧分解的碳载纳米金催化剂制备及性能表征

以煤质活性炭为载体,分别采用柠檬酸钠和PVA做保护剂,通过溶胶固载法制备用于分解臭氧的载金催化剂,并对其进行SEM和比表面积表征.结果表明,通过两种方法制备的载金催化剂纳米金颗粒呈半球状负载在活性炭表面,而且分散度高,颗粒尺寸均匀.以PVA为保护剂的催化剂纳米金颗粒粒径在5～10nm,以柠檬酸钠为保护剂纳米金颗粒粒径在20nm左右.以柠檬酸钠为保护剂制备的催化剂总孔容以及中孔孔容均比以PVA做保护剂的催化剂小,而微孔孔容却比后者大,是由于纳米金颗粒进入到中孔中的量较多,而进入微孔中较少的缘故.以柠檬酸钠为保护剂所制备的载金催化剂对臭氧的去除比PVA做保护剂的具有更好的催化活性.     

准均相的银纳米催化剂用于高选择性催化还原芳香硝基化合物

银纳米催化剂作为硝基还原催化剂具有活性高、成本低、合成简单的优势。以聚酰胺酸盐为稳定剂,在水相中以硼氢化钠为还原剂、原位制备了聚酰胺酸盐负载的银纳米粒子(AgNPs-PAAS)。表征显示AgNPs的平均粒径为7.8 nm,在PAAS的稳定作用下,AgNPs在水相中呈“准均相”分散。常温、纯水相条件下,以硼氢化钠为还原剂,研究了AgNPs-PAAS催化剂对芳香硝基化合物的还原反应的催化性能。结果表明,AgNPs-PAAS催化剂对芳香硝基化合物的还原反应具有较高的催化活性,且能耐受一些底物的敏感基团(对位卤素原子和羰基)。基于聚酰胺酸盐的pH敏感性,AgNPs-PAAS催化剂可通过调整溶液pH值实现回收再利用,在重复催化3次后仍保持初始活性。     

负载铁沸石催化剂催化氧化降解偶氮染料活性黑5的研究

采用浸渍法,以FeSO_4溶液为浸渍剂对沸石进行浸渍制备负载铁沸石催化剂。研究了H_2O_2存在条件下负载铁沸石催化剂催化氧化降解染料活性黑5的性能及机理。结果表明,负载铁沸石催化剂对染料活性黑5的催化降解效果明显优于未负载沸石,其最优制备条件为FeSO_4溶液浓度0.1 mol/L,浸泡时间12 h,焙烧温度450℃,焙烧时间3 h;在反应时间为60 min,反应温度30℃,染料废水p H为3,H_2O_2浓度为200 mg/L,催化剂投加量1.5 g/L的条件下,活性黑5降解效率最高,为98.9%。负载铁沸石催化剂催化氧化降解偶氮染料活性黑5过程中,·OH自由基起主导作用。     

硅藻土负载纳米Fe_2O_3复合材料的光催化性能研究

本研究选择提纯后的硅藻土充当Fenton催化剂基础载体,采用水解沉淀法将纳米Fe_2O_3颗粒负载在硅藻壳体表面制备得到一种新型的非均相Fenton复合材料,以罗丹明B作为染料废水检验催化剂的催化性能,研究结果表明,在光照条件下加入硅藻土负载Fe_2O_3催化剂和H_2O_2,反应120 min后,罗丹明B的脱色率可达到98.33%。     

强碱型活性白土生物柴油合成催化剂的制备及其应用

提出了一种强碱型活性白土催化剂的制备方法,并将此催化剂用于催化油脂的酯交换反应合成生物柴油。首先在活性白土载体上负载氢氧化钙,覆盖活性白土的酸活性中心并提供弱碱中心,然后在弱碱中心上负载氢氧化钠活性组分制备了负载固体碱催化剂。实验结果表明,氢氧化钙负载量为0.67 mmol/g就能覆盖活性白土的酸活性中心,然后在80℃、4倍水中,加入17 mmol NaOH/g土,氢氧化钠加入速度为1.11 mmol/min时,得到氢氧化钠负载量为3.4 mmol/g的固体碱催化剂。将该催化剂用于生物柴油酯交换反应,当催化剂用量为油脂质量的3%时,甲酯转化率超过97%,反应完成后生物柴油无需洗涤。     

用膨润土作载体的酸催化剂制备及其性能结构分析

研究采用浸渍蒸发法制备ZnCl2/膨润土负载型固体酸催化剂，以催化苯与苄氯烷基化模型反应考察了膨润土酸化时间、ZnCl2负载量和活化温度等制备参数，对催化性能的影响，利用XRD、BET、TG-DTA、Harnmctt指示剂法、吡啶吸附FTIR对催化剂的结构进行表征分析。结果表明，制备参数通过影响催化剂的孔结构和表面酸性，影响了催化剂的催化性能；酸催化烷基化性能试验表明，膨润土负载ZnCl2型固体酸催化剂可望应用于环境友好的酸催化工业过程。     

矾土尾矿载体氧化物组分对甲苯催化燃烧的影响

利用固体废弃物矾土矿尾矿制备催化剂载体,采用浸渍法将氧化物活性组分载于催化剂载体,对甲苯催化燃烧进行了研究。实验结果表明:以矾土矿尾矿制备的催化剂载体,所选4种单一活性组分中,催化效果较好的为Mn/Zr O2和Cu/Zr O2整体催化剂,其负载14%Mn/Zr O2整体催化剂在260℃时转化率为47%,负载16%Cu/Zr O2整体催化剂在300℃时转化率为49%,均接近起燃温度。     

臭氧催化剂对煤化工高盐废水有机物去除性能研究

基于臭氧催化氧化技术在煤化工高盐废水处理上具有广泛的应用前景,为确定最佳臭氧催化剂及优化试验工艺参数,对催化剂制备工艺、载体及活性组分类型对COD去除率的影响进行研究,以确定催化剂制备工艺及最佳催化剂。采集宁夏某煤化工高盐废水开展工艺条件优化实验确定最佳工艺参数,最后对催化剂进行稳定性能评价及反应动力学研究。结果表明：废水中难降解有机物主要为含氮有机化合物;浸渍法催化效果优于混合法;活性氧化铝催化效果优于陶粒;活性组分铈催化效果优于锰和铁;最佳工艺条件：催化剂投加量1.0 L/L废水,臭氧投加量200 mg/L;臭氧催化剂反应70 h, COD去除率稳定在47%～50%;出水COD含量稳定在230 mg/L～245 mg/L,即臭氧催化剂具有足够的催化稳定性,通过臭氧催化氧化反应动力学研究发现催化剂的反应速率常数大于纯臭氧氧化,即臭氧催化氧化工艺可有效降解水中有机物,提高COD去除率。     

Assessing the potential of activated bagasse as gold adsorbent for gold–thiourea

This study was conducted to establish the potential of bagasse, the fibrous by-product of sugarcane milling operation, as a precursor for preparing adsorbents for gold–thiourea complex. It was also of interest to identify the carbon properties, which promotes adsorption. Bagasse was activated in this study by physical (gasification) and chemical techniques. It was found bagasse is more amenable to activation by physical techniques producing activated carbon with surface areas exceeding 1000 m²/g. Among the chemical activating agents, it was found that ZnCl₂ was most effective in developing the surface structure of bagasse. Gold–thiourea adsorption was found to be favoured in carbon exhibiting high surface area. Finer pore sizes are developed with higher surface area. As such the extent to which the surface area could improve adsorption was limited by steric hindrance in the finer pore size. It was found that steric hindrance affected gold–thiourea adsorption in mean pore sizes less 20 Å. The effect was particularly significant when the carbon pH was greater than 7.0, where the alkaline nature of the carbon may have shifted the Tu/Au ratio to higher values such that the formation of the larger AuTu₂⁺ and AuTu₃⁺ are promoted. The greater development of physically activated bagasse favoured gold–thiourea adsorption. The optimum adsorption capacity by the physically activated bagasse was approximately 318 mg Au/g of adsorbent (ash free), achieved after 25 h of gasification in 15% CO₂. This was comparable to adsorption capacities obtained from commercial activated carbon and resins of 197–321 mg Au/g adsorbent (ash free). These results are encouraging and confirm the potential of activated bagasse as gold–thiourea adsorbent.     

煤热解焦油催化裂解和乙烷水蒸气重整耦合提高焦油品质

本文旨在通过在炭基催化剂上发生的煤焦油原位催化裂解与乙烷水蒸气重整过程耦合以提高轻质焦油产率。以平朔煤(PS)为煤样,利用常压固定床反应器在氮气以及乙烷水蒸气混合气氛下进行焦油提质实验,并使用半焦(Char),活性炭(AC)以及活性炭负载金属钴和镍(Co/AC,Ni/AC)作为提质催化剂,对比考察催化剂种类和反应气氛对提质过程中焦油及气体产物的影响。同时,为了解提质过程所得焦油产物的组成和性质,利用模拟蒸馏,GC-MS等表征手段对焦油进行检测分析。结果表明,活性炭负载Ni催化剂(Ni/AC)可催化乙烷水蒸气重整反应,产生的·CH x,·C 2H x,·H等小分子自由基可与焦油催化裂解产生的自由基结合,避免焦油过度裂解。与未加催化剂得到的平朔煤热解焦油相比,采用Ni/AC使轻质焦油(沸点低于360℃馏分)的质量分数和产率分别提高54.3%和52.4%,同时焦油中BTEXN(苯、甲苯、乙苯、二甲苯和萘)等芳烃组分产率明显提高;乙烷水蒸气混合气氛下(耦合过程)比同条件氮气下的焦油产率和轻质焦油产率分别提高38.1%和35.3%,焦油中C2~C3烷基取代苯和C1~C2烷基取代酚的相对含量有明显提高,说明乙烷和水蒸气被活化并参与了焦油形成过程。煤热解焦油的原位催化裂解的总体效果是将焦油中重质组分转化为轻质焦油和热解气,其提质效果与催化剂的活性组分密切相关,且反应气氛在煤焦油的形成过程中具有重要作用。     

碱性低氧环境中pH对活性炭金吸附的影响

研究了常温碱性低氧环境中pH对活性炭吸附氰金络合阴离子Au(CN)₂^-的影响。等温吸附试验显示,该过程放热,从能级判断应属物理吸附。溶液化学计算和XPS分析显示,在常温碱性低氧的条件下,溶液中或活性炭上的金几乎都为Au(CN)₂^-或其离子对,金吸附过程无明显化学变化。吸附试验表明,金吸附量受pH与离子强度共同作用,且金吸附量随pH的变动规律受离子强度控制,即高离子强度下与pH负相关,反之则正相关。结合电动电位分析和离子对吸附理论推测,在低离子强度下,碱提供吸附紧缺的阳离子,虽然增大体系的电斥力,但整体上仍加强了吸附;而在高离子强度下,体系中阳离子充足,加碱则增大电斥力,削弱了吸附。研究结果表明,金吸附试验必须控制离子强度才能准确反映pH的作用。     

Preconcentration of gold by rice husk ash

The goal of this research was to develop a new, efficient adsorbent of gold-thiourea complex, [Au(CS(NH₂)₂]⁺. In this experiment, rice husk was heated at three different temperature: 300°C, 400°C and 500°C. Rice husk ash heated at 300°C adsorbed gold thiourea complex, whereas rice husk ash heated at 400°C and 500°C did not. The structure of rice husk ash heated at 300°C had specific silanol groups and oxygen functional groups of carbon, while rice husk ash heated at 400°C and 500°C contained siloxane groups. Maximum gold adsorption of rice husk ash heated at 300°C and activated carbon, was 21.12 and 33.27 mg Au/g adsorbent, respectively. However, rice husk ash absorbed 0.072 mg thiourea/g adsorbent, which was less than activated carbon adsorbed (0.377 mg thiourea/g adsorbent). In addition, the adsorbed gold could be eluted from this rice husk ash by sodiumthiosulfate more easily than from activated carbon. The results revealed that rice husk ash heated at 300°C can be used as a new adsorbent for gold thiourea complex.     

Comparison of gold adsorption by Chlorella vulgaris,rice husk and activated carbon

Chlorella vulgaris and rice husk were selected from microorganisms and agricultural waste, respectively, to create new gold-eluteable adsorbents for adsorption of gold–thiourea complex, and compared with activated carbon. The maximum gold adsorption of heated-immobilised C. vulgaris, heated rice husk, and activated carbon was 10.34, 28.22 and 35.88 mg Au/g adsorbent, respectively. FTIR spectrum, thermodynamic study and elution tests indicated that heated-immobilised C. vulgaris and heated rice husk adsorbed gold by chemical adsorption: co-ordinate covalent bond. The active functional groups of heated-immobilised C. vulgaris were ketone, carboxylate and ester, while the groups of heated rice husk were ketone, carboxylate and siloxane. Activated carbon mainly adsorbed gold by physical adsorption. Gold adsorbed onto heated-immobilised C. vulgaris, heated rice husk, and activated carbon was able to be eluted by 0.5 M Na₂S₂O₃ to 100, 87 and 41%, respectively. Although heated-immobilised C. vulgaris had the highest eluteability, it adsorbed less gold. Therefore, heated rice husk could be used as an alternative adsorbent for gold–thiourea pre-concentration.     

Combined bio-hydrometallurgical process for gold recovery from refractory stibnite

The aim of this work concerns the recovery of gold by a combined biometallurgical and hydrometallurgical treatment. The biooxidation of a refractory gold-bearing stibnite (antimony sulphide) favours the increase of gold recovery during the subsequent hydrometallurgical process (cyanidation, adsorption onto activated carbon, desorption from activated carbon and electrowinning).Tests were conducted at laboratory scale utilising a refractory stibnite ore. The gold content of the sample was 32 g/t Au. Bacterial cultures utilised in the biological test consisted predominantly of Thiobacillus genus. After a long leach time (24 hours) low recovery was obtained by direct cyanidation (less than 4% Au), while a gold extraction yield of about 80% was achieved combining biometallurgical and hydrometallurgical process.Experimental results have shown the technical feasibility of the biometallurgical pretreatment prior to the hydrometallurgical process. A complete process flow-sheet has been outlined.     

炭纤维表面原位生长碳纳米管/纤维及其微观结构研究

采用均匀沉淀法在炭纤维表面加载纳米Ni催化剂, 在实验室立式化学气相沉积炉中, 以天然气或甲烷为碳源气体, 氢气为稀释气, 控制温度、炉压和碳/氢比, 在炭纤维表面原位制备了碳纳米管/纤维, 并对其形貌和结构进行了初步研究。结果表明: 采用均匀沉淀法可以在炭纤维表面成功制备颗粒比较均匀的纳米级催化剂Ni。相对于纯甲烷气而言, 天然气因其组分较多, 影响炭纤维表面原位生长纳米碳管或纤维的形貌及其完整性。采用催化裂解法在炭纤维表面生长的碳纳米管/纤维与炭纤维的界面结合良好。     

硫代硫酸盐浸金体系中活性炭表面Zeta电位研究

研究了硫代硫酸盐浸金体系下基底试剂浓度与pH值、模拟浸出液pH值与搅拌时间等对活性炭表面Zeta电位的影响。结果表明,活性炭零电点为2.13; 其表面Zeta电位随硫代硫酸盐浓度增加而负值减小,随硫酸铜浓度增加而正值减小,随氨水浓度增加保持不变; 氨水溶液pH值大于9.0时,活性炭Zeta电位开始负值增大; 而活性炭Zeta电位几乎不随硫代硫酸盐溶液pH值变化而变化。模拟浸出液中,活性炭表面Zeta电位随pH值、搅拌时间变化较小; 当pH值为9.0时,活性炭对Au(S₂O₃)₂^3-的吸附率最大,为27.8%。模拟浸出液中活性炭表面主要优先吸附了含硫含氮化合物,表面Zeta电位始终为负值,活性炭通过静电作用难以吸附Au(S₂O₃)₂^3-。     

Modelling of gold (I) cyanide adsorption based on the properties of activated bagasse

Bagasse, the fibrous residue from sugar cane milling operation, was subjected to physical activation using CO₂ to establish its suitability as a precursor for gold adsorption, specifically for the recovery of gold from cyanide medium. Mathematical modelling, which correlates the effects of carbon properties on the adsorption behaviour, was conducted to formulate a basis for tailor making the adsorbent for this particular application. The developed model suggests carbon properties of alkali pH, high total surface area and small pore diameters are required for optimum adsorption capacity. The optimum adsorption capacity attained by the developed carbon in this study was 227% that of the test commercial activated carbon, which exhibited an adsorption of 101mg Au/g carbon. Hence this demonstrates bagasse as a promising precursor for the manufacture of activated carbon for gold cyanide adsorption.     

Photochemical preparation and application research of Au nanoparticles

Gold nanoparticles protected by organic small molecular compounds or macromolecule have attracted considerable attention and their preparation is one of hotspots in the nano-chemical material field due to their ongoing and potential applications in optics, electronics, catalysts and biosensors. In recent years there are many liquid phase chemistry methods to prepare monodispersed gold particles. Among them, the photochemical method is quite attractive because of its some important advantages for size-controlled synthesis of gold nanoparticles. Therefore, in this paper the recert progress of the photochemical preparing Au nanoparticle materials was briefly introduced and mainly emphasized authors' own works of this area.