【作者】 陈孝云；

【导师】 刘守新；

【作者基本信息】 东北林业大学 ， 林产化学加工工程， 2007， 硕士

【摘要】 本论文以TiCl₄为钛源，采用酸催化水解法合成了纳米TiO₂；通过N、S掺杂改性制得了可见光响应催化剂TON、Ti_2-xS_yO₂；以AC为载体合成了高活性、长寿命、高效率的TiO₂／AC复合光催化剂；以可见光催化剂的可见光响应机制和TiO₂／AC复合光催化剂的活性炭与TiO₂之间的协同作用机制为理论基础，制得了AC负载N掺杂可见光响应光催化功能材料TON／AC；采用DRS、SEM、XRD、XPS、FTIR、低温氮物理吸附技术表征催化剂微观形貌、晶相结构、界面特征、光谱特征和孔径结构；并在此基础上，初步进行了吸附-光催化双功能炭吸附材料的合成探索。具体内容如下：在NH₃／N₂气氛下程序升温处理ZiO₂前驱体，制得N掺杂TiO₂可见光响应光催化剂（TON）。研究表明，掺杂N后锐钛矿TiO₂可见光催化活性显著提高，在500℃焙烧5h制得的催化剂在可见光区及紫外光区均表现出最高的光催化活性。N掺杂对TiO₂的晶粒大小、比表面积和晶相结构影响不大。适量N掺杂可在TiO₂表面形成Ti-O-N键，形成新的能级结构，使催化剂的吸收带边红移至490～550nm；同时该结构亦可有效提高TiO₂的紫外光催化活性。以硫脲为硫源，制得浅黄色S掺杂Ti_1-xS_yO₂光催化剂。研究表明，掺杂S以S⁶⁺形式置换TiO₂晶格中的Ti⁴⁺，适量的S掺杂Ti_1-xS_yO₂在可见光区、紫外光区及太阳光下均表现出较高光催化活性。掺杂S在TiO₂表面形成新的能级结构，使催化剂吸收红移至450～550nm，诱发可见光催化活性；紫外光照射下，新形成的能级结构与体相TiO₂形成复合半导体结构，捕获光生空穴，提高光生电子—空穴分离效率。同时，S掺杂可以改善TiO₂的分散性，增加其比表面积并提高相转变温度。在多孔活性炭（AC）表面合成TiO₂／xAC复合光催化剂。研究表明：适宜AC含量的TiO₂／AC（AC，5 wt％）具有较高的光催化活性，可多次循环使用不致失活，在较宽溶液pH范围内都保持较高的活性，而且催化剂容易从液相中分离。适宜的AC掺杂可以使TiO₂粒子分布均匀，减小粒子凝聚，但对TiO₂的晶相结构、晶粒大小以及表面性质影响不大，对ZiO₂能阈结构不产生影响。ZiO₂与AC结合牢固，接触界面处有Ti-O-C键生成。TiO₂／5AC表现出高光催化活性的主要原因是：AC所提供的适宜高浓度环境及对纳米尺寸ZiO₂团聚的有效抑制。TiO₂／5AC的高活性、不易失活、易分离以及活性受pH变化影响较小的特性，使其在实际废水处理方面具有潜在应用价值。另外，还系统研究了AC修饰对TiO₂形态结构及光催化活性的影响。研究表明，AC可抑制TiO₂晶粒生长，减缓TiO₂粒子间团聚，提高锐钛矿相向金红石相转变温度，减缓相转化速度。以不同种类／性质的活性炭为载体，合成了TiO₂／AC复合光催化剂，系统研究了活性炭种类／性质对TiO₂／AC复合光催化剂催化活性的影响。研究表明，AC的微孔及表面含氧官能团不利于催化剂的分散。较多数量的中孔及较少的表面含氧官能团可以大大提高TiO₂／AC（n）复合光催化剂的光催化活性。AC表面含氧官能团对催化还原金属离子的影响要大于对催化氧化有机化合物的影响。AC性质对TiO₂的晶相结构、晶粒大小以及能阈结构影响不大。以非金属离子掺杂后可见光催化剂的可见光响应机制和TiO₂／AC复合光催化剂的活性炭与TiO₂之间的协同作用机制为理论基础。合成AC负载N掺杂宽光域响应TiO_2-xN_y／AC光催化剂。研究表明，适量N掺杂的TON／AC在紫外光区、可见光区及太阳光下均表现出较高的活性。N掺杂在TiO₂表面生成Ti-O-N键，形成新的能级结构，使催化剂的吸收红移至450～550nm，诱发TiO₂可见光催化活性。AC负载可降低TiO₂团聚体的尺寸，增加催化剂比表面积，为光催化降解提供高浓度环境，从而提高光催化效率；同时AC负载还可改善催化剂分离性能，提高催化剂使用寿命。以TiO₂／AC复合光催化剂的C／TiO₂之间的协同作用机制为理论基础。合成了吸附-光催化双功能材料（xTiO₂／AC）。实验表明，吸附-光催化双功能材料，在暗吸附条件下，AC的平衡吸附量有所降低；但在光照条件下，AC的平衡吸附量明显提高，且延长了达到饱和时间，宏观上表现为提高了吸附量，实际则为TiO₂对污染物进行了降解。TiO₂负载为8％，且在CO₂气氛中经600℃活化，所制得的xTiO₂／AC对苯酚去除效率最高。更多还原

【Abstract】 In the present work, nano-size TiO₂ photocatalyst、the N-doped visible-light responsenanosize TiO₂ photocatalyst （TON）、the S-doped visible-light response nanosize TiO₂photocatalyst (TiS_xO_2-y)、TiO₂/AC composite photocatalyst, Activated carbon supportedvisible-light response N-doped TiO₂ photocatalyst （TON/AC） and adsorption-photocatalysis hi-functional activated carbon materials were prepared by acid catalyzed hydrolysis method usingTiCl₄ as precursor. DRS、XRD、SEM、FTIR、XPS and N₂ （77K） adsorption isotherm wereused for materials characterization. The details were as follows:The N-doped visible-light response nanosize TiO₂ photocatalyst was prepared by acidcatalyzed hydrolysis method followed by calcination in NH₃/N₂ atmosphere. The resultsshowed that the N-doped TiO₂ showed obvious photocatalytic activity under visible lightirradiation. The TON catalyst calcined at 500℃for 5 h exhibited the highest activity in bothUV and visible light region. N-doping showed little effect on the crystalline structure, surfacearea and crystal size of TiO₂. The Ti-O-N bond formed on the surface of N-doped TiO₂, whichcan not only extend the adsorption edge to visible light region （490～550nm）, but alsobenefitial the photocatalytic acitivity of TiO₂ under UV irradiation. The newly formed Ti-O-Nbonds and the less agglomeration of single crystal mainly lead to the high activity of N-dopedTiO₂ in both UV and visible light region.A yellowish Ti_1-xS_yO₂ photocatalyst exhibited high activity in wide light spectrum range wasprepared by acid catalyzed hydrolysis method. The results showed that cationic S⁶⁺ wasincorporated into TiO₂ lattice and substitutes part of Ti⁴⁺. Ti_1-xS_yO₂ with optimum S-dopingexhibited the highest activity in both Vis and UV region. The new band-gap formed by doped-Scan induce a second adsorption edge （450～550nm） which can be excited by Vis irradiationand induce Vis activity. Under UV irradiation, the new formed band-energy can accept holesgenerated by bulk TiO₂ and formed a composite semiconductor structure, then improve hole-electron pairs separation. In addition, doped-S also beneficial for TiO₂ dispersion, increase S_BETand retard phase transformation.TiO₂/xAC composite photocatalysts were prepared by acid catalyzed hydrolysis methodfollowed by calcinations in N₂ atmosphere. The results showed that TiO₂/xAC catalysts withoptimal AC content 5%（wt） exhibited more higher activity than P-25（TiO₂） and TiO₂, as wellas good decantability, less activity lost after several runs and less sensitive to pH change. Result of DRS revealed no electronic change when activated carbon （AC） added. Better TiO₂distribution and less agglomeration can be achieved when optimal AC content adopted. Resultof FTIR suggest a conjugation effect was present between the AC bulk and Ti-O bond.Suitable pollutant concentration environment and less agglomeration provided by AC was themian cause for the high activity of TiO₂/5AC. The performance of the prepared TiO₂/5ACcatalyst revealed great practical potential in wastewater deeply treatment field. Another, effectof activated carbon modification on the structure chracteristics and photocatalytic activity ofTiO₂ photocatalyst were system investigated. The results showed that TiO₂/AC exhibitedhigher activity than TiO₂ within a wide range calcination temperature. AC was beneficial toTiO₂ size control and phase transformation retardment.Effect of activated carbon properties on the photocatalytic activity of TiO₂/AC compositephotocataylyst was investigated. The results showed that microstructure and surface oxygenacid groups of AC were disadvantage to the dispersion of nano-size TiO₂. Larger number ofmesopores and less surface oxygen containing acid groups were beneficial to the higheractivity. Surface oxygen acid groups of AC exhibited more significant effect on metal ionreduction than organics oxidation for the TiO₂/AC composite photocataylyst. Result of DRS、XRD revealed that surface properties of AC has less effect on the electronic structure,crystalline size and crystal phase of TiO₂.Activated carbon （AC） supported nitrogen doped TiO₂ photocatalysts （TON/AC） with widerange light response were prepared by calcination of the TiO₂/AC precurse which wereprepared by acid catalyzed hydrolysis method in NH₃/N₂ atmosphere. The results showed thatTON/AC with suitable nitrogen doping exhibited the high activity in UV light, visible light andsolar light. Nitrogen doped can form a new bond gap, and the adsorption edge to visible lightregion 450～550 nm, that can induce TiO₂ visible light activity. And better TON distribution,less agglomeration and increase surface area can be achieved when AC supported, which canenhance photocatalyst activity. In addition, AC supported could also beneficial for TiO₂decantability and less activity lost after several runs.Based on the synergy mechanism obtained, adsorption-photocatalysis bi-functional carbonmaterials （xTiO₂/AC） could be prepared by deposition of TiO₂ precursor on the surface ofporous AC followed by calcinations under N₂ or CO₂ atmosphere. Although the absorptioncapability of xTiO₂/AC reduced under dark, but it increased greatly when light irradiated. The8TiO₂/AC in calcined under CO₂ at 600℃for 2 h exhibited the highest pollutant removal capability when light irradiated.更多还原