Foam-structured Activated Carbon-ceramic as TiO2 Supports for Photocatalytic Degradation of Phenol

An activated foam-structured carbon-ceramic(AFCC) was prepared and investigated as TiO₂ support for the photocatalytic degradation of phenol. AFCC and TiO₂/AFCC catalysts were characterized by N₂ adsorption- desorption and X-ray diffraction(XRD). The effects of AFCC on the photocatalytic activity and the crystallinity of TiO₂ were studied. The results show that the crystallinity and anatase/rutile ratio of TiO₂ loaded on AFCC could be significantly influenced by the calcination temperature. The degradation rate of phenol benefited from the synergistic effects of the adsorption of activated carbon(AC) and the photocatalysis of TiO₂, which suggests that a high surface area of AC is essential to achieve high degradation rates and efficiencies. It was found that the larger mean cell size of AFCC increased the light transmission within the foam.     

MoS_2/TiO_2复合催化剂的制备及其在紫外光下的光催化制氢活性

为了研究复合光催化剂在光催化中的制氢效率,采用水热法制备了Mo S2纳米片,然后通过水热法在Mo S2纳米片上负载了TiO_2纳米颗粒,形成了Mo S2/TiO_2异质结复合催化剂。采用冷场发射扫描电子显微镜(FE-SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、紫外-可见吸收光谱(UV-Vis)、拉曼光谱(Raman),X射线光电子能谱(XPS)对材料的结构和光学性能表征并进行分析。通过光催化制氢测试对光催化剂进行评价,实验结果表明,在波长为365 nm的紫外光照射下,最高光催化制氢速率为1004μmol·h-1·g-1,对应的催化剂的Mo S2含量为30%,其催化速率远大于单一的Mo S2和TiO_2,表明Mo S2/TiO_2复合催化剂在紫外光照下能显著提高光催化产氢性能。基于Mo S2/TiO_2复合光催化剂优越的光催化产氢性能,本文对复合光催化剂的产氢机理做了研究和分析。     

TiO2/Bi2O3纳米复合体的制备及可见光催化产氢性能

首先采用相分离的水解-溶剂热法制备了Bi₂O₃纳米粒子,然后利用简单的湿化学法在Bi₂O₃表面负载不同比例的TiO₂纳米颗粒,进而得到TiO₂/Bi₂O₃纳米复合体。通过气氛调控的表面光电压谱(SPS)等测试表明,表面负载适量的TiO₂后能够提高Bi₂O₃光生电荷分离。可见光催化产氢和降解污染物测试结果进一步证明,表面负载适量的TiO₂后可显著提高其可见光催化活性,其中Ti/Bi摩尔比为7%时具有最高的光催化活性。这主要归因于TiO₂具有较为合适的导带能级位置,可以接收Bi₂O₃在可见光激发下所产生的高能级电子,从而抑制光生电子-空穴对复合,并且维持了高能级电子较高的还原能力。     

Si掺杂TiO2催化剂的结构与可见光催化活性研究

采用溶胶-凝胶法制备出Si⁴⁺离子掺杂的TiO₂可见光催化剂 (TiO₂-xSi),该催化剂的可见光催化活性高于纯TiO₂和N掺杂的TiO₂(TiO₂-N).利用XRD、XPS、FT-IR和UV-Vis DRS等表征技术,研究了TiO₂-xSi催化剂的晶体结构、能带结构和表面性质.研究发现:掺入Si⁴⁺离子在TiO₂粒子表面主要形成Ti-O-Si结构,并在导带下0.2-0.6 eV区域形成表面态能级,该表面态能级的存在是催化剂产生可见光响应、实现可见光催化的根本原因.另外,讨论了Si⁴⁺离子的掺杂对金红石相和晶粒的生长抑制作用,以及催化剂的比表面积和表面羟基物种增加对可见光催化活性的影响.     

可见光下高催化活性不同结构Sr/TiO2催化剂的制备和表征

采用分步沉积法制备不同Sr/Ti 摩尔比例的Sr/TiO₂催化剂, 以X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、傅里叶变换红外(FT-IR) 光谱、紫外-可见漫反射光谱(UV-Vis RDS)等手段对样品进行了表征, 以可见光催化降解亚甲基蓝为模型反应考察样品光催化活性. 结果表明, 催化剂的活性和结构随Sr/Ti 摩尔比(n(Sr)/n(Ti))的变化而变化, 当n(Sr)/n(Ti)≤3/2 时, 催化剂呈由TiO₂和SrTiO₃组成的球状结构; 而当n(Sr)/n(Ti)在3/2 与4/1 之间时, 催化剂呈片状结构, 且随着n(Sr)/n(Ti)增大, 催化剂组成由SrTiO₃ 和Sr₂₄ 变为Sr₂₄和Sr(OH)₂·H₂O; 当n(Sr)/n(Ti)=9/1 时, 催化剂呈以Sr(OH)₂·H₂O为主的针状结构. 其中, n(Sr)/n(Ti)=4/1的样品表现出最高的光催化活性, 一级反应速率为SrTiO₃钙钛矿催化剂的5.0倍, 商用P25的86.7倍.     

改性活性炭纤维可见光催化联合脱硫脱硝的研究

利用水合肼还原法制备的TiO₂/Cu₂O复合光催化剂对活性炭纤维(ACF)进行改性,利用SEM、XPS、BET以及XRD对其进行表征,研究改性后ACF的性质及其脱硫脱硝效果。研究表明,TiO₂/Cu₂O同时改性后的ACF表面孔径减小,但表面石墨碳和羰基(C=O)官能团增加,增强了ACF对NO和SO₂的吸附能力,从而提高了脱硫脱硝的效率,该催化剂在40℃、可见光的催化下脱硫效率达90%,脱硝效率达60%。     

负载型Rh基催化剂上的CO加氢制乙醇反应：载体效应

Ethanol has great application prospects given it is an important essential chemical and a substitute for traditional energy sources. Currently, ethanol production is achieved through grain fermentation and petroleum-based ethylene hydration. However, the inefficient fermentation processes and increasingly depleted crude oil resources hinder the large-scale production of ethanol. Therefore, the development of alternative technologies for ethanol production has become an important issue. The direct production of ethanol from syngas (CO + H₂) is considered to be a new strategy to acquire high value-added products and achieve clean utilization of carbonaceous resources such as coal, natural gas, and biomass. Supported Rh-based catalysts have been extensively studied as the most promising and effective systems for the direct production of ethanol from syngas. The use of promoters and supports is generally effective in increasing the activity and ethanol selectivity of supported Rh-based catalysts. Fe is widely used in the research on Rh-based catalysts, as it is one of the most effective promoters for enhancing ethanol selectivity. In this work, with the aim of exploring the role of the support, we used the incipient wetness impregnation method to prepare Fe-promoted Rh-based catalysts supported by CeO₂, ZrO₂, and TiO₂ for the synthesis of ethanol from syngas. CO conversion of CO on the RhFe/TiO₂ catalyst was as high as 18.2% under the reaction conditions of 250 ℃ and 2 MPa, and the selectivity to ethanol in the alcohol distribution was 74.7%, which was much higher than that observed with RhFe/CeO₂ and RhFe/ZrO₂ under the same conditions. The characterization results showed that the specific surface of the catalyst followed the order RhFe/CeO₂ < RhFe/ZrO₂ < RhFe/TiO₂; the dispersion of Rh increased sequentially, and the particle size decreased in the same order. A larger specific surface area may favor the dispersion of the Rh species, and the highly dispersed Rh species would imply a greater number of active sites on the surface of the support. The results of H₂-temperature-programmed reduction indicated possible interactions between Rh and the support as well as between Rh and Fe, and partial reduction of TiO₂ under the experimental reduction conditions; however, the other supports did not undergo reduction. The results of X-ray photoelectron spectroscopy indicated that the RhFe/TiO₂ catalyst had the largest amount of Rh⁰ as well as Rh⁺ species. Thus, this catalyst has more (Rh_x⁰-Rh_y⁺)-O-Fe^δ+ active sites for the synthesis of ethanol, which greatly increases the ethanol selectivity. CO-temperature programmed desorption was used to confirm the CO adsorption capacity of different catalysts. The results showed that TiO₂ enhances the adsorption of CO due to the presence of more O vacancies and Ti³⁺ ions, which is beneficial to the improvement of the catalyst activity.     

MoS_2负载量对MoS_2/TiO_2光催化降解苯酚效率的影响及其作用机理研究

通过水解法制备TiO_2纳米颗粒,与经过超声处理后的MoS_2片层纳米材料复合制备MoS_2/TiO_2纳米催化剂,考察不同MoS_2负载量对其光催化降解苯酚效率及路径的影响。XRD、SEM、EDS、FT-IR和UV-vis DRS等表征结果表明,复合催化剂主要由锐钛矿型TiO_2和MoS_2组成;剥离后的MoS_2呈现薄片层状结构,均匀地分散在TiO_2纳米颗粒当中。光催化降解苯酚性能测试结果显示,对于MoS_2/TiO_2催化剂,MoS_2负载量的提高有利于光催化降解苯酚效率的提高;当MoS_2负载量为27%时,复合M o S2/TiO_2纳米颗粒的光催化性能最佳,反应80 min后可将苯酚完全降解。通过对苯酚降解过程中生成中间产物跟踪发现,MoS_2负载量的提高有利于促进中间产物苯醌、对苯二酚以及邻苯二酚的生成,进而提升了MoS_2/TiO_2复合材料的光催化性能。     

一维TiO2锐钛矿/金红石异相结的制备及光催化降解甲醛性能

TiO₂异相结主要通过高温方法制备,所制备材料的形貌和组成较难控制,尤其是在较低温度下一步制备一维TiO₂异相结仍具有一定的挑战性。采用简单、方便的一步水热法,在较低温度下(180℃)制备了一维纳米TiO₂异相结材料。X射线衍射(XRD)和高分辨透射电镜(HRTEM)分析表明,制备的材料以一维金红石相TiO₂纳米棒(长度:(400±50)nm,直径:(60±5)nm)为基本结构,粒径分布均匀的锐钛矿相TiO₂纳米粒子(直径:(9.5±0.5)nm)高密度、单分散地负载在纳米棒上。通过控制水热反应时间成功调控了异相结中锐钛矿相TiO₂的含量(20%~50%),进而实现了其光催化降解HCHO性能的调控。实验结果表明,当锐钛矿相TiO₂的含量为33%时(TiO₂-24,水热时间24 h制备的样品),异相结光催化剂表现出最佳的HCHO降解性能:在低光强LED灯(波长为365 nm,光强为12.26 mW·cm^-2)照射下,浓度约为120 mg·L^-1的HCHO气体在25 min后的降解率达到了92%,实现了高效、快速地去除空气中的HCHO(矿化为CO₂)。稳态荧光光谱和光电化学测试表明,与其他水热时间的样品相比,TiO₂-24具有更高效的光生电荷分离和传输效率。一维TiO₂异相结不仅有利于光生电荷的传输,而且对电荷的分离具有定向驱动作用,使其具有较高的光催化降解HCHO性能。     

LaCoO_3-TiO_2纳米管阵列的构筑及可见光光催化性能

TiO_2纳米管阵列具有较高的光催化活性,但可见光吸收弱,限制了其太阳能利用和环境应用。窄带隙的钙钛矿(ABO3)型氧化物能够吸收大范围波段的可见光,且稳定性高,但光催化活性低。本文首先采用溶胶-凝胶法合成了LaCoO_3纳米颗粒,然后利用电泳沉积技术将LaCoO_3纳米颗粒修饰于TiO_2纳米管阵列表面,构筑了LaCoO_3-TiO_2纳米管阵列。扫描电子显微镜(SEM)、透射电子显微镜(SEM)、X射线衍射(XRD)和X射线光电子能谱(XPS)的表征结果显示溶胶-凝胶法合成的纳米颗粒为LaCoO_3,其尺寸均匀,结晶度高,平均粒径约为100nm。LaCoO_3纳米颗粒与TiO_2纳米管阵列之间的结合力好。紫外可见吸收光谱(DRS)显示,随着电泳沉积时间的延长,LaCoO_3-TiO_2纳米管阵列的吸收带边逐渐红移700nm。可见光下光催化降解甲基橙(MO)的结果表明,电泳沉积15 min制得的LaCoO_3-TiO_2纳米管阵列对MO的光催化效率最高,其降解速率是相同条件下TiO_2纳米管阵列的4倍。光致发光光谱和电化学阻抗谱证实LaCoO_3纳米颗粒的负载有效地促进了光生电荷的分离和传输,可见光光催化活性明显增强。     

TiO_2载体掺杂对Mn-Ce/TiO_2催化剂低温脱硝性能影响研究

以TiO_2、TiO_2-Al_2O_3及TiO_2-SiO_2为载体,选取Mn为活性组分,Ce为活性助剂,采用分布共混法制备低温SCR催化剂,分析了TiO_2载体掺杂Al_2O_3、SiO_2改性后对Mn-Ce/TiO_2催化剂低温脱硝活性的影响,运用BET、SEM、XRD、H2-TPR以及NH_3-TPD等测试手段对催化剂进行了表征。结果表明,TiO_2载体经掺杂改性后,Mn-Ce/TiO_2催化剂的比表面积、孔结构参数以及表面孔结构形貌均得到改善和提高;Mn-Ce/TiO_2-Al_2O_3和Mn-Ce/TiO_2-SiO_2催化剂中TiO_2的结晶度均有不同程度降低;经TiO_2载体掺杂改性后的催化剂表面低温还原峰面积及催化剂表面酸性位种类及酸性大小显著改善,这都有助于提高催化剂的脱硝活性。通过对TiO_2载体掺杂SiO_2和Al_2O_3改性后,催化剂的脱硝活性明显提高,反应温度在80-140℃时,催化剂SCR脱硝活性的顺序是:Mn-Ce/TiO_2-SiO_2M n-Ce/TiO_2-Al_2O_3M n-Ce/TiO_2。     

A comparative study of bismuth-based photocatalysts with titanium dioxide for perfluorooctanoic acid degradation

The fabricated bismuth-based photocatalysts presented an outstanding performance as compared to commercial TiO₂ (P25) for PFOA degradation under 254 nm UV light irradiation.     

铋掺杂介孔二氧化钛的制备及光催化动力学

以介孔分子筛(KIT-6)为载体,采用溶液浸渍法合成了铋(Bi)掺杂的介孔二氧化钛(TiO₂)光催化剂。利用XRD、TEM、SEM、XPS、N₂吸附-脱附法和拉曼光谱法等技术手段对材料的结构和形貌进行表征。通过紫外-可见吸收光谱法考察了催化剂对罗丹明B光催化降解效率,进一步考察了Bi的掺杂量对光催化反应速率的影响,并对光催化降解动力学进行了初步研究。结果表明,Bi掺杂的介孔TiO₂具有较窄的孔径分布(3~4 nm),而且吸收范围扩展到可见光区,其光催化活性明显高于商品TiO₂(P25)。随之Bi掺杂量的提高,反应速率常数也增大,其光催化降解罗丹明B的反应均符合准一级动力学方程。     

Preparation and Photocatalysis of Mesoporous TiO2 Nanofibers via an Electrospinning Technique

Mesoporous TiO₂ nanofibers have been synthesized by a new method that combines sol-gel chemistry and electrospinning technique. The obtained mesoporous TiO₂ nanofibers were characterized with scanning electron microscopy(SEM), X-ray diffraction(XRD), transmission electron microscopy(TEM) and nitrogen adsorption-desorption isotherms. The photocatalytic performance was evaluated by the photocatalytic degradation of Rhodamine B under UV light irradiation. The results show that mesoporous TiO₂ nanofibers exhibit higher photocatalytic activity compared with nonporous TiO₂ nanofibers.     

耐高温核/壳结构TiO2/SiO2复合气凝胶的制备及其光催化性能

以钛酸四丁酯为源, 采用苯胺-丙酮原位生成水溶胶-凝胶法, 在乙醇超临界干燥过程中用部分水解的钛醇盐和硅醇盐对TiO₂凝胶进行超临界修饰制备了具有核/壳纳米结构的块体TiO₂/SiO₂复合气凝胶. 制备的复合气凝胶具有优异的机械性能, 其杨氏模量可达4.5 MPa. 复合气凝胶同时具有极好的高温热稳定性. 经过1000 ℃热处理后, 线性收缩由纯TiO₂气凝胶的31%降至复合气凝胶的10%, 且比表面积由纯TiO₂气凝胶的31 m²·g^-1提升至复合气凝胶的143 m²·g^-1. 此外, 该复合气凝胶经1000 ℃热处理后具有优异的光催化降解亚甲基蓝的性能. 其优异的光催化性能得益于TiO₂/SiO₂复合气凝胶1000 ℃处理后高的比表面积和小的颗粒尺寸. 优良的耐热性能、力学性能和光催化性能使获得的具有核/壳纳米结构的TiO₂/SiO₂复合气凝胶在光催化领域具有良好的应用前景.     

制备方法及载体类型对Ni_2P/TiO_2催化剂加氢脱硫性能的影响

以两种类型的TiO2(锐钛矿anatase、晶须载体whiskers)为载体,分别采用程序升温还原(H2-TPR)法和溶剂热法制备Ni2P/TiO2催化剂,并用X射线衍射(XRD)、N2吸附比表面积(BET)测定、N2等温吸附脱附、CO吸附表征、X射线光电子能谱(XPS)技术、扫描电镜(SEM)对催化剂的结构和性质进行了表征。考察了不同的制备方法及不同类型TiO2载体对Ni2P/TiO2催化剂二苯并噻吩(DBT)加氢脱硫(HDS)性能的影响。结果表明,溶剂热法制备催化剂过程中,保持了TiO2晶体结构,抑制了TiPO4的形成,HDS活性高于H2-TPR法制备的催化剂;与锐钛矿TiO2为载体的催化剂相比,以晶须TiO2为载体的催化剂具有更优良的表面性质,能生成较多晶体颗粒粒径较小、分散性好的Ni2P活性相,具有更高的HDS活性。以晶须TiO2为载体,采用溶剂热法制备的Ni2P/TiO2催化剂,具有最好的加氢脱硫活性,在340℃、3.0MPa、氢油体积比为500、质量空速(WHSV)2.0h-1的条件下,二苯并噻吩转化率达到为98.2%。     

Pt-TiO2/Graphene催化剂的氧还原和甲醇氧化电催化性能研究

以二(2-羟基丙酸)二氢氧化二铵合钛（TBA）和氧化石墨烯（GO）为前驱体,通过水热法合成出不同TiO₂含量的TiO₂/Graphene（TiO2/G）复合材料,随之用微波醇热法还原Pt前驱体可得Pt-TiO₂/G催化剂. 实验结果表明,TiO₂可与Pt相互作用,添入适量TiO₂的Pt-TiO₂/G催化剂具有较高的氧还原电催化活性及甲醇氧化的电催化活性与稳定性. 但TiO₂电导率偏低,过量TiO₂的添入反而使其电催化性能降低.     

复合氧化物负载的Ni基催化剂上愈创木酚加氢脱氧性能

分别以Al₂O₃-SiO₂,Al₂O₃-TiO₂,TiO₂-SiO₂和TiO₂-ZrO₂双金属氧化物为载体研究Ni基催化剂的愈创木酚加氢脱氧性能. 重点考察了催化剂载体、溶剂种类、反应温度和压力对愈创木酚转化率及产物选择性的影响,并对催化剂的抗积碳性能、重复利用性能和愈创木酚加氢脱氧反应机理进行了探讨. 通过BET（Brunauer-Emmett-Teller）比表面积、X射线衍射（XRD）、NH₃程序升温脱附（NH₃-TPD）和H₂程序升温还原（H₂-TPR）等表征手段对催化剂的比表面积、物相结构、表面酸性、可还原性能进行了表征. 结果表明,Ni/TiO₂-ZrO₂催化性能相对较优. 在300 ℃、初始氢压4 MPa、以十氢萘为溶剂的最佳反应条件下,愈创木酚的转化率为100%,环己烷选择性高达86.4%. 该催化剂还具有抗积碳性能,反应后的催化剂上仅检测到3.2%（质量分数）的积碳量.     

ZnO-TiO2和WO3-TiO2复合薄膜光催化剂的制备与性能

采用溶胶一凝胶法在多孔钛片上制备了 ZnO-TiO₂和WO₃-TiO₂复合半导体光催化剂,用甲基橙的光催化降解反应对所得薄膜的催化活性进行评价,并通过XRD和DTA等手段对样品进行了表征.结果表明,ZnO和WO₃的掺入降低了TiO₂的相转变温度,ZnO适宜掺杂量为0.1 mol%, WO₃适宜掺杂量为0.5 mol%, ZnO-TiO₂和WO₃-TiO₂复合薄膜比纯TiO₂薄膜光催化活性分別高出77.0%和96.7%.