稀土掺杂TiO2光催化还原CO2

采用溶胶-凝胶法制备了稀土掺杂TiO₂纳米光催化剂,并应用于光催化还原CO₂/H₂O体系中。通过XRD对光催化性能进行表征,研究稀土离子掺杂和焙烧温度对光催化性能的影响。结果表明,稀土La和Ce的加入可以抑制TiO2的晶相转变,提高光催化性能。催化剂800 ℃焙烧可达到最好的光催化活性,在反应时间7 h、CO₂流量200 mL·min^-1和反应液中NaOH与Na₂SO₃浓度均为0.10 mol·L^-1条件下,甲醇产率高达315.49 μmol·g^-1。并对稀土掺杂TiO₂催化剂光催化还原CO₂的机理进行了探究。     

层序空间多孔结构TiO2实现高效光催化CO2还原

以葡萄糖为原料,经一步水热法生成葡萄糖基碳球(GCs),粒径约500nm,利用微乳液聚合法合成粒径约270nm的聚苯乙烯微球(PSs)。通过真空抽滤,制备了GCs和PSs层层组装的多级模板,TiCl₄完全浸润模板并经干燥和高温煅烧,获得了空间层序多级孔结构的TiO₂。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、N₂吸附-脱附等手段表征了所制备催化剂的形貌、组分和孔结构。在饱和CO₂气氛下加入H₂O,利用催化剂在模拟太阳光条件进行光催化还原试验。结果表明：经过7h的光催化测试,相较于商用P25和无空间结构的TiO₂,层序空间多孔TiO₂生成还原产物CO的产率均得到明显提高。其中,空间复合多级孔TiO₂在结构失配的情况下仍表现出较高的CO产率。结合实验结果和表征证实：纳米微球层所形成的层序空间多孔TiO₂具有较高的比表面积和丰富的孔结构,有利于形成大量表面活性位点。三维网状多孔结构暴露出...     

光致热催化还原CO2研究进展

基于光热催化在CO₂还原及制备碳氢燃料方面的优势,重点介绍了光热催化分类中的光致热催化还原CO₂反应,包括其反应机理、近期进展、应用及催化剂分类。同时,从强化光反应、热反应、表面反应不同方面对光致热催化还原CO₂反应的性能提升策略进行了归纳分析。该反应可将CO₂和H₂O催化生成C1、C2产物,光照下催化剂表面局部温度的升高有利于增强光致热催化CO₂还原反应速率。最后,对该方向存在的问题进行了深入分析,提出了未来主要研究方向的建议。     

V2O5-MoO3/TiO2 催化剂的NOx选择性催化还原及SO2氧化活性

采用浸渍法以TiO₂为载体制备V₂O₅-MoO₃/TiO₂ 选择性催化还原催化剂,研究V₂O₅和MoO₃负载量对于催化剂选择性催化还原反应及SO₂氧化活性的影响,并考察氧含量、氨氮物质的量比和反应空速对3%V₂O₅-6%MoO₃/TiO₂催化剂选择性催化还原脱硝活性的影响。结果表明,随着催化剂中V₂O₅负载质量分数增加,V₂O₅-MoO₃/TiO₂ 催化剂的选择性催化还原活性和SO₂氧化活性均呈上升趋势。MoO₃的负载对催化剂的SO₂氧化活性有明显抑制作用。MoO₃负载质量分数超过9%,制备的催化剂既保持较高的低温选择性催化还原活性,又使选择性催化还原反应中的SO₂转化率小于1%。     

电催化还原CO2研究进展

用于还原二氧化碳(CO₂)获得低碳燃料,包括CO,HCOOH/HCOO^-,CH₂O,CH₄,H₂C₂O₄/HC₂O^-₄,C₂H₄,CH₃OH,CH₃CH₂OH等的电催化剂的最新进展。电催化剂主要分为金属、金属合金、金属氧化物、金属络合物、聚合物/簇、酶和有机分子等。主要分析了实现高活性和高稳定性电催化还原CO₂所面临的挑战,并提出了几个实际应用的研究方向,旨在克服出现的挑战,促进该领域的研究和开发。     

热助光催化CO2还原研究进展与展望

光热催化是一种极具前途的CO₂还原策略,可利用太阳光谱的广泛吸收来激发热化学和光化学过程的结合,从而协同推动催化反应的进行,使CO₂在较为温和的条件下实现高效转换。作为光热催化的一种,在光催化中引入热能,可提高太阳光利用率,促进载流子的激发和分离,加快反应分子扩散,提升反升性能。对当前光热催化CO₂还原的概念和原理进行分类,并对热助光催化还原CO₂反应的研究现状进行总结。基于反应产物的差异,介绍热助光催化反应的催化剂选择、反应条件和反应机理,同时介绍了该类反应试验过程中关键的局部测温技术,最后对热助光催化CO₂还原技术的发展进行了展望,未来的研究重点应是提升CO₂转化率和产物选择性,同时利用先进的原位表征技术和理论计算对反应机理进行探究。     

Ag@AgCl/TiO2/GO催化剂制备及其光催化性能

以AgNO₃、聚乙烯吡咯烷酮(PVP)、钛酸四正丁酯、石墨烯等为原料,利用溶剂热法合成AgCl/TiO₂/GO复合光催化剂,经紫外光照还原得到Ag@AgCl/TiO₂/GO,并将其应用于罗丹明B的太阳光催化降解反应中。结果表明,该催化剂具有较高的光催化活性和稳定性。在100 mL 3 mg·L^-1罗丹明B溶液中,投加0.5 g·L^-1的Ag@AgCl/TiO₂/GO催化剂,光照75 min后,罗丹明B降解率高达98%以上。     

CdS/C-TiO2复合光催化剂光催化还原CO2性能研究

采用沉淀-水热法制备了CdS/C-TiO2系列复合光催化剂,通过XRD、UV-Vis、FESEM、XPS等分析手段对催化剂晶体结构、形貌及光电性能进行了表征,考察了柠檬酸(CA)/TiO2质量比R对CdS/C-TiO2复合光催化剂光催化性能的影响。实验结果表明,碳掺杂影响催化剂的晶体结构及其微观形貌,掺杂后光催化活性显著提高。在紫外光照射下进行光催化还原CO2反应,当CA/TiO2质量比R=3/1时,催化活性最高,还原产物HCOOH和HCHO总收率达到533μmol/(g.h)。     

H2气氛中TiOx的形成及其对Ni/TiO2催化剂顺酐液相加氢性能的影响

采用等体积浸渍法制备了Ni/TiO₂催化剂,利用N₂物理吸附、H₂-TPR、XRD、H₂-TPD及CO-TPSR等表征手段研究H₂气氛中随着热处理温度升高,Ni/TiO₂催化剂结构和织构变化规律,并考察催化剂的顺酐液相加氢性能。研究表明,随着热处理温度的升高,催化剂C-C键加氢活性逐渐增高,而CO加氢活性先增高后降低。产生这一现象的原因与TiO_x物种随H₂气氛中热处理温度的升高而逐渐增多有关。     

{001}面TiO2光催化降解罗丹明B的研究

以钛酸四丁酯为钛源、HF为形貌控制剂,采用水热法在不同反应温度条件下制备纳米片状{001}面TiO2,并以罗丹明B的光催化降解为模型反应,考察了不同反应温度对{001}面TiO2形貌结构的影响,研究了反应温度、pH及催化剂投加量对光催化活性的影响。结果表明,所有{001}面TiO2均具有良好的锐钛矿相衍射峰,并且在紫外光区域具有明显的光吸收;当反应温度为180℃、溶液pH为2、投加量为1 g/L时,样品对罗丹明B光催化降解活性最高,紫外光照射20 min后罗丹明B降解率可达100%。     

薄层氮化碳光催化还原CO_2性能研究

以氮化碳(g-CN)为原料,采用水蒸汽焙烧剥离法在Ar/H2O氛围下制备薄层氮化碳(Hg-CN),并对其进行XRD、TEM、FT-IR、BET和UV-Vis DRS等表征。结果表明,进行剥离后,H-g-CN比表面积相比剥离前明显增大。H-g-CN的光催化还原CO_2活性大大高于未剥离gCN的活性,光照反应9 h,H-g-CN光催化还原CO_2活性由剥离前的11. 4μmol·g~(-1)提高至24. 6μmol·g~(-1),H-g-CN的CO选择性为91. 2%,未剥离的g-CN的CO选择性为89. 1%,并提出相应的反应机理。     

Reactivity of V2O5-WO3/TiO2 catalysts in the selective catalytic reduction of nitric oxide by ammonia

The physico-chemical characteristics and the reactivity of sub-monolayer V₂O₅-WO₃/TiO₂ deNO_x catalysts is investigated in this work by EPR, FT-IR and reactivity tests under transient conditions. EPR indicates that tetravalent vanadium ions both in magnetically isolated form and in clustered, magnetically interacting form are present over the TiO₂ surface. The presence of tungsten oxide stabilizes the surface V^IV and modifies the redox properties of V₂O₅/TiO₂ samples. Ammonia adsorbs on the catalysts surface in the form of molecularly coordinated species and of ammonium ions. Upon heating, activation of ammonia via an amide species is apparent. V₂O₅-WO₃/TiO₂ catalysts exhibits higher activity than the binary V₂O₅/TiO₂ and WO₃/TiO₂ reference sample. This is related to both higher redox properties and higher surface acidity of the ternary catalysts. Results suggest that the catalyst redox properties control the reactivity of the samples at low temperatures whereas the surface acidity plays an important role in the adsorption and activation of ammonia at high temperatures.     

Newly-modeled graphene-based ternary nanocomposite for the magnetophotocatalytic reduction of CO2 with electrochemical performance

The development of CO₂ into hydrocarbon fuels has emerged as a green method that could help mitigate global warning. The novel structured photocatalyst is a promising material for use in a photocatalytic and magneto-electrochemical method that fosters the reduction of CO₂ by suppressing the recombination of electron−hole pairs and effectively transferring the electrons to the surface for the chemical reaction of CO₂ reduction. In our study, we have developed a novel-structured AgCuZnS₂–graphene–TiO₂ to analyze its catalytic activity toward the selective evolution of CO₂. The selectivity of each nanocomposite substantially enhanced the activity of the AgCuZnS₂–graphene–TiO₂ ternary nanocomposite due to the successful interaction, and the selectivity of the final product was improved to a value 3 times higher than that of the pure AgCuZnS₂ and 2 times higher than those of AgCuZnS₂–graphene and AgCuZnS₂–TiO₂ under ultra-violet (UV)-light (λ = 254 nm) irradiation in the photocatalytic process. The electrochemical CO₂ reduction test was also conducted to analyze the efficacy of the AgCuZnS₂–graphene–TiO₂ when used as a working electrode in laboratory electrochemical cells. The electrochemical process was conducted under different experimental conditions, such as various scan rates (mV·s^–1), under UV-light and with a 0.07 T magnetic-core. The evolution of CO₂ substantially improved under UV-light (λ = 254 nm) and with 0.07 T magnetic-core treatment; these improvements were attributed to the facts that the UV-light activated the electron-transfer pathway and the magnetic core controlled the pathway of electron-transmission/prevention to protect it from chaotic electron movement. Among all tested nanocomposites, AgCuZnS₂–graphene–TiO₂ absorbed the CO₂ most strongly and showed the best ability to transfer the electron to reduce the CO₂ to methanol. We believe that our newly-modeled ternary nanocomposite opens up new opportunities for the evolution of CO₂ to methanol through an electrochemical and photocatalytic process.     

Hydrogenation of CO2 over sprayed Ru/TiO2 fine particles and strong metal–support interaction

Ru/TiO₂ catalysts were prepared by spray reaction (SPR) and conventional impregnation (IMP) methods. The catalytic activities of SPR fine particles were much higher than those of IMP catalysts for CO₂ hydrogenation. A high temperature reduction greatly promoted the activity of SPR catalyst. A model of surface structure was proposed which exhibits the enhancement of decoration and the formation of more boundaries over spr-Ru/TiO₂. The high activity of SPR catalyst is attributed to the occurrence of new active sites at the metal–support perimeters and not any SMSI phenomenon. EXAFS reveals that the Ru atom was interacting with TiO₂ by oxygen atom so strongly on the SPR catalysts that a part of the Ru atoms, located near the internal interface between Ru particles and TiO₂ support, existed as Ruⁿ⁺ (n<4) cations even if SPR catalyst was subjected to a high temperature reduction. These Ruⁿ⁺ cations are responsible for the inhibition of SMSI formation over SPR catalysts.     

Support effects in Pt/TiO2–ZrO2 catalysts for NO reduction with CH4

ZrO₂–TiO₂ mixed oxides, prepared using the sol–gel method, were used as supports for platinum catalysts. The effects of catalyst pre-reduction and surface acidity on the performance of Pt/ZT catalysts for the reduction of NO with CH₄ were studied. The diffuse reflectance infrared Fourier transformed (DRIFT) spectra of CO adsorbed on the Pt/ZT catalysts, and also on the Pt/T and Pt/Z references, pre-reduced at 773 K in hydrogen, revealed that an SMSI state is developed in the Ti-rich oxide-supported platinum catalysts. However, no shift in the binding energy of Pt 4f_7/2 level for Pt/T and Pt deposited on Ti-rich support counterparts pre-reduced at 773 K was found by photoelectron spectroscopy. The DRIFT spectra of the catalysts under the NO+O₂ co-adsorption revealed the appearance of nitrite/nitrate species on the surface of the Zr-containing catalysts, which displayed acidic properties, but were almost absent in the Pt/T catalyst. The intensity of these bands reached a maximum for the Pt/ZT(1:1) catalyst, which in turn exhibited a larger specific area. In the absence of oxygen in the feed stream, the NO+CH₄ reaction showed DRIFT spectra assigned to surface isocyano species. Since the intensity of this band is higher for the Pt/ZT (9:1) catalyst, it seems that such species are developed at the Pt–support interface.     

N、Ni共掺杂TiO2光催化剂的制备及对亚甲基紫降解性能研究

以硫脲、硝酸镍、钛酸四丁酯为原料,用溶胶-凝胶法制备了纯TiO2和不同比例N、Ni掺杂的TiO2的光催化剂样品,用紫外-可见分光光度计进行了表征。结果表明,经过掺杂的TiO2光催化剂的吸收边向可见光方向移动,TiO2可见光催化活性提高,掺杂量为0.15 g,pH=9,温度为30℃时,对亚甲基紫的脱色效果最好。     

CO2吸附强化CH4/H2O重整制氢催化剂研究进展

CO_2吸附强化CH_4/H_2O重整制氢是提供低成本高纯氢气和实现CO_2减排的方法之一。其中,催化剂和吸附剂是该工艺的重要组成部分,其活性与选择性制约了反应速率和产率,寿命长短关系到生产成本。综述了CO_2吸附强化CH_4/H_2O重整制氢催化剂和吸附剂的研究现状及存在的问题,机械混合的催化剂与吸附剂在反应过程中存在吸附产物包覆催化活性位点的问题,导致催化剂活性迅速下降。针对该问题,进一步探讨了不同结构双功能复合催化剂的结构特性、研究现状及其在循环-再生过程中存在的问题,核壳型双功能催化剂具有吸附组分与催化剂组分相对独立、催化组分分散分布和比表面积大等优点,在吸附强化制氢中有进一步研究的潜力。利用双功能催化剂的结构特点,实现反复循环再生过程中催化与脱碳反应的匹配,是推动CO_2吸附强化CH_4/H_2O重整制氢技术工业化发展的关键。     

Effective synthesis of ethanol from CO2 on polyfunctional composite catalysts

Synthesis of ethanol by hydrogenation of carbon dioxide has been investigated by developing the novel composite catalysts. The three different kinds of elementary reaction functions for ethanol synthesis were undertaken. The catalytic functions are partial reduction of CO₂ to CO, C–C bond formation, and –OH group insertion. For this purpose, supported Rh catalyst, Fe-based modified Fisher–Tropsch catalyst, and Cu-based modified methanol synthesis catalyst were combined by different ways. As a result, high space–time yields of ethanol as high as 0.8–0.9 kg/l h were obtained.