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探索Au纳米粒子对新型材料的催化性能可以显著拓宽金催化剂的应用范围。使用TiO2-B作为载体,担载Au纳米粒子并应用于低温CO氧化反应体系。TiO2-B为长度5~20?m的微米级纤维,Au纳米粒子粒径在3 nm以下,均匀地分散在TiO2-B表面。CO氧化测试表明,Au纳米粒子的性能受TiO2-B焙烧温度的影响,不同焙烧温度会引起Au分散性以及Au纳米粒子与载体相互作用的改变。分散于纯TiO2-B载体上的金的催化活性可与其分散在锐钛矿纳米粉体上的相媲美。此外,300℃下活化的Au纳米粒子表现出了最佳的CO氧化性能,在氧化性气氛中活化的催化剂的催化性能优于在惰性和还原性气氛中活化的催化剂。 相似文献
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以溶胶-凝胶法制备TiO2载体,用沉积-沉淀法制备出一系列负载型Au/TiO2。系统考察了焙烧温度、金的负载量、反应液pH值、沉淀剂种类以及Cl-存在与否等制备参数对催化剂活性的影响。以室温下CO的催化氧化为探针反应,确定催化剂的最适宜制备参数,并对优化的质量分数为1.0%的Au/TiO2催化剂进行了活性稳定性测试。结果表明:Au/TiO2的最适宜焙烧温度是200~350℃;反应液的最适宜pH值为9;最适宜沉淀剂是NaOH;金的负载量(质量分数,下同)在0.5%~5.0%范围内时,金含量越高,催化剂活性和热稳定性越好。大量Cl-的存在能导致催化剂活性的显著下降。对优化的Au/TiO2催化剂在室温下催化氧化不同浓度的CO进行循环测试,经历3次循环,连续反应2 160 min后,CO的转化率仍为100%。 相似文献
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目前具有一维纳米结构的TiO2薄膜在电致变色领域应用主要受限于材料光调制幅度小、响应时间长、循环稳定性差等缺点。为了解决上述问题,本文采用沉积法将B型二氧化钛纳米管(TiO2-B)与氧化石墨烯复合,以TiO2粉末为原料,采用水热法得到钛酸纳米管后,利用沉积法在氟掺杂的氧化锡玻璃(FTO)基底上制备了高透明度、大光调制范围以及优良循环性能的氧化石墨烯复合B型二氧化钛纳米管电致变色薄膜(GO/TiO2)。借助XRD、XPS、Raman、FESEM、HR-TEM等分析手段研究了氧化石墨烯用量对GO/TiO2复合薄膜电致变色性能的影响。研究结果表明,当GO与钛酸纳米管的质量比(GO/钛酸)为7%时,GO/TiO2复合薄膜离子扩散系数为1.46×10-8cm2/s,着色效率值为38.1cm2/C,具有良好的电致变色性能。在-1.6V、633nm处,GO/TiO2电致变色薄膜的光调制幅度可达77%,GO/TiO2薄膜的着色和漂白时间分别为28.6s和4.8s,100次循环后的光调制幅度保持率为96.1%。 相似文献
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采用改性溶胶凝胶法和水热合成法制备了掺C多孔纳米TiO2,并以其为载体制备了一种RuAg/TiO2-C甲醇催化剂。采用X射线衍射(XRD)、透射电镜(TEM)、X射线能谱(EDS)和X射线光电子能谱(XPS)等对催化剂进行了表征,测定了其对甲醇的电催化氧化性能。实验结果表明,RuAg的负载和C的掺杂能提高TiO2对甲醇的电催化性能,RuAg/TiO2-C对甲醇电催化的循环伏安曲线中未见甲醇氧化中间产物的氧化峰,0.544 V处有一个较大的甲醇氧化峰,其峰电流密度5.8 mA/cm2,RuAg/TiO2-C比商用PtRu/C催化剂具有更高的催化活性和抗毒性,RuAg合金的负载以及RuAg合金与掺C多孔纳米TiO2载体之间较强的相互作用是其对甲醇催化性能提高的主要因素。 相似文献
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CoPc/TiO2催化剂的制备及其光催化还原CO2的研究 总被引:2,自引:0,他引:2
以钴酞菁(CoPc)为活性组分,TiO2为载体,采用浸渍法进行负载,制备CoPu/TiO2催化剂.用正交实验得到的最佳催化剂制备条件为CoPc负载量为TiO2的1.0%,焙烧温度600℃,浸渍时间12
h,溶剂为甲苯.将此催化剂用于CO2还原,在可见光照下,即可将CO2还原为HCOOH、CO、CH4等,其中HCOOH为主产物,产量最高可达450.64μmol/g.另外,实验中还发现了光照下产生电子转移,CoPc变为CoPc·+,而CO2在TiO2表面获得电子被还原. 相似文献
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CO低温氧化催化剂研究进展 总被引:2,自引:0,他引:2
文章概述了目前使用的CO低温氧化催化剂存在的缺点,分析了贵金属,非贵金属催化剂的研究进展和稀土助剂在此类催化剂中的应用,指出了今后开发此类催化剂的方向包括降低贵金属用量,改善传统催化剂在高湿度条件下的使用寿命和抗中毒同时应加大稀土类催化剂的开发力度。 相似文献
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Preoxidized Au/TiO2 showed no initial activity during a first heating stage up to 70°C, while prereduction yielded a high initial CO conversion
at room temperature. With FTIRS, two different CO absorption bands were detected. One band is usually attributed to CO on
an oxidic gold species (2151 cm-1), the other one is characteristic of CO on metallic gold (2112 cm-1). The presence of the first species appears to have a detrimental effect on the CO oxidation by O2. The present results do not support a model in which the activity of supported gold catalysts in CO oxidation is ascribed
to ionic Au particles.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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After a high-temperature reduction (HTR) at 773 K, TiO2-supported Au became very active for CO oxidation at 313 K and was an order of magnitude more active than SiO2-supported Au, whereas a low-temperature reduction (LTR) at 473 K produced a Au/TiO2 catalyst with very low activity. A HTR step followed by calcination at 673 K and a LTR step gave the most active Au/TiO2 catalyst of all, which was 100-fold more active at 313 K than a typical 2% Pd/Al2O3 catalyst and was stable above 400 K whereas a sharp decrease in activity occurred with the other Au/TiO2 (HTR) sample. With a feed of 5% CO, 5% O2 in He, almost 40% of the CO was converted at 313 K and essentially all the CO was oxidized at 413 K over the best Au/TiO2 catalyst at a space velocity of 333 h–1 based on CO + O2. Half the chloride in the Au precursor was retained in the Au/TiO2 (LTR) sample whereas only 16% was retained in the other three catalysts; this may be one reason for the low activity of the Au/TiO2 (LTR) sample. The reaction order on O2 was approximately 0.4 between 310 and 360 K, while that on CO varied from 0.2 to 0.6. The chemistry associated with this high activity is not yet known but is presently attributed to a synergistic interaction between gold and titania. 相似文献
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In the course of our studies on CO oxidation over Au/Mg(OH)2 we have discovered a catalyst which exhibits an apparent negative activation energy when studied under ultra‐dry conditions (80 ppb moisture content). A review of current literature suggests that the oxidation of CO may occur by a reaction between CO and OH radicals and not by oxygen as previously thought. Substantial differences in catalytic behaviour between low and high temperature suggest that the reaction is complex and that more than one reaction pathway is present. This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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A model Pd/Fe2O3 catalyst prepared by the vacuum technique has been studied in the carbon monoxide oxidation in the temperature range of 300–550 K at reagent pressures P(CO)=16 Torr, P(O2)= 4 Torr. It has been shown that the activity of the fresh catalysts is determined by palladium. According to the XPS data, the reduction with carbon monoxide results in the formation of Fe2+ (formally Fe3O4) and appearance of the catalytic activity in this reaction at low temperatures (350 K). High low-temperature activity of the catalyst is supposed to be connected with the reaction between oxygen adsorbed on the reduced sites of the support (Fe2+) and CO adsorbed on palladium (COads) at the metal–oxide interface. 相似文献
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采用溶胶凝胶法制备了栽体TiO2,在负栽Mn(Ac):制备Mn/TiO2时掺杂cu,制备了Mn—Cu/TiO2催化剂。考虑了cu的掺杂量、活性组分负载量、焙烧温度等制备条件对其催化氧化No性能的影响。结果表明,最佳条件下制备的催化剂,在反应温度200℃、空速41000h~、No浓度为300×10-6(书)及O2含量为10%条件下,NO氧化率可迭53.08%,250℃时NO氧化率达到74.76%。在220℃以上时H2O对其影响较小,但其抗硫性能还有待进一步研究提高。 相似文献