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31.
CO2/CH4重整镍基催化剂制备与性能的关系 总被引:5,自引:3,他引:2
一般浸渍法与真空浸渍法的比较说明,真空浸渍制备的催化剂,其表面具有较多的Ni原子,催化活性较高,现场TPO实验表明,CO岐化的积炭量大于CH4解离的积炭量。从而提出镍基催化剂的积炭主要来自反应生成气CO的岐化。 相似文献
32.
氧化钙和氟化钾负载高岭土固体碱催化制备新型生物柴油 总被引:1,自引:0,他引:1
以高岭土为载体,利用浸渍法制备了氧化钙和氟化钾负载高岭土固体碱(GCK);利用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、红外光谱(FT-IR)和哈密特指示剂法等技术手段对催化剂进行表征;考察了KF负载量和反应条件对月桂酸甲酯(ML)与乙二醇单甲醚(EGME)酯交换反应制备新型生物柴油产率的影响。 结果表明,GCK碱强度(H_)在7.2~18.4之间,KCaF3为主要活性组分,当氟化钾负载量为25%、EGME与ML摩尔比3.0、催化剂用量相对于ML的质量分数为4.5 %、120 ℃下反应2 h,新型生物柴油的收率高达97.1%。 最后对催化剂的重复利用性能进行了考察。 相似文献
33.
Liane Meneses Rita Craveiro Ana Rita Jesus Maria A. M. Reis Filomena Freitas Alexandre Paiva 《Molecules (Basel, Switzerland)》2021,26(16)
In this work, we propose the utilization of scCO2 to impregnate ibuprofen into the mcl-PHA matrix produced by Pseudomonas chlororaphis subs. aurantiaca (DSM 19603). The biopolymer has adhesive properties, is biocompatible and has a melting temperature of 45 °C. Several conditions, namely, pressure (15 and 20 MPa) and impregnation time (30 min, 1 h and 3 h) were tested. The highest ibuprofen content (90.8 ± 6.5 mg of ibuprofen/gPHA) was obtained at 20 MPa and 40 °C, for 1 h, with an impregnation rate of 89 mg/(g·h). The processed mcl-PHA samples suffered a plasticization, as shown by the decrease of 6.5 °C in the Tg, at 20 MPa. The polymer’s crystallinity was also affected concomitantly with the matrices’ ibuprofen content. For all the impregnation conditions tested the release of ibuprofen from the biopolymer followed a type II release profile. This study has demonstrated that the mcl-PHA produced by P. chlororaphis has a great potential for the development of novel topical drug delivery systems. 相似文献
34.
不同制备工艺钒系SCR催化剂理化及催化性能研究 总被引:2,自引:0,他引:2
本文研究了制备工艺对 TiO2-WO3-V2O5- 载体型催化剂理化特性及其在 NH3-SCR 反应中催化性能的影响.通过 XRD、TG/DTA 等分析方法考察了煅烧温度等对催化剂中各组分晶体结构的影响,确定了制备负载型催化剂的最佳煅烧温度为 500℃.不同制备工艺催化剂理化性能的对比表明,多步浸渍法不仅提高了锐钛矿型 TiO2 向金红石型 TiO2 的转变温度,而且使更多的钒氧化物处于较低的价态,有利于提高还原反应的催化性能;催化活性评价试验也表明使用多步浸渍法制备的 SCR 催化剂具有较高的催化活性和更宽的高活性反应温度窗口.最后考察了反应空速对多步浸渍法所制备催化剂 NOx 转化效率的影响,结果表明:随空速的增加,NOx 转化效率逐渐降低. 相似文献
35.
36.
Yuhong Wang Yunting Gan Roger Whiting Guanzhong Lu 《Journal of solid state chemistry》2009,182(9):2530-2534
A new method has been developed for the preparation of sulfated titania (S-TiO2) supported on mesoporous silica. The use of direct exchange of metal containing precursors for the surfactants in the as-synthesized MCM-41 substrate produced a product with high sulfur content without serious blockage of the pore structure of MCM-41. The pore sizes and volumes of the resultant S-TiO2/MCM-41 composites were found to vary markedly with the loading of TiO2. The strong acidic character of the composites obtained was examined by using them as catalysts for the esterification of acetic acid and n-butanol. 相似文献
37.
Plasma treatments are established methods to functionalise carbon nanotubes (CNTs) and modify their surface structure. This paper presents a mild glow‐discharge plasma treatment of aligned arrays of multi‐walled carbon nanotubes employing sulfur hexafluoride (SF6), ammonia (NH3), and their mixtures as process gases. For the latter, sulfur was detected at the tip and sidewalls of the nanotubes via energy‐dispersive X‐ray spectroscopy, while electron microscopy served as method to verify the structural integrity of the CNTs after the plasma treatment. This approach provides the basis for an easy and quick alternative to existing sulfur functionalisation methods of MWCNTs. Furthermore, the proposed method can conveniently be applied to carbon nanotube arrays on substrate while preserving their structure and alignment.
38.
Polytetrafluoroethylene-modified silica/12-silicotungstic acid (abbreviated as HSiW/SiO2-PTFE) catalyst was prepared by the ultrasonic impregnation method. The SEM results reveal there are a number of nanowires connecting microspheres with others, botryoidal structure. The diameters of these nanowires vary mainly from 30 nm to 60 nm. An asymmetric ESR signal is found in the ESR spectra of HSiW/SiO2-30 wt% PTFE, which can be concluded to be peroxyl radical by spectral line shapes, g factor (2.0132). 相似文献
39.
High-pressure impregnation, a new preparation method for sorbents to remove H2S from hot coal gas, is introduced in this paper. Semi-coke (SC) and ZnO is selected as the support and active component of sorbent, respectively. The sorbent preparation process includes high-pressure impregnation, filtration, ovendry and calcination. The aim of this research is to primarily study the effects of the impregnation pressure on physical properties and desulfurization ability of the sorbent. The desulfurization experiment was carried out in a fixed-bed reactor at 500°C and a simulated coal gas used in this work was composed of CO (33 vol%), H2 (39 vol%), H2S (300 ppm in volume), and N2 (balance). Experimental results show that the pore structure of the SC support can be improved effectively and ZnO active component can be uniformly dispersed on the support, with the small particle size of 10-500 nm. Sorbents prepared using high-pressure impregnation have better desulfurization capacity and their active components have higher utilization rate. P20-ZnSC sorbent, obtained by high-pressure impregnation at 20 atm, has the best desulfurization ability with a sulfur capacity of 7.54 g S/100g sorbent and a breakthrough time of 44 h. Its desulfurization precision and efficiency of removing H2S from the middle temperature gases can reach <1 ppm and >99.7%, respectively, before sorbent breakthrough. 相似文献
40.
考察了ZrO2、Ru或Pt助剂对Co/Al2O3催化剂结构及浆态床费托合成反应性能的影响。实验结果表明,添加ZrO2助剂可阻止或降低难还原铝酸钴的形成、促进催化剂的还原、提高Co/Al2O3催化剂对费托合成反应的催化活性、降低甲烷选择性并提高C5+烃选择性。H2-TPR表征结果表明,少量Ru或Pt助剂均能降低Co-ZrO2/Al2O3催化剂中钴物种还原温度(Co3O4→CoO和CoO→Co0),提高催化剂的还原度,催化剂呈现出良好的CO加氢反应活性。此外,催化剂组分间浸渍次序对费托合成反应性能有重要影响,载体γ-Al2O3先浸渍Zr组分,可有效抑制难还原化合物形成;Co、Ru组分共浸渍加强了Co和Ru组分密切接触程度,更利于钴物种的还原;Co、Pt组分依次浸渍更利于活性组分的均匀分布,催化剂具有最佳的费托合成反应性能。 相似文献