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排序方式: 共有211条查询结果,搜索用时 15 毫秒
51.
52.
Samira Slyemi Siham Barama Juliette Blanchard Hassiba Messaoudi Sandra Casale 《Chemical Engineering Communications》2018,205(9):1288-1298
This paper reports the study of physicochemical, surface, and catalytic properties of two series of VMgO catalysts prepared by two different methods: wet impregnation and sol–gel. The characterizations of the elaborated materials were performed using N2-sorption (Brunauer, Emmett and Teller (BET)), X-ray diffraction, Raman, transmission electron microscopy–energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy analyses. The catalytic properties of the elaborated materials were investigated in the isopropanol decomposition reaction to determine their acid–base character and in the selective oxidation of n-butane to evaluate their dehydrogenation properties. The preparation method and vanadium content strongly affected the properties of our materials. The sol–gel method leads to smaller crystallite size, higher specific surface area, and uniform particle distribution compared to the impregnation one. Both impregnation and SG solids promote the formation of acetone, which is related to the presence of strong basic sites (O2? species) on the catalytic exposed surface. The more pronounced basic character was obtained through the SG samples. The sol–gel samples exhibited the highest catalytic activity and C4-olefin selectivity in the partial oxidation of n-butane. Whatever the preparation procedure, the nature of surface oxygen species plays an important role in the orientation of catalytic performances. 相似文献
53.
采用水热合成法制备Na-ZSM-35分子筛。用不同浓度NH_4NO_3溶液对ZSM-35分子筛进行铵交换,不同焙烧温度下进行焙烧处理,制成H-ZSM-35分子筛。采用XRD、SEM、FT-IR和NH3-TPD对酸改性ZSM-35分子筛催化剂进行表征,并用于丙烯水合反应,考察其催化性能。结果表明,交换液浓度0.4 mol·L-1和450℃焙烧处理的ZSM-35分子筛催化剂的B酸中心最多,丙烯水合制异丙醇催化性能最佳。在丙烯水合制异丙醇反应中,反应产物异丙醇物质的量分数为15.96%,选择性为98.52%。 相似文献
54.
通过水热法和退火处理制备了不同Pr浓度(0%,1%,2%,4%)的Pr6O11/SnO2复合材料。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和X射线光电子能谱仪(XPS)等方法对制备材料的物相结构、微观形貌和元素组成进行了表征,并制成旁热式气敏元件,对异丙醇气体进行气敏测试。实验结果表明,基于2%样品的Pr6O11/SnO2气体传感器的气敏性能最佳,在最佳工作温度200℃下对100×10^-6异丙醇气体响应达到16.2,是纯相SnO2传感器响应的2.3倍。最后,对基于Pr6O11/SnO2复合材料气体传感器的气敏机理进行了分析讨论。 相似文献
55.
G. Fóti C. Mousty K. Novy Ch. Comninellis V. Reid 《Journal of Applied Electrochemistry》2000,30(2):147-151
Platinum coatings on Ti were prepared by a two-step process: partial thermal decomposition of chloroplatinic acid followed by electroreduction of the coating. Effects of preparation temperature and of cathodic polarization on the roughness factor were studied. Roughness factors greater than 570 were achieved, leading to an enhancement of the activity towards isopropanol electrooxidation in 1M H2SO4. 相似文献
56.
摘 要:采用水热-煅烧法制备了Cd2SnO4,并使用超声混合法制备一系列不同质量比例的g-C3N4-Cd2SnO4复合材料。通过X射线衍射(XRD)、扫描电镜(SEM)、X射线光电子能谱(XPS)等方法对g-C3N4-Cd2SnO4复合材料进行了表征,研究了不同比例的g-C3N4-Cd2SnO4复合材料的气敏性能。气敏性能研究结果表明:当g-C3N4的加入量为2.5 wt%(质量分数)时,g-C3N4-Cd2SnO4复合材料对于异丙醇气体的灵敏度最高,在170℃的最佳工作温度下,对100 μL/L的异丙醇气体的灵敏度可达117,与纯Cd2SnO4的灵敏度1.4相比提高了78倍,最低检测限为0.1 μL/L。 相似文献
57.
58.
以异丙醇、氢氧化钠、二硫化碳为原料,合成了液体异丙基黄原酸钠。通过考察物料配比、反应时间、反应温度和NaOH浓度对产品收率的影响,得出适宜的工艺条件为:n(二硫化碳)∶n(氢氧化钠)∶n(异丙醇)=1∶1∶1,反应时间2.5 h,反应温度30℃,氢氧化钠浓度为40%。在此条件下,异丙基黄原酸钠的产率最高可达92.2%。 相似文献
59.
60.
《分离科学与技术》2012,47(15):3071-3091
Abstract NH4Y zeolite‐filled chitosan membranes were developed for the separation of water‐isopropanol mixture using pervaporation process. The NH4Y zeolite‐filled chitosan membranes were prepared using a solution technique with the variation of NH4Y zeolite loading (0, 0.1, 0.2, 0.3, 0.4, 0.5 wt.%). The membranes morphologies were studied using Scanning Electron Microscopy (SEM) and the membranes mechanical strength were tested using the parameter of tensile strength and percent strain at maximum. The effects of NH4Y zeolite loading on the liquid sorption characteristics and pervaporation performance were also evaluated. The diffusion coefficient of water and isopropanol for the chitosan membranes at different NH4Y zeolite loading is estimated. The presence of NH4Y zeolite in the chitosan membranes caused non‐homogeneous dispersion of NH4Y zeolite crystals and membrane swelling due to its hydrophilic properties. However, the presence of NH4Y zeolite was able to improve both tensile strength and percent strain at maximum of chitosan membranes. The presence of NH4Y zeolite also increased the total permeation flux and separation factor simultaneously. The Pervaporation Separation Index shows that 0.2 wt.% of NH4Y zeolite‐filled membrane gave the optimum performance in the pervaporation process. The diffusion coefficient estimated proves that the membranes were highly water selective. 相似文献