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101.
102.
稠油热采注汽管道由于长期在高温、高压下运行,极易发生各种损伤,如腐蚀、裂纹、材料退化等,极易造成管道承压能力降低,发生失效事故。如何检测出潜在危险性缺陷,判断注汽管道能否继续使用,是保证注汽管道安全运行的关键问题。探讨了高温压力管道在线检测技术发展现状及其应用范围。 相似文献
103.
大庆蜡油在酸性催化剂上反应机理的研究 总被引:11,自引:5,他引:6
以大庆蜡油为原料,采用两种不同类型的催化剂,在流化床反应器实验装鬣上进行催化裂化反应。结果表明,大庆蜡油在酸性催化剂上反应所产生的干气组成与高烯烃催化裂化汽油相同,干气的产生主要是单分子裂化反应所造成的。从干气产率、组成以及液化气组成可以看出,大庆蜡油在不同类型的催化剂上明显地表现出裂化反应类型的差异。 相似文献
104.
Ahmet Ekmekyapar Nizamettin Demirkran Asm Künkül 《Chemical Engineering Research and Design》2008,86(9):1011-1016
Ulexite is an important boron mineral used for the production of boron compounds. The aims of this study are to examine the dissolution kinetics of ulexite in acetic acid solutions, and to present an alternative process to produce boric acid. In order to investigate the dissolution kinetics of ulexite in acetic acid solutions, the concentration of solution, reaction temperature, solid-to-liquid ratio, and particle size were selected as experimental parameters. It was determined that the dissolution rate of ulexite increased with increasing solution concentration and temperature and decreasing particle size and solid-to-liquid ratio. The activation energy of the process was found to be 55.8 kJ/mol. 相似文献
105.
Ahmad Nozad Golikand Elaheh Lohrasbi Mohammad Ghannadi Maragheh Mehdi Asgari 《Journal of Applied Electrochemistry》2008,38(6):869-874
The effect of carbon surface oxidation on platinum supported carbon particles (Pt/C) with nitric acid was investigated by
cyclic voltammetry, electrochemical impedance spectroscopy, polarization experiments and chronoamperometry. Cyclic voltammograms,
polarization curves and electrochemical impedance spectra showed that the treated catalyst had much larger active surface
area and higher ionic conductivity than the untreated catalyst, and provided enhanced performance for oxygen reduction. The
formation of acidic groups was examined by IR spectra. The Pt/C surface oxidation had a large effect on the performance of
a gas diffusion electrode for oxygen reduction reaction. 相似文献
106.
Debasmita Das Purabi Rani Samaddar Pratik Kumar Sen Kaushik Das 《Journal of Applied Electrochemistry》2008,38(6):743-749
Galvanostatic steady state current potential measurements were carried out for oxidation of a series of aliphatic alcohols
having varying number of hydroxyl groups. The anodically deposited layer of MnO2 on platinum was used as the electrode material. The deposit was characterised by scanning electron microscopy (SEM), energy
dispersive X-ray analysis (EDAX) and electrode potential measurements. The catalytic role of MnO2 in the electro-oxidation of alcohols was indicated by the chronopotentiograms and the cyclic voltammograms. An analysis of
the electrochemical data indicated a catalytic EC mechanism in which Mn (V) is generated electrochemically and consumed chemically
in succession. Based on this and the hydrogen bonding interaction between alcoholic hydroxyl groups and MnO2 layer, a mechanism was proposed which accounts for the variation in the observed electrochemical reaction orders. Tafel behaviour
was found to be followed only approximately. Current efficiency of the electrochemical oxidation of polyols was studied. Replacement
of platinum by carbon as current collector was found to leave the electrocatalytic activity of the MnO2 deposit practically unaltered. 相似文献
107.
Polyoxymethylene (POM) composites filled with low-density polyethylene (LDPE) and rice husk flour (RHF) were prepared by injection molding. The POM/5 wt % LDPE/7.5 wt % RHF composite exhibited the lowest wear rate, whereas the coefficient of friction remained low, and the POM/5 wt % LDPE/5 wt % RHF composite had the best mechanical properties. X-ray diffraction analysis was carried out, and the worn surfaces were examined with scanning electron microscopy. The results showed that the addition of the filler reduced the crystallinity degree of the POM composites. The main wear mechanism for unfilled POM was adhesion, whereas for the POM composites, wear seemed to occur mainly by fatigue and abrasion. It was experimentally confirmed that the POM composite filled with LDPE and RHF, which is well-performing, low-cost, and environmentally friendly, could be a potential material for tribological applications. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
108.
Methylmethacrylate (MMA) and octadecyl acrylate (OA) were grafted to poly(methylhydrosiloxane) (PMHS) by hydrosilylation, respectively, with hexachloroplatinic acid as catalyst, and the former was further hydrolyzed to prepare methacrylic acid (MAA)‐graft‐PMHS under the alkaline condition. Through orthogonal experiment, main factors affecting the graft reaction between OA and PMHS were discussed and arranged in a decreasing order according to their abilities of the effect on the hydrosilylation of OA with PMHS: catalyst dosage, reaction temperature, reaction time, material ratio, and solvent dosage. It was found that the hydrosilylation of OA with PMHS was easier to that of MMA with PMHS. Under optimal conditions, the grafting ratios of MMA with PMHS and OA with PMHS reached about 90 and 95%, respectively. FTIR and 1H NMR spectra indicated that the hydrosilylation reactions followed the Markovnikov's rule and played a strong preference toward β‐1,2‐addition. The test of contact angle indicated that surface energy of a system was mainly dependent on the polar groups. The surface energy of OA‐graft‐PMHS (35.07 mN/m) was similar to those of PMHS (35.62 mN/m) and polyoctadecyl acrylate (36.57 mN/m), and lower than that of MAA‐graft‐PMHS (43.50 mN/m). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008 相似文献
109.
110.