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以TiCl4醇溶液作钛源在水热体系中合成钛硅分子筛TS-1 总被引:7,自引:1,他引:6
钛硅分子筛TS-1的制备研究是催化领域的一个热点,采用异丙醇为溶剂调节TiCl4的水解活性,并对其为钛源在TPABr(四丙基溴化铵)-NH4OH体系中合成出了晶粒尺寸为3*2μm的钛硅分子筛TS-1,用XRD、IR、UV-Vis、SEM等手段对所制备的样品进行了表征。通过对不同溶剂所起的作用的对比,发现醇溶剂分子的体积对钛硅分子筛的合成及着重要影响,其中异丙醇的使用能够有效的降低TiCl4的水解活性,使其与硅源的性质相匹配并促进沸石骨架上钛原子的引入;制得的分子筛TS-1在丙烯与过氧化氢的环氧化反应中表现出优异的催化性能。 相似文献
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采用四丙基溴化铵(TPABr)为模板剂,分别以正丁胺(NBA)、己二胺(HDA)、二乙胺(DEA)、乙二胺(EDA)、三丙胺(TPA)和四乙基氢氧化铵(TEAOH)调节凝胶碱度,成功地合成出TS-1沸石.采用IR,XRD,UV-Vis和NMR等表征技术,详细考察了有机胺的作用及对钛进入沸石骨架的影响.结果表明,以TEAOH为碱源时抑制钛进入骨架;以EDA为碱源时合成的钛硅沸石结晶度低;以TEAOH或NBA为碱源时合成的钛硅沸石晶粒较均匀.有机胺在TS-1合成过程中只起到调节碱度的作用,未与TPABr联合起模板作用. 相似文献
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讨论了用两种不同硅源合成钛硅沸石TS-1的方法和合成过程中应注意的问题,并通过XRD、IR、TEM和SSA等手段对沸石的结构及热稳定性进行了表征和研究,确认了钛已进入沸石骨架,初步探讨了TS-1沸石合成时TPA离子的模板作用机理,此外,通过在温和条件下用H2O2选择性氧化正己烷的反应,考察了TS-1沸石的催化活性,得到了比较满意的结果。 相似文献
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采用廉价的四丙基溴化铵(TPABr)的模板剂合成了TS-1分子筛,在晶化过程中,运用XRD,ICP,IR,^29SiMASNMR和UV-Vis光谱等表征手段,系统地研究了钛原子引入分子筛骨架的机制,观察到钛原子随分子筛的形成同步进入骨架的规律,另外,尽管在晶化初期固相中没有TiO2结晶出现,但存在分散态的TiOx物种,随晶化时间的延长,液相中钛物种之间聚合的几率增加,使固相中TiO2晶体不断形成。 相似文献
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无机钛硅原料体系合成TS-1催化丙烯环氧化反应 总被引:7,自引:0,他引:7
研究了无机钛硅原料体系合成的TS-1催化丙烯环氧化的反应,并与经典法、修正法制得样品的催化性能进行了比较。考察了搅拌、Na2CO3加入量、反应时间、反应温度、双氧水加量、催化剂量及溶剂等对丙烯环氧化反应的转化率、选择性等的影响,并初步探讨了无机钛硅原料合成的TS-1的再生性能。结果表明,对于丙烯环氧化反应,无机钛硅原料合成TS-1样品与经典法和修正法制取样品的催化性能相当;反应条件对丙烯环氧化反应 相似文献
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以四丁基溴化铵(TBABr)+四乙基氢氧化铵(TEAOH,n(TBA^+)/n(TEA^+)=1)或以四丙基溴化铵(TPABr)+TEAOH为模板剂,钛酸四丁酯和正硅酸乙酯为原料,于170℃水热合成出TS-1分子筛。对合成的TS-1样品进行了XRD,FT-IR,SEM和BET比表面积分析,证实了样品中钛已进入Silicalite-1骨架。选择戊烷氧化为探针反应,考察了TS-1的催化活性。结果表明以 相似文献
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On-line fermentation gas analysis is of general interest because it permits the determination of metabolic rates in almost any biological process using living organisms. The consumption and production of gases (O2, CO2, CH4, etc.) and volatile compounds may be determined without causing any risk of infection. Elemental balancing permits the determination of other metabolic rates if the stoichiometry is known. This was studied with the production of poly-β-hydroxybutyrate (PHB) by Alcaligenes latus. Estimations were based on the measurement of gas partial pressure and flow-rates, pH and alkali consumption rate. Experiments with a small quadrupole mass spectrometer showed unacceptable error propagation. Therefore, dynamic error propagation for all rates was studied using simulation. It was found that, for example, a 1% relative offset-calibration error for oxygen can result in an error in PHB estimation of > 50%. It is suggested that this culture is used in combination with elemental balancing for thorough tests of the accuracy of on-line gas analysis equipment. An on-line process gas analyser based on a quadrupole mass spectrometer (Balzers PGM 407) gave the following precision values (abs. vol.?%) during cultivation of Bacillus subtilis: nitrogen (m/z 14), 0.024; oxygen (m/z 32), 0.020; argon (m/z 40), 0.0011; and carbon dioxide (m/z 44), 0.0034. These values, combined with automatic recalibration, would be sufficient for reasonable estimation of PHB, biomass and substrates. 相似文献
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Giridharan Loganathan Suresh Krishnaraj Jayaprakash Muthumanickam Ravichandran K 《Journal of Chemometrics》2015,29(1):59-68
In order to bring out the nature of the factors influencing lake water composition, multivariate statistical analysis and trend analysis were performed based on the hydrochemical data of the study area, namely, South Chennai. Change in land use pattern and settlements along the banks of the lakes alters the quality and quantity of the surface water. In the present study, the R‐mode factor analysis and cluster analysis were applied to the geochemical parameters of the water to identify the factors affecting the chemical composition of the lake water. Dendograms of both the seasons give three major clusters, reflecting the groups of unpolluted to moderately polluted, polluted, and heavily polluted stations. The movement of stations from one cluster to another clearly brings out the seasonal variation in the chemical composition of the lake water. The complex hydrochemical data of the surface water were interpreted by condensing them into three major factors. Factor score analysis was used successfully to delineate the stations under study and the role of the contributing factors, and the nature of factors responsible for the variation in chemical composition of the water has been clearly brought out. Results of trend analysis using ArcGIS clearly indicate that the trend in water quality is deteriorating at a faster rate in the eastern part of the study area. It is understood that although natural shifts probably can account for some of the variation, it is most likely that human activities play a major role in affecting the water quality on a regional scale. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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A. Saravanakumaar A. Senthilkumar S. S. Saravanakumar M. R. Sanjay Anish Khan 《International Journal of Polymer Analysis and Characterization》2018,23(6):529-536
This study aims to examine the effect of sodium hydroxide (NaOH) treatment on the physico-chemical properties, structure, thermal, tensile and surface topography of Carica papaya fibers (CPFs). The surface of raw CPFs was modified by soaking with 5% NaOH solution for 15, 30, 45, 60, 75 and 90?min. The results of thermo-gravimetric analysis revealed that the optimum treatment time for alkali treatment was 60?min. It was found that the alkali treatment improved the properties of the CPFs. The results of TGA, FT-IR, XRD and AFM suggest that the treated CPF is a suitable alternative as reinforcement in polymer composites. 相似文献
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Analysis of time series tries to extract tendencies from measured values dependent on time. For this purpose the cusum technique has proved to be a very sensitive tool for the evaluation of both current and completed time series. Even very weak tendencies can be detected at a high level of noise. Time-series analysis further tries to predict values to come from hitherto performed measurements. As a very flexible model exponential smoothing could be successfully used. Even for processes with a high extent of non-stationarity this model allowed a good prediction owing to the dynamics of the process. Three types of time-series analysis, i.e., evaluation of current measurements, retrospective evaluation and prediction of data (also known as “in vivo”, “post mortem” and “in futurum” time-series analysis) are demonstrated for problems stemming from analytical process control. 相似文献
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文章介绍了新材料的重要性及发展方向,分析化学在新材料研制中起着耳目的作用,另一方面新材料也为分析化学的进展提供了课题与条件。微量分析、微区分析、表面分析是此领域中的重点。在未来的发展中,分析化学在材料的发展中的地位不会改变,并期待着分析灵敏度与空间分辩率的进一步提高。 相似文献
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Edmund R. Malinowski 《Journal of Chemometrics》2011,25(6):323-328
Determining the rank of a chemical matrix is the first step in many multivariate, chemometric studies. Rank is defined as the minimum number of linearly independent factors after deletion of factors that contribute to random, nonlinear, uncorrelated errors. Adding a matrix of rank 1 to a data matrix not only increases the rank by one unit but also perturbs the primary factor axes, having little effect on the secondary axes associated with the random errors in the measurements. The primary rank of a data matrix can be determined by comparing the residual variances obtained from principal component analysis (PCA) of the original data matrix to those obtained from an augmented matrix. The ratio of the residual variances between adjacent factor levels represents a Fisher ratio that can be used to distinguish the primary factors (chemical as well as instrumental factors) from the secondary factors (experimental errors). The results gleaned from model studies as well as those from experimental studies are used to illustrate the efficacy of the proposed methodology. The method is independent of the nature of the error distribution. Limitations and precautions are discussed. An algorithm, written in MATLAB format, is included. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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《Analytical letters》2012,45(6):899-908
Abstract To determine mercury in geological materials, samples are digested with nitric acid and sodium dichromate in a closed teflon vessel. After bringing to a constant weight, the digest is mixed with air and a sodium chloride-hydroxylamine hydrochloride-sulfuric acid solution and then Hg(II) is reduced to Hg with stannous chloride in a continuous flow manifold. The mercury vapor is then separated and measured using cold vapor atomic absorption spectrophotometry (CV-AAS). For a 100 mg sample the limit of detection is 20 parts per billion (ppb) Hg in sample. To obtain a 1% absorption signal, the described method requires 0.21 ppb Hg solution (equal to 16 ppb in sample). Precision is acceptable at less than 1.2% RSD for a 10 ppb Hg aqueous standard. Accuracy is demonstrated by the results of the analysis of standard reference materials. Several elements do interfere but the effect is minimal because either the digestion procedure does not dissolve them (e.g., Au or Pt) or the; are normally of low abundance (e.g., Se or Te). 相似文献
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Based on tin(II) chloride reduction in basic medium, a method of general use is proposed for the estimation of the whole gamut of multiple trace metals in natural waters by the atomic absorption method. The quantitative aspects of the method related to variables such as pH of the medium, amount of reductant and operational conditions are studied as a function of absorption sensitivity. The proposed method utilizes only a 50.0 ml portion of the water sample and yields above 90 per cent recoveries for various metals from a single aliquot of the sample. The reported data pertain to the estimation of silver, chromium, copper, iron, lead, mercury, manganese, magnesium, nickel and strontium, reported as averaged over replicate measurements at +-2S confidence level. The precision in individual cases is found to be better than +1.8%. 相似文献