共查询到20条相似文献,搜索用时 15 毫秒
1.
将可见光催化、不对称合成、分子氧氧化和连续化集成,创新性地用玻璃微通道反应器实现可见光活化分子氧氧化的β-酮酸酯类化合物的不对称α-羟基化反应的连续工艺。用金鸡纳碱衍生的相转移有机催化剂在气-液-液多相体系内实现可见光催化,分子氧不对称氧化连续反应。在心形微通道反应器内,1-茚酮-2-甲酸金刚酯底物完全氧化为(S)-2-羟基-1-茚酮-2-甲酸金刚酯,产物收率95%,对映选择性87.0%。与间歇反应相比,采用微反应器的连续反应在保持产物高立体选择性基础上将30 min反应停留时间缩短至1.08 min。该方法具有快速、低能耗、连续、高效等优势,具有良好的工业化前景。 相似文献
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The reaction of allyl alcohol using zeolite Y as catalyst has been investigated and it is shown that it can be converted into a range of products, including hydrocarbons, acrolein and diallyl ether. Control of product selectivity can be achieved by careful selection and manipulation of the charge balancing cation, a series of catalysts can be prepared which, for the conversion of allyl alcohol, lead almost exclusively to the initial formation of either (a) C2-C6 hydrocarbons and coke (H-NaY), (b) acrolein (H-CsY), (c) propene (Li-NaY) or (d) diallyl ether (Cs-NaY). The effects of addition of H2 and H2O to the reactant are described and discussed with respect to the reaction mechanism and the reaction of potential intermediates (2-propanol and propene oxide) is also described. Mechanisms of formation of the major products are proposed that involve the concerted action of Brønsted acid and basic sites within the zeolite. In particular, since the addition of H2O does not affect the product distribution, it is considered that the mechanism of hydrocarbon formation does not involve the allyl cation as an intermediate. 相似文献
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丙烯氧气氧化制环氧丙烷工艺开发进展 总被引:4,自引:0,他引:4
以分子氧为氧源的丙烯环氧化反应是近年来发展起来的一种清洁型环氧丙烷合成技术。综述了丙烯氧气氧化工艺的开发背景、开发进展及其经济性。丙烯与O2氧化工艺以及丙烯与O2、H2氧化工艺因反应过程和反应机理不同而采用相异的催化剂和工艺条件,虽然丙烯氧气氧化工艺存在产率低、生产成本高的缺点,但作为具有最佳原子经济性和较低投资费用的新工艺路线,具有工业化应用前景。 相似文献
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Measurement of rates of formation of acrolein and acetaldehyde in the partial oxidation of propylene over a copper molybdate catalyst were made under steady-state and transient modes. These measurements disclosed a rate of product formation multiplicity apparently attributable to the oxidation state of the catalyst and not to surface phenomena usually thought to be the source of hysteresis in catalytic systems. 相似文献
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In this review the state-of-the-art of catalytic processes known today for selective epoxidations using aqueous H2O2 as the oxidant is presented. Recent achievements from our laboratories on the development of catalysts for epoxidations with H2O2 are given as well. For all systems their viability for application in green catalytic processes is evaluated, based on selectivity of the reaction, turnover frequency, substrate scope and solvent needed. 相似文献
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Selective reduction of nitric oxide by methane on H-form zeolite catalysts in oxygen-rich atmosphere
Katsunori Yogo Michiaki Umeno Hirotake Watanabe Eiichi Kikuchi 《Catalysis Letters》1993,19(2-3):131-135
Selective reduction of NO by CH4 in the presence of excess oxygen was investigated using H-form zeolite catalysts. H-ZSM-5, H-ferrierite, and H-mordenite showed high catalytic activity and selectivity. On the contrary, H-USY and Al2O3 were not effective for this reaction. Both NO-CH4 and O2-CH4 reaction hardly proceeded on H-ZSM-5. Higher NOx conversion was obtained in the NO2-O2-CH4 and NO2-CH4 systems than in the NO-O2-CH4 system under high GHSV condition. It seemed that NO2 plays an important role for selective reduction of NO by CH4 on H-form zeolites. 相似文献
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Using statistical design procedures an initial-rate study of the oxidation of propylene over a silica-supported bismuth molybdate catalyst was carried out using a differential-bed reactor over the following range of conditions: temperatures from 350 to 390°C, oxygen and propylene concentrations from 1.0 to 8.0 mmol/L. Among the models considered a Redox Steady-State Model (with half-order oxygen concentration) involving oxygen adsorption and reaction with propylene from the gas phase was found to provide the best fit to the data. 相似文献
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A sequential design strategy was used to direct an experimental kinetic study of propylene oxidation over bismuth molybdate. Two statistical criteria were used to design experiments. The first is a joint criterion for the dual problem of model discrimination and parameter estimation which was proposed by Hill et al. (1968), but which to the best of our knowledge has not been tested in an experimental program. Using this joint criterion design, it was demonstrated that both the objectives of model discrimination and precise parameter estimation were effectively accomplished. After model discrimination had been achieved, a design strategy for further improvement in parameter precision was found, as expected, to be effective for that purpose. 相似文献
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以脱脂棉为模板制备了多孔管状结构的Al2O3材料,用不同浓度的氢溴酸对多孔管状结构的Al2O3材料进行化学剪裁,制备了活性量可控,比表面积可调,不同形貌的负载型催化剂Al2O3-AlBr x。采用电场发射扫描电镜(SEM)和X射线衍射仪(XRD)对催化剂进行了表征。结果表明,该催化剂较好地复制了棉纤维的宏观和微观结构,呈现出明显的生物形貌特征。在光照条件下以空气为氧化剂的醇的选择性氧化反应中,发现催化剂Al2O3-AlBr x-3可以高选择性地将醇氧化为相应的醛、酮或酸,并对反应机理进行了探讨。该催化剂循环使用3次仍保持较高的催化活性。 相似文献
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Xingfa Zhou Renjie Deng Yingdi Zhang Xulong Wang Fangruo Zeng Yao Tian Huajie Liu 《加拿大化工杂志》2023,101(7):4118-4127
In this paper, we reported the preparation, characterization, and catalytic performance of TiO2 doped with Mn for the selective oxidation of toluene to benzyl alcohol and benzaldehyde without any solvent. The structure of the catalyst was determined by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption–desorption analysis (Brunauer–Emmet–Teller [BET]), scanning electron microscope (SEM), transmission electron microscope (TEM), and mapping. The results demonstrated that the catalytic properties of Mn-TiO2 were higher than those of pure Mn3O4 and TiO2. The effects of reaction temperature, reaction time, oxygen pressure, and the amount of catalyst were studied. Under the optimal conditions, Mn-TiO2 could afford 6.4% toluene conversion at a combined benzyl alcohol/benzaldehyde selectivity of 58.6%. Moreover, the catalyst can be repeated in the experiment for five times without significant loss of activity. 相似文献
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Catalytic ethane oxidation, with O2, using H-ZSM-5 and H-mordenite containing different discrete types of isolated Cu(II) cations was studied. An ESR spectroscopic study was carried out on copper ion coordination in zeolites. It was shown that the intrinsic activity of Cu(II) ion depends strongly on the Cu2+-site local topography. Covalent-bonded Cu(II) cations in the most coordinatively unsaturated square-planar coordination in H-ZSM-5 demonstrated the highest activity in C2H6 complete oxidation. 相似文献
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V-MCM-41催化环己烯环氧化性能 总被引:1,自引:0,他引:1
采用水热法合成了V-MCM-41,并用ICP-AES、FTIR、DRS-UV-Vis、XRD、BET等技术对其进行了表征,发现只有部分V进入分子筛,所合成的V-MCM-41具有较高的结晶度,并且其结晶度随晶化液中V/Si摩尔比的增大而升高。V-MCM-41催化环己烯/H2O2氧化反应结果表明,当V-MCM-41中V含量大于1.10%(摩尔分数)时,骨架V-O-V物种在催化环己烯氧化反应的同时,也可加速H2O2的分解;乙腈是该反应体系的最佳溶剂,最佳反应温度为70℃。最佳反应结果表明,环己烯的单程转化率和H2O2有效利用率可分别达到23.91%和95.4%。 相似文献
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合成了3种不同晶粒尺寸的ZSM-5分子筛,并制得MTP催化剂,对ZSM-5分子筛催化剂在MTP反应中的性能进行系统研究。采用XRD、SEM、N2物理吸附和TGA等对ZSM-5分子筛催化剂进行表征,发现小晶粒的ZSM-5分子筛具有良好的抗积炭性能,在MTP反应中具有较高的稳定性。采用小晶粒分子筛制成的催化剂,考察反应工艺条件对催化剂催化性能的影响,结果表明,丙烯选择性随反应温度和空速提高而增加,降低反应压力和提高水醇质量比也有利于提高丙烯选择性,为调整MTP工艺的产物分布和优化反应工艺条件提供了技术依据。 相似文献
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Chaohui He Rajamani Krishna Yang Chen Jiangfeng Yang Jinping Li Libo Li 《中国化学工程学报》2021,37(9):217-221
The removal of trace propyne (C3H4) from propyne/propylene (C3H4/C3H6) mixtures is a technical and challenging task during the production of polymer-grade propylene in view of their very similar size and physical properties.While some progress has been made,it is still very challenging to use some highly stable and commercially available porous materials via an energy-efficient adsorptive separation process.Herein,we report the ultrafine tuning of the pore apertures in type-A zeolites for the highly effi-cient removal of trace amounts of C3H4 from C3H4/C3H6 mixtures.The resulting ion-exchanged zeolite 5A exhibits a large C3H4 adsorption capacity (2.3 mmol g-1 under 10-4 MPa) and high C3H4/C3H6 selectivity at room temperature,which were mainly attributed to the ultrafine-tuned pore size that selectively blocks C3H6 molecules,while maintaining the strong adsorption of C3H4 at low pressure region.High pur-ity of C3H6 (>99.9999%) can be directly obtained on this material under ambient conditions,as demon-strated by the experimental breakthrough curves obtained for both 1/99 and 0.1/99.9 (V/V) C3H4/C3H6 mixtures. 相似文献
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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