共查询到18条相似文献,搜索用时 78 毫秒
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微波是一种能量传递方式。与传统电加热相比,微波加热具有加热速度快、热惯性小、选择性加热等特点,因而被视为一种优质的能量来源。微波催化是一种使用微波对反应系统供能,从而推动催化反应进行的化学过程。近年来,许多研究者致力于探索和发展微波催化技术,包括利用微波技术提升化学反应速率、开发具有出色微波吸收能力的催化剂、建立节能环保的微波催化系统等。本文首先介绍了微波的相关理论,讲述了材料对微波的吸收原理;然后从微波催化降解挥发性有机物(Volatile Organic Compounds, VOCs)、微波催化污水处理、微波催化生物质热解和微波催化碳氢化合物转化等方面综述了微波催化在能源环境中的应用;最后对微波催化过程的机理展开了讨论。 相似文献
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辛仁轩 《中国无机分析化学》2013,3(1):1-10
微波等离子体光源是一类重要的有较强激发能力的原子发射光谱光源,主要包括微波感生等离子体光源,电容耦合微波等离子体光源及微波等离子体炬光源。本文是微波等离子体光谱技术发展的第二部分,主要介绍了电容耦合微波等离子体光源及微波等离子体炬光源的结构原理和性能。并对它们的技术特点和进展进行评述。 相似文献
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以微波为热源处理放射性废物的相关技术和装备的研究,在国外已经达到较高水平,在我国的相关研究较少。微波加热即物料在微波场中吸收消耗微波能量,并转化为热能用于物料温度升高。对于物料的处理效果主要与微波的有效输出功率有关。参考Schillman法测定了包括放射性废物微波处理装置的微波炉的有效输出功率,且经验证测定结果准确。微波有效输出功率的确定将对放射性废物微波处理工艺的研究打下基础。 相似文献
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《理化检验(化学分册)》2012,(7):861
近日上海新仪微波化学科技有限公司向市场推出了两款微波消解仪和微波合成仪。这两款产品代表了微波化学界新的发展方向,其中MASTER超高通量微波消解/萃取仪可以兼容70罐、40罐、18 相似文献
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研究了微波萃取烟草中游离氨基酸和微波水解烟草蛋白质的样品前处理方法,对微波萃取和微波水解条件进行了优化。微波萃取后的游离氨基酸及微波水解后的氨基酸总量采用氨基酸分析仪测定,蛋白质中的氨基酸用差减法计算。微波萃取氨基酸的最佳条件为:盐酸浓度0.05 mol·L-1,物料比1∶20,微波萃取温度50℃,微波萃取时间10 min,该条件下得到的游离氨基酸萃取率与超声30 min的结果基本一致;微波水解蛋白质的最佳条件为:盐酸浓度6 mol·L-1,物料比1∶100,水解温度140℃,水解时间60 min,与传统水解24 h的结果基本一致。用微波辅助法萃取烟草中的游离氨基酸及水解烟草蛋白质,样品前处理时间大大缩短,分析结果令人满意。 相似文献
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采用单因素实验与正交实验法结合,以提取剂浓度、固液比、微波功率、微波提取时间为考察因素,以熊果酸提取率作为评价指标,优化了熊果酸的微波提取工艺。最优微波提取条件为:90 % 乙醇作为提取剂、料液比1∶20 g/mL、微波功率250 W、微波提取时间120 s。 相似文献
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A series of five known asymmetric organocatalytic reactions was re-evaluated at elevated temperatures applying both microwave dielectric heating and conventional thermal heating in order to probe the existence of specific or nonthermal microwave effects. All transformations were conducted in a dedicated reactor setup that allowed accurate internal reaction temperature measurements using fiber-optic probes. In addition, the concept of simultaneous external cooling while irradiating with microwave power was also applied in all of the studied cases. This method allows a higher level of microwave power to be administered to the reaction mixture and, therefore, enhances any potential microwave effects while continuously removing heat. For all of the five studied (S)-proline-catalyzed asymmetric Mannich- and aldol-type reactions, the observed rate enhancements were a consequence of the increased temperatures attained by microwave dielectric heating and were not related to the presence of the microwave field. In all cases, in contrast to previous literature reports, the results obtained either with microwave irradiation or with microwave irradiation with simultaneous cooling could be reproduced by conventional heating at the same reaction temperature and time in an oil bath. No evidence for specific or nonthermal microwave effects was obtained. 相似文献
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微波在有机合成化学中的应用及进展 总被引:31,自引:4,他引:27
简述了微波有机合成的机理和特点,介绍了近年来微波辐射技术在有机合成中的应用,展望了微波促进有机合成化学的发展方向。参考文献30篇。 相似文献
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The impact of microwave drying and binders (copolyvidone and povidone) on the degradation of acetylsalicylic acid (ASA) and physical properties of granules were compared with conventional drying methods. Moist granules containing ASA were prepared using a high shear granulator and dried with hot air oven, fluid bed or microwave (static or dynamic bed) dryers. Percent ASA degradation, size and size distribution, friability and flow properties of the granules were determined. Granules dried with the dynamic bed microwave dryer showed the least amount of ASA degradation, followed by fluid bed dryer, static bed microwave oven and hot air oven. The use of microwave drying with a static granular bed adversely affected ASA degradation and drying capability. Dynamic bed microwave dryer had the highest drying capability followed by fluid bed, static bed microwave dryer and conventional hot air oven. The intensity of microwave did not affect ASA degradation, size distribution, friability and flow properties of the granules. Mixing/agitating of granules during drying affected the granular physical properties studied. Copolyvidone resulted in lower amount of granular residual moisture content and ASA degradation on storage than povidone, especially for static bed microwave drying. In conclusion, microwave drying technology has been shown to be a promising alternative for drying granules containing a moisture-sensitive drug. 相似文献
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微波辐射无皂乳液聚合制备聚氰基丙烯酸正丁酯微球 总被引:3,自引:0,他引:3
在微波辐射的"非致热效应"作用下,采用不含乳化剂的无皂乳液聚合,制备了聚氰基丙烯酸正丁酯(PBCA)微球。通过透射电子显微镜观察了微球的形态结构,利用激光光散射粒度测定仪测定了微球的粒径大小及其分布,探讨了柠檬酸浓度、氰基丙烯酸正丁酯(BCA)用量、微波辐射功率等对微球粒径的影响。研究结果表明,与常规无皂乳液聚合相比较,微波作用下的无皂乳液聚合反应时间缩短,得到的PBCA微球粒径更小,分散性更好。柠檬酸浓度增加,PBCA微球粒径逐渐增大;单体浓度增加,或微波功率增加,PBCA微球的粒径先减小后增大。当柠檬酸质量分数为0.005%、BCA体积分数为1.0%、微波功率为600W时,所制得的微球粒径最小,为200nm左右。 相似文献
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微波-炭还原法处理一氧化氮的研究 总被引:16,自引:0,他引:16
报道了一种不需要催化剂而直接采用微波-炭还原技术处理-氧化氮(NO)的新方法.讨论了气体流量、反应温度、微波功率和施加微波时间对活性炭与一氧化氮发生还原反应的影响.比较了连续施加微波和间歇式施加微波方式下一氧化氮与活性炭发生化学反应转化为无公害的氮气(N2)和二氧化碳(CO2)的效率.研究结果表明,微波功率和反应器的类型及升温速率对一氧化氮与活性炭反应效率的影响较大.在连续施加微波时,一氧化氮与活性炭反应率可达98%以上.此外,还对一氧化氮与活性炭反应后的产物进行了表征. 相似文献
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Panzarella B Tompsett GA Yngvesson KS Conner WC 《The journal of physical chemistry. B》2007,111(44):12657-12667
The enhancement of synthesis reactions under microwave heating is dependent on many complex factors. We investigated the importance of several reaction engineering parameters relevant to microwave synthesis. Of interest to this investigation were the reaction vessel size, volume of precursor reacted, microwave power delivery, and microwave cavity design. The syntheses of NaY zeolite and beta-zeolite were carried out under a number of varying conditions to determine the influence of these parameters on the nucleation rate, the crystallization rate, and the particle size and morphology. The rates of NaY and beta-zeolite nucleation and crystallization were more rapid in the multimode CEM MARS-5 oven compared to the more uniform field CEM Discover. The faster synthesis rate in the MARS-5 may be the result of the multimode microwave electric field distribution. Slower rates of NaY and beta-zeolite formation observed in the Discover and a circular waveguide may be the result of a more uniform microwave electric field distribution. Changes in reaction vessel size and precursor volume during the microwave synthesis of beta- and NaY zeolite were found to influence the rate of zeolite formation. These results indicate that reactor geometry needs to be considered in the design of systems used for microwave synthesis. Comparative synthesis reactions were carried out with conventional heating, and microwave heating was shown to be up to over an order of magnitude faster for most of these syntheses. 相似文献