Monitoring of chemical reactions within microreactors using an inverted Raman microscopic spectrometer
Monitoring of chemical reactions within microreactors using an inverted Raman microscopic spectrometer
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DOI：
10.1002/elps.200305532
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发表时间：
2003-09-01
期刊：
影响因子：
2.9
通讯作者：
Zhang, XL
中科院分区：
文献类型：
--
作者：
Fletcher, PDI;Haswell, SJ;Zhang, XL
一个倒置的拉曼显微光谱仪已被用来配置文件的反应物和产品浓度的空间演变的化学反应在流体动力学流量控制下运行的微反应器内。拉曼光谱仪配备有波长为780 nm的激光源、共焦光学器件、全息透射光栅和电荷耦合器件（CCD）检测器。微反应器由蚀刻在0.5mm厚的玻璃底板内的T形通道网络组成，所述玻璃底板热结合到0.5mm厚的玻璃顶板。通道网络的末端连接到试剂储器，所述试剂储器连接到注射器泵，用于通过通道内的流体动力泵送来驱动溶液。微通道为221 μ m宽和73 μ m深。以乙醇和乙酸为原料合成乙酸乙酯为模型体系，研究了微反应器中各反应物和产物的拉曼散射谱带。每个谱带的拉曼光谱强度与每个物质的浓度成比例，因此在校准后可以定量测量所有浓度。通过扫描特定的拉曼频带内的微通道网络中的选定区域在给定的步骤中的X-Y平面，空间分辨的浓度分布，获得稳态流动条件下。在所使用的流动条件下，浓度曲线内的不同位置对应于试剂接触和混合后的不同时间，从而能够观察到产物形成的时间依赖性。拉曼显微术为UV/维斯吸光度和荧光方法提供了有用的补充技术，用于原位监测和分析在UV中具有太远而不能使用的最低S-0-S-1吸收带的化学反应物质，因为它们可能与来自其他反应物、产物和溶剂分子的带重叠。
An inverted Raman microscope spectrometer has been used to profile the spatial evolution of reactant and product concentrations for a chemical reaction within a microreactor operating under hydrodynamic flow control. The Raman spectrometer was equipped with a laser source at wavelength of 780 nm, confocal optics, a holographic transmission grating, and a charge-coupled device (CCD) detector. The microreactor consisted of a T-shaped channel network etched within a 0.5 mm thick glass bottom plate that was thermally bonded to a 0.5 mm thick glass top plate. The ends of the channel network were connected to reagent reservoirs that were linked to a syringe pump for driving the solutions by hydrodynamic pumping within the channels. The microchannels were 221 mum wide and 73 mum deep. The synthesis of ethyl acetate from ethanol and acetic acid was investigated as a model system within the microreactor as Raman scattering bands for each reactant and product species were clearly resolved. Raman spectral intensities of each band were proportional to concentration for each species and hence all concentrations could be quantitatively measured after calibration. By scanning specific Raman bands within a selected area in the microchannel network at given steps in the X-Y plane, spatially resolved concentration profiles were obtained under steady-state flow conditions. Under the flow conditions used, different positions within the concentration profile correspond to different times after contact and mixing of the reagents, thereby enabling one to observe the time dependence of the product formation. Raman microscopy provides a useful complementary technique to UV/VIS absorbance and fluorescence methods for the in situ monitoring and analysis of chemical reaction species having their lowest S-0-S-1 absorption bands too far in the UV to be of use, due to their probable overlap with the bands from other reactant, product and solvent molecules.