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单光束红外光谱技术(原位傅立叶透射变换红外、原位漫反射红外和衰减全反射红外光谱技术)虽然已经用于气固相多相催化反应的原位表征中,但这些光谱在真实反应条件下会受到气体分子振动光谱和加热条件下产生的发射光谱的严重影响,不能实时获得催化剂表面的真实信息.另外,由于在真实的气固相多相催化反应过程中,催化剂本底的信息会随着反应时间的延长而发生变化,因此单光束红外光谱技术在扣除本底信息方面存在误差.为了实现在反应条件下,实时、原位表征催化剂表面的状态,我们报道了一种双光束红外光谱表征技术.该技术包括双光束红外光谱系统及双光束红外反应池.其特征在于:实时双光束原位红外光谱系统由两台完全相同的红外光谱仪和双光束红外反应池组成.双光束红外反应池由完全相同的样品池和参考池连接而成,样品池和参考池处于同一水平线上分别对应于样品光谱仪和参考光谱仪,由计算机同步控制两台红外光谱仪,排除实时状态下的气体分子振动光谱干扰和加热条件下产生的发射光谱干扰.该技术可以对真实反应条件下的气固相多相催化反应进行实时原位表征.通过应用程序的关联可以实时、同步采集样品光束和背景光束谱图来得到催化剂表面物种随反应时间变化的真实信息.该技术克服了单光束红外光谱在原位多相催化反应表征方面的缺陷,使表征结果变得更加精确可靠.该技术还可以在变化的气相组分条件下,获得不同温度下、实时的催化剂表面活性中心、活性相和中间物种的信息.采用上述双光束红外光谱仪对丁烯在纳米HZSM-5催化剂上芳构化反应过程进行了实时、原位观测,首次在实际反应条件下,观察到了异丁烯在纳米HZSM-5沸石的表面Br?nsted酸中心上经历吸附、活化、聚合、环化等反应步骤生成芳烃的过程.
Although single-beam infrared spectroscopy (in-situ Fourier transform infrared, in-situ diffuse infrared and attenuated total reflectance infrared spectroscopy) has been used in the in-situ characterization of heterogeneous catalytic reactions in gas-solid phase, these spectra under the true reaction conditions Will be subject to gas molecular vibrational spectroscopy and heating conditions produced by the emission spectrum of serious influence, not real-time access to the catalyst surface of the real information.In addition, due to the real gas-solid heterogeneous catalytic reaction process, the catalyst background information As the reaction time changes, the single-beam infrared spectroscopy has the error of subtracting the background information.In order to realize the real-time and in-situ characterization of the catalyst surface under the reaction conditions, we report a two-beam infrared The technology includes the two-beam infrared spectroscopy system and the double-beam infrared reaction cell, and is characterized in that: the real-time two-beam in-situ infrared spectroscopy system consists of two identical infrared spectrometers and a double-beam infrared reaction cell; The reaction cell is composed of exactly the same sample cell and reference cell connected, the sample cell and the reference cell in The same horizontal line corresponds to the sample spectrometer and the reference spectrometer respectively, and the two infrared spectrometers controlled by the computer synchronously eliminate the gas molecular vibrational spectroscopy interference under real-time conditions and the emission spectrum interference generated under the heating conditions. This technique can be used under real reaction conditions Real-time in-situ characterization of gas-solid phase heterogeneous catalysis The real-time and simultaneous acquisition of sample beam and background beam spectra by real-time correlation of application programs can be used to obtain real information on the change of catalyst surface species with reaction time.This technology overcomes single beam infrared The defect of the spectrum in the characterization of in situ heterogeneous catalysis can make the characterization result more accurate and reliable.The technique can also obtain the real-time catalyst surface active center and active phase under different gas phase conditions The information of the intermediate species was obtained.Using the above two-beam infrared spectrometer, the aromatization reaction of butene on the nano-HZSM-5 catalyst was observed in situ and in situ for the first time under the actual reaction conditions. The surface Brönsted acid undergoes adsorption, activation, polymerization on the center of the ring And other reaction steps to generate aromatics process.