In Situ Measurement of Submicron Particles During Synthesis from Gaseous Precursors

表征气溶胶反应器内的粒径分布、浓度和温度对于正确理解和控制该过程至关重要。第一阶段的研究展示了一种新的傅里叶变换红外（FT-IR）发射/透射（E/T）技术，以解决上述合成TiO颗粒的问题。TiO粒子在小于1000/cm的波数处有很强的吸收，因此测量到的消光与粒子质量成正比。相比之下，1000/cm以上的消光是由散射引起的，并且是粒径分布的强烈函数。利用Mie理论，可以对消光光谱进行反卷积，估计几何平均直径在实际值的10%以内。除了颗粒质量和大小，E/T FT-IR还可以同时测量颗粒温度以及气体浓度和温度。该二期项目将开发一种用于亚微米级颗粒在线原位分析的仪器。本研究将(1)改进FT-IR和程序，以优化传输和发射数据的获取；(2)改进和扩展与测量透射光谱有关的理论；(3)通过将红外反褶积与其他粒度测定技术进行比较，评估仪器和分析软件。(4)在一个商业化的TiO2生产设备上对仪器和软件进行现场测试。该提案结合了三个关键组织的专业知识：(1)先进燃料研究公司提供其广泛的FT-IR技术知识；(2) Hemant Pendse教授（美国缅因大学）是衰减谱中粒径分布反褶积的专家；(3)辛辛那提大学的Sotiris Pratsinis教授将评估FT-IR结果，并将其与传统的粒度测定技术进行比较。上述仪器将进行气溶胶的尺寸测量，以及测量颗粒质量，颗粒温度，气体成分和气体温度。该仪器将是坚固耐用，用户友好，便携，相对便宜。该仪器的应用包括催化剂载体、烧结陶瓷、金属颗粒、光学材料和电子材料的合成。

Characterizing the particle size distribution, concentration, and temperature within an aerosol reactor is essential to the proper understanding and control of the process. Phase I research has demonstrated a novel Fourier transform infrared (FT-IR) emission/transmission (E/T) techniques to address the above problems for the synthesis of TiO particles. TiO particles strongly absorb at wavenumbers less than 1000/cm, and thus the measured extinction is directly proportional to the particle mass. In contrast, extinction above 1000/cm is due to scattering and is a strong function of the particle size distribution. Using Mie theory, one can deconvolute extinction spectra to estimate the geometric mean diameter within 10% of its actual value. In addition to particle mass and size, E/T FT-IR can also simultaneously measure particle temperature as well as gas concentrations and temperature. This Phase II project will develop an instrument for on-line in- situ analysis of submicron sized particles. This research will (1) develop improvements to the FT-IR and procedures to optimize the acquisition of transmission and emission data, (2) improve and extend the theory relating measured transmission spectra to particle size, (3) evaluate the instrument and analysis software by comparing the IR deconvolution to other particle sizing techniques, and (4) field test the instrument and software on a commercial TiO2 production facility. This proposal combines the expertise of three key organizations: (1) Advanced Fuel Research provides its extensive knowledge of FT-IR technology; (2) Prof. Hemant Pendse (University of Maine) is an expert in the deconvolution of particle size distributions from attenuation spectra; and (3) Prof. Sotiris Pratsinis (University of Cincinnati) will evaluate the FT-IR results and compare them to conventional particle sizing techniques. The above instrument will perform size measurements of aerosols as well as measuring particle mass, particle temperature, gas composition, and gas temperature. The instrument will be rugged, user friendly, portable, and relatively inexpensive. The applications for such an instrument include the synthesis of catalyst supports, sinterable ceramics, metal particles, optical materials, and electronic materials.