Process design of ultrasonic spray pyrolysis synthesis of RuO2/TiO2 nanoparticles for catalytic applications

工业氯化过程产生大量的副产品，远远超过市场的吸收能力，导致有毒废物处理问题。在目前的工艺中，氯是在氧化过程中从氯化氢中回收的，其中使用的是钛电极，电极上涂有一层钛、Ru和/或其他贵金属的混合氧化物。在DFG-SPP计划的框架内，本研究的主要目标是开发具有先进性能的RuO2/TiO2型纳米催化剂的新工艺设计。使用超声喷雾热解USP，从前驱体溶液的气溶胶液滴一步即可得到金红石结构。由于CuO、CoO、NiO等过渡金属氧化物纳米粒子的制备更为简单，且可能成为高效的纳米粒子，因此将被作为新的替代物进行研究。以二氧化钛为催化剂载体，硝酸铝和氯化铝为原料合成氧化铝。超声形成的气溶胶中的平均液滴大小主要取决于溶液的性质(粘度、表面张力、浓度、密度、流变性)以及超声波频率。为了更好地控制液滴形态和最终粉末特性，将特别针对纳米颗粒的合成设计所研究的工艺。与传统工艺相比，USP合成纳米结构颗粒是一种全新的方法，可以更好地控制液滴形态和最终粉末。一个相应的理论模型：一滴对一纳米颗粒可以有效地预测纳米颗粒的分布，考虑到前体的不同特性，这种现有的想法将得到改进。使用激光衍射测量产生的气溶胶将允许原位预测最终的纳米颗粒尺寸。

Industrial chlorine processes produce large amounts of by-product, much more than the market can absorb, resulting in a toxic-waste disposal problem. In current processes chlorine is recovered from HCl in oxidation processes, where titanium electrodes coated with a layer of mixed oxides of titanium, ruthenium and/or other noble metals are used. The main target of this study in the frame of the DFG-SPP Program is to develop novel process designs for RuO2/TiO2 nanocatalysts with advanced properties. The rutile structure shall be reached in one step from aerosol droplets of a precursor solu-tion using the ultrasonic spray pyrolysis USP. Because of more simple preparation and possible high effectivity nanoparticles of transition metal oxide such as CuO, CoO, NiO will be investigated as new alternatives. Instead TiO2 as catalyst carrier the synthesis of Al2O3 from aluminium nitrate and alumin-ium chloride will be performed. The average droplet size in an aerosol formed ultrasonically depends mostly on the solution properties (viscosity, surface tension, concentration, density, rheology) as well as the ultrasound frequency. For a better control of droplet morphology and final powder properties the investigated process will be especially designed with respect to the synthesis of nanosized particles. In contrast to conventional processes, the synthesis of nanostructured particles by USP is a com-pletely new approach that offers better control of droplet morphology and final powder. A correspond-ing theoretical model: one droplet to one nanoparticle shall allow for efficient prediction of nanoparticle distribution, such existing ideas will be improved considering different characteristics of precursor. Us-ing a laser diffraction measurement of produced aerosol will allow in situ prediction of the final nanoparticle size.