Abstract
Platinum decorated alumina particles have the potential of being a highly (cost-)effective catalyst. The particles are synthesized from platinum(II) acetylacetonate dissolved in a mixture of isopropanol and acetic acid with dispersed alumina carriers. The process is simulated by means of large eddy simulation with reaction kinetics and aerosol dynamics modeling. A two mixture fraction approach for tabulated chemistry with a thickened flame model is used to consider the complex reaction kinetics of the solvent spray combustion. Diffusion is described followings Ficks law with a unity Lewis number for the gas phase species, whereas the particle diffusion coefficients are calculated according to the kinetic theory. An extended model for aerosol dynamics, capable of predicting deposition rate and surface particle growth, is derived from the classical sectional technique. The simulations are compared and validated with product particle characteristics obtained from the experimental observations. Distributions for different locations within the simulation domain show the evolution of particle sizes deposited on the alumina particle surface, and transmission electron microscopy (TEM) images of the composite particles are shown in comparison to 3D particles ballistically reconstructed from simulation data. The ratio of deposited platinum on the alumina carrier particles and the mean diameters of the deposited particles are in good agreement with the experimental observation. Overall, the new method has demonstrated to be suitable for simulating the particle decoration process.
Highlights
Platinum powders play an integral role as the catalyst for processes in the automotive, chemical and pharmaceutical industry
The present paper describes the simulation of platinum particle synthesis and their subsequent deposition on alumina carrier particles; it is structured as follows: The section presents the experiment, the synthesis setup and the employed characterization methods followed by the the models and numerical methods as a central topic of this work
The code is optimized for large eddy simulations and has been proven to perform well in massively parallel computational fluid dynamics (CFD)
Summary
Platinum powders play an integral role as the catalyst for processes in the automotive, chemical and pharmaceutical industry. Rittler et al [10] showed an LES with tabulated chemistry approach, coupled with the monodisperse moment method model to predict the spray-flame synthesis of silica nanoparticles. This approach was used for the assessment of the newly developed SpraySyn Burner [4]. Abdelsamie et al [11] presented a direct numerical simulation (DNS) of the SpraySyn burner, but without modeling the particle dynamics It should, be stressed that even with LES, closure modeling of nanoparticle synthesis is in its early development, and that more sophisticated models will be needed in the future. The results, experiment and simulation of the synthesis process are discussed in Section 4, while the details on verification and validation of the proposed simulation strategy are discussed in the Appendix A
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