1D phenomenological model of Propane Aromatization in a Fluidized Bed Reactor

Samenvatting

In this thesis an one-dimensional phenomenological model of propane aromatization in a fluidized bed reactor with Geldart type A of catalysts is developed for BioBTX. BioBTX is a company, which is working on the investigation toward technologies that enables the conversion of plastic waste into platform chemicals, including aromatics, especially BTX (Benzene, Toluene, and Xylenens). These aromatics are the basis of 40% of all petrochemicals produced worldwide. This process allows the achievement of circularity and sustainability targets, such as CO2 reduction and minimization of the use of fossil resources. BioBTX is in the development phase and is currently working on the pilot plant scale phase. The pilot plant consists out of two reactors, a pyrolysis reactor where the plastic waste is converted toward light alkanes and alkenes, and a fluidized bed reactor where the light alkanes and alkenes are aromatized toward aromatics. In order to gain more insight into the process of the fluidized bed reactor, in this thesis a 1D phenomenological model of propane aromatization in a fluidized bed reactor is developed. The aromatization of light alkanes and alkenes is a complex reaction scheme. For simplifications of the study, propane is used as feed, because it is one of the main products of the pyrolysis reactor. Furthermore, a lumped component reaction scheme is used, where propane reacts toward cracking products, benzene, toluene, xylene, and other products. To conclude what influence the particle properties have on the results of the model, such as bubble size and velocity, phase fractions, conversion of propane, etc. A parametric study of the particle properties is performed by the of a model. Moreover, a process design optimization is performed, to conclude what the ideal height and area of the bed and the gas velocity are. With some adaptions, the model can be used for the design of a demonstration or commercial plant.
From the results of the parametric study of the particle properties, it can be concluded, that the sphericity of the particle has a relatively big influence on the conversion of propane and the yield toward BTX. The lower the sphericity of the particle, the lower the conversion and yield are obtained. Furthermore, the particle size has less influence on the results compared to the sphericity, but have still noticeable influence. A smaller particle size leads to the lower conversion of propane and yield toward BTX. The particle density has a negligible influence on the results compared to the sphericity and particle size.
The \optimal\ fluidized bed reactor design is a trade-off between a high conversion of propane and high yield toward BTX against a large molar product flow of BTX. A low gas velocity and small bed area result in high conversion of propane and high yield toward BTX. However, this results in less molar product flow of BTX. Furthermore, for the \optimal\ process design it is recommended to execute a techno-economic study considering the option of separation of the products and the (re-)use of the byproducts.

Datum prijs	29 sep. 2021
Originele taal	Engels
Begeleider	Morteza Hadian (Afstudeerdocent 1) & Kay A. Buist (Afstudeerdocent 2)