Abstract

The heterogeneous catalysts are pivotal in many industrial processes, ranging from ammonia synthesis to crude oil refinery and petrochemical and polymer production. Catalysts serve as the essential drivers of these processes, significantly enhancing reaction efficiency and enabling the production of crucial chemicals while minimizing energy consumption and environmental impact.

The thesis aims to advance the engineering of catalyst bodies from powder to a few millimeters using extrusion and spray-fluidized bed methods. The catalytic active phases are typically costly and have relatively poor properties to be used directly in the reactors. Microscale engineering leverages the fields of agglomeration, powder technology, and composite engineering to utilize the catalytic active phases at their best, facilitating mass and heat transport and enhancing catalyst stability performance. The microscopic features affect the nanoscopic properties, underscoring the required multiscale approach for catalyst synthesis.

This research integrates experiments, modeling, and simulation to optimize catalyst-shaping processes. Performance metrics extend beyond catalysis activity, including thermal conductivity, mechanical strength, and active phase distribution. A comprehensive analytical framework incorporating statistical, dimensionless, and multivariate analyses, along with multi-characterization techniques, was employed to elucidate the mechanisms governing catalyst particle growth and the impact of process parameters on catalyst characteristics and performance.

The framework was initially developed for packed bed catalyst particles used in hydrogen production via reforming, utilizing extrusion methods to improve crushing strength, thermal conductivity, and catalytic performance. For fluidized bed catalyst particles used in methanol-to-hydrocarbons conversion, a novel bottom spray-fluidized bed approach was developed to address the challenge of fluidizing nanoparticles. Investigations into top spray fluidization revealed the influence of process parameters on particle size distribution, morphology, and zeolite distribution. A model based on population balances was developed to understand the agglomeration process. The study proposed a correlation equation to predict collision efficiency, highlighting the critical role of atomization and viscosity parameters.

This dissertation presents a framework for optimizing catalyst-shaping processes. It analyzes the shaping implications in two catalytic processes (steam reforming and methanol-to-hydrocarbons). It combines studies of different reactor dispositions of the spray (top and bottom) to finalize with a model for the agglomeration process in the most promising disposition (bottom).