A microcrystalline, aluminum-rich industrial HZSM-5 zeolite (Si/Al = 12) was impregnated with phosphoric acid including washing with hot water and different pre- and post-synthetic steps to realize phosphate distribution and fixation. The impact of the multi-step treatments on the durability in the conversion of ethanol and the combustion of coke by air was investigated and correlated with the diffusion limitations of phosphates, hydrocarbon species and coke combustion inside micropores. By aid of a theses-based approach good phosphate distribution and fixation, ethanol conversion performance and regenerability is achieved by preliminary pore-cleaning by leaching and posterior thermal fixation to avoid diffusion restrictions. This important boundary condition for phosphate impregnation on aluminum-rich, microcrystalline HZSM-5 was correlated with solid-state characterization (physisorption, TGA, XRD, TRAD), deactivation and model-based product formation behaviour.