Alumina binder effects on the hydrothermal stability of shaped zeolite-based catalyst bodies

Abstract

The development of shaped zeolite-based catalyst bodies with high performance for the production of fuels and chemicals requires the addition of binder materials. Thus, alumina binder effects and their impact on the hydrothermal stability are crucial for shaped catalyst bodies and their catalytic performance in the methanol-to-hydrocarbon (MTH) reaction. Here, a side-by-side comparison of zeolite powder and zeolite-alumina catalyst extrudates is made to elucidate the effect of the extrusion process and/or the hydrothermal treatments in combination with the binder effects. Characterization of the acidic properties was carried out with Fourier-transform infrared (FT-IR) spectroscopy to understand the role of the binder material. It was found that the alumina binder increases the Lewis acidity, while it protects the zeolite material from dealumination during the hydrothermal treatments. Testing of the samples, before and after steaming, showed that the extrusion and steaming lead to a more stable and selective catalyst material, while altering the physicochemical properties of the alumina binder plays a crucial role in achieving the optimal ethylene-to-propylene ratio. Operando UV-vis diffuse reflectance spectroscopy (DRS) revealed the higher formation of conjugated polyaromatic species for the technical catalyst bodies. This study illustrates the impact of the extrusion process and the binder material in combination with the hydrothermal treatments and the major effect of the binder properties on the physicochemical properties and the product distribution.