Catalytic cracking of polypropylene using aluminosilicate catalysts

• Polypropylene (PP) cracking was studied over acid-solid porous catalysts.
• Both meso- and micro-porous catalysts provided a PP conversion value of >80%.
• Final products were mainly C7–C8 hydrocarbons, n-butane, C5+ and propene.
• Microporous H-MCM-22 zeolite produced mainly gases (n-butane, C5+ and propene).
• Mesoporous H-Al-SBA-15 gave mainly liquid C7–C8 hydrocarbons.

The microporous and mesoporous structured aluminosilicate materials MCM-22 and SBA-15, respectively, were successfully synthesized by hydrothermal treatment and then modified to H-Al derivatives. All prepared catalysts were investigated for their physicochemical features, including the surface area, pore volume and acidity, using powder X-ray diffraction, N2 adsorption-desorption, 27Al NMR spectroscopy, temperature programmed desorption of ammonia and scanning electron microscopy. The derived catalysts were then utilized for the catalytic cracking of polypropylene (PP) in a batch reactor at atmospheric pressure, 350–400 °C for 30 min with a catalyst loading of 10 wt% (of the PP mass) and a nitrogen flow of 20 mL min−1. Under these conditions, the PP conversion value was over 97% and 80% for the acid H-Al-SBA-15 and H-MCM-22 catalysts, respectively. For the mesoporous H-Al-SBA-15 catalyst, the major product was a liquid fraction (mostly low temperature distillate oil), such as C7–C8 hydrocarbons, with a boiling point similar to that of gasoline. With the microporous H-MCM-22 catalyst, the main products were gases that principally consisted of n-butane, C5+ hydrocarbons and propene.

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