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The synthesis and characterization of aluminum loaded SBA-type materials as catalyst for polypropylene degradation reaction

The performance of pure and aluminum containing SBA-type catalysts prepared using different aluminum sources and different Al/Si ratios were investigated in the polypropylene degradation reaction using a thermogravimetric analyzer. For the synthesis of catalysts, aluminum isopropoxide and aluminum sulphate were used as the aluminum sources. Synthesized materials had high surface areas and exhibited nitrogen adsorption isotherms of type IV. EDS results showed that the aluminum incorporation into the structure was very effective. Al-27 MAS NMR spectra of the catalysts exhibited tetrahedrally and octahedrally coordinated aluminum species in the structure. TEM images of synthesized catalysts showed well-ordered hexagonal arrays of uniform mesopores with cylindrical channels. With the aluminum loading, DRIFTS analysis of the pyridine adsorbed materials revealed the existence of Bronsted acid sites in the synthesized catalysts in addition to Lewis acid sites. Thermogravimetric analysis results showed a marked reduction in the degradation temperature in the presence of aluminum containing SBA-type catalysts. The activation energy value of the degradation reaction decreased to about 51-70 kJ/mole in the presence of catalysts synthesized using aluminum sulphate as the aluminum source and when aluminum isopropoxide was used as the aluminum source activation energy value of the reaction decreased to 82-89 kJ/mol.