Structure and catalytic activity of highly ordered AlMCM-48 materials with different Si/Al ratios on the degradation of high-density polyethylene

Abstract

Catalysts of AlMCM-48 with different Si/Al molar rations were synthesized by modified hydrothermal method with respect to previous works. As a consequence, the materials showed different porous structures making them of high adsorption capacities and high efficiency to high-density polyethylene (HDPE). Samples synthesized with various Si/Al molar ratios were characterized by X-ray diffraction (XRD), nitrogen adsorption at – 196 °C, scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared (FTIR) and dispersive energy X-ray spectrometry (EDX). Characterization results suggested the presence of tetrahedral Al species on AlMCM-48(x), giving highly ordered materials that exhibit thermal stability. It is important to highlight that the use pseudoboehmite as a promising Al source for the synthesis of this type of molecular sieves, leading to materials with slight morphological differences due to the formation of interconnected particles spherical. The catalytic performance showed that the high-density polyethylene (HDPE) degradation reaction occurs in complex reaction steps in the heating rates 5, 10 and 20 °C min−1. The pore diameters of the catalysts influence the degradation process under non-isothermal condition. Furthermore, on the conditions studied, the AlMCM-48(x) catalysts exhibited high conversion values and play important roles in the decrease of HDPE degradation temperature, potentially leading to an efficient process in terms of energy expenditure.