Catalytic degradation of polyethylene by Al-MCM-41: Comparison of post-synthetic metal grafting and direct sol-gel synthesis methods

The pyrolysis characteristics of high-density polyethylene (HDPE) were investigated over Al-MCM-41 catalysts synthesized through post-synthetic grafting (Al-MCM-41-P) and direct sol-gel (Al-MCM-41-D) methods. To estimate the activation energy of the catalytic decomposition reaction, thermogravimetric analysis was carried out under static conditions. Lower activation energies for the catalytic decomposition reaction of HDPE were observed when Al-MCM-41-P was applied. The higher catalytic activity of Al-MCM-41-P seems to be due to the easier accessibility to active sites and smaller pore diameters. However, both incorporation methods of Al into MCM-41 provided similar pyrolysis products. Al-MCM-41-P would be more competitive in the pyrolysis of HDPE because of its higher catalytic activity relative to that of Al-MCM-41-D.