Synthesis of pillared bentonite starting from the Al–Fe polymeric precursor in solid state, and its catalytic evaluation in the phenol oxidation reaction

A new methodology for the modification of a bentonite via pillaring was evaluated in this work, employing a mixed Al–Fe polyhydroxocation and clay powder, placing the two solid materials in contact into a dialysis membrane. The modified solids were characterized by X-ray diffraction (XRD) and elemental chemical analysis and their catalytic activity is probed on the phenol oxidation reaction in diluted aqueous phase. The results show that pillared clay with the solid Al–Fe polyhydroxocation has similar properties to the solid modified by the conventional method, which involves the use of a large quantity of water in the synthesis (clay suspension 2% and dilute pillaring solution). The catalytic tests with the modified solids show, in all cases, 100% of phenol conversion after 2 h and total organic carbon (TOC) elimination between 49 and 53%, in 4 h of reaction, results which can be compared with pillared bentonite from diluted suspensions.