Effect of phosphoric acid on catalytic combustion of trichloroethylene over Pt/P-MCM-41 Original Research Article

Pt-loaded MCM-41 catalysts modified with phosphorus acids at various Si/P ratios were prepared. Phosphoric acid molecules may react with surface Si–OH groups, which prevented the direct attack of H2PtCl4 on mesostructure and improved the structural stability of Pt-loaded catalysts. Ammonia temperature-programmed desorption (NH3-TPD) indicated that P-MCM-41 samples possessed weak Brønsted acidities, and the Brønsted acidities on P-MCM-41 decreased with the incorporation of Pt, depending on the phosphoric acid loading. The interaction of Pt with phosphoric species resulted in the change of Pt oxidation state and the Brønsted acidity strength. The results of catalytic combustion of trichloroethylene over these catalysts showed that the modification with phosphoric acid endowed the catalysts with good catalytic performance of high trichloroethylene conversion and absence of tetrachloroethylene. The combination of Brønsted acidities and oxidation state Pt would propose a novel catalytic material suitable for the combustion of chlorinated volatile organic compounds. Carbon deposit over acid sites resulted in the deactivation of Pt/P-MCM-41 catalysts, and the deactivated catalysts were recovered at 500 °C in air.