Synthesis and characterization of aluminum and Al/REE pillared clays and supported palladium catalysts for benzene oxidation

Volatile organic compounds (VOCs) are considered as a major pollutant in indoor and outdoor air. More stringent environmental regulations have been implemented in order to reduce the VOC emissions. One of the techniques available for destructive removal of VOCs is catalytic oxidation. In the present work, Al/Rare Earths (REE: Y, Ce, La, Pr and Nd) pillared clays (PILCs) were used to support 0.2 wt.% of palladium for the complete oxidation of low concentration of benzene. The supports and catalysts were characterized by XRD, N-2 adsorption/desorption, FTIR spectroscopy, HRTEM and H-2-TPR techniques. The results indicated that after Al and Al/REE pillaring, the basal spacing, S-BET, A(mic) and V-mic of Al and AlREE-PILC had a considerable increase compared with those of Na-mmt. Activity tests of deep oxidation of benzene showed that the catalytic activity of Pd catalysts supported on Al and AlREE-PILC were much higher than that on initial clays, which was due to the fact that optimized structure of PILCs, such as large basal spacing, high S-BET and porosity, improved Pd dispersion and increased the active sites of Pd. Especially for Pd/AlCe-PILC, the temperature of complete oxidation was about 280 degrees C, exhibiting the highest catalytic activity.