Al/Ce pillared clays with high surface area and large pore: Synthesis, characterization and supported palladium catalysts for deep oxidation of benzene

Large pore Al/Ce pillared clays (AlCe-PILC) were synthesized and used as supports for Pd catalysts in deep oxidation of low concentration of benzene (130-160 ppm). The supports and catalysts are characterized by X-ray powder diffraction (XRD), N-2 adsorption/desorption, high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX) and temperature-programmed reduction techniques (TPR). The results showed that AlCe-PILC are characterized by basal spacings of 1.79-2.83 nm and have high surface areas of 343.6-377.4 m(2)/g. Catalytic activity tests show that the catalytic activity of Pd catalysts in benzene deep oxidation is greatly dependent on the type of supports. Temperature for the complete benzene conversion using the following catalysts decreases in the order: Pd/Na-mmt (>400 degrees C) > Pd/Al-PILC (340 degrees C) > Pd/AlCe-PILC (<= 300 degrees C). And the effects of hydrothermally treated time and different loading of Ce of Al/Ce pillaring solution on the activity of Pd/AlCe-PILC catalysts were also investigated, results of which show that high mesopore surface area and large pore structures of the supports are the key factors in improving the activity of the Pd/AlCe-PILC catalysts. The temperature for complete oxidation of benzene with Pd/AlCe-PILC (5;30) catalyst was 250 degrees C, exhibiting the highest catalytic activity. (C) 2008 Elsevier B.V. All rights reserved.