Use of SiO2 - TiO2 Nanocomposite as Photocatalyst for the Removal of Trichlorophenol: A Kinetic Study and Numerical Evaluation

A series of silica-titania nanocomposite materials with different silica–titania ratios was prepared in presence of a novel ethoxylated sulphanilamide of molecular weight 1053 by the sol-gel method. Several characterisation techniques were adopted such as thermal analysis (differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA)), N2-adsorption-desorption, X-ray diffraction (XRD), Fourier transform infrared (FTIR), and transmission electron microscopy (TEM) connected with energy dispersive spectroscopy (EDS). The surface acidity was investigated by pyridine adsorption using FTIR spectroscopy. The photocatalytic activity and the adsorptive ability of the composites were evaluated based on the photodegradation of 2, 4, 6- trichlorophenol (TCP) under UV irradiation with a wavelength of 254 nm. The maximum TCP adsorption onto the composites was measured in darkness. The results showed that there was no adsorption of TCP on pure SiO2. The 10% TiO2-SiO2 catalyst showed the highest rate of TCP removal among the synthesised composites. The removal % reached to 87 % after 90 min irradiation time. This activity was caused by the large surface area and pore volume as well as the formation of a mesoporous structure, as evidenced from the pore size distribution curve. Finally, the numerical evaluation of the photodegradation of TCP was conducted. Keywords: Nanocomposite, Ethoxylated sulphanilamide, Photocatalytic degradation, UV irradiation, 2,4,6-TCP, Numerical evaluation

Characterization and catalytic activity of NiO/mesoporous aluminosilicate AlSBA-15 in conversion of some hydrocarbons

Mesoporous aluminosilicate AlSBA-15 was synthesized and adopted as a support for NiO with 3, 6 and 9 wt.% loadings. Characterization of various samples was performed through XRD, FTIR, DSC-TGA, TPR, SEM and TEM techniques. Textural and morphological characteristics were examined using N2 adsorption–desorption isotherms. Catalytic activities were measured in cumene cracking for parent AlSBA-15 and in n-hexane and toluene cracking and cyclohexane dehydrogenation for supported NiO samples. Uniformity of the ordered 2D-hexagonal structure of AlSBA-15 was evident even after loading with NiO. NiO and NiOOH phases could be detected particularly in the sample containing 9 wt.% NiO. TPR profile of solid loaded with 3 wt.% NiO sample showed negative peaks at 400 and 600 °C, related to hydrogen spillover on reduced sample. Selectivity towards n-hexane and toluene cracking increased with both temperature and metal oxide loading, achieving 100% at 350 °C. In cyclohexane dehydrogenation, the sample loaded with 3 wt.% NiO was the most active and selective one towards benzene formation

Optimization of silica content in alumina-silica nanocomposites to achieve high catalytic dehydrogenation activity of supported Pt catalyst

The present work aims at obtaining a suitable and selective catalyst for catalytic dehydrogenation reactions through designing pore structures of silica-containing alumina nanocomposites by optimizing silica content in the structure. In this trend, series of silica-containing alumina nanocomposites with different molar ratios Al2O3/SiO2 were prepared by the solvothermal method. According to surface characterization of silica-containing alumina nanocomposites, the sample with the highest molar ratio of Al2O3/SiO2 (2.06) showed mesoporous structure with selective pore sizes of 3.7 and 4.6 nm. In addition, it had a high surface area value of 308 m2/g. Furthermore, SEM and TEM images of the same sample showed ultra fine sized particles in the nano size (7–17 nm). Dehydrogenation catalysts, as developed structures, were then achieved by loading 0.6 wt.% platinum metal over the prepared nanocomposites. Performances of the prepared nanocatalysts were investigated via the dehydrogenation of a model compound namely; cyclohexane. Experimental results showed that the Pt catalyst supported on the silica-containing alumina nanocomposites with the highest molar ratio of Al2O3/SiO2, is an efficient and selective catalyst toward the dehydrogenation reaction. This was revealed in terms of 100% selectivity of this catalyst toward the conversion of cyclohexane at all ranges of temperatures with the conversion reaction being temperature dependent. Practically, the total conversion of cyclohexane increased with increasing reaction temperature and reached 100% at 450 °C while the prepared catalyst demonstrated absolute selectivity