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

Abstract

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 Al 2 O 3 /SiO 2 were prepared by the solvothermal method. According to surface characterization of silica-containing alumina nanocomposites, the sample with the highest molar ratio of Al 2 O 3 /SiO 2 (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 m 2 /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 Al 2 O 3 /SiO 2 , 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. ª 2014 Production and hosting by Elsevier B.V. on behalf of Egyptian Petroleum Research Institute.

Hydroprocessing of Oleic Acid for Production of Jet-Fuel Range Hydrocarbons over Cu and FeCu Catalysts

“…The XRD patterns of the silica-alumina-supported catalysts and its support are shown in Figure 1. The 23° diffraction peak on the diffuse XRD pattern of silica alumina support coincides with the literature [16][17][18][19][20] and the broadness of the peaks shows the material is amorphous. The two peaks at 36° and 43° diffraction angles are ascribed to copper (I) oxide [21].…”

Preparation of Silica-Alumina Nanoparticles via Blast-Furnace Slag Dissolution in Low-Concentration Acetic Acid for Carbonation

“…The XRD pattern of the Si-Al nanoparticles exhibits a single broad amorphous peak. The center of this broad peak is positioned at a lower angle compared to that of BFS; at around 24 • this peak is at a similar position to that previously reported for silica-alumina nanocomposites [20]. …”

Hydrodeoxygenation of Propylphenols on a Niobia‐Supported Platinum Catalyst: Ortho, Meta, Para Isomerism, Reaction Conditions, and Phase Equilibria

“…As for the dehydrogenation of cyclohexanes, it is favored on Pt catalysts, in atmospheric pressure, and at temperatures above 300 °C. [ 52–55 ] Thus, the low propylcyclohexane dehydrogenation observed in this work was likely due to the high H 2 pressure used in the experiment. The observed deoxygenated byproducts can be explained as being formed mostly from propylbenzene.…”