The Synthesis of Al-SBA-16 Materials with a Novel Method and Their Catalytic Application on Hydrogenation for FCC Diesel

摘要

A series of aluminum modified Al-SBA-16 rnaterials with different Si and Al molar ratios (50, 40, 30, 20, and 10) were successfully synthesized through a two-step preparation method using aluminum isopropoxide as Al source. Meanwhile, the corresponding catalysts were prepared by impregnating Ni and Mo active metals on the as-synthesized samples. The hydrogenation performances of the obtained catalysts were tested under the same conditions in a fixed-bed microreactor by using FCC diesel as feedstock. Furthermore; the hydrogenation reaction conditions over the NiMo/AS-20 (Al-SBA-16 with a Si/Al ratio of 20) catalyst were studied and optimized. The as-synthesized materials and their corresponding NiMo catalysts were characterized by N-2 adsorption and desorption, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectrecopy, Al-27 MAS NMR, UV-vis diffuse reflectance spectroscopy, temperature programmed, reduction, Pyridine Fourier transform infrared spectroscopy, and Raman spectra. It was found that Al-SBA-16 materials with highly ordered structures were successfully prepared through the above method. The catalysts evaluation results exhibited that, as the Si/Al ratio reached 20, NiMo/AS-20 presented the highest hydrodesulfurization and hydrodenitrogenation of 97.0% and 96.1%, respectively. The main reasons were ascribed to that the support of AS-20 possessed the relatively excellent textural properties; NiMo/AS-20 possessed the highest Mo(Oh) distribution and weakest interaction between the AS-20 support and NiMo active metal species, which would lead to a high hydrogenation activity. The NiMo/AS-20 catalyst presented better acidity properties comparing with other NiMo/Al-SBA-16 catalysts. In addition, the evaluation result displayed that the hydrogenation performance had a trend to increase with the value of H-2 pressure, temperature, H-2/oil, and residence time.