A Study of Platinum Catalysts Based on Ordered Al-\MC\M-41 Aluminosilicate and Natural Halloysite Nanotubes in Xylene Isomerization

Hierarchical composite materials based on ordered aluminosilicates of the Al-MCM-41 type and halloysite nanotubes (HNTs) with different Al-MCM-41/halloysite weight ratios have been synthesized and studied as components of supports of platinum catalysts for the isomerization of the C-8 aromatic fraction of reforming. At each synthesis stage, the materials have been characterized by transmission electron microscopy (TEM), low-temperature nitrogen adsorption, X-ray fluorescence analysis, X-ray diffraction (XRD) analysis, and temperature-programmed desorption of ammonia (NH3-TPD). Catalyst systems with an Al-MCM-41/HNT weight ratio of 90 : 10 wt % have shown the highest efficiency in xylene isomerization providing a higher conversion of ethylbenzene and m-xylene than the conversion provided by the HNT-based catalyst. It has been found that the synthesized catalysts exhibit a higher selectivity for the target product of the process-p-xylene-than the selectivity of a commercial counterpart in a temperature range of 360-440 degrees C. The maximum p-xylene selectivity (70%) has been achieved in the presence of a Pt/Al-MCM-41/HNT(90 : 10)/Al2O3 catalyst at 360 degrees C.