A Study of Platinum Catalysts Based on Ordered Al–МСМ-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 C8 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°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°C.