Efficient conversion of light paraffinic naphtha to aromatics over metal-modified Mo/MFI catalysts

The transformation of light naphtha to value-added aromatic compounds is gaining momentum in the petrochemical industry. In this work, a series of metal modified Mo–M/MFI catalysts (M = Fe, Ce, Pt, Ga, and Zn) were synthesized by wet co-impregnation method. Aromatization of light paraffinic naphtha was investigated using modified Mo–M/MFI catalysts at a temperature of 550 °C, atmospheric pressure, and WHSV of 0.81 h⁻¹. Compared to the parent MFI catalyst, the modified bimetallic Mo–Ga/MFI and Mo–Zn/MFI catalysts significantly improved catalytic performance with excellent selectivity (62 wt%) for BTEX (benzene, toluene, ethylbenzene and xylenes) along with 5.4 to 0.6 wt% of C9+ aromatics and ratio of toluene/benzene 0.5 and 0.6, respectively. The higher selectivity to aromatic is attributable to two important factors, the acidity of zeolites and the improved dehydrogenation activity of Mo and the M-modifier. These species effectively transform light naphtha to olefins and then to aromatics by secondary reactions (e.g. isomerization, cracking, dimerization etc.). The modified Mo–Zn/MFI bimetallic catalyst exhibited good stability and selectivity to aromatics with lower ratio of toluene/benzene i.e. ~ 0.6.