Catalytic conversion of benzothiophene over a H-ZSM5 based catalyst

This study reports an attractive route for light diesel fraction desulfurization using a H-ZSM5 zeolite dispersed in a silica–alumina matrix. This catalyst was characterized using standard techniques including: (a) NH3-TPD, (b) N2 adsorption, (c) Particle size distribution, (d) X-ray diffraction, (e) SEM–EDX, and (f) Pyridine FTIR. Characterization results showed that Brønsted acid sites were dominant over Lewis acid sites. In addition, the silica–alumina matrix displayed no contribution to the catalyst total acidity. Catalytic and thermal runs were performed in the CREC Riser Simulator that mimics the industrial FCC unit. This reaction system was operated at close to atmospheric pressure, 350–450 °C temperatures, and 3, 5, 7 s reaction times. Benzothiophene and n-dodecane model compounds were selected to represent the sulfur containing compounds and the diesel cut respectively. Thermal cracking was found to be negligible under the studied reaction conditions. Experimental results from catalytic runs showed a higher benzothiophene conversion over n-dodecane conversion. This was true despite the difference in benzothiphene and n-dodecane molecular sizes. Benzothiophene was mainly removed as coke with a small fraction converted into alkyl-benzothiophenes and no H2S gas produced.