عنوان مقاله [English]
In this study trimetallic Ni-Mo-W/alumina catalysts with different percentages of tungsten were synthesized by a hybrid method of ultrasound-precipitation. Synthesized catalysts were characterized by XRD, BET, FTIR, FESEM and EDX and then were evaluated in hydrodesulfurization of thiophene. Thiophene removal in trimetallic Ni-Mo-W/alumina catalysts reached to 89.23% while was 66.72% for bimetallic similar catalyst. Among different tungsten contents the highest thiophene removal and butane/butene ratio was attributed to the catalyst with 6% wt. tungsten. This catalyst showed small nano crystallites of metal oxides with uniform morphology with average size of 13 nm. The post characterization tests confirmed the stability in crystals of catalyst but some changes in morphology and functional groups were observed. Moreover the effect of residence time and thiophene concentration on the activity and selectivity of the trimetallic catalyst with 6% wt. tungsten was studied and the results showed with increasing the reaction time and reducing thiophene concentration, activity of the catalyst enhanced.