HDS of dibenzothiophene with CoMoS2 synthesized using elemental sulfur

Abstract

An unsupported cobalt molybdenum sulfide catalyst was prepared using ammonium heptamolybdate, cobalt nitrate and elemental sulfur under reflux in ammonium hydroxide. The crystal structure of the precursor was identified using XRD and was determined to be a mix of CoMoO4 and elemental sulfur. The refluxed samples were decomposed in a tube furnace at 450°C under a constant flow of 10% H2:90% Ar gas mix. The freshly prepared catalyst was characterized using XRD and the LeBail fitting procedure, which confirmed the sample was a biphasic mixture of Co9S8MoS2. The synthesized sample was tested for the hydrodesulfurization of dibenzothiophene at 350°C. The removal of the dibenzothiophene was found to follow pseudo zeroth order reaction with two catalytic rates of 1.63×10−5molL−1·s−1 for the first 3.5h and 6.81×10−5molL−1·s−1 observed in the second 1.5h (or catalytic activities of 24.5 and 9.27molg−1s−1). After 5h of reaction, the catalyst showed approximately 93% conversion of the dibenzothiophene. The primary product of the hydrodesulfurization of the dibenzothiophene was biphenyl, which was approximately 80% of the products, and the minor product was cyclohexylbenzene at approximately 13%.