Conversion and reaction kinetics of coke oven gas over a commercial Fe−Mo/Al₂O₃ catalyst

Abstract

Producing methanol from coke oven gas (COG) is one of the important applications of COG. Removal of sulfur from COG is a key step of this process. Conversion and reaction kinetics over a commercial Fe−Mo/Al₂O₃ catalyst (T-202) were studied in a continuous flow fixed bed reactor under pressures of 1.6−2.8 MPa, space time of 1.32−3.55 s and temperatures of 240−360 °C. Though the COG contains about 0.6 mol/mol H₂, hydrogenation of CO and CO₂ is not significant on this catalyst. The conversions of unsaturated hydrocarbons depend on their molecular structures. Diolefins and alkynes can be completely hydrogenated even at relatively low temperature and pressure. Olefins, in contrast, can only be progressively hydrogenated with increasing temperature and pressure. The hydrodesulfurization (HDS) of CS₂ on this catalyst is easy. Complete conversion of CS₂ was observed in the whole range of the conditions used in this work. The original COS in the COG can also be easily converted to a low level. However, its complete HDS is difficult due to the relatively high concentration of CO in the COG and due to the limitation of thermodynamics. H₂S can react with unsaturated hydrocarbons to form ethyl mercaptan and thiophene, which are then progressively hydrodesulfurized with increasing temperature and pressure. Based on the experimental observations, reaction kinetic models for the conversion of ethylene and sulfur-containing compounds were proposed; the values of the parameters in the models were obtained by regression of the experimental data.

Keywords

coke oven gas / conversion / Fe−Mo/Al₂O₃ catalyst / sulfur-containing compound / kinetics

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