Cobalt Molybdenum Catalyst Sulfurization Reaction

cobalt molybdenum catalyst image

Cobalt molybdenum catalyst sulfurization reaction can help to improve catalyst shift activity and improve the efficiency of the catalyst. It can use H2S gas for sulfurization and also can use CS2 for sulfurization under hydrogen atmosphere.

Using hydrogen sulfide for sulfurization the temperature should can be lower which is about 150-250 ℃, sulfurization reaction equations are as follows: MoO3 + 2H2S + H2 + MoS2 + 3H2O + 48.15KJ / mol (1) CoO + H2S CoS + H2O + 13.40KJ / mol (2). The reaction belongs to the exothermic reaction, so it is necessary to control the bed temperature. If the temperature is too high, there is reduction reaction occurred to reduce cobalt molybdenum catalyst activity, so H2S concentration should not be too high.

Using water gas for sulfurization there are some reaction will occur: CO + H2O CO2 + 41.17KJ / mol (3), CO + 3H2CH4 + H2O + 206.2KJ / mol (4). In order to reduce the heat which produces in reaction as much as possible should avoid these two reactions, especially the reaction (4). Generally catalyst transforms into sulfurization state is good for reaction (3) is advantageous, but the catalyst at oxidation state and at higher pressure is good for reaction (4), so we can through  control the temperature to avoid the reaction happen.

Using synthesis gas for sulfurization, in order to meet the requirements of the synthesis gas H2S content can add a certain amount of sulfur in the mill to improve the synthesis gas H2S content to 2500 ~ 6000ppm and water gas systems should control at 0.4MPa. In addition, during the sulfurization process should to strictly control the total amount of nitrogen gas flow and water flow in 8000 ~ 10000Nm3 / h, in order to prevent system overpressure to cause nitrogen can not enter the system, causing the bed overtemperature. At the initial stage of sulfurization the nitrogen gas and water volume ratio is 3: 1. At the later period of sulfurization according to bed temperature can gradually increase water gas flow and reduce nitrogen flow. When outlet gas sulfide solubility increase indicated the sulfurization reaction finished.

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