Based CoMo sulphided catalysts supported on hydroxyapatite: Dimethyldisulphide (DMDS) hydrogenolysis

A series of Ca-deficient and Co-containing hydroxyapatite samples, noted A_r and C_x, respectively, where r is the total Ca/P molar ratio (r - 1.46-1.62) and x the Co wt%, were prepared by precipitation in aqueous media. The catalytic activities of CoMo/A_r and Mo/C_x sulphided catalysts have been examined for the S-S bond hydrogenolysis of dimethyldisulphide (DMDS) under relatively mild operating conditions (200°C, 1 atm). The overall activity depends on the Co depositing mode and the hydroxyapatite carrier Ca/P molar ratio. Depositing Co by impregnation on hydroxyapatite samples with low Ca/P molar ratios involves an increase of the catalytic activity until approaching that corresponding to CoMo/Al₂O₃ catalyst. This can be attributed probably to a better dispersion of the CoMo sulphided catalysts on apatitic carrier with low Ca/P molar ratios. DMDS is selectively reduced to CH₃SH on the CoMo/A_1,46 sulphided catalyst than on the CoMo/Al₂O₃ one, even at conversions as higher as 100%.