Effects of Adding Cobalt and Potassium to MoS₂-based Catalysts on Mixed Alcohol Synthesis

Abstract

Several unsupported and supported molybdenum-based catalysts were prepared by precipitation and impregnation, and characterized by N2 adsorption, XRD, H2-TPR, and XPS. The catalytic activity for alcohol synthesis was evaluated using a fixed-bed pressurized flow reaction system under the following conditions: 250-350 , 5.0 MPa, GHSV of 5000 h -1, and H2/CO ratio of 1.0. Addition of Co to the unsupported MoS2-bulk catalyst enhanced the selectivity for C2 alcohols and total alcohols, and reduced the selectivity for hydrocarbons. Addition of K to Co04MoS improved the selectivity for total alcohols and suppressed the formation of hydrocarbons, increased the selectivity for methanol and CO2, and decreased carbon-chain growth. The alumina-supported catalyst was the most favorable for Fischer-Tropsch synthesis but was unfavorable for C2 alcohol synthesis. The silica-supported catalyst was more favorable for C2 alcohol synthesis than the unsupported catalyst.

Effect of TiO2 Coating on Morphology of Active Phase on Sulfided CoMo/Al2O3 Hydrotreating Catalysts

“…The second peak is attributed to the reduction of TiMoS, when the third one of the CoMoTi catalyst is attributed to reduction of CoMoS and MoS 2 . These results are in good agreement with previous reports. ,− Thus, the amount of H 2 used plays a factor in indirect measurement of quantity of these active phase formations. The finding that the area of the latter peaks of catalysts with TiO 2 added were bigger than CoMoAl reveals that a large amount of CoMoS (and TiMoS, MoS 2 ) was present.…”

Nanosheet-structured K–Co–MoS2 catalyst for the higher alcohol synthesis from syngas: Synthesis and activation

“…The Co-Mo-S phase is suggested to be the active site for CO non-dissociative/dissociative adsorption, non-dissociative CO insertion, carbon chain growth and thus favorable for the alcohol formation. While the Co 9 S 8 phase which promotes CO and H 2 dissociative adsorption is involved in the formation of by-product hydrocarbons and inactive for the alcohol synthesis [6][7][8] . The composition of the two phases strongly depends on the preparation methods [9] .…”

“…The composition of the two phases strongly depends on the preparation methods [9] . The common methods for the preparation of alkali modified Co-MoS 2 catalysts include impregnation/coprecipitation methods, reverse microemulsion technique and mechano-chemical activation and so on [6,10,11] . Taking the impregnation as an example, the as-prepared Co-MoS 2 catalyst mainly contained the Co-Mo-S phase if the Co/Mo atomic ratio less than 0.4.…”