Conversion Of Syngas To Higher Alcohols Over Cu-Co&Co-Ga Based Catalysts

Facing the increasingly serious energy and environmental problems,higher alcohols synthesis?HAS?from syngas possess broad application prospects.This article focuses mainly on exploring the catalytic performance of Cu-Co and Co-Ga based catalyst for HAS from syngas.Cu-Co/Al₂O₃ was prepared by using a layered double hydroxide as the precursor and used for HAS from syngas in slurry reactor.It showed high selectivity to ethanol and the mass fraction of ethanol in total alcohols kept above 70 wt.%in the 750 hours running.The NPs of Cu-Co alloy supported on Al₂O₃ were obtained after reduction.Cu-Co alloy would decompose into Cu and Co NPs after reaction for 100 h.After reaction for 300 h,Co₂C started to generate and core-shell structure of Cu@Co@Co₂C supported on Al₂O₃ matrix was formed as reacted for 500 h.Then,during 500 to 750 h,metallic cobalt was transformed to Co₂C and Co₂C protected cobalt from losing and copper nanoparticles from sintering for the Cu@Co@Co₂C composite.In the whole reaction,the high selectivity to ethanol is mainly owing to the synergistic effect of Cu-Co alloy,Cu and Co nanoparticles in close contact and Co₂C in contact with Co.Meanwhile,the slurry solvent PEG-400 as the liquid phase medium favors the synthesis of ethanol from the syngas and avoids C-chain growth.However,the phase separation,the sintering of active metals and Co losing accelerated the rate of catalyst deactivation.Using the citrate complexation method preparing the Co-Ga based catalysts,which use the perovskite-type oxides as the catalyst precursors for HAS.The best catalyst of Co/La₂O₃-La₄Ga₂O₉ derived from the reduction of LaCo_0.65Ga_0.35O₃,which exhibited high selectivity to alcohol.It mainly was attributed to the syngeneic effect between Co nanoparticles and La₂O₃-doped La₄Ga₂O₉ support.The conversion of CO is 13%,the selectivity to alcohols is 45%and the mass fraction of C₂₊OH in total alcohols is 72wt.%?ethanol is above 50%?at 310oC,3 MPa and GHSV of 3900 m L?gcat h?^-1after reaction 200 h.La₂O₃-doped La₄Ga₂O₉ as a support showed excellent thermodynamics stability.As the La₄Ga₂O₉ as the first time as support to used for HAS,further study of the promoting effect of the La₄Ga₂O₉ component is going on in our laboratory.