Preparation Of Cufemn Catalysts And Its Application In Syngas Conversion

Syngas conversion is an important industrial reaction,which plays an important role in relieving energy pressure and improving energy structure.Low carbon olefin,which is an important product of syngas conversion,is a basic chemical raw material and is widely used.Therefore,synthesis gas conversion to low carbon olefin has important application value.In this paper,a series of CuFeMn catalysts were prepared for characterization and performance comparison,aiming at obtaining catalysts with high low carbon olefin selectivity and low methane selectivity.Meanwhile,try to limit the activity of the water gas shift reaction（WGS）and reduce CO₂ selectivity as much as possible.The preparation process of CuFeMn catalyst was investigated.Cu Fe-based catalysts under different preparation conditions can be obtained by changing preparation conditions,such as preparation method,type and concentration of precipitator and adding proportion of each active component.By means of scanning electron microscopy（SEM）,energy-dispersion X-ray spectroscopy and surface element distribution（EDS-Mapping）and X-ray diffraction（XRD）and the test data in the fixed-bed evaluation device,It is found that the catalyst prepared by coprecipitation method with 2 mol/L（NH₄）₂CO₃ as precipitator and active component Cu:Fe:Mn=0.4:2:1 has small particle size,low crystallinity,high dispersion,and uniform distribution of active components,showing good performance in the reaction.When the reaction temperature is 280℃,the reaction pressure is 2.0 MPa,H₂/CO=2,and the space speed is 10000 m Lg_cat^-1h^-1,the CO conversion rate is 25.7%,the methane selectivity is only 10.7%,the C_2-4 olefin selectivity is 40.2%,the C_2-4 enane ratio is 5.1,and the CO₂ selectivity is 30.6%.The activation conditions and reaction conditions of catalyst were also investigated.The investigation of reduction process includes activation atmosphere,activation temperature,activation strategy and activation pressure,and the investigation of reaction process includes reaction temperature,reaction pressure and reaction space velocity.The results of systematic investigation show that the optimum activation and reaction conditions of the prepared catalyst are pure hydrogen,atmospheric pressure,activated at 320℃for 2hours,then activated at 350℃for one hour,and then reacted at 270℃,2.0 MPa,10000m Lg_cat^-1h^-1.Under this condition,the catalyst can run stably for 72 h,which shows the good stability and good application prospect.