| As important chemical materials and intermediates,light olefins were mainly prepared by petroleum cracking,which are prominent in demand contradictory.China is a country with the energy structure characteristics of rich coal but meager petroleum,it's an essential way to alleviate the shortage of petroleum resources in our country and optimize utilization of coal resources by developing the process route of transformation of syngas to light olefins directly,which is of great research significance.In this paper,Fe-Zn catalysts were mainly studied on a one section fixed bed reactor for the syngas convert to light olefins directly.The catalysts were characterized by TG?BET?XRD?H2-TPR?SEM?CO2-TPD to analyze the pHysicochemical performance of catalysts.And the effects of parameters such as catalyst preparation methods,pretreated temperature,reaction conditions and promoter modification were investigated in detail.The results show that Fe-Zn catalyst made by parallel flow precipitation method by Na2CO3 got the best performance,and the activation was 95.09%and selectivity of C2=C4=reached 53.32%;When the Fe-Zn mole ratio was1:1,the pore structure and catalytic activity were the best;The best pretreat temperature between 300400?,and reaction conditions were respectively330350?,2.0 MPa,20003000 mL/?g·h?,in which the catalyst showed good stability within 100 hours.Addition of supercritical medium has high performance than gas pHase reaction,The conversion of CO reached 99%and the selectivity of C2=C4=reached 57%.Promoters modification for Fe-Zn catalysts found that Na?K were all promote the CO dissociative adsorption,suppress H2 adsorption,restrain the production of CH4,then improved the CO conversion and selectivity of C2=C4=,but K modification effect is better was better;The catalytic activity of Fe-Zn reduced with the increase of Mg but promoted WGS reaction and suppress the light olefins;Promoting with La can slightly improve the selectivity of C2=C4=,but Ce weakened the interaction between Fe-Zn then reduced the catalytic performance;The different forces between Al2O3,SiO2,TiO2 with Fe lead to catalytic properties are not as good as Fe-Zn catalyst. |
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