通过Na和K等碱金属溶液对ZSM-5载体进行离子交换改性，采用等体积浸渍法制备合成气制低碳烯烃铁基催化剂，采用N₂吸附-脱附、SEM、XRD、TPR等测试手段对催化剂进行表征。在固定床催化反应装置中考察了铁基催化剂在纯氢气氛围中预还原4 h后，在325℃、1.5 MPa、气体空速为1 200 h^-1、V（H₂）：V（CO）=2：1条件下进行合成气制低碳烯烃的催化性能研究。结果表明，改性后载体孔径变大，加速原料气在催化剂的内部扩散，产物烯烃可及时析出，避免二次反应生成烷烃，提高了CO的转化率和烯烃的选择性。通过碱金属对ZSM-5的改性，合成气的转化率可提高30%~40%，转化率与碱金属活性成正比。此外，催化剂的催化活性随KOH溶液浓度的增加先增加后降低，当KOH溶液浓度为0.1 mol/L时，CO+H₂的转化率和烯烃的选择性均最高，分别为81.84%和49.67%。

ZSM-5 carriers are modified by NaOH,KOH and KNO₃ solutions,respectively via ion-exchange.A series of iron-based catalysts for synthesis of light olefins from syngas are then prepared by equal volume impregnation method using modified ZSM-5 as carrier.The prepared catalysts are characterized by BET,SEM,XRD,TPR,etc.and their catalytic performances are evaluated through a fixed bed reactor.The iron-based catalysts have been pre-reduced in a pure hydrogen atmosphere for 4 h,and are then used to catalyze the conversion of syngas to light olefins at T=325℃,P=1.5 MPa,GHSV=1,200 h^-1 and V(H₂)/V(CO)=2.The experimental results show that the pore size of the carrier becomes larger after modification,which can accelerate the diffusion of feed gas in the catalyst and the product olefins can be released in time to avoid secondary reaction to form an alkane.Both the conversion of CO and the selectivity of olefins are improved.The conversion rate of syngas can be increased by 30%-40% due to the modification of ZSM-5 by alkali metal compounds,and is strongly related to the activation and alkalinity of alkali ions.In addition,it is found that the catalytic activity of the catalyst varies with the increase of KOH concentration.The best conversion of CO+H₂ and selectivity of olefins can be obtained over the catalyst with ZSM-5 carrier that is modified by 0.1 mol·L^-1 of KOH solution,which are 81.84% and 49.67%,respectively.