还原时合成气H2/CO摩尔比对铁基催化剂浆态床费-托合成反应性能的影响

摘要

在浆态床反应器中,详细考察尾气循环状态下还原时合成气H2/CO摩尔比对SFT418工业铁基费-托合成催化剂还原和反应后的物相以及费-托合成反应性能的影响.结果表明:还原后催化剂的比表面积大幅度下降,平均孔径明显增大,孔体积下降.还原时合成气H2/CO摩尔比影响催化剂的还原程度、费-托合成反应活性和失活速率,在较低H2/CO摩尔比下还原得到的催化剂中铁碳化物含量较高,费-托合成初始反应活性较高,失活速率较大；在较高H2/CO摩尔比下还原得到的催化剂中铁碳化物含量较低,费-托合成初始反应活性较低,但其失活速率比在较低H2/CO摩尔比下还原得到的催化剂低.催化剂还原时适宜的合成气H2/CO摩尔比为20.%The synthesis performance of a spray-dried spherical iron-based F-T catalyst SFT418 reduced with difference H2/CO molar ratio syngases was investigated in a continuous stirred slurry tank reactor and the bulk composition of the catalyst after reaction was characterized by M(o)ssbauer (MES).The results indicate that the BET surface area and the pore volume of the reduced catalyst decrease,while the average pore size is the opposite after reduction.The catalyst is easier to reduce with low H2/CO ratio syngas and has more FexC phase and higher conversion at the start-of-run but faster deactivation rate.Higher H2/CO ratio syngas give the reversive results.It is proven that the most appropriate H2/CO molar ratio of reduction syngas is 20 ∶ 1.