Catalytic Performance of Fe-Mn Catalyst for Fischer-Tropsch Synthesis II. Performance of Catalyst during Middle and Late Period of Reaction

The effects of reaction conditions on the performance of Fe Mn catalyst for F T synthesis during the middle and late period of the run process have been investigated in an integral fixed bed reactor. Firstly, 900 h stability test for the catalyst shows that the catalyst has relatively high activity and excellent stability, and the CH 4 selectivity apparently increases compared with in the early period. In the late period of the catalyst run for 1?800 h, the effects of reaction pressure and H 2/CO ratio on the catalyst performance have been evaluated and the CH 4 selectivity further increases to some extent. After 2?200 h, the catalyst also has relatively high activity; the selectivity for hydrocarbon products can be apparently improved by decreasing the H 2/CO ratio in feeding gas and increasing the reaction pressure. The conversion of CO and the selectivity for (C = 2～4 +C 5+ ) and CH 4 are 75 6%, 89 0% and 5 7%, respectively, under the conditions of n (H 2) / n (CO) =0 62, GHSV= 2?300 h -1 , p =3 02 MPa and θ =283 ℃. Compared with the middle period of reaction after 900 h under the conditions of n (H 2) / n (CO) =2 07, GHSV= 2?400 h -1 , p =2 30 MPa and θ =283 ℃, the selectivity for (C = 2～4 +C + 5) increases but the selectivity for CH 4 decreases, indicating that the catalyst has very good longevity and promising application in the production of light olefins and high quality liquid fuels.