钾掺杂对Fe/GO催化合成气制α-烯烃的影响

Effect of potassium on GO-modified large Fe_(3)O_(4)microspheres for the production ofα-olefins

铁基催化剂在费托合成反应中对高附加值α-烯烃具有高选择性,然而,催化剂容易由于碳沉积而失活,并且高CO_(2)选择性明显降低了合成气的碳利用效率。为此,本文开发了一种简单有效的铁基催化剂制备方法来解决这一问题。具体地说,采用水热法制备了平均粒径约580 nm Fe_(3)O_(4)微球,并将其与GO在溶液中超声混合,离心、干燥后即得到Fe/GO催化剂。GO引入能使大的Fe_(3)O_(4)微球在反应过程中逐渐演变成小尺寸碳化铁纳米粒子(约9.1 nm),有效地抑制了催化剂的烧结和积炭。催化剂显示了优异的活性、稳定性和高α-烯烃选择性。表征结果表明,K加入到Fe_(3)O_(4)微球中,催化剂在演变过程中形成了更高的ε′-Fe2.2C含量(约为58.9%),有利于显著降低CO_(2)选择性。

Despite that iron-based catalysts are preferred for the high selectivity to value-addedα-olefins via Fischer-Tropsch synthesis(FTS)reaction,the carbon deposition leads to deactivate catalyst more readily and CO_(2)selectivity as high as~50%leads to low carbon efficiency.Herein,we developed an innovative approach to fabricate iron-based catalysts to deal with this issue.In detail,Fe_(3)O_(4)microspheres with an average particle size of~580 nm were prepared via hydrothermal method and mixed with GO.The GO modification can effectively inhibit the sintering and coking of the large Fe_(3)O_(4)microspheres(580 nm)by assisting its evolution into much smaller iron carbide nanocapsules(~9.1 nm).The obtained catalyst exhibits excellent reaction activity,stability and highα-olefin selectivity.The addition of K into Fe_(3)O_(4)microsphere produces majorε′-Fe2.2C about 58.9%in the evolution process and facilitates lower CO_(2)emission obviously.