单相Co2C的制备及其费-托合成催化性能研究

Synthesis and catalytic performance of single phase Co_2C catalyst for Fischer-Tropsch synthesis

采用CO与金属钴在温度280℃,压力2 MPa的条件下反应48 h后制备得到单相Co_2C催化剂。通过XRD、H2-TPR、TEM和XAS对催化剂的结构和组成进行表征并考察了单相Co_2C催化剂在费-托合成反应中的稳定性与催化性能。结果表明,随着费-托合成反应的进行,Co_2C催化剂的活性缓慢上升,同时伴随着产物中甲烷的选择性逐渐降低,C5+的选择性逐渐升高。对比反应前后催化剂发现,反应后的催化剂为Co_2C和少量金属Co的混合相,表明在费-托合成反应条件下,单相Co_2C会发生部分分解,生成的金属Co会导致CO的转化率和产物的选择性发生变化。

Single phase Co 2C catalysts were prepared by carburizing Co with CO at 280℃and 2 MPa for 48 h.X-ray diffraction(XRD),transmission electron microscopy(TEM),H 2 temperature-programmed reduction(H 2-TPR),and X-ray absorption spectroscopy(XAS)were carried out to explore the structure and composition of the prepared Co 2C samples.The Co 2C catalysts were also evaluated in the Fischer-Tropsch synthesis to study their stability and catalytic performance.It was interesting to observe that the CO conversion and the selectivity for C 5+products gradually increased,but the selectivity to methane decreased during the reaction.Comparing the fresh catalysts with used catalysts,it was easy to find that the used catalysts were the mixture of metallic Co and Co 2C.The newly generated metallic Co may lead to the changes of CO conversion and product selectivity during the reaction.