自然科学版
陕西师范大学学报(自然科学版)
合成气定向催化转化科学与技术专题
pH操作窗口影响沉淀铁催化剂费托合成性能的研究
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武鹏
(北京低碳清洁能源研究院, 北京 102211)
武鹏,女,高级工程师,主要研究方向为工业催化剂。E-mail: wupeng@nicenergy.com
摘要:
以Na2CO3为沉淀剂,在pH值介于6~8的条件下,采用并流沉淀法制备了费托(F-T)合成沉淀铁Fe-Cu-K-SiO2催化剂。利用X射线衍射(XRD)、N2吸附/脱附、氢气程序升温还原(H2-TPR)及穆斯堡尔谱(MES)对催化剂的晶型结构、晶粒尺寸、孔结构、还原性能及碳化程度进行了表征,并在工业测试条件下考察了沉淀铁制备pH值对其催化费托合成反应性能的影响。结果表明,该操作窗口内pH值的变化对催化剂物化性能影响显著,提高沉淀pH值所制催化剂的晶粒增大,比表面积降低,从而增加了其还原和碳化的难度,使得相应催化剂的CO转化率和CH4选择性降低,而CO2和C5+选择性增加。将MES表征结果与催化性能关联,发现CO转化率与Fe5C2相密切相关,而CO2的选择性主要与Fe3O4相相关。
关键词:
沉淀铁催化剂;费托合成;pH值;晶粒;活性相
收稿日期:
2018-10-20
中图分类号:
TP391.42
文献标识码:
A
文章编号:
1672-4291(2019)01-0022-07
基金项目:
国家重点研发计划(2017YFB0602500)
Doi:
Effect of pH on the catalytic properties of precipitated iron for Fischer-Tropsch synthesis
WU Peng
(National Institute of Clean-and-Low-Carbon Energy, Beijing 102211, China)
Abstract:
A serial of Fischer-Tropsch synthesis catalysts (Fe-Cu-K-SiO2) was prepared by the co-precipitation method with varied pH of 6~8. The properties of the catalysts, i.e. crystal phase, particle size, pore structure, reducibility and carburization, were studied by XRD, N2 adsorption, H2-TPR, and Mssbauer spectroscopy. The catalysts were evaluated for Fischer-Tropsch synthesis under typical industrial conditions. The results indicate that the increase of pH values increases the particle size and decreases the surface area, which inhibit the reduction and carburization of the catalysts. As a result, a lower CO conversion and a lower selectivity of CH4 but a higher selectivity of CO2 and C5+ products were obtained in Fischer-Tropsch synthesis. By correlating the Mssbauer characterization with catalytic results, the CO conversion is revealed to be dependent on the Fe5C2 phase while CO2 selectivity is related to Fe3O4 phase over the catalyst.
KeyWords:
precipitated iron; Fischer-Tropsch synthesis; pH; particle size; active phase