聚苯胺衍生碳材料负载的Fe基合成气直接制低碳烯烃催化剂：载体碳化温度的影响

doi:10.11949/j.issn.0438-1157.20170996

摘要/Abstract

摘要：

低碳烯烃是重要的基础化工原料，广泛应用于中间体和聚合物的生产。开发非石油路线的合成气直接制取低碳烯烃工艺具有重要的意义。在CO加氢反应中，载体对催化剂的性能影响显著。通过等体积浸渍法制备了不同碳化温度的聚苯胺（PANI）衍生碳材料负载的Fe基催化剂，考察了碳化温度对负载型Fe基催化剂CO加氢性能的影响。结果表明，随着PANI衍生碳材料碳化温度的升高，低碳烯烃选择性和烯烷比均有所升高；Fe₂₀/NC-800催化剂表现出最好的低碳烯烃选择性（41.05%）。通过扫描电子显微镜（scanning electron microscope，SEM）、Raman光谱（Raman spectrum）、X射线光电子能谱（X-ray photoelectron spectroscopy，XPS）对载体表面研究，发现随着碳化温度提高，载体形貌变化较小，但载体石墨化程度增高，载体总含氮量减少，吡啶氮增加，季氮减少，吡咯氮小幅降低后再升高。此外，通过XPS和原位X射线衍射（in situ XRD）等对催化剂表面和体相结构的表征发现，碳化温度的提高导致载体表面高结合能N物种减少，对Fe供电子作用增强，弱化了载体-金属间相互作用，促进了活性金属Fe的还原、碳化及团聚能力，进而促进了低碳烯烃的生成。

关键词: 加氢, 催化, Fe基催化剂, 低碳烯烃, 选择性, 碳化温度, 构-效关系

Abstract:

Light olefins are key building blocks for production of many chemical intermediates and polymers in chemical industry, which makes strategically important to produce light olefins directly from non-petroleum syngas resources. It has been found that catalyst carriers significantly affect catalyst performance in CO hydrogenation. A series of Fe-based catalysts on PANI-derived N-containing carbon material, prepared by incipient wetness impregnation at various carbonization temperature, were used to study carbonization temperature on catalytic performance. With the increase of carbonization temperature, both light olefin selectivity and O/P ratio were increased. Fe₂₀/NC-800 catalyst had the highest light olefin selectivity of 41.05%. Catalyst characterization by scanning electron microscope, Raman spectrum and X-ray photoelectron spectrum showed that carbonization temperature increase didn't change carrier structure much, but improved degree of graphitization and decreased total nitrogen content and amount of quaternary nitrogen species. It was also found that amount of pyridinic nitrogen was improved but amount of pyrrole nitrogen species was slightly dropped first and then increased with the increase of carbonization temperature. Moreover, XPS and in situ XRD analysis on surface and bulk structures of catalysts showed that carbonization temperature increase reduced number of high binding energy N species on carrier surface, strengthened electron donating effect on iron, and weakened metal-carrier interaction, which promoted reduction, carbonization and agglomeration of active metal iron and finally enhanced yield of light olefins.

Key words: hydrogenation, catalysis, iron-based catalysts, low olefins, selectivity, carbonization temperature, structure-performance relationship

中图分类号:

TQ018

石变芳, 查斌斌, 张俊, 张征湃, 徐晶, 韩一帆. 聚苯胺衍生碳材料负载的Fe基合成气直接制低碳烯烃催化剂：载体碳化温度的影响[J]. 化工学报, 2018, 69(2): 699-708.

SHI Bianfang, ZHA Binbin, ZHANG Jun, ZHANG Zhengpai, XU Jing, HAN Yifan. Iron-based catalyst on PANI-derived N-containing carbon carriers: effect of carrier carbonization temperature on direct syngas conversion to light olefins[J]. CIESC Journal, 2018, 69(2): 699-708.

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