摘要
在惰性气体中焙烧SBA-15制得孔壁被碳修饰的SBA-15C样品,以它和SBA-15为载体,采用等量浸渍法制备了负载型Co基催化剂,并运用X射线衍射、N2物理吸附、程序升温还原、NH3吸附量热等手段对样品进行了表征.结果表明,SBA-15C仍保持原有的六方有序的中孔结构,但其孔壁经碳修饰后发生增厚,比表面积略有下降.Co的负载使得SBA-15和SBA-15C样品的孔径基本不变,但比表面积和孔体积下降,仍保持其中孔分子筛的特征.Co3O4在SBA-15C上的晶粒较小,但还原度较低,表明碳的存在有利于Co物种的分散.比较了Co/SBA-15和Co/SBA-15C上的费托合成反应性能,发现两者对C5+的选择性均较高(达80%左右),但Co/SBA-15C催化剂稳定性优于Co/SBA-15.
Carbon coated mesoporous SBA-15,named SBA-15C,was obtained from as-synthesized SBA-15 after graphitization in inert gas.With SBA-15 and SBA-15C as supports and cobalt nitrate aqueous solution as precursor,the supported cobalt-based catalyst samples were prepared by a wet impregnation method.The catalyst samples were characterized by X-ray diffraction,N2 physisorption,tempera-ture-programmed reduction,and NH3 microcalorimetric adsorption.The results suggested that upon doping the inner walls of SBA-15 with carbon,the hexagonal ordered mesoporous framework was retained while the surface area decreased a little and the thickness of pore wall increased.The supported cobalt-based catalyst retained the mesoporous characteristics with decreased surface area and pore volume.The average particle size of Co3O4 on SBA-15C was smaller than that on SBA-15,which suggested that the existence of carbon improved the dispersion of Co3O4 particles.However,the modification of SBA-15 with carbon films did not seem to increase the reducibility of Co3O4.Both Co/SBA-15 and Co/SBA-15C exhibited high selectivity for C5＋ hydrocarbons（～80%）,but Co/SBA-15C showed higher stability in the F-T synthesis reactions.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2011年第8期1370-1375,共6页
基金
国家自然科学基金(20673055)
科技部国际科技合作基金(2004DFB02900)~~
关键词
SBA-15分子筛
孔壁碳修饰
钴基催化剂
费托合成
SBA-15 zeolite
pore wall modification
cobalt-based catalyst
Fischer-Tropsch synthesis
