摘要
采用分步浸渍法制备负载型Ru-Fe3O4/γ-Al2O3催化剂,并利用透射电子显微镜(TEM)、X射线衍射(XRD)、N2吸附-脱附(BET)、傅里叶变换红外(FTIR)光谱与X射线光电子能谱(XPS)表征催化剂的纳米颗粒粒径分布、晶相组成、表面结构及吸附物种等性质.将Ru-Fe3O4/γ-Al2O3催化剂用于3,4-二氯硝基苯选择性原位液相加氢反应,考察了反应条件对催化活性的影响,并讨论了不同制备条件下催化剂的稳定性能.结果表明,在473K、液压3MPa、原料质量分数2%,乙醇/水体积比75:25的反应条件下,3,4-二氯硝基苯的转化率为100%,3,4-二氯苯胺的选择性高达96.4%.Fe3O4含量对催化剂稳定性能有显著影响,当Ru和Fe的质量分数分别为2%和6%时,催化剂可稳定200h以上.表面吸附CO与积碳是导致催化剂失活的主要原因,以Fe3O4作为高效的助剂,进行水汽转换(WGS)反应与费托合成(FTS)可移除CO,而采用煅烧法去除表面积碳.晶相变化与纳米颗粒的聚集可能导致催化剂部分失活,其原因以及再生方法需进一步考察.
Ru-Fe3O4 /γ-Al2O3 was synthesized by stepwise impregnation method and applied to the in-situ liquid phase selective hydrogenation of 3,4-dichloronitrobenzene（3,4-DCNB）.The nanoparticle size and distribution,metallic crystalline constitution,surface structure parameters,and adsorption species were systematically characterized by transmission electron microscopy（TEM）,X-ray diffraction（XRD）,Fourier transform infrared（FTIR） spectroscopy,N 2 adsorption-desorption（BET）,and X-ray photoelectron spectroscopy（XPS）.The Ru-Fe3O4 /γ-Al2O3 catalyst was investigated using the in-situ liquid phase hydrogenation of 3,4-DCNB as probe reaction,the effect of different reaction conditions and different synthetic factors on the catalytic properties was studied.Experimental results showed that the catalytic properties of the Ru-Fe3O4 /γ-Al2O3 catalyst were significantly influenced by its Fe3O4 content,under the optimum condition of 473 K,3.0 MPa,2%（w） 3,4-DCNB concentration with 75% ethanol and 25% water,the Ru-Fe3O4 /γ-Al2O3 catalyst with Ru and Fe mass fractions of 2% and 6% exhibited the highest activity and stability,with 100% conversion of 3,4-DCNB,96.4% selectivity of 3,4-dichloroaniline（3,4-DCAN）,and this catalyst could be stabilized for more than 200 h.The main reason for the deactivation of the catalyst is CO coverage on active centers,and the poisoning-deactivated catalysts were regenerated by water-gasshift（WGS） reaction and Fischer-Tropsch synthesis（FTS）,which employ Fe3O4 modified Ru/Al2O3 as catalyst due to its high efficiency of CO transformation.Carbon deposition on the catalyst surface is the reason second only to carbon monoxide poisoning,and this could be removed through calcination.Crystalline phase change and nanoparticles aggregation may cause partial deactivation,and investigation of the mechanism and catalyst regeneration are in progress.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2013年第4期799-805,共7页
Acta Physico-Chimica Sinica
基金
国家自然科学基金(20676124
21076197)
浙江省自然科学基金(Y4090440)
浙江省钱江人才项目(2010R10038)资助~~
关键词
钌
四氧化三铁
催化剂稳定性
3
4-二氯硝基苯
原位液相加氢
CO中毒失活
Ruthenium
Iron oxide
Catalytic stability
3,4-Dichloronitrobenzene
In-situ liquid phase hydrogenation
CO poisoning deactivation
