摘要
以椰壳活性炭(BAC)为载体,采用H_(2)还原法制备出高分散性纳米零价铁催化剂[Fe^(0)/BAC-φH_(2)-θ(t)][φ为H_(2)体积分数(0、0.05%、2%、100%);θ为煅烧温度(600、700、800℃);t为煅烧时间(1、3、5 h)],采用固定床反应器考察了催化剂制备过程中H_(2)体积分数、煅烧温度及时间对催化剂分散性、催化还原NO性能、催化剂再生以及CO对催化剂还原NO的影响。采用XRD、TEM、SEM、XPS、N_(2)吸附-脱附对催化剂进行了表征,并对CO还原NO反应机理进行了推测。结果表明,催化剂活性随着H_(2)体积分数以及煅烧时间的增加逐渐增强,但随着煅烧温度的升高先升高后降低。Fe^(0)/BAC-100%H_(2)-700(3)催化剂中Fe^(0)粒径达到9 nm且均匀分散在BAC表面。在325℃时该催化剂可使NO转化率达100%,表现出了良好的NO脱除效果。还原NO过程中,Fe^(0)逐渐被氧化成Fe_(3)O_(4),导致催化剂最终失活,失活后的催化剂经再生处理后可恢复活性,CO的加入可以还原Fe_(3)O_(4)再次生成Fe^(0),提供活性位点,有效地延长催化剂的寿命,减缓催化剂失活的速率。
Coconut shell activated carbon(BAC)was used as support to prepare highly dispersed nano zerovalent iron catalysts[Fe^(0)/BAC-φH_(2)-θ(t)]by hydrogen reduction method.Here,φis the volume fraction of H_(2)(0,0.05%,2%,100%),θis calcination temperature(600,700,800℃)and t is calcination time(1,3,5 h).The effects of H_(2) volume fraction,calcination temperature and time on the dispersion,catalytic reduction of NO,regeneration of the catalyst and catalytic reduction of NO in the presence of CO were investigated in a fixed bed reactor.The catalysts were characterized by XRD,TEM,SEM,XPS and N2absorption-desorption.The mechanism of CO reduction of NO was speculated.The results showed that the activity of the catalyst enhanced gradually with the increase of H_(2) volume fraction and calcination time,while that first increased and then decreased with the increase of calcination temperature.In Fe^(0)/BAC-100%H_(2)-700(3),Fe^(0) nanoparticles had a particle size of 9 nm and were evenly dispersed on the surface of BAC.Fe^(0)/BAC-100%H_(2)-700(3)exhibited a good NO removal effect at 325℃with a NO conversion rate of 100%.In the process of NO reduction,Fe^(0) was gradually oxidized to Fe_(3)O_(4),leading to the deactivation of the catalyst.The deactivation of the catalyst could be recovered after regeneration treatment.The addition of CO could reduce Fe_(3)O_(4) and generate Fe^(0) active sites again,effectively extending the life of the catalyst and slowing down the rate of catalyst deactivation.
作者
王焕然
李先春
李丽
王思怡
WANG Huanran;LI Xianchun;LI Li;WANG Siyi(School of Chemical Engineering,University of Science and Technology Liaoning,Anshan 114051,Liaoning,China)
出处
《精细化工》
EI
CAS
CSCD
北大核心
2021年第12期2523-2530,共8页
Fine Chemicals
基金
国家自然科学基金(U1910215)。
关键词
CO
NO
零价铁
还原
纳米粒子
催化技术
carbon monoxide
nitric oxide
zero-valent iron
reduction
nanoparticles
catalytic technology
