The Preparation Of Supported Ru Nanaoparticle Catalysts Protected By Ionic Liquid And Its Application In Water-gas Shift Reaction

Water-gas shift reaction(CO+H2O→CO2+H2)can be used for hydrogen purification,regulating the H2/CO ratio of synthesis gas used for ammonia,methanol and other chemical products,recently,the WGS reaction has attracted great interest again because of its application in fuel cell for reducing CO content,which poisoned platinum electrode.Traditional WGS reaction catalyst can’t satisfy the require of high activity and stability at low temperature for fuel cell,so looking for relatively cheap,high activity and stability WGS reaction catalyst at low temperature is one of the key technologies for commercial applications of fuel cell.Considering special properties of metal nanoparticles,Ru nanoparticles catalysts were prepared by the ionic liquid [BMIM][BF4] as protective agent,NaBF4 as reducing agent.The effect of Ru particle size,TEOS hydrolysis conditions(Ion gel catalyst),ZnO morphology on WGS reaction were studied at low reaction temperatures.The conclusions were shown as follows:(1)Ru nanoparticles with different sizes were prepared by changing the molar ratio of Ru(NO)(NO3)3 to [BMIM]BF4.The catalysts were prepared by impregnated Ru-[BMIM][BF4] in mesocellular foam silica(MCF)and studied for low-temperature WGS reaction.The catalysts WGS reaction activity decreased with the increasing of particles size on the tested temperatures.The reasons mainly due to on the one hand,much more active sites were present in catalyst with small particle size on the same Ru loading;On the other hand,WGS reaction was sensitive to the structure of the activate site,small nanoparticles had much more low-coordinated perimeter and corner sites which were the active site for WGS reaction.(2)The iongel catalysts were prepared by sol-gel method to confine the Ru nanoparticles protected by ionic liquid [BMIM][BF4] in silica gel under acidic and basic conditions.Compared to Ru/[BMIM]BF4-(1:10)@SiO2-Base catalyst,the Ru/[BMIM]BF4-(1:10)@SiO2-Acid iongel catalyst had larger surface area,pore volume to confine the active component in the silica matrix,gave high CO conversion rate and stability.The highest CO conversion of 37.8% was achieved at 140 oC and remained stable in 25 h over Ru/[BMIM]BF4-(1:10)@SiO2-Acid iongel catalyst.(3)Four different morphologies of ZnO were used as supports to prepare Ru-[BMIM]BF4/ZnO catalysts by incipient wetness impregnation method.The disklike ZnO supported Ru catalyst showed much lower catalytic activity and higher activation energy than those for rodlike ZnO supported Ru catalysts with higher surface area of ZnO {100}crystal face.Controlled experiments indicated that CO2 from WGS reaction tended to absorb on the ZnO {100} nonpolar plane,and enhanced the CO adsorption on the catalytic sites,improving the catalytic activity.