摘要
用原位红外研究了CO的吸附与脱附,CO/H2的共吸附及反应,考察了焙烧温度对Ru/Al2O3及Ru/SiO2催化剂的影响结果表明,经不同温度焙烧的催化剂样品,其吸附性能有很大差别.随着焙烧温度的升高,金属-载体相互作用增强,导致CO吸附量减少.Ru/Al2O3吸附的CO较稳定,而Ru/SiO2吸附的CO在高温易脱附、各不同CO吸附态间,多重态更易发生反应.在未焙烧的Ru/SiO2上,低压CO/H2反应生成较多的甲烷,焙烧过的催化剂上则只有很少的甲烷生成;在未焙烧的Ru/Al2O3上.反应生成少量甲烷和甲酸,而高温焙烧过的催化剂上则不生成这些产物.结果还表明,Ru/Al2O3上金属-载体作用更强;在金属-载体相互作用弱的钌中心上,CO易于加氢.
he features and reactivities of CO adsorbed on 1% Ru/SiO2 and1% Ru/Al2O3 catalysts and their correlation with calcination temperature have been studied by in situ IR spectroscopy. The adsorption properties of the SiO2- and Al2O3-supported ruthenium catalysts calcined atdifferent temperatures are varied significantly. The interaction betweenmetal and support is enhanced and CO adsorption decreases as the calcination temperature incresaes. The CO adsorbed on Ru/SiO2 catalyst isnot so stabble as on Ru/Al2O3 catalyst and is easier to be desorbed athigher temperature. The multiple CO among various adsorbed stateshas higher reactivity with H2. The CO+H2 reaction on uncalcined Ru/SiO2 catalyst at low pressure forms more amount of CH4. On the otherhand, IR bands of CO adsorbed on calcined Ru/SiO2 catalyst are weak,and only little methane is produced by hydrogenation. On uncalcinedRu/Al2O3 catalyst, small amount of methane and formic acid areformed, while on the calcined one, no methane or no formic acid is detected, indicating that CO hydrogenation on the sites with weak metalsupport interaction is easier to take place.
关键词
钌
催化剂
吸附
一氧化碳
红外光谱
ruthenium, carbon monoxide, hydrogenaion, adsorption,infrared spectroscopy