【摘要】 用反应测试、程序升温还原（TPR）及氧化（TPO）等方法考察了载体及Ru 担载量等因素对Ru 催化剂用于CO 加氢合成长链烷烃的催化性能的影响。0.5%Ru/Al₂O₃催化剂对生成C₁₀—C₁₅正构烷烃具有良好的活性及选择性,而担载于SiO₂上的相同Ru含量的催化剂则反应性能不佳。当Ru 含量增加至5%时,则担载在Al₂O₃及SiO₂上的Ru 催化剂在催化性能上基本相同,且活性比0.5%Ru 的催化剂有较大提高,但生成C₁₀—C₁₅正构烷烃的选择性则明显下降。从TPR 及TPO 的考察结果发现,对于0.5%Ru/Al₂O₃的催化剂,Al₂O₃载体与金属Ru 之间有较强的相互作用,但在0.5%Ru/SiO₂催化剂上Ru 只与SiO₂发生很弱的相互作用。当Ru 含量增加至5%时,可能是由于Ru 分散度大大下降,无论担载在Al₂O₃上还是SiO₂上的Ru 都不与载体发生明显的相互作用。根据这些结果,对0.5%Ru/Al₂O₃与0.5%Ru/SiO₂上存在着载体效应,而5%Ru/Al₂O₃与5%Ru/SiO₂则没有载体效应的原因进行了解释。认为在0.5%Ru/Al₂O₃催化剂上,由于Ru 与Al₂O₃之间所发生的较强相互作用而导致了一种特殊的活性中心的形成,这种活性中心有利于C₁₀—C₁₅正构烷烃的生成。反之,在0.5%Ru/SiO₂、5%Ru/Al₂O₃及5%Ru/SiO₂催化剂上,其活性中心则与载体没有明显的相互作用而主要显示出金属Ru 本身的催化性能,因而催化剂活性与载体的性质无关。与存在着金属—载体相互作用的中心相比,这种活性中心对合成C₁₀—C₁₅正构烷烃的活性和选择性都较差。这一解释与我们的及文献上的结果能较好地符合。更多还原

【Abstract】 The influences of supports and ruthenium loading on the catalyticbehavior of ruthenium catalysts for the synthesis of long chain alkanesby carbon monoxide hydrogenation were investigated by means of micro-reactor evaluation,temperature programmed reduction（TPR）and oxida-tion（TPO）.Catalysts with 0.5 w% Ru supported on Al₂O₃ were highin activity and selectivity for the formation of C₁₀—C₁₅normal alkanes,while catalysts supported on SiO₂ with the same Ru loading showed poorreactivity.By increasing the Ru loading to 5 w%, differences in acti-vity and selectivity disappeared on the alumina and silica supported ca-talysts.Furthermore,activity of the catalysts increased considerably ascompared to that of the low metal loading catalysts,while selectivity forthe formation of C₁₀—C₁₅normal alkanes decreased remarkably.Results from the TPR and TPO studies revealed that there was arather strong interaction between Ru and Al₂O₃ in the 0.5% Ru/Al₂O₃catalysts,while only very weak interaction appeared in the 0.5% Ru/SiO₂ catalysts.However,in the case of the 5% Ru catalysts,probablydue to the greatly decreased dispersion of Ru,the interaction between Ruand either of these two supports was found to be also very weak.Basedon these observations,explanation is given for the reasons why supporteffect exists on the low metal loading catalysts,but not on the highmetal loading catalysts.It is proposed that,because of the rather stronginteraction between Ru and Al₂O₃,a special kindof active sites is produced in the 0.5% Ru/Al₂O₃ catalysts,and these active sites are favo-rable for the formation of C₁₀—C₁₅normal alkanes.On the contrary,since the interaction between Ru and the supports is weak in the 0.5%Ru/SiO₂,5% Ru/Al₂O₃ and 5% Ru/SiO₂ catalysts,their active sitescan be expected to possess similar catalytic properties as the Ru metalitself,and are independent of the supports.Moreover,these active sitesseem to be inferior in activity and selectivity for the formation of C₁₀—C₁₅normal alkanes,as compared with the active sites which have astrong interaction between the metal and the support.This explanation isin consistent with the results from our work as well as from the litera-ture.更多还原