二氧化硅固载Ru基催化剂上二氧化碳加氢合成甲酸的研究(III): 配体对催化剂反应性能的影响

考察了不同配体对原位合成的固载Ru基催化剂上CO₂加氢合成HCOOH反应活性的影响, 对于以单齿三苯基类ZPh₃分子为配体的催化剂, 活性大小顺序为: PPh₃＞AsPh₃＞NPh₃. 以PPh₃为配体时, 其相应的原位合成催化剂上HCOOH的TOF值为656 h^－1. 其次, 双齿膦配体的使用能带来比单齿膦配体更高的活性. 以dppe 1,2-双(二苯基膦基)乙烷]为配体时, 其相应的原位合成催化剂上HCOOH的TOF值为1190 h^－1. 量子化学的理论计算结果表明, 具有适中的σ给予性和π接受性, 较小的空间位阻, 较好的电子离域作用的PPh₃配体性能优于其它单齿三苯基类配体. 而具有较好的电子离域作用, 并且有螯合作用的双齿膦配体性能优于单齿膦配体.

Silica Immobilized Ruthenium Catalyst for Formic Acid Synthesis from Carbon Dioxide Hydrogenation (III): Effect of Ligand on the Catalyst Performance

The effect of ligand on the activity of immobilized ruthenium complexes synthesized in situ was investigated. The activity of the catalyst containing ZPh₃ ligand changed as follows: PPh₃＞AsPh₃＞NPh₃. When PPh₃ was used as ligand, the corresponding TOF of formic acid was 656 h^－1 over the catalyst. In addition, using bidentate phenyl phosphine as ligand instead of PPh₃ resulted in an even higher TOF, the value was 1190 h^－1 when dppe was used as ligand. The results of quantum chemistry theoretic calculation indicated that the PPh₃ ligand which had the moderate capability of σ-donor and π-acceptor, less steric hindrance and preferable electron delocalization, acted as a better ligand than the other ZPh₃ ligand. The bidentate phenyl phosphine ligands which had good electron delocalization and chelation acted as a better ligand than monodentate phosphine ligand.