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

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

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656h-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1190h-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.

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.