Functions of organoaluminum and proton donor compounds in the formation and functioning of nanosized Ziegler-type nickel-containing hydrogenation catalysts

• Published in: Kinetics and catalysis Vol. 56; no. 5; pp. 574 - 583
• Main Authors: Shmidt, F. K., Titova, Yu. Yu, Belykh, L. B.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.09.2015
• Subjects: Catalysis; Chemistry; Chemistry and Materials Science; Physical Chemistry; Ziegler systems; nickel; catalysis; nanoparticle; hydrogenation; functions of a cocatalyst
• ISSN: 0023-1584; 1608-3210
• DOI: 10.1134/S0023158415040151

The turnover frequency (TOF) and turnover number (TON) in styrene hydrogenation have been determined for catalytic systems based on Ni(acac) 2 · n H 2 O ( n = 0, 0.5, and 3.0), Ni(COD) 2 (COD = cycloocta-1,5-diene), and AlEt 3 at different Al/Ni molar ratios. The amount of water of crystallization determines the TON and TOF of the nickel catalysts and their dependence on the Al/Ni ratio. The TON and TOF of the nickel catalysts are markedly increased by the introduction of an optimum amount of a proton donor. The model of the ligand shell stabilizing the nickel nanoparticles has been refined. The refined model provides an explanation for the activating action of proton donor compounds in the formation of the hydrogenation catalysts. The functions of the organoaluminum compounds are not limited to Ni(II) reduction to Ni(0); they are also involved in the stabilization of the nickel-containing nanoparticles.