Examination of Milstein Ru-PNN and Rh-Tribi/Tetrabi dual metal catalyst for isomerization-linear-hydroformylation of C4 raffinate and internal olefins

Isomerization-linear-hydroformylation is demanding, however, not an addressed issue, for production of value-added linear aldehydes by converting cheap and abundant internal alkenes available from bio- & petrochemical industry. In this paper, a dual metal catalysis system combining a Ru-isomerization catalyst and a Rh-linear-hydroformylation catalyst satisfying the “4S” criterions was reported for isomerization-linear-hydroformylation of C4 raffinate (mixed butenes) and internal olefins. The optimized dual metal catalyst system hydroformylated Raffinate II feed to valuable valeraldehyde in 98% linear selectivity (n:i ​= ​49), 80% conversion and high activity of 1069 h TOF whereas 96% linear selectivity (n:i ​= ​24), 71% conversion and 948 h TOF were observed using only the Rh-hydroformylation catalyst. Notably, valeraldehyde are produced in million tons scale annually for making non-toxic plasticizer DPHP. Various 2-olefins were also converted to linear aldehydes in > 98% linear selectivity (n:i ​> ​49), 78%–82% conversion and high activity of 802–851 h TOF.