Direct hydrogenation of nitrile butadiene rubber latex using M41 catalyst

Hydrogenated nitrile butadiene rubber (HNBR) is a high‐performance elastomer widely used in the petrochemical and automotive industries. A ruthenium‐based catalyst, namely [1,3‐bis(2,4,6‐trimethylphenyl)‐2‐imidazolidinylidene]‐[2‐[[(4‐methylphenyl)imino]methyl]‐4‐nitrophenoyl]chloro[3‐phenylindenylidene]ruthenium(II) (M41), was investigated for the direct hydrogenation of NBR latex. The catalytic selectivity for the hydrogenation of CC bond instead of CN group was confirmed by both Fourier transform infrared and 1H NMR spectroscopies. The effects of reaction conditions (such as temperature, pressure, catalyst levels, agitation speed and solid content) on the hydrogenation reaction were examined, and hydrogenation products with over 95 mol% conversion were obtained for only 3 h with a catalyst/NBR ratio of 0.05 wt% and no gel was formed within HNBR. The results suggest that the current limitations in the hydrogenation of NBR latex could be addressed with this catalyst. © 2023 Society of Industrial Chemistry. A ruthenium‐based catalyst (M41) was investigated and a catalytic mechanism is proposed for the direct hydrogenation of nitrile butadiene rubber (NBR) latex. The hydrogenation products of NBR with over 95 mol% conversion were obtained for only 3 h with a catalyst/NBR ratio of 0.05 wt% and no gel was formed.