The selective hydrogenation of nitrile-butadiene rubber (NBR) is a significantly important process to produce high quality hydrogenated NBR (HNBR) with exceptional resistance against thermal-oxidative degradation and notably improved mechanical properties. Herein, silica hollow microspheres (SHMs) with the penetrating macropores in the shells are prepared by a simple one-step method with water/oil/water ternary phase emulsion system, which can serve as a superior support to fabricate supported palladium catalysts. Before mixed with palladium precursor solution, the surface of SHMs was first modified with N-Propylethylendiamine (N-SHMs) and then the palladium components were bound to the surface of N-SHMs by means of the coordination of -NH2- and -NH- ligands with palladium (Pd/N-SHMs) as shown in Fig.1. The result showed that the resultant catalysts possessed well-dispersed small Pd nanoparticles with the average size of 2 nm. It can be verified that the grafting amount of amino groups plays an important role in controlling the size of Pd nanoparticles. A comparative study was made between the Pd/N-SHMs and Pd/SHMs prepared by a conventional impregnation method, and the Pd/N-SHMs showed higher activity and stability and the residual Pd in HNBR was only 5 ppm by elemental analysis. The hydrogenation degree of HNBR could reach 95.0% under mild condition (60 oC, 2.0 MPa H2, 1 h) without any gelation and the selectivity to C=C is 100%. Furthermore, the effect of solvents for the heterogeneous hydrogenation system were studied and found that the size of NBR molecules in solution can be controlled by changing solvent. This research provides an efficient and recyclable supported catalyst for the selective hydrogenation of NBR and may promote the development of heterogeneous catalytic hydrogenation for NBR.

Tailored design of Pd catalyst supported on chemically modified silica hollow microspheres with penetrating macroporous shells for NBR hydrogenation

253rd National Meeting (2017)

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