(513cl) Sulfur Promoted Nickel Catalysts for the Selective Hydrogenation of Hydrocarbon Resin

Hydrocarbon resins are low molecular weight amorphous polymers mainly used as adhesives and the hydrogenation is essential process for improving color and stability of the resin by removing vulnerable double bonds. Supported Ni powder catalyst is very effective in the slurry phase hydrogenation of hydrocarbon resin, however, commercial reference of using Ni-based catalysts in the selective hydrogenation has not been found since their selectivity against aromatic group is very poor. The purpose of selective hydrogenation is to remove the olefinic double bond without reducing the aromatic content significantly, so the aromatic hydrogenated resin can show great compatibility with block copolymers representing higher midblock solubility.

Sulfur-promoted nickel catalysts were newly developed for the selective hydrogenation in a slurry type reactors such as stirred tank rectors or loop reactors while most commercial plants use supported precious metal catalysts in fixed bed reactors for the purpose. In this reaction with sulfur-promoted Ni catalyst, not only significant changes in selectivity to olefinic double bond has occurred but enhancement of activity also has appeared and the promotional effect can be controlled by the dose of sulfur a catalyst is exposed to. The addition of a sulfur to the catalyst results in the geometric blockage of adsorption site, so the hydrogenation of aromatic group was severely limited whereas catalytic activity to the olefinic double bond was maintained due to higher degree of reduction of the catalyst. The adsorbed sulfur is thought to contribute for the reducing metal-support interaction at preparation, so is responsible for the concurrent enhancement of the selectivity and activity.