【摘要】 <正> 高分子保护金属胶体是近年来金属催化剂领域中引人注目的研究课题。它除了具有负载型金属催化剂的优点外,还具备下列新优点:a.胶体分散体系可形成“均相”溶液;b.保护高分子可以屏蔽胶体催化剂,减小毒物或空气的不良影响;c.胶体溶液的透光性能比颗粒要好得多,由此最近高分子保护金属胶体常被用于光化学研究中的催化剂;d.高分子保护金属胶体与普通金属胶体相比较,不仅具有较稳定的特点,而且尺寸小(1—10nm)、分布窄,表现出极高的催化活性和选择性;e.保护高分子对金属的修饰作用,可更多还原

【Abstract】 The derivatives of natural polymer chitin and chitosan: sodium salt of carboxymethyl-chitin and chitosan acetate, were examined as the protective polymers for the formation of the precious metal colloids. In the presence of carboxymethylchitin or chitosan acetate, stable metallic colloids of palladium, rhodium, ruthenium, platinum silver and gold were formed in a methanol-water solvent system. Particularly, TEM measurements illustrate that the narrowly dispersed metallic colloids with fine particle size can be formed in the case of palladium- rhodium or ruthenium carboxymethylchitin or chitosan acetate systems. That is in carboxymethylchi’in protective system, palladium sol is mostly distributed in the range of 4.0-5.0 nm with an average diameter of 4.6 nm and rhodium sol or ruthenium sol is in 3.5-4.5 nm with an average diameter of 4.0 nm or in 3.0-3.5 nm with an average diameter of 3.2 nm, respectively; in chitosan acetate protective system, rhodium sol is in 4.0-5.0 nm with an average diameter of 4.6 nm. Palladium, rhodium and platinum sols were tested as catalysts for the partial hydro-genation of 1,3-cyclooctadiene and showed quite a good activity as well as selectivity.更多还原