Synthesis of chitosan-stabilized platinum and palladium nanoparticles and their hydrogenation activity

• Published in: Journal of molecular catalysis. A, Chemical Chemical, 2004-04, Vol.212 (1), p.141-149
• Main Authors: Adlim, M, Abu Bakar, Mohamad, Liew, Kong Yong, Ismail, Jamil
• Format: Article
• Language: English
• Subjects: Catalysis; Catalysts: preparations and properties; Chemistry; Chitosan; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Hydrogenation; Nanoparticles; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Size control; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/j.molcata.2003.08.012

Chitosan-stabilized Pt or Pd particles of size of 1–2 nm, were synthesized using CH 3OH or NaBH 4 as the reducing agents. Activity for the hydrogenation of octene and cyclooctene of Pt was much higher than Pd. Pd but not Pt, also catalyzed the isomerization of the double bond. Chitosan-stabilized Pt (chi-Pt) or Pd (chi-Pd) colloidal nanoparticles catalyst prepared with various chitosan–metal molar ratios and reducing agents were characterized. Chitosan could stabilize Pt and Pd with minimum chitosan:M ratio of 5:1 and 2:1 respectively. The finest and well-dispersed particles of chi-Pt or chi-Pd were obtained when methanol or NaBH 4 were used as the reducing agents. Chi-Pt and chi-Pd reduced by hydrazine gave aggregated particles in all chitosan molar ratios. Chitosan could control particle size of Pt or Pd to within 1.9–2.2 nm when CH 3OH or NaBH 4 was used as the reducing agents. Palladium or Platinum catalysis on cyclooctene hydrogenation gave cyclooctane. Hydrogenation of octene catalyzed by chi-Pd gave octane, 2-octene and 3-octene while chi-Pt prepared by methanol reduction showed 99.99% selectivity and conversion to octane. The catalytic activity of chi-Pt was higher than chi-Pd for both the hydrogenations.