Stereo-selective hydrogenation of 3-hexyne over low-loaded palladium catalysts supported on mesostructured materials

• Published in: Applied catalysis. A, General General, 2010-10, Vol.387 (1), p.26-34
• Main Authors: Alvez-Manoli, G., Pinnavaia, T.J., Zhang, Z., Lee, D.K., Marín-Astorga, K., Rodriguez, P., Imbert, F., Reyes, P., Marín-Astorga, N.
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Catalysis; Catalysts; Chemisorption; Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Hydrogenation; MCM-48; Mesoporous; MSU-γ; Palladium; Porous materials; SBA-15; Stereo-selectivity; Surface physical chemistry; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Toluene; Transmission electron microscopy
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2010.07.062

[Display omitted] ▶ Preparation, characterisation and screening of palladium based catalysts. ▶ Mesostructured materials were used as support of palladium catalysts. ▶ 1% Pd/SBA-15 showed high activity and stereo-selectivity for semi-hydrogenation of 3-hexyne. ▶ The starting 3-hexyne produces primarily cis-3-hexene, which subsequently is either hydrogenated to hexane or isomerized to trans-3-hexene and 2-hexenes that are found in very small amounts depending on the nature of the support used. This paper studies the effect of mesostructured materials in the stereo-selective hydrogenation of 3-hexyne at 298 K and 40 psig pressure of H 2 over Pd-supported catalysts at different substrate:palladium (S:Pd) molar ratios. The catalysts were prepared by impregnation using a toluene solution of Pd(acac) 2 to obtain a metal content close to 1 wt.% over SBA-15 with one-dimensional hexagonal structure, MCM-48 silica with cubic structure and three-dimensional pore system and MSU-γ alumina with a lathlike particle morphology. All the supports were characterised by nitrogen adsorption–desorption isotherms at 77 K, TEM, XRD and H 2 chemisorption and TEM measurements. The reactions were found to be zero order with respect to 3-hexyne concentration. The starting 3-hexyne produces primarily cis-3-hexene, which subsequently is either hydrogenated to hexane or isomerized to trans-3-hexene and 2-hexenes that are found in very small amounts depending on the nature of the support used. Palladium catalysts supported on SBA-15 was the most active and selective catalyst.