Various characteristics of multi-modified rice husk silica-anchored Ni or Pt nanoparticles as swift catalytic systems in some petrochemical processes

摘要

Considering the local rice husk (RH) as a renewable source for production of value added silica, new swift catalysts based on the extracted silica (RHS) were designed in this work. RHS was texturally tuned by using both CTAB (cationic surfactant) and Span40 (nonionic surfactant). Surfaces of RHS xerogel and CTAB-templated RHS were functionalized with mixed 3-aminopropyltriethoxysilane and triethoxymethylsilane for in situ anchorage of Ni or Pt nanoparticles. Ni nanoparticles were also immobilized onto Span40-templated RHS surface through dual tuning effect. The as-synthesized samples were characterized via N-2 physisorption, H-2 chemisorption, XRD, FTIR, TEM and TGA-DSC techniques and applied in ethanol dehydrogenation at different temperatures. Anchored Ni nanoparticles were embedded in the protecting organo-functionalized silica monolayer in a uniform dispersion profile, displaying higher dehydrogenation activity and stabilized performance with reaction time-on-stream for selective production of acetaldehyde (77.8 and 63.6% over F-SG-Ni and F-CTAB-MS-Ni, respectively). Attached Pt nanoparticles to pendant amine groups of functionalized RHS xerogel surface appeared in spherical shapes of larger average sizes with low edges and corners. They tended to aggregate in nanocrystallites with distorted tetrahedral (111) facets of damped and less stabilized catalytic performance to produce only 17.3% acetaldehyde. Span40-templated RHS-Ni exhibited lower activity to produce 53.3% acetaldehyde, although with high selectivity comparable with RHS-Ni. (C) 2015 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.