Application of POSS nanotechnology for preparation of efficient Ni catalysts for hydrogen production

Abstract

\u3cp\u3ePOSS (polyhedral oligomeric silsesquioxanes) nanotechnology was applied for preparation of efficient Ni catalysts for hydrogen production through autothermal reforming of methane (ATR of CH\u3csub\u3e4\u3c/sub\u3e). The novel metal-POSS precursor [Nickel (II) ‒ HeptaisobutylPOSS (C\u3csub\u3e4\u3c/sub\u3eH\u3csub\u3e9\u3c/sub\u3e)\u3csub\u3e7\u3c/sub\u3eSi\u3csub\u3e7\u3c/sub\u3eO\u3csub\u3e9\u3c/sub\u3e(OH)O\u3csub\u3e2\u3c/sub\u3eNi] of Ni nanoparticles was introduced into Ce\u3csub\u3e0.5\u3c/sub\u3eZr\u3csub\u3e0.5\u3c/sub\u3eO\u3csub\u3e2\u3c/sub\u3e support with following calcination and reduction stages of activation. The peculiarity of the genesis of Ni/SiO\u3csub\u3e2\u3c/sub\u3e/Ce\u3csub\u3e0.5\u3c/sub\u3eZr\u3csub\u3e0.5\u3c/sub\u3eO\u3csub\u3e2\u3c/sub\u3e nanomaterials and their characteristics versus deposition mode were studied by X-ray fluorescence spectroscopy, thermal analysis, N\u3csub\u3e2\u3c/sub\u3e adsorption, X-ray diffraction, high-resolution transmission electron microscopy and H2 temperature-programmed reduction. The two kinds of supported Ni-containing particles were observed: highly dispersed Ni forms (1‒2 nm) and large Ni-containing particles (up to 50‒100 nm in size). It was demonstrated that the textural, structural, red-ox and, consequently, catalytic properties of ex-Ni-POSS catalysts depend on the deposition mode. The increase of a portion of difficultly reduced Ni\u3csup\u3e2+\u3c/sup\u3e species is found upon application of intermediate calcination during Ni-POSS deposition that has detrimental effect on the activity of catalyst in ATR of CH4. The Ni/SiO\u3csub\u3e2\u3c/sub\u3e/Ce\u3csub\u3e0.5\u3c/sub\u3eZr\u3csub\u3e0.5\u3c/sub\u3eO\u3csub\u3e2\u3c/sub\u3e catalyst prepared by one-step Ni-POSS deposition exhibits the highest H\u3csub\u3e2\u3c/sub\u3e yield ‒ 80% at T = 800 °C.\u3c/p\u3