Porous SiOC monoliths with catalytic activity by in situ formation of Ni nanoparticles in solution‐based freeze casting

Abstract

Micro‐ and macroporous monoliths with in situ formed nickel nanoparticles were prepared for the first time by the combination of solution‐based freeze casting and preceramic polymers (methyl polysiloxane). This one‐step process results in macroporous monoliths composed of microporous and catalytic active nickel‐containing polymer‐derived ceramic. Four different complexing and cross‐linking siloxanes with amino functionality were screened for their ability to create small nickel particles. TEM analysis confirmed 3‐aminopropyltriethoxysilane being most efficient. High BET‐specific surface areas of 344‐461 m2 g−1 were achieved. Increased ratio of complexing groups to nickel improves the dispersion of nickel to (3.61 ± 1.49) nm. The nickel size dependence of conversion (maximum 0.49) and CH4 selectivity (maximum 0.74) in CO2 methanation emphasizes the importance of controlling the nickel size. The hydrophobic surface characteristic is hypothesized to be the main reason polymer‐derived catalysts having better catalytic activity compared with nickel‐impregnated silica. The promising catalytic activity combined with the versatile freeze casting process can prospectively address heat‐ and mass‐transfer considerations in heterogeneous monolith catalysis.

Silicon oxycarbonitride ceramic containing nickel nanoparticles: from design to catalytic application

“…Micro-mesoporous PDCs with high surface areas have been reported as promising catalytic supports. [18][19][20] For instance, metal-containing (e.g. Co and Ni) SiOC nanocomposites with hierarchical porosity, derived from polysiloxanes polymers, show high catalytic activity for CO2 methanation and Fischer-Tropsch Synthesis.…”

“…Co and Ni) SiOC nanocomposites with hierarchical porosity, derived from polysiloxanes polymers, show high catalytic activity for CO2 methanation and Fischer-Tropsch Synthesis. 18,[20][21][22][23][24] Similarly, some transition metalscontaining (e.g. Cu, Ru, Pd, and Ir) SiCN nanocomposites have been reported as heterogeneous catalysts for liquid-phase oxidation, 25 hydrogeneration, 26,27 and sustainable synthesis.…”

Novel hydrogen chemisorption properties of amorphous ceramic compounds consisting of p-block elements: exploring Lewis acid–base Al–N pair sites formedin situwithin polymer-derived silicon–aluminum–nitrogen-based systems

“…There is still room for further study on optimizing hydrogen adsorption-desorption properties by controlling several material parameters such as the chemical composition and micro/ mesoporosity. Moreover, the unique H2-affinity of present SiAlN suggests other applications such as a novel non-oxide catalysis support which is recently highlighted for the impressive catalytic activities in hydrogenation of polymer derived transition metal/Si-based non-oxide ceramic nanocomposites of palladium silicide containing SiCN by Motz and Kempe et al, 20 and Ni-SiOC by Wilhelm and Rezwana et al, 21 or Pt-TiN/Si3N4 nanocomposites which in our very recent study 22 showed enhanced catalytic performance for dehydrogenation of sodium borohydride in water. Therefore, polymer-derived amorphous SiAlN ceramics are expected to have an impact on catalytic processes as a transition or noble metal-free advanced material and be of significant interest for clean energy applications such as advanced hydrogen production, storage and transportation systems.…”

“…Through a precursor route called polymer-derived ceramics (PDCs), [13][14][15][16][17][18][19][20][21][22] we recently demonstrated 19 the in situ growth of nanostructured AlN into a robust, protecting silicon carbide (SiC) matrix to form amorphous single-phase Si-Al-C-N ceramics at low temperatures and an AlN/SiC solid solution at high temperatures. By changing the nature of the atmosphere (ammonia instead of nitrogen) and considering the same commercially available poly(vinylmethyl-co-methyl)silazane (Durazane® 1800, silicon nitride precursor) chemically cross-linked with N,Ndimethylethylaminealane (EtNMe2$AlH3), we have designed a novel amorphous single-phase ceramic based on the Si-Al-N system at low temperatures.…”

Polymer-Derived Si-Based Ceramics: Recent Developments and Perspectives

“…Therefore, the shapes of polymers could be tailored according to specific requirements after pyrolysis. At present, the most widely studied PDCs systems are mainly PDCs-SiC [5][6][7][8][9][10][11][12], PDCs-SiOC [13][14][15][16][17][18][19][20][21][22], and PDCs-SiCN [23][24][25][26][27][28][29][30][31][32] systems.…”