Monolithic emulsion based ceramers with hierarchical porosity
were obtained by using a HIPE or LIPE process, starting with
siloxane precursors, which introduces a high amount of methyl and
aminopropyl and ethoxy groups (MK, APTES, TEOS) in the samples.
Three different siloxane precursor were used to generate materials
with high content of different organic groups (>75 mol-%) in the
cross-linked state. Nickel nanoparticles could be embedded successfully
by using NiCl2 together with the complexing agent APTES.
Several characteristics like pore size distribution, SSA, surface characteristics
in terms of hydrophobicity/hydrophilicity and size ofthe
nickel nanoparticles of the investigated MEBC and Ni-MEBC can be
specifically tailored. Using different types of emulsions (HIPEs or
LIPEs) result in a controllable pore size distribution. The resulting
hollow spheres, which consist of MK, were functionalized on
the surface with the decomposition products of APTES and TEOS
and exhibit different pore size distributions. The SSA and surface
characteristics can be tailored by using different pyrolysis conditions
or by selection of precursor and precursor combinations.
Additionally, the incorporation of nickel leads to a tailorable SSA
due to the higher decomposition degree. The pyrolysis of different
precursor composition at 500 or 600 ◦C results in specific BET surface
areas up to 550 m2/g without losing the monolithic structure.
Nickel nanoparticles in Ni-MEBC are generally well distributed and
show metal nanoparticles in average particle size in a range from
35 to 69 nm for the samples pyrolyzed if the samples pyrolyzed at
600 ◦C. These materials possess a sufficient handling stability and
high specific BET surface areas. Especially the Ni-MEBC is highly
suitable for applications in catalysis. The supposed high accessibility
of the nickel naonoparticles for different chemicals will be
investigated in future studies.