@article{2818720,
    title = "Strategies toward catalytic biopolymers: Incorporation of tungsten in alginate aerogels",
    author = "Patrina Paraskevopoulou and Pavel Gurikov and Grigorios Raptopoulos and Despoina Chriti and Maria Papastergiou and Zacharenia Kypritidou and Vassilis Skounakis and Ariadne Argyraki",
    journal = "Polyhedron",
    year = "2018",
    volume = "154",
    number = "-",
    pages = "209-216",
    publisher = "Elsevier",
    issn = "0277-5387",
    keywords = "Aerogel, Alginate, Metal–metal bond, Tungstates, Tungsten",
    abstract = "We report the synthesis of W-doped biopolymer aerogels with potential applications to catalysis. The
biopolymers were based on alginate, a cost-efficient natural material, and were prepared in environmentally
friendly water/ethanol solutions. Gelation of alginate was induced by crosslinking with Ca2+. The
resulting wet-gels were impregnated with an ethanolic solution of the ditungsten complex
[W2(μ-OEt)2(OEt)2(EtOH)2Cl4] ({W =W}8+) and were dried with supercritical fluid (SCF) CO2 to yield
W-doped alginate aerogels containing 10% w/w tungsten. Dry materials were characterized with FTIR,
SEM/EDS, TGA, N2 porosimetry and He pycnometry. The bulk densities were low (<0.1 g cm-3), porosities
were high (96% v/v), as well as the BET surface areas (380 m2/g). Pyrolysis of those aerogels at 800 oC
under Ar yielded carbon along with a mixture of calcium tungstates, i.e., CaWO4 and Ca3WO6 (weight
ratio: 70:30), while pyrolysis under O2 yielded the same tungstates, but with a different weight ratio
(10:90). This can be a new process for Ca3WO6, which, due to its ordered double perovskite structure,
is ideal for doping with metal ions, at relatively low temperature (800 oC versus >1000 oC in the
literature)."
}