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Author: search.filters.author.Sooknoi, TawanSubject: search.filters.subject.Lepidocrocite titanate

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    Inclusion of alkali carboxylate salts at the two-dimensional space of layered alkali titanate via carboxylic acids intercalation
    (2020-11-01)
    Maluangnont, Tosapol
    ;
    Sooknoi, Tawan
    The formation of organic salts trapped at the two-dimensional (2D) space of layered solids is typically not well-defined, lacks stoichiometric relation, and depends on the chain length of the organic moieties. In contrast to this conventional salt intercalation, we report herein the inclusion of alkali carboxylates by intercalation of carboxylic acids to lepidocrocite-type alkali titanate microcrystals. The intercalated organic content of 15.9–37.0 ​wt% is high for a solid with low specific surface area (3 ​m<sup>2</sup>/g). A small interlayer expansion (~0.7 ​Å) was observed with decanoic, palmitic, and sebacic acids which form the trapped carboxylate salts. Meanwhile, acetic acid produced a typical protonic titanate as with mineral acids. The inclusion of carboxylate anion and the accompanying carboxylic acid spectator was proven by their characteristics IR vibrations. Using K<inf>0.8</inf>M<inf>y</inf>Ti<inf>2-y</inf>O<inf>4</inf> (M ​= ​Zn, Ni, Co, Fe, Mg, Li), we showed that the host-guest, acid-base interaction influenced the thermal decomposition of the intercalated species. A correlation was observed between the partial charge at the O atom (normalized by the intercalate content) vs the decomposition temperature of the trapped species. The formation of sodium carboxylates similarly occurred with sodium titanate nanotubes.
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    Extending the basic function of lattice oxygen in lepidocrocite titanate – The conversion of intercalated fatty acid to liquid hydrocarbon fuels
    (2017-12-01)
    Maluangnont, Tosapol
    ;
    Arsa, Pornanan
    ;
    Sooknoi, Tawan
    We report herein the basicity of the external and internal lattice oxygen (O<inf>L</inf>) in lepidocrocite titanates with respect to CO<inf>2</inf> and palmitic acid, respectively. Several compositions have been tested with different types of the metal M aliovalently (co)substituted for Ti, K<inf>0.8</inf>[M<inf>y</inf>Ti<inf>2−y</inf>]O<inf>4</inf> (M = Li, Mg, Fe, Co, Ni, Cu, Zn, Cu/Ni and Cu/Zn). The low CO<inf>2</inf> desorption peak temperature (70–100 °C) suggests that the external O<inf>L</inf> sites are weakly basic similar to TiO<inf>2</inf>. However, the internal O<inf>L</inf> sites are sufficiently basic to deprotonate palmitic acid, forming the intercalated potassium palmitate at the interlayer spaces. The latter serves as a two-dimensional (2D) molecular reactor for the production of liquid hydrocarbon fuels via deoxygenation under atmospheric N<inf>2</inf>. A relationship has been observed between the yield of the liquid products vs the partial charge of the lattice oxygen (δ<inf>O</inf>). Since the deoxygenation pathway is highly dependent on the metal substitution, the redox-active sites might also play some roles. The co-substituted K<inf>0.8</inf>[Cu<inf>0.2</inf>Ni<inf>0.2</inf>]Ti<inf>1.6</inf>O<inf>4</inf> produced ~68.0% yield of the liquid products, with ~ 51% saturated and ~ 15% unsaturated C<inf>15</inf> hydrocarbons at 350 °C.