11 research outputs found
Upgrade of Biomass-Derived Levulinic Acid via Ru/C-Catalyzed Hydrogenation to γ‑Valerolactone in Aqueous−Organic−Ionic Liquids Multiphase Systems
A liquid triphase system made by an aqueous phase, an
organic phase, and an ionic liquid was designed and applied to the
catalytic hydrogenation/dehydration of biomass-derived levulinic acid to
γ-valerolactone. This paper demonstrates that, by operating at 100−150
°C and 35 atm of H2, both in the presence of Ru/C or of a homogeneous
Ru precursor, the use of the triphase system designed to match the
investigated reaction allows the following: (1) to obtain up to quantitative
conversions and 100% selectivity toward the desired product; (2) to
recover the product by simple phase separation; and (3) to preserve the
catalyst activity for in situ recycles without loss of metal. Globally the
investigated reaction proves the concept that a cradle-to-grave approach
to the design of a catalytic reaction system can improve the global sustainability of a chemical transformation by improving
efficiency, product isolation, and catalyst recycle
Temperature-Dependent Transport Properties of a Redox-Active Ionic Liquid with a Viologen Group
A redox-active ionic liquid (IL),
1-butyl-1′-heptyl-4,4′-bipyridinium
bis(trifluoromethanesulfonyl)imide, has been synthesized and its transport
processes were investigated. The conductivity and viscosity of the
IL, as well as the diffusion coefficients of its components were studied
over a 50 °C wide temperature range: for the diffusivity studies,
both the pulsed-gradient spin–echo (PGSE)–NMR technique
and voltammetric measurements have been applied. The measured data
are presented in the paper and are compared to each other. It was
found that the diffusion coefficients determined by means of NMR and
chronoamperometry measurements are, within the range of experimental
error, equaland they are (in accordance with other ionic liquid
studies) higher than what the conductivity or viscosity measurements
indicate. The results are interpreted in the light of the existing
theories. The measured diffusion coefficients and bulk conductivities
can be well interrelated based on the “ionicity” concept
(that is, by treating the ionic liquid as a weak electrolyte). In
agreement with the empirical Walden rule, a direct comparison between
the measured conductivities and viscosities is also possible, for
which a hole conduction model is utilized. Based on the fact that
both the electrochemical and the NMR measurements yield practically
the same diffusion coefficients in the system, there is no evidence
that interpretations based in other redox-active IL systems on “homogeneous
electron transfer” apply to the system studied here