A new reaction system for the highly selective, hydrobromic acid catalyzed conversion of lactide into acrylic acid under mild conditions is reported. The applied liquid reaction system consists of a temperature-stable bromide-containing ionic liquid and 2-bromopropionic acid as a source of dry HBr, with no volatile organic solvent being used. This allows for the in situ removal of the formed acrylic acid, leading to an unmatched acrylic acid selectivity of over 72 % at full lactide conversion. Accounting for leftover reaction intermediates on the way to acrylic acid, which could be recycled in an elaborate continuous process, the proposed reaction system shows potential for acrylic acid yields well above 85 % in the liquid phase. This opens new avenues for the effective conversion of biogenic lactic acid (e.g., obtained by fermentation from starch) to acrylic acid. The resulting bio-acrylic acid is a highly attractive product for, for example, the diaper industry, where we expect consumers to be especially sensitive to aspects of sustainability.
The lattice parameter changes in three types of Nb 3 Sn superconducting wires during uniaxial stress-strain measurements at 4.2 K have been measured by high-energy synchrotron x-ray diffraction. The nearly-stress-free Nb 3 Sn lattice parameter has been determined using extracted filaments, and the elastic strain in the axial and transverse wire directions in the different wire phases has been calculated. The mechanical properties of the PIT and RRP wire are mainly determined by the properties of Nb 3 Sn and unreacted Nb. This is in contrast to the bronze route wire, where the matrix can carry substantial loads. In straight wires the axial Nb 3 Sn pre-strain is strongest in the bronze route wire, its value being smaller in the PIT and RRP wires. A strong reduction of the non-Cu elastic modulus of about 30% is observed during cool-down from ambient temperature to 4.2 K. The Nb 3 Sn Poisson ratio at 4.2 K measured in the untwisted bronze route wire is 0.35. The present study also shows that the process route has a strong influence on the Nb 3 Sn texture.
Synthesis of bulk
chemicals from biogenic resources is gaining
increasing interest in industry and academia. In the present study,
we demonstrate the continuous production of acrylic acid (AA) from
biogenic lactide in a liquid-phase reaction using the ionic liquid
tetrabutylphosphonium bromide as reaction medium and 2-bromopropionic
acid as acid catalyst precursor. We here present a first continuous
setup for AA production from LA derivatives in the liquid phase on
a 10 L scale. The process operates at 200 °C and leads to AA
yields of 72% in industrially relevant space–time–yields
of up to 50 g/(h·L). We demonstrate continuous operation over
6 h time-on-stream, efficient product isolation and successful catalyst
recycling.
Liquid organic hydrogen carriers (LOHC) are a technology that allows storing hydrogen in a safe and dense manner by reversible chemical conversion. They constitute a very promising option for energy storage, transport, and release combined with electric power generation by fuel cells in large‐scale applications like trains. In order to establish trains running on LOHC, it is mandatory to ensure the reliability of the system. This study evaluates various system configurations concerning reliability and resilience. The fault tree analysis method has been used to quantify the probability of failure. The S‐P matrix was applied to assess the different failure modes in context of severity as well as their probability. The MTTF of the system can be more than doubled by introducing single redundancy for the fuel cell and the reactor, while more than two redundant components diminish the positive effect on reliability due to higher complexity. It is estimated that the systems full functionality is available for more than 97% of its operating time.
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