Biopolymer
chitosan has a large amount of hydroxyl and amino groups
which can interact with metals and modify physicochemical properties
at interfaces and are ideal as supports in catalytic systems. Here,
we show the catalytic system that leverages reactive metal–biopolymer
interactions for selective hydrogenation of acetylene, which represents
one of the most important reactions in the petrochemical industry.
Approximately 100% conversion and ∼90% selectivity to ethylene
can be achieved at 90 °C. In situ diffuse reflectance infrared
Fourier transform spectrometer identifies the di-σ adsorption
of acetylene over metal sites, which competes favorably with ethene
adsorption, resulting in high selectivity. Quantum-chemical simulations
suggest that the perpendicular mode of chitosan adsorption via the
NH2 group is energetically favorable on Pd(111) compared
to others by ∼0.6 eV. Compared with pristine Pd(111), *C2H4 is favorable to desorb into the gas phase rather
than further hydrogenation over Pd/CTS due to the lowering of the
electronic d-states of Pd upon adsorption of chitosan.
With an increasingly complex and rapidly changing construction circumstance, owners and their contractors are confronting challenges from risk management while maintaining control and improving performance. With great capabilities for project management solution, Monte Carlo simulation was used to forecast projects' execution results. In this paper, a practical example, construction and installation engineering in cargo area of Kunming Changshui international airport project is studied to show explicitly the benefits of using Monte Carlo simulation to assess risk in practical scheduling.
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