A model for the rate of catalytic oxidation of methanol in a fixed bed reactor

Oxidation of methanol to formaldehyde, using a mixture of ferric and molybdenum oxides as catalyst, has been studied in a fixed bed integral reactor, 150 mm long, 25 mm o.d. and 10 mm i.d. The catalyst was prepared by reaction between aqueous solutions of ammonium heptamolybdate and ferric chloride. It has been shown that, under experimental conditions similar to those employed in industry, neither external nor internal diffusion had been effective in the process and isothermal conditions prevailed in both gas and solid phases. A two-step mechanism has been put forward for the oxidation of methanol. According to such a mechanism, methanol is first oxidized to formaldehyde, accepting an oxygen molecule from the catalyst and changing the latter into a reduced form. In the second step, the reduced catalyst is transformed into the original form on obtaining an oxygen molecule from the gas phase. Based on this scheme, a rate model has been derived and verified by experimental results.     

Synthesis of fluorescent ABA triblock copolymer via click reaction

A hyperbranched–linear–hyperbranched (ABA) triblock copolymer containing poly(ethylene glycol) (PEG) as linear block and polyglycerol (hbPG) as hyperbranched blocks has been synthesized through a copper‐catalysed click reaction. In order to synthesize the hyperbranched block, propargyl alcohol‐initiated ring‐opening multibranching polymerization of glycidol was used to prepare hbPG with the propargyl segment in the focal point (CH?C? hbPG). Separately, PEG was functionalized at both ends using cyanuric chloride, and then the chloride groups of cyanuric chloride were substituted by azide groups. Finally, the azide‐functionalized PEG was conjugated to CH?C? hbPG via a click reaction. Substitution of the chlorine atoms of cyanuric chloride under different conditions together with click chemistry allows the synthesis of a variety of polymeric architectures. In the last step, fluorescein was attached to the block copolymer as a fluorescent probe in order to study the cell internalization of this copolymer. This type of triblock copolymer is a promising future nanomaterial for simultaneous drug delivery and cell imaging. © 2016 Society of Chemical Industry     

Forecasting Groundwater Levels using a Hybrid of Support Vector Regression and Particle Swarm Optimization

Water Resources Management - Forecasting the groundwater level is crucial to managing water resources supply sustainably. In this study, a simulation–optimization hybrid model was developed...     

Calculation of the second virial coefficient of nonspherical molecules: Revisited

An accurate Hartree–Fock dispersion individually damped (HFD-ID) potential type improved by Boyes for argon has been used as a core potential to calculate both the spherical and nonspherical contributions to the second virial coefficient of simple molecules. The auxiliary functions that occur in the perturbation terms for calculating the nonspherical contributions, have been calculated numerically and are tabulated over a wide range of temperatures from T^*=0.5 to T^*=10, where T^*=kT/ and is the potential well-depth. By fitting the well-depth and the position of the minimum in the core potential, we have calculated the second virial coefficient of N₂, O₂, CO, NO, and CO₂ over the whole temperature range reported in the literature. The calculated results are compared with the large body of experimental data in the literature, and with the pervious calculations by Boushehri et al. (1987). The agreement with both experimental data and theoretical calculations is quite good.