72 research outputs found
Advances in simulated moving bed chromatographic separations
The development of some unconventional Simulated Moving Bed (SMB) strategies, such as the introduction of nonsynchronous inlet/outlet shifts (the Varicol process), variable flux or variable composition in the inlet/outlet streams (PowerFeed and Modicon, respectively), and also the use of multiple feed or distributed feed, have increased the potential of this technique for a wide range of binary separations. For multiple component separations, different strategies has been investigated, including a cascade of SMB, more complex SMB units composed by several adsorption zones, and the JO process operating in two different separation steps
Screening of Heterogeneous Photocatalysts for Water Splitting
In this contribution, a simple method for the screening of photocatalytic activity of catalyst materials is presented. The method is based on two steps the immobilization of the photocatalyst and the subsequent testing of their photocatalytic activity, using the gas evolution at the solid liquid interface. Up to four catalysts can be tested under the same conditions. The observed gas evolution for selected photocatalysts is consistent with trends reported in the literature from conventional photocatalytic reactor
Cyclic steady state of simulated moving bed processes for enantiomers separation
Simulated moving bed (SMB) technology developed by UOP in early 1960s has expanded greatly in the last decade, finding new applications in the area of natural products, fine chemistry and pharmaceutical industry. SMB processes are periodic processes designed to operate in cyclic steady state (CSS) and, therefore, the correct determination of CSS is needed for the assessment of the SMB performance. Two approaches can be used for determination of CSS: the dynamic simulation until CSS is reached and direct prediction of CSS. The direct prediction of CSS could be obtained in two ways: (i) considering that at CSS the spatially distributed SMB unit state at the end of the cycle is identical to that at its beginning (Method 1); or (ii) considering that at CSS the spatially distributed SMB unit state at the end of a switching time interval is identical to the state at the beginning of the interval, apart from a shift of exactly one column length (Method 2). The mathematical models assume axial dispersion flow and linear driving force (LDF) approximation for intraparticle mass transfer. Mathematical models were solved using the g (general Process Modelling System) software package. Both approaches (dynamic simulation and direct CSS prediction) were applied to the prediction of cyclic steady state of SMB unit for 1,1′-bi-2-naphthol enantiomers separation. The direct CSS predictions were compared with the standard dynamic simulation CSS prediction in terms of accuracy of SMB performance and computing time requirements; the Method 2 for CSS prediction is more efficient than the standard dynamic simulation
Elemental composition, heat capacity from 2 to 300 K and derived thermodynamic functions of 5 microorganism species
FT-IR spectroscopic investigation of Hofmann Td-type complexes of 2-, and 3-chloropyridine
Hofmann-type modified clathrate hosts containing 2- or 3-chloropyridine molecules attached to metal (II) tetracyanocadmate frame, with a given formula: M(Clpy)(2)Cd(CN)(4), where M = Mn, Ni or Cd; Clpy = 2- or 3-chloropyridine, have been synthesised for the first time. Their FT-IR spectra are reported in the 400-4000 cm(-1) region. All the vibrational modes of coordinated Clpy are characterised. The spectral features of the compounds studied are found to be similar to each other indicating that they have analogous structures. The coordination effect on the Clpy modes is analyzed
Temperature Dependent Vibrational Spectroscopic Study of Montmorillonite From the Republic of Macedonia: I. Interaction of 2-Aminopyrimidine with Montmorillonite
Modeling adsorption equilibria of xylene isomers in a microporous metal–organic framework
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