The reversible interactions of dissolved CO(2) with H(2)O and OH(-) to form H(2)CO(3) and HCO(3)(-) in aqueous solution have been investigated using spectrophotometric stopped-flow measurements. The progress of the reactions was monitored via indicators coupled to the pH changes during the reactions. The study, involving global analysis of the complete data set, spanned the temperature range 6.6-42.8 degrees C and resulted in the evaluation of all rate and equilibrium constants as well as activation parameters for the kinetic data and the reaction enthalpies and entropies for the equilibrium constants.

Removal of carbon dioxide from fossil-based power generation is a potentially useful technique for the reduction of greenhouse gas emissions. Reversible interaction with aqueous amine solutions is most promising. In this process, the formation of carbamates is an important reaction of carbon dioxide. In this contribution, a detailed molecular reaction mechanism for the carbamate formation between MEA (monoethanolamine) and dissolved CO(2) as well as carbonate species in aqueous solution is presented. There are three parallel, reversible reactions of the free amine with CO(2), carbonic acid, and the bicarbonate ion; the relative importance of the three paths is strongly pH dependent. Kinetic and equilibrium measurements are based on (1)H NMR and stopped-flow measurements with rate constants, equilibrium constants, and protonation constants being reported.

A model has been developed to predict the CO2 capacity of amine-based solvent systems as well as the enthalpy associated with absorption/desorption. This model can be used to accurately predict the behavior of well-characterized solvent systems under a range of different conditions. Alternatively, the model can be used to estimate the properties of less well-defined systems as part of an initial rapid screening procedure. Investigation into the effects of varying amine basicity and degree of carbamate formation indicates that there is considerable room for improvement on the standard MEA (monoethanolamine) system in terms of both capture capacity and enthalpy of CO2 desorption.

Review:In an overview of technologies for fossil fuel-fired power plants with drastically reduced CO 2 emissions the three main technologies postcombustion capture, pre-combustion capture, and oxyfuel technology are presented and compared. Postcombustion capture using reactive absorption is discussed in detail due to its potential for application on a large scale in the near future. Research Article: Methanol with the potential to be synthesized via renewable feedstocks is a good substitution for petroleum fuel if the process economics were scaled down. One way to address this issue is the development of the process to a level with high hydrocarbon yield. Pressure proved to be an important parameter to achieve higher selectivity toward hydrocarbons. Deoxygenation of Methanol over ZSM-5 in a High Hydrodynamics of a Tapered Bubble ColumnA. Bandyopadhyay*, M. N. Biswas The study of their hydrodynamic characteristics gives important information on the operation of these systems. Axial dispersion, holdup, and pressure drop depend on process conditions, greatly affect the performance of the string reactors, and are indispensable in process simulation.

No abstract

No abstract

No abstract

Different thermodynamic properties of aqueous solutions of butyltriacetonediamine (BuTAD), unloaded and loaded with carbon dioxide, are studied experimentally. For unloaded mixtures of BuTAD and water, protonation equilibrium constants between 283 and 333 K and liquid–liquid equilibria between 313 and 353 K, including the lower critical point, are determined at atmospheric pressure. Furthermore, the solubility of carbon dioxide in aqueous solutions of BuTAD between 313 and 393 K is determined at low loadings with an analytic method based on headspace gas chromatography and at high loadings with a synthetic method using a high pressure view cell. In the loaded system, solid precipitation, liquid–liquid phase split, and the presence of metastable states are observed in certain ranges. The data is interesting for assessing the aqueous solution of BuTAD as solvent for carbon capture. A short-cut method is used for comparing the new solvent with an aqueous solution of monoethanolamine (MEA) with respect to the energy requirement of an absorption/desorption process for CO2 scrubbing. Furthermore, a new and simple gas chromatographic method for determining the loading with carbon dioxide of aqueous solutions of amines is described.