Rosa Nomen

Detection and characterisation of water alcohol hydrates by on-line FTIR using multivariate data analysis

Abstract In the current work, several chemometric functions based on the principal component analysis (PCA) are studied in order to determine the number of absorbing species in an infrared data matrix acquired during a mixing process. Applying a target factor analysis (TFA), the concentration profiles of the chemical substances are obtained without the need for a calibration of the spectrometer. Different considerations concerning the objective function of the optimisation process have been tried. The chemical systems tested for such techniques are alcohol–water mixtures. The study is completed with calorimetric data that confirm the hypothesis of the presence of a hydrate suggested by the information from the spectra. The mathematically extracted concentration–time profile results are finally verified with traditional methods of quantitative analysis. This particular case will also confirm the validity of the experimental design, according to the rank compatibility test (RCT) for semibatch reactors proposed by our group.

Sensitivity analysis of the 2-methylpyridine N-oxidation kinetic model

A sensitivity analysis of a previously developed global kinetic model, of the N-oxidation of 2-methylpyridine, involving seven kinetic and equilibrium constants, has been performed. It has been identified how individual constants influence the power evolution profile. The conditions, which ensure measurements sensitive to all constants, are outlined. A readily applicable, simple methodology has been developed to achieve accurate evaluation of the kinetic constants involved.

Maximum temperature attainable by runaway of synthesis reaction in semibatch processes

Abstract A new scenario for the calculation of the adiabatic temperature increase for semi-batch processes is presented. In the safety assessment of chemical reactions it is necessary to determine the value of the Maximum Temperature attainable by runaway of the Synthesis Reaction for the worst case. We demonstrate that the batch scenario is not always the most dangerous way to carry out a reaction. In addition, an improvement in the calculation of the MTSR is presented in order to obtain more realistic scenarios.

A comparison of calorimetric measurements by using different reaction calorimeters

For a great number of European safety groups, reaction calorimetry is the key technique for analysis of the main reaction in the risk assessment of chemical processes. A comparison of calorimetric studies of model reactions, the N-oxidation of two substituted pyridines with hydrogen peroxide, made by several European groups, can open the door to standardization of the methodologies used. However, the intrinsic experimental complexity of the model reactions, which included dosing at high temperature, a multiphase system and evaporation, and the different evaluation criteria, produced a considerable dispersion between the results obtained by the various groups.

Numerical simulation of fixed bed for CO 2 capture in a fossil fuel emission points by Pressure Swing Adsorption system

Abstract In many previous works, zeolites are the commercially available adsorbents mostly studied for CO 2 capture, with attention to zeolite 5A and zeolite 13X. In this study, we have modelled the adsorption equilibrium and simulated the breakthrough curves for the adsorption of carbon dioxide on Pressure Swing Adsorption (PSA) processes for CO 2 capture from a mixture with 15% CO 2 –85% N 2 (simulating dry post-combustion flue gases of a coal-fired power station) using the experimental characterization of zeolite 5A and zeolite 13X published in a recent bibliography. A model based on the Linear Driving Force (LDF) approximation for the mass balance, including energy balance and momentum, was used for the simulation of CO 2 capture in pressure swing adsorption systems. The models were described by partial differential equations (PDEs) coupled with Algebraic Equations (PDAEs) including conservation equations, models for equation of state, equilibrium, thermodynamic, and transport properties. This work was implemented and solved with Matlab™ software. We present numerical results that adequately reproduce the experimental data for the studied temperatures, suggesting that the assumptions on which the model is based on could be valid for this system and can be used to design a PSA cycle to separate CO 2 /N 2 mixtures.

Nonparametric Kinetic Methods

As all classic methods for kinetic analysis of data from thermal analysis experiments, the nonparametric kinetics method, NPK, assumes that the general expression for the reaction rate of a simple reaction is

Measurement of pollution levels of organochlorine and organophosphorus pesticides in water, soil, sediment, and shrimp to identify possible impacts on shrimp production at Jiquilisco Bay

{\dot{\alpha } = g(\alpha ) \cdot f(T)}

Thermal decomposition of tricyclohexylidene triperoxide

(16.1) where g(α) symbolizes the kinetic model of the process and f(T) accounts for the temperature dependence of the reaction.