Determinação de parametros de qualidade da gasolina e estudo de contaminantes utilizando espectros do infravermelho proximo na fase vapor

AUTOR(ES)

Eliane Rodrigues de Sousa

DATA DE PUBLICAÇÃO

2005

RESUMO

A near infrared based on an acoustic optic tunable filter (AOTF) was constructed for spectra acquisition of gasoline in the vapor phase. The measuring system of the instrument was composed by a detection cell and a sample cell, where temperature sensors were adapted to monitor the temperature of the gasoline vapor and the temperature of the silicone bath used for heating the sample, respectively. Spectra from 1500 to 2400 nm were obtained in the temperature range of 25 - 90 ºC, in steps of 5 ºC. The quality parameters of the gasoline (10%, 50% and 90% distilled volume, end point of distillation, density, MON and RVP) were predicted by employing vapor phase spectra and Partial Least Square (PLS). The RMSEP and correlation coefficient values were compared with those obtained with measurements performed in liquid phase. The 10% distilled volume parameter showed better predicted values for the vapor phase, presenting RMSEP and correlation coefficient of 1.70 and 0.8082, respectively. Multiway methods, such as unfolded PLS and three-way PLS, were also employed for prediction of quality parameters of gasoline, based on the spectra obtained in the vapor phase at different temperatures. Considering the RMSEP and correlation coefficient values, the latter chemometric method provided better results for 10% distilled volume (1.87 ºC / 0.680), end point of distillation (2.68 ºC / 0.760) and MON (0.57 / 0.880). The system was also evaluated regarding its ability to identify contaminants, such as the hexane, toluene, pentane and ethanol in several concentrations, by employing the Principal Components Analysis, showing better discrimination for compounds with low point of boiling such as hexane and pentane.

ASSUNTO(S)

gasolina gasoline analise multivariada multivariate analysis espectroscopia no infravermelho proximo near infrared spectroscopy

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