Analysis of experimental errors in catalytic tests for production of synthesis gas

Abstract

The proper determination of experimental errors in catalytic processes may be very important because experimental errors can exert a major impact upon the analysis of experimental results. For this reason, the influence of temperature upon the experimental errors observed during the combined carbon dioxide reforming and partial oxidation of methane over Pt/γ-Al 2O 3 is studied here. It is shown that fluctuations of output stream compositions may decrease more than one order of magnitude as reactor temperature increases in the range from 600 to 1100 °C during catalytic tests. Additionally, it is shown that the covariance matrix of composition measurements is not diagonal, as usually assumed, and may change very significantly with the experimental conditions. Therefore, experimental errors should not be regarded as constant and covariance matrices should not be assumed to be diagonal a priori for kinetic model building and parameter estimation. It is also shown that the covariance matrix may contain significant amount of information about the reaction mechanism, which can be used for model building and interpretation of kinetic experiments. Particularly, it is shown that the actual experimental error may be much smaller than usually obtained when covariance terms are neglected and that fluctuation of catalyst activity may concentrate most of the experimental fluctuations observed experimentally.