Optimization of reducing acid of high-acid feedstock of biodiesel based on artificial neural networks

Abstract

In order to get the optimal conditions of reaction, based on single factor experiment, oleic acid as the high-acid feedstock of biodiesel, orthogonal experiment and artificial neural networks were applied to optimize the synthetic conditions for reducing acid of high-acid biodiesel feedstock catalyzed by SO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2-</sup> /ZrO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> solid super acid. Based on orthogonal experiment, the three layers error back-propagation network (BP network) model was trained to reflect correlation of experimental data. And the optimal conditions were obtained from this network model as follows: SO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2-</sup> /ZrO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> solid super acid was 4%(W/W) as catalyst, reaction temperature was 97.5°C, reaction time was 180mins, and flow rate of gaseous methanol was 1.65 L-min <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . Under the optimal conditions, validated experiment showed that the conversion rate of oleic acid was 96.89%, and the relative error was 0.03% compared with the predicted value. Therefore, the optimal conditions obtained based on BP artificial neural network are reliable and have better practical value.