초록
<P><B>Abstract</B></P><P><B>BACKGROUND</B></P><P><B>The coenzyme NAD<SUP>+</SUP> (nicotinamide adenine dinucleotide) is commonly used in biocatalytic oxidations catalysed by the enzyme alcohol dehydrogenase (ADH). As the price of the coenzyme NAD<SUP>+</SUP> is extremely high, it is essential to regenerate the reduced form of the coenzyme back into the oxidized form. In this work the regeneration of the coenzyme NAD<SUP>+</SUP> was carried out in a microreactor by reversible oxidation of ethanol to acetaldehyde with the ADH enzyme</B>.</P><P><B>RESULTS</B></P><P><B>A 100% conversion of NADH was achieved for a residence time of just <I>τ</I> = 0.8 s when the concentration of acetaldehyde was in excess <I>(c</I><SUB>i,</SUB><SUB>NADH</SUB> = 5.5 mmol dm<SUP>‐3</SUP>, <I>c</I><SUB>i,</SUB><SUB>acetaldehyde</SUB> = 44 mmol dm<SUP>‐3</SUP>, <I>γ</I><SUB>i,</SUB><SUB>ADH</SUB> = 0.2 g dm<SUP>‐3</SUP>, 75 mmol dm<SUP>‐3</SUP> glycine‐pyrophosphate buffer pH = 9; <I>T</I> = 25°C). A 2D mathematical model for the description and prediction of microreactor performance was developed. Model simulations were validated using data from independent experiments</B>.</P><P><B>CONCLUSION</B></P><P><B>The high conversions that were obtained for short residence times mean that the microreactors can be considered as good and efficient methods for coenzyme regeneration. © 2013 Society of Chemical Industry</B></P>