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BACKGROUND: Acidic hydrolysis of a birch (Betula pendula) xylan produced by a novel semi‐industrial‐scale aqueous‐based and highly sustainable method was studied in a batch reactor. Five commercial acidic heterogeneous catalysts were screened and significant differences in their performance were observed. Dowex 50WX2‐100 was selected for further studies and the influence of the reaction parameters, including stirring speed, pH (0.5–1.5), temperature (115–145 °C) and catalyst particle size (50–400 mesh) were studied. The goal was to maximize xylose yield by balancing between the kinetics of hydrolysis and the undesired degradation of monosaccharides. RESULTS: The results show that the maximum achieved yield of xylose was 76%, but higher yields were hindered by the consecutive dehydration of sugars. It was also observed that the hydrolysis and dehydration reactions do not follow the same dependence on the experimental parameters, which leaves room for optimization of the yield. A kinetic model was developed based on the data, which takes into account the consecutive reaction pathway and the influence of the experimental conditions, and a very good fit of the model to the experimental data was achieved. An activation energy of 119 and 88 kJ mol–1 was obtained for the hydrolysis and dehydration steps, respectively. CONCLUSION: Hydrolysis results of this novel, well‐characterized hemicellulose extract have not been published previously, and they contribute significantly to the understanding of the hydrolysis and dehydration of real feedstock, instead of highly purified and typically very deacetylated model compounds with different characteristics and behaviour in hydrolysis. © 2021 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

• Industrial xylan was converted into xylitol in a continuous reactor. • Isothermal single flow through using two catalyst beds was utilized. • The selectivity of the process was enhanced compared to conventional processes. • Over 90% yield was achieved. Xylan obtained from birch (betula pendula) by a novel semi-industrial scale aqueous based method was used for studying the hydrolysis and consecutive hydrolysis-hydrogenation processes in continuous reactors. Dowex 50WX2-100 was chosen as the hydrolysis catalyst based on the results of catalyst screening performed previously in batch reactor. It was also observed to perform well in continuous reactor converting xylan to xylose in high yield under the studied reaction conditions. The influence of several reaction parameters were investigated for optimization. Similar experimental conditions used in the hydrolysis were then applied for studying one flow through hydrolysis and hydrogenation of the semi-industrial xylan. A consecutive catalyst bed consisting of ruthenium on carbon was introduced into the continuous reactor downstream from the hydrolysis bed to hydrogenate monosaccharides to xylitol. Hydrogen was co-fed into the reactor with the xylan solution. Reaction parameters, including temperature, residence time and hydrogen pressure, were varied to maximize the xylitol yield. The developed continuous process was demonstrated to be highly selective and efficient for the valorization of the semi-industrial xylan by yielding over 90% xylitol under optimal experimental conditions. It was noticed, that co-feeding hydrogenation decreased the degradation of monosaccharides during hydrolysis, thus improving the selectivity towards the target product and enabling remarkable process intensification. Moreover, mathematical modelling was performed for the hydrolysis and one flow through hydrolysis and hydrogenation processes. The models take into account the consecutive reaction pathways and the influence of the experimental conditions. Good fits of the model to the experimental data were obtained. The conversion of this novel, well characterized wood-based xylan to produce xylose or xylitol in continuous reactors has not been studied previously. The current work contributes significantly to understanding the processing of real feedstock in one flow through employing consecutive reactions and provides necessary data for process intensification. Graphical Abstract [Display omitted]. [ABSTRACT FROM AUTHOR]