Production of Furfural from Industrial Hemp Shives in the Pretreatment Stage of a Biorefinery System

In this work the effect of aluminum sulfate on the degradation of the hemicellulose part of shives of industrial cannabis (Cannabis sativa L.) and on the conversion of pentoses into furfural during hydrolysis was determined. By changing the temperature of the hydrolysis process (140–180 °C), the amount of aluminum sulfate (0–7 %, calculated on the absolutely dry matter) and the duration of the treatment (30–90 min), the research succeeded to obtain both from hemp shives – the high yield of furfural (67.8 kg from one absolutely dry ton) and to preserve cellulose in a solid residue (99.7 % of the initial quantity) for further processing. For example, a total dry ton of such solid residue could produce 307 L ethanol, equivalent to the quantity that can be obtained from wheat grain. As a result, it can be argued that a new environmentally friendly and equipment friendly hydrolysis process has been developed during research. Proposed hydrolysis process allows the integration of the furfural production process into the biorefinery system. Without furfural, compounds such as acetic acid, 5-hydroxymethyl furfural, levulinic acid and formic acid were also identified and quantified in the obtained hydrolyzate using a high-performance liquid chromatograph. Among these compounds, the amount of acetic acid was the largest. The quantity of acetic acid, which can be obtained in parallel with furfural, is 51.4 kg from one ton of absolutely dry hemp shives. In addition, this acetic acid can be used in food, which gives it greater value. Consequently, a solution has been provided for the useful use of hemp shives and for the diversification of the biorefinery system, which follows the cascade principle – biomass is used primarily for the production of high added value products followed by the production of a less valuable product.