The influence of torrefaction temperature and reaction time on the properties of torrefied sun‐dried millet and sorghum straws from the arid and semi‐arid zones of western Africa

There are increasing demands for syngas production. Fossil-based fuels expensive and environmentally unfriendly. Affordable, sustainable, healthy alternatives sustainable fuel sources needed. This study focused on producing tor-chars from two different tropical biomasses (from Nigeria, West Africa), which were torrefied characterized to improve their properties potential use as feedstocks in an entrained flow gasifier Torrefaction temperatures of 230, 240, 250, 270 °C residence times 30 60 min used torrefy sundried sorghum straw (SS) millet (MS) at particle size ≤5 mm. The MS SS improved significantly due torrefaction. optimum conditions pretreatment 240 min, increased energy density compensated the severe mass loss significant degradation hemicellulose cellulose. Under these conditions, respective yields 53 wt% 75% 49 straw. O:C atomic ratio decreased 0.3 0.2 resulting higher heating values 25 MJ kg−1 27 kg−1, respectively. ash content by 107% be approximately 7 tor-char, 118% about tor-char. These promising co-firing plants or gasification systems. © 2022 Authors. Biofuels, Bioproducts Biorefining published Society Industrial Chemistry John Wiley & Sons Ltd.