Lab to pilot scale assessment on the pretreatment of empty fruit bunch using anhydrous ammonia

Abstract

Laboratory and pilot scale pretreatment processes were assessed for empty fruit bunch (EFB) at different morphologies using anhydrous ammonia pretreatment (AAP). The AAP was used to deconstruct the complex structure of EFB through physical and chemical reaction to promote efficient conversion of the carbohydrates to monomeric sugars. Different morphologies of EFB samples used were unpressed EFB (UE), pressed EFB (PE), pressed and shredded EFB (PES), and lastly pressed, shredded and ground EFB (PESG). The APP process was optimized using a 1.0 L laboratory scale reactor and further scaled up to a 22 L pressure vessel (AAPB). AAP-PESG contained 76.2%, and AAP-PES contained 75.5% of structural carbohydrates, showing no significant difference. AAP-UE showed the lowest glucan conversion of 28%. The optimal laboratory conditions adopted were 135 °C, 30 min, moist to dry EFB loading of 2:1, and ammonia to dry EFB loading of 1:1. Glucan conversion of AAP-PES were 87%, 80%, and 62% at 1%, 3%, and 6% glucan loadings, respectively. The AAP-PES detected acetamide concentration at 7.3 mg/g, while AAPB-PES was only at 4.4 mg/g. Chemical composition, Fourier transform infrared spectroscopy, Brunauer Emmett Teller surface area, and scanning electron microscopy supported the assessment of AAP and AAPB processes.