Fast pyrolysis of mannan-rich ivory nut (Phytelephas aequatorialis) to valuable biorefinery products

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2019-10, Vol.373, p.446-457
• Main Authors: Ghysels, Stef, Estrada Léon, Adriana Elena, Pala, Mehmet, Schoder, Katharina Alexandra, Van Acker, Joris, Ronsse, Frederik
• Format: Article
• Language: English
• Subjects: Biochar; Biorefinery; Fast pyrolysis; Ivory nut mannan; Levomannosan; Platform chemicals
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2019.05.042

[Display omitted] •Fast pyrolysis of mannan-rich ivory nut was performed at 350 °C and 500 °C.•Pyrolysis liquids (yield 58–60 wt%) were rich in levomannosan and 5-hydroxymethyl furfural.•Biochar and non-condensible gases (NCGs) were characterized.•Biochar holds potential for e.g. soil applications, NCGs hold potential for e.g. syngas processes. Ivory nut residues from the palm Phytelephas aequatorialis were converted via fast pyrolysis into a set of valuable biorefinery products, being (i) pyrolysis liquids rich in levomannosan and 5-hydroxymethyl furfural (5-HMF), (ii) biochar, with potential for soil applications, (iii) and non-condensable gases with potential for upgrading and syngas processes. The ivory nut residues were mannan-rich leftovers from button manufacturing in Ecuador. A handful of studies, dating back from the 20th century, have investigated gram-scale valorization of ivory nut to e.g. mannose. Nevertheless, advances in science and technology on biorefinery products called for a comprehensive reassessment of the valorization potential of this underutilized feedstock. A fully equipped, continuously operated lab-scale reactor (200 g.h−1 feed) was used for pyrolysis at 350 °C and 500 °C. The pyrolysis liquid yield was 57.53 wt% at 350 °C and 60.36 wt% at 500 °C. The aqueous phase obtained at 350 °C contained 17.5 wt% (d.b.) anhydrosugars, of which 90% was levomannosan, and contained 11.6 wt% (d.b.) furans, of which 56% was 5-HMF and 17% furfural. The carbon stability of the biochars, measured with the Edinburgh accelerated ageing tool, were 40.6% and 64.6%, respectively. Non-condensable gases during pyrolysis at 350 °C only were composed of CO2 and CO (CO2:CO molar ratio of 4:1), while at 500 °C, gases were obtained with a CO2:CO:H2:CH4 molar ratio of 9:9:4:1. Overall, the results demonstrate that pyrolysis of ivory nut holds potential as starting point for valuable biorefinery products.