Valorization of "Leucaena leucocephala" for energy and chemicals from autohydrolysis

Abstract

In this work, Leucaena leucocephala K366 was characterized chemical and energy terms, and assessed its potential as a lignocellulosic raw material and energetic and industrial crop specie, and its integral fractionation by autohydrolysis by evaluating its calorific value, holocellulose, glucan, xylan, arabinan, lignin and oligomers and monomers contents in autohydrolysis liquor and solid phase. Also, this paper will consider the influence of the temperature and time of autohydrolysis process from L. leucocephala K366 to obtain valuable liquor and a suitable solid phase to produce energy by combustion.

Valuable liquor was obtained from the autohydrolysis of L. leucocephala by simultaneously using operating temperatures and times in the medium–high ranges studied, namely: 172–184 °C and 15–30 min. The optimum processing conditions provided an acceptable yield (16–26%), and high xylose and xylo-oligomer contents in the liquor (10.0 and 58.6%, respectively, of the amounts present in the starting raw material when operating at 184 °C for 30 min) in comparison with other raw materials. The arabinan fraction was extracted virtually completely —only 8.3% remained in the solid fraction—, and the acetyl group fraction was recovered in full. In addition, these conditions reduced the glucose content of the liquor to 2.9% of the amount present in the raw material while largely preserving the integrity of cellulose fibers.

Klason lignin was scarcely dissolved under the operating conditions of the autohydrolysis process. This increased the calorific value of the solid phase by 9% (under the most drastic operating conditions) with respect to the starting raw material.