Biorefinery process for production of paper and oligomers from Leucaena leucocephala K360 with or without prior autohydrolysis

Lignocellulosic material from Leucaena leucocephala was subjected to a two-stage fractionation process to obtain a valorized effluent containing hemicellulose derivatives and a solid phase for producing cellulose pulp by conventional soda-anthraquinone delignification. This solid phase allows the production of cellulose pulp, under less rigorous conditions from NaOH-AQ process (177 °C, 21%, 120 min) than without pretreatment delignification (185 °C, 25%, 150 min) and better or similar properties in the paper sheets obtained (yield 27.6 and 34.0%, brightness 39.3 and 31.6% ISO, tensile index 7.8 and 10.5 N m/g, burst index 0.43 and 0.29 MPa m(2)/kg with and without previous autohydrolysis) have be found. Also, the first autohydrolysis stage allows up to 46.6% of the initial hemicellulose in the raw material to be extracted as xylooligomers, xylose and furfural into the liquid phase.

Optimization the soda-AQ process for cellulose pulp production and energy content of black liquor from L. leucocephala K360

A commercial variety of Leucaena leucocephala K360 was used for pulp production and papermaking employing the soda-anthraquinone process. Also, the chemical and energy contents of the resultant black liquors were determined to simultaneously optimize: pulp and paper production and energy generation. A process temperature of (185°C), an operating time of (120 min) and an active alkali concentration of (21%) provided sheets of paper with good strength (tensile index of 12.12 Nm/g, burst index of 0.38 kPa m(2)/g, tear index of 1.29 mN m(2)/g and a Kappa number of 20.5) and black liquor with a greater calorific value (14.1 MJ/kg) than that obtained with higher active alkali concentrations. However, reducing the active alkali concentration to a level in the low operation range led to less marked degradation of cellulose and allowed paper sheets with good properties to be obtained and energy to be optimally produced from the black liquor.