The new concept of integrated biorefineries has significantly changed pulp and paper industries. Lignin, which until then was only burned to generate energy, is now an important raw material for new products production. Kraft lignin (KL) fractions obtained by sequential fractionation with five organic solvents. This sequence allows to extract fractions from lower molar mass to higher molar one, resulting in more homogeneous samples. Lignin’s fractions were characterized by FTIR, GPC, TGA and Higher Heating Value (HHV). HHV for KL was 24966, the lowest being 17,891 (F5) and the highest being 27051 J/g (F1), inversely proportional to the molar masses of fractions. This is a very important result indicating that the lower HHV fractions can be used for certain applications, such as antioxidants, additives, polymers, among others, adding value to kraft lignin. Fractions with higher HHV could be used for energy generation in the cellulose paper industry.

一体化生物精炼厂的新概念已大大改变了纸浆和造纸行业。直到那时才被燃烧产生能量的木质素，现在已成为新产品生产的重要原料。通过用五种有机溶剂顺序分馏获得的硫酸盐木质素（KL）馏分。此顺序允许从较低的摩尔质量到较高的摩尔质量中提取馏分，从而得到更均一的样品。木质素的馏分通过FTIR，GPC，TGA和较高的热值（HHV）进行表征。KL的HHV为24966，最低为17,891（F5），最高为27051 J / g（F1），与馏分的摩尔质量成反比。这是一个非常重要的结果，表明较低的HHV分数可用于某些应用，例如抗氧化剂，添加剂，聚合物等，为牛皮纸木质素增加价值。具有较高HHV的馏分可用于纤维素纸工业中的能量产生。