New biorefinery in the traditional pulp and paper industry
Lignocellulosic raw materials are the most abundant renewable biomass resources on the planet, including wood and wood processing residues, agricultural production waste, forest processing waste and some energy plants. Due to the difference in chemical structure and reaction performance of each component, the separation of components of lignocellulosic raw materials is one of the necessary prerequisites for high value utilization, and the pretreatment method of raw materials is one of the key technologies, and it is also the current restriction of wood fiber.
Pretreatment of lignocellulosic feedstock is a critical step in achieving an economically viable biorefinery. Traditional methods require harsh conditions for pretreatment of biomass, consume large amounts of energy, require significant capital investment, and produce inhibitors that are detrimental to downstream biological processes. These traditional methods also destroy many of the characteristics of naturally occurring polymers and constrain the use of raw materials. The ideal pretreatment should result in higher "availability" of cellulose and hemicellulose, lignin, and other polymers in the lignocellulosic feedstock in subsequent steps, producing a small amount of inhibitory compound, keeping its structure substantially intact, and Limit the loss of biomass.
How to achieve green biorefinery in the traditional pulp and paper industry?
In the pulping and papermaking process, it must be equipped with plant fiber raw material cooking equipment, slurry and black liquor solid-liquid separation equipment, fiber washing and screening equipment, fiber bleaching equipment, alkali recovery equipment, and the like. On this basis, we have made improvements in the separation of plant components. Most of the original equipment can be put into use after simple modification, which can control the technical transformation cost within a reasonable range and reduce the pressure on the existing pulp and paper enterprises.
Under this background, traditional pulp and paper enterprises have become a new type of green bio-refining, with unique advantages and opportunities, and the road to sustainable development in the pulp and paper industry will be easier.
The technical route to achieve green biorefinery in the pulp and paper industry
In order to achieve green biorefinery, the pulp and paper industry mainly needs to carry out the following transformations:
Changes in pulping methods
Pretreatment of raw materials with solvents can effectively protect carbohydrates, reduce fiber degradation and promote efficient removal of lignin due to the specificity of the reagents. At the same time, the cooking temperature is much lower than that of the conventional pulping method. The cooking process can be carried out under normal pressure, which can greatly reduce the pressure and temperature of the cooking, the heating time can be effectively shortened, the cost is reduced, and the safety is improved. The cellulose component obtained after the end of the pretreatment will no longer be limited to papermaking applications. Since the lignin in the fiber is fully removed, and the fiber is degraded to a proper extent during the cooking process, the fiber has excellent floatability and plasticity, and can be further processed to prepare high value-added fiber products, such as dissolving pulp, Microcrystalline cellulose, nanocrystalline cellulose, cellulose acetate, and the like.
Change of chemical recovery method
New solvent pulping, drug recovery is mainly recovered by distillation, and the related process is quite mature, which can ensure the recycling of cooking reagents to the utmost.
Changes in the extraction method of lignin and hemicellulose
After the pretreatment, the cellulose is purified according to the traditional pulping route-washing and sieving, and the lignin is separated from the hemicellulose-degraded saccharide by solid extraction. The raw lignin and sugar liquid can further extract the sugar liquid to produce xylose and furfural for different product routes. Or use lignin and sugar liquid as platform compounds to produce higher value-added chemicals and materials, such as lignin-based carbon fiber materials, furfural-based 2,5-furandicarboxylic acid, and the like.
Through scientific technological transformation, it can not only greatly enrich the product lines of traditional bio-refining enterprises (such as paper making, sugar making, wood processing, bio-fermentation, etc.), improve the comprehensive profitability of enterprises, but also effectively solve their environmental problems. The road to scientific development in the paper industry must go through.