The present synergies for at least two parallel cooking plants, e.g., one producing dissolving pulp in a prehydrolysis kraft process, and the other producing kraft pulp by kraft pulping process, which may facilitate increased cooking yield in the kraft cooking plant producing kraft pulp by recovering the hemicelluloses solubilized in the acidic hydrolysate of the prehydrolysis kraft process. In some implementations, there may be no cold caustic extraction step on the dissolving pulp line as the target pulp purity can be achieved by performing just a prehydrolysis step, with reutilization of an acidic hydrolysate stream in a kraft pulp line.

The present invention relates to a supported anthraquinonic catalyst which may be obtained by radical polymerization of a reaction mixture comprising styrene; at least one initiator generating free radicals; at least one cross-linking agent which is at least difunctional, at least one pore-forming agent; and at least one anthraquinonic styrenic monomer of formula (I)

##STR00001## wherein n is an integer varying from 1 to 5.

The method is for the preparation of kraft pulp with increased pulping yield from lignin-containing cellulosic material using polysulfide cooking liquor. In order to increase carbohydrate stabilization and hence the yield from a kraft cooking process a first impregnation stage using polysulfide cooking liquor is implemented at high alkali and polysulfide concentration and at a low temperature. Knots are added to a high-pressure conduit extending between an impregnation vessel and a digester.

The method is for the preparation of kraft pulp with increased pulping yield from lignin-containing cellulosic material using polysulfide cooking liquor. In order to increase carbohydrate stabilization and hence the yield from a kraft cooking process a first impregnation stage using polysulfide cooking liquor is implemented at high alkali and polysulfide concentration and at a low temperature. Knots are added to a high-pressure conduit extending between an impregnation vessel and a digester.

Discloses are a method for preparing fluff pulp from bamboos, and the fluff pulp prepared thereby. The method comprises the following steps: treating the bamboos with high-concentration alkali at a relatively mild temperature, after a certain period of treatment, replacing a treatment liquid for separating hemicellulose with a weak black liquor; Kraft cooking the treated bamboos to obtain unbleached bamboo pulp, removing rejects in the unbleached bamboo pulp by using a slotted screen; then removing miscellaneous cells by using a microporous sieve; carrying out two stages of oxygen delignification on the screened pulp; carrying out ECF bleaching treatment of a D.sub.0EpD.sub.1P process; and finally obtaining the bamboo fluff pulp which has high whiteness, low DCM extract content, low ash content and long fiber length, contains 4.2-4.6 million fibers per gram, and has relatively high bulkiness.

A super strong and tough densified wood structure is formed by subjecting a cellulose-based natural wood material to a chemical treatment that partially removes lignin therefrom. The treated wood retains lumina of the natural wood, with cellulose nanofibers of cell walls being aligned. The treated wood is then pressed in a direction crossing the direction in which the lumina extend, such that the lumina collapse and any residual fluid within the wood is removed. As a result, the cell walls become entangled and hydrogen bonds are formed between adjacent cellulose nanofibers, thereby improving the strength and toughness of the wood among other mechanical properties. By further modifying, manipulating, or machining the densified wood, it can be adapted to various applications.

A piece of plant material (e.g., wood) can have a lignin content in a range of 5-16 wt %, inclusive, and a microstructure including native lumina bounded by cellulose-based cell walls extending in a first direction. The piece of plant material can be pressed along a second direction crossing the first direction, such that the lumina collapse and facing portions of the collapsed lumina are brought into contact with each other. The piece of plant material prior to the pressing can have a first density. After the pressing, the piece of plant material can have a second density greater than the first density, for example, at least 1 g/cm.sup.3.

The APPARATUSES, METHODS AND SYSTEMS FOR APPARATUSES, METHODS AND SYSTEMS FOR YIELD INCREASE IN A KRAFT COOKING PLANT present synergies for at least two parallel cooking plants, e.g., one producing dissolving pulp in a prehydrolysis kraft process, and the other producing kraft pulp by kraft pulping process, which may facilitate increased cooking yield in the kraft cooking plant producing kraft pulp by recovering the hemicelluloses solubilized in the acidic hydrolysate of the prehydrolysis kraft process. In some implementations, there may be no cold caustic extraction step on the dissolving pulp line as the target pulp purity can be achieved by performing just a prehydrolysis step, with reutilization of an acidic hydrolysate stream in a kraft pulp line.

A method for substantially removing constituents of a lignocellulosic biomass into separate streams, where said method comprises the following steps: Step 1: providing said lignocellulosic biomass comprising: cellulose; hemicellulose; and lignin; Step 2: exposing the lignocellulosic biomass to a delignification step performed at a temperature below 55 C. using a modified Caro's acid and generating a reaction mixture, said delignification step is carried out for a first period of time sufficient to dissolve enough of the lignin present in said lignocellulosic biomass to obtain a kappa number for the remaining solids of less than 10; Step 4: recovering, from the reaction mixture, a liquid stream comprising depolymerized lignin constituents and said remaining solids comprising cellulose and hemicellulose and having a lignin content of less than 1.5% lignin; Step 5: exposing said remaining solids to a caustic composition at a low temperature, (preferably below 60 C.), to generate a caustic mixture comprising said caustic composition, hemicellulose and cellulose; Step 6: allowing sufficient time for at least 85% of the remaining hemicellulose present to be dissolved by said caustic composition, and wherein exposure to said caustic composition yields a final solids portion; Step 6: optionally, separating said dissolved hemicellulose from said final solids portion; and Step 7: optionally, recovering said final solid portion; and Step 8: recovering said hemicellulose from said dissolved hemicellulose, wherein said hemicellulose recovered constitutes over 85% of the hemicellulose present in said remaining solids portion and is mainly in a polysaccharide form.

A digestion accelerator includes a specified quaternary ammonium compound, and at least one amine compound selected from the group consisting of a specified primary monoamine, a specified secondary monoamine, and a specified tertiary monoamine. A mass ratio between the quaternary ammonium compound and the amine compound is 5:1 to 10000:1. A method for producing pulp includes a digestion step of adding at least one main agent selected from the group consisting of an alkaline main agent and a sulfite-based main agent, and a digestion accelerator, to digest a material including lignocellulose, in which the digestion accelerator is the above digestion accelerator.