A method of producing chemical pulp including at least the following steps: a) wood chips or other comminuted ligno-cellulosic fibrous material is treated with a polysulfide-containing cooking liquor in an impregnation stage at a temperature of 90-145 C., and b) slurry of fibrous material from step a) is heated into cooking temperature and cooked for producing pulp having a desired kappa number. After step a) mercaptide ions are added into the slurry of fibrous material and the fibrous material is treated at cooking temperature in step b).

The disclosure relates to the technical field of dissolving pulp preparation, and particularly relates to a method for producing acetate grade dissolving pulp utilizing poplar residual slabs. The method comprises the following steps: adding an auxiliary agent for prehydrolysis, performing a Soda/AQ cooking I segment, performing a Soda/AQ cooking II segment, performing OpD.sub.QE.sub.PP bleaching and performing enzyme coprocessing, thereby preparing high-purity high-reactivity poplar residual slab acetate grade dissolving pulp. In the method, used chemicals are clean and environmental friendly, and production process is clean.

A process for producing refined cotton with a high polymerization degree includes: a. selection of material; b. impurity removal; c. impregnation; d. pretreatment: compounding triethanolamine, sodium carbonate, copper sulfate and magnesium oxide in equal proportion to form a cooking compound adjuvant with a mass concentration of 0.2-0.5%, putting the cooking compound adjuvant into a spherical digester together with the cotton linter subjected to the impregnation treatment, heating to 70 C, stopping heating, and subjecting to idling pretreatment for 40-60 min; e. cooking; f. cooling of the spherical digester; g. formulating a chlorine dioxide bleaching stabilization solution; h. a first stage of bleaching; I. alkali treatment; J. a second stage of bleaching; K. dechlorination; and l. rolling and drying by baking.

A system comprising a pulper configured to (i) accept surfactant, a liquid and fiber stock and (ii) generate a foam that suspends the fiber stock, wherein the foam has a half-life; a headbox configured to receive the foam-suspended fiber stock from the pulper and displace the foam-suspended fiber stock onto a forming wire, wherein a time it takes the foam-suspended fiber stock to move from the pulper to the headbox is less than the half-life; and a foam return device that removes at least some of the foam from the forming wire and returns the at least some of the foam to the pulper.

Disclosed are a pulp for Juncao spinning and a preparation method and use thereof. The method includes: placing a Juncao in a solution prepared from a lye, a catalyst, and an auxiliary agent and cooking to obtain a cooked solution, and then subjecting the cooked solution to pulping to obtain the pulp for Juncao spinning.

A process to separate lignin from a lignocellulosic feedstock, said process comprising the steps of: providing said lignocellulosic feedstock; providing a composition comprising; an acid; a modifying agent selected from the group consisting of: sulfamic acid; imidazole; imidazole derivatives; taurine; a taurine derivative; a taurine-related compound; alkylsulfonic acid; arylsulfonic acid; triethanolamine; and combinations thereof; a peroxide salt; and a peroxide; exposing said lignocellulosic feedstock to said composition for a period of time sufficient to depolymerize substantially all of the lignin present in said lignocellulosic feedstock into lignin oligomers and lignin monomers;
wherein said process is carried out at atmospheric pressure.

According to an example aspect of the present invention, there is provided a process for the conversion of cellulosic waste material into a recycled cellulose product comprising the steps of cooking the waste material in a cooking liquor to remove lignin from the waste material and provide a delignified pulp, dissolving the delignified pulp in an ionic liquid to provide a spinning dope suitable for dry jet-wet spinning in an ionic liquid solution, and subjecting the spinning dope to a further processing step to provide a recycled cellulose product, said further step selected from the group of spinning cellulose fibers for use in textiles from the solution, extruding a film product for use in packaging, regenerating the dope as a hydrogel and regenerating the dope as an aerogel.

Methods of fractionating lignocellulosic biomass using hydrotropic solid organic acids are provided. Also provided are methods of forming lignin particles, furans, sugars, and/or lignocellulosic micro- and nanofibrils from the liquid and solid fractions produced by fractionation process. The fractionation can be carried out at low temperatures with short reaction times.

An aqueous composition comprising: sulfuric acid; a heterocyclic compound; an alkanesulfonic acid; and a peroxide. Said composition being capable of delignifying biomass under milder conditions than conditions under which kraft pulping takes place.

In alternative embodiments, provided are methods and industrial processes for generating pulp from lignocellulosic feedstocks, comprising directly contacting a lignocellulosic feedstock with a system comprising a super critical or sub-super critical fluid or mixture of fluids, whereby the partial pressure of the system provides for the hydrolysis or a combination thereof of the feedstock at reduced temperatures and pressures, followed by an upgrading step wherein a low-purity cellulosic material generated in the super critical or sub-super critical reaction step is treated with an alkaline solution. In alternative embodiments, provided are systems and methods for producing a cellulose material using reduced amounts of water.