CS260303B1 - Method of lignocellulose materials delignification by means of sulphite boiling - Google Patents

Abstract

The way of delignification of ligpocellulose of sulfite-based materials accelerating delignification. That purpose is achieved by contacting the brewing solution molybdenum compounds are added molybdenum-containing ions 0.02 to 0.2 wt. % / O based on the mass lignocellulosic or material. Method of delignification sulphite lignocellulosic materials cooking is used in pulp and paper industry.

Description

The present invention relates to a process for delignifying a lignocellulosic material by sulfite cooking.

The sulphite delignification process is well known and is applied for the production of low-yield bleached softwood pulp in various variations depending on the content of sulfur dioxide and the base used, which may be calcium, magnesium, ammonium or sodium [Κ. V. Sarkanen, C. H. Ludwig: Lignins, Occurence, Formation, Structure and Reaction, Ed .: Wiley Interscience, New York-London-Toronto, p. 599 (1972)] The greatest removal of pentosans is achieved with a magnesium base, which is also used to delignify deciduous trees, and to accelerate sulfite delignification in order to better utilize the capacity of the brewing apparatus and to increase the strength properties. [I. Nomura: Japan Tappi 34, 50 (1980)] In addition, in the sulphite process, organic solvents are mainly added to alcohols which reduce the brewing time [SP Mun, K. Sakal, H. Imamura: Mokuzai Gakkaishi 30, 478 (1984)].

The disadvantages of using these additive compounds are their high cost, regeneration problems and, in the case of alcohol, the pressure increase in the digester. In carbohydrate chemistry they are used! catalytic amounts of molybdenum ions, for epimerization of aldoses [V. Bilik: Chem. rumors 26, 183 (1972), ibid. 26, 372 (1972), Chem. sheets 77, 496 (1983); V. Bilik, P. Biely, M. Matulova: Chem. rumors 33, 782 (1979)). Molybdenum compounds form complexes with many organic compounds [M. A. Porai-Koshits, L. O. Atovmjan: Kristalokhimija i stereokhimija koordiacionnych soedinenij molibdena, Izd. Nauka, Moscow (1977)].

The above disadvantages are substantially eliminated by the method of delignification of lignocellulosic materials by sulfite cooking, which consists in adding molybdenum compounds in the form of molybdenum ions with a molybdenum content of 0.02 to 0.2 wt. %, based on the mass of the lignocellulosic material.

The advantage of the proposed method of delignifying lignocellulosic materials from beech wood by modified semi-acid sulphite dellgnification is that by adding molybdenum ions it is possible to shorten the batch time at a maximum temperature of 135 to 145 degrees Celsius to 85 ° / o. Molybdenum can be regenerated together with inorganic cooking chemicals, which is a difference from organic catalysts, e.g. antracliinónom. Molybdenum compounds are anticorrosive, non-toxic and do not pollute the environment.

Example 1

Beech chips (100 g) are heated in an autoclave with magnesium bisulfite (350 ml) containing 2.25 wt. % bound and 6 wt. % of total sulfur dioxide for 154 minutes at a maximum temperature of 145 ° C in the presence of 0.02 wt. percent molybdenum applied as sodium molybdate. The pulp was obtained in a yield of 54.2 wt. % with a lignin content of 2.3 wt. ° / o.

Example 2

The procedure was as in Example 1 except that the beech chips were heated at a maximum temperature of 135 ° C for 105 minutes in the presence of 0.2 wt. % molybdenum applied as ammonium molybdenum. The pulp was obtained in a yield of 58.3 wt. % with a lignin content of 4 wt. %.

In order to compare the catalytic effect of molybdenum compounds with the hitherto used acidic process for producing sulphite pulp, the following are examples:

Example 3

Beech chips (100 g) are heated in an autoclave with magnesium bisulfite (350 ml) containing 2.25 wt. % bound and 6 wt. % of total sulfur dioxide for 180 minutes at a maximum temperature of 145 ° C. The pulp was obtained in a yield of 54.8 wt. % with a lignin content of 2.5 wt. %.

attaches

The procedure is as in Example 3 except that the beech chips are heated for 120 minutes at a maximum temperature of 135 ° C. The pulp was obtained in a yield of 58.0 wt. % with a lignin content of 4.4 wt. %.

The invention can find use in the pulp and paper industry, in the semi-acidic delignification of hardwoods.

Claims (1)

Method for the delignification of lignocellulosic materials by sulfite cooking, characterized in that molybdenum compounds in the form of the malybdenum of ANALEZ of new ions containing 0.02 to 0.2 wt. percent molybdenum based on the mass of the lignocellulosic material.