A Bleaching Process
AssigneeAB Enzymes Oy
InventorsWerner BESENMATTER, Mauricio QUIROS, Hendrik HELLMUTH, Kim LANGFELDER
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Abstract
A bleaching process of pulp is disclosed comprising performing a delignification of the pulp by carrying out in a following sequence: an enzymatic treatment step comprising contacting the pulp with a glycoside hydrolase family GH11 xylanase enzyme at a pH of at least 9.5 and a temperature of at least 85° C., an oxidation step wherein a bleaching agent is added, an alkaline extraction step wherein an alkaline agent is added, and recovering bleached pulp, wherein the GH11 xylanase enzyme has an ability to cause at least 20% reduction in viscosity of a xylan-containing mixture at 90° C. and pH 10.5, compared to the same mixture without any xylanase enzyme.
Claims18
A bleaching process comprising:
- providing pulp;
- performing a delignification of the pulp by carrying out in the following sequence:
- a) an enzymatic treatment step (X) comprising contacting the pulp with a glycoside hydrolase family GH11 xylanase enzyme at a pH of at least 9.5 and a temperature of at least 85° C.;
- b) an oxidation step (D), wherein a bleaching agent is added;
- c) an alkaline extraction step (E), wherein an alkaline agent is added;
- and
- d) recovering bleached pulp;
- wherein the GH11 xylanase enzyme has an ability to cause at least 20% reduction in viscosity of a xylan-containing mixture at 90° C., pH 10.5 and at a concentration of 3.0 μg or less of the GH11 xylanase enzyme protein per gram of said xylan-containing mixture, when compared to the xylan-containing mixture without any xylanase enzyme, wherein the xylan-containing mixture comprises 0.07 g/ml or less of xylan.
A pulp composition comprising:
- (a) pulp having a pH of at least 9.5;
- and
- (b) 0.01-200 g of a glycoside hydrolase family GH11 xylanase enzyme protein per 1000 kg of dry matter pulp;
- wherein the GH11 xylanase enzyme protein has:
- xylanase activity, and
- an ability to cause within 20 minutes at least 20% reduction in viscosity of a xylan-containing mixture at 90° C., pH 10.5 and at a concentration of 3.0 μg or less of the GH11 xylanase enzyme protein per gram of said xylan-containing mixture, when compared to the xylan-containing mixture without any xylanase enzyme, wherein the xylan-containing mixture comprises 0.07 g/ml or less of xylan.
Dependencies are inferred from the claim text.