文档介绍：Cooking Chemistry with Additives
accelerating the delignification rate
increasing the delignification selectivity
increasing pulp yield
improving pulp properties
eliminating or reducing air pollution
The aims
1. Adding anthraquinone (AQ) or its derivatives
AQ AHQ = anthrahydroquinone
anion , very soluble
(1) Electrochemical reduction in anthraquinone pulping
(2) Oxidation process in anthraquinone pulping
The reaction of AHQ with phenolic lignin units leads to a cleavage of β–aryl ether bonds after the addition of AHQ anions to quinone intermediates, thus acceletating the delignification.
(3) Redoxylic action of anthraquinone
SAQ-Soluble anthraquinone
THAQ-Tetrahydroanthraquinone
DDA-Dihydrodihydroxylanthracene
DHAQ-Dihydro anthraquinone
AHQ acts the function as Na2S
º
Oxidative stabilization of reducing end-groups against the endwise peeling reaction
Improved selectivity of Pulp
Minimum cellulose loss
Maximum lignin removal
For lower kappa number
Same yield
Same black liquor solids/ton pulp
(4) Adding THAQ
THAQ can dissolved in alkaline solution which is favorable for even cooking