Study On Salt-catalyzed Ethanol Pulping Of Poplar

Due to the disadvantages of the leading KP pulp, such as severe air pollution, hugeinvestment for alkali recycling, waste of outgrowth lignin etc., no pollution pulp has beenattracting great attention. And ethanol pulp has become its mainstream recently because of thecontaining recyclable ethanol and usability of the lignin as new resource from waste liquor.Our group choose a high cooking temperature（205℃～210℃）for the auto-catalyzed ethanolpulping of poplar. Owing to the low boiling of ethanol, cooking pressure has to be high（3.0MPa upwards）, which demands capability of cooking equipment and much energy. So itis significant and practical to find out and do research on the method of reducing cookingtemperature and pressure without lowering pulp quality or influencing the recycling ofethanol and lignin from waste liquor.In the paper, inorganic salt is used as catalyzer. We adopt condition experiment to discussthe influencing factors to pulp and improve the condition of the auto-catalyzed ethanolpulping of poplar so as to upgrade cooking conditions, reducing temperature and pressureincluded. Finally, the goal to lower the capability of cooking equipment could be achieved.And we also discuss the influences of different typies of inorganic salt catalyzers to the pulpcondition and performance of the salt-catalyzed ethanol pulping of poplar. In the samecooking condition, the catalyzed result of divalent metal inorganic salt turns out well andmagnesium chloride even better. If the dosage of catalyzer （magnesium chloride） is3.5％（oven dry）, the best pulp condition is with the holding temperature of175℃, ethanolconsistency of65%, liquor ratio of1：10, heat reservation of3.5h. The cooking temperaturedrops from205℃to175℃while cooking pressure drops from2.34MPa to1.26MPa，haddepressed1.08MPa,compared to the auto-catalyzed ethanol pulping. Also, the pulp yield is47.95%, the Kappa number is27.22, which are close to those of the auto-catalyzed ethanolpulping（pulp yield47.38%, Kappa number26.56）. The cooking condition has been greatlyreduced and part of the theoretical basis has been supplied to the industrialization of ethanolpulp.The research to the reaction course of delignification and kinetics shows that the delignification reaction of salt-catalyzed ethanol pulping of poplar is first order reaction. Thedelignification reaction is divided into two phases of the principal delignification （frombeginning of heat reservation to2.5h） and residual delignification （from2.5h to the end ofheat reservation）. For the principal delignification, the reaction velosity constant is0.0095min^-1 and the activation energy is51.85KJ/mol while the residual delignification, thereaction velosity constant0.002735min^-1, activation energy87.31KJ/mol. And the activationenergy is close to that of the auto-catalyzed ethanol pulping of poplar and lower than that ofthe KP. So the delignification during the salt-catalyzed ethanol pulping of poplar is easier thanthat during the KP and the poplar is adaptive to the salt-catalyzed ethanol pulping.The theory needs to be researched more deeply and the equipment for production alsoneeds to be improved, therefore, in the future while doing further study of the theory, weshould focus on the realization of industrialization as well.