用木材生产生物燃料与纸浆

杨木木片硫酸盐制浆前,进行缓和的碱抽提处理,抽提出半纤维素用作生物燃料(生物乙醇),在温度90℃,NaOH 1～2M,液比1∶4条件下进行碱处理,不需要高压设备,每吨木片得到半纤维素40～50kg,经碱抽提后木片进行硫酸盐蒸煮,与未经碱抽提木片参照对比,纸浆得率基本相同,但是需要很好地控制碱抽提与硫酸盐蒸煮工艺条件,能缩短蒸煮时间和节省化学品用量。碱预抽提木片得到的硫酸盐纸浆中纤维素/半纤维素的比率稍高,导致纸浆的抗张指数稍有降低(约10%),但是纸浆白度较高且筛渣含量低,为使硫酸盐纸浆的质量和得率保持较高水平,采用缓和的碱预抽提,使半纤维素得率较低,而回收的半纤维素的浓缩和离析比木片自水解或稀酸水解回收糠醛更加容易。

From Wood to Biofuels and Pulp Production

A mild alkaline treatment was applied to aspen chips prior to kraft pulping in order .to ex- tract hemicellulose for use as biofuels（bioethanol）,the extraction was performed at 90℃, NaOH 1-2M,liguor towood ratio 1-4. It resulted in a recovery of 40-50kg of hemicellulose per ton of chips and yieled the same amount of pulp after subsequent pulping of the extracted chips,as compared to a control cook. The pre-extract process requires careful optimization of the pulping process and allows shorter cooking time and lower chemical charges. The process did not costly pressurized reaction ves- sels. Kraft pulps obtained from per-extracted chips have a slightiy higher cellulose/hemicellulose ratio and demonstrate a small decrease in tensile index（10%）, but improved brightness and shive content, while the hemiecllulose yield for this process is low, this problem is outweighed by the fact that pulp properties and pulping yield can be maintained at a high level. The recovered hemicellulose can be con- centrated and isolateed more easily than furfural obtained by autohydrolysis or dilute acid treatment.