超临界CO_2萃取分离生物油

Supercritical CO_2 extraction of bio-oil

考察了超临界CO2萃取前后玉米秸杆快速热裂解生物油的分离提质效果,并对提质后生物油的品质进行了初步评价.醛类、酮类、酚类等弱极性化合物可被scCO2选择性的萃取,而酸类和水则主要残留于萃余相中;提质后生物油中GC-MS可识别的物质种类由17种提高到80种,这表明利用超临界萃取与GC-MS分析相结合,可显著地提高生物油的定性和半定量分析的准确性.提质后生物油由不透明的黑褐色变为浅黄色透明的液体,且具有较高的耐热稳定性,含水率降至原来的五分之一,热值提高了将近1倍,pH值也从2.1提高到了4.1.确定的适宜萃取工艺条件为55℃和30.0 MPa.

Combining with GC-MS analysis, scCO2 extraction of a real bio-oil, obtained by fast pyrolyis of corn stalk, was explored. Also, the quality of the upgraded bio-oil was assessed. Compounds with weak polarity like aldehydes, ketones, phenols could be enriched into the extract fraction, whereas acids and water were largely left in the faffinate. After extraction treat- ment, the detectable compounds by GC-MS increased from 17 species to 80 species, strongly sug- gesting scCO2 extraction as a pretreatment technique can remarkably improve the accuracy in qualitative and quantative determination of bio-oils. The upgraded bio-oil became from dark- brawn opaque to light-yellow transparent liquid with relatively high thermal stabiltiy. Water content was only one-fifth of that in orginal bio-oil, heating value was doubled, and pH value increased from 2.1 to 4. 1. The appropriate operation conditions were also determined, 55℃ and 30.0 MPa.