萃取耦合化学转化法提质生物油油溶相的研究

Upgrading the oil-soluble fraction of bio-oil by solvent extraction coupling with chemical conversion

采用萃取耦合化学转化技术对生物油油溶相进行了提质研究。将稻壳快速裂解油加入适宜水使其自然分为水溶相和油溶相。以正丁醇为萃取剂和转化剂,通过在线萃取将油溶相中的酸、醛、酮等可萃物不断萃取出来,再经酯化、缩醛化反应,转化为相应正丁醇的酯、缩醛和半缩醛等。与生物油直接酯化提质相比,萃取耦合化学转化法可以显著抑制提质过程中的结焦问题,降低了提质油相的含水量和酸值,提高了其热值和可挥发性。此外,还考察了油溶相预氧化和预还原对萃取耦合化学转化提质的影响。结果表明,预氧化后可将油溶相中的醛类转化为酸,再经酯化转化为稳定性好的酯类,提质后的油品水含量低于4%,热值高于30 MJ/kg,酸值低于2 KOH mg/g,并且结焦率为零。

Upgrading the oil-soluble fraction, which was obtained by water extraction of bio-oil from fast pyrolysis of rice husk, was investigated with simultaneous esterification and acetalation in butanol with online solvent extraction （SEAWOSE）. The results show that almost all of the acids, aldehydes and ketones in the oilsoluble fraction can be converted to the corresponding esters, hemiacetals and acetals by SEAWOSE. In comparing with direct esterification and acetalation without extraction, the char formation is significantly suppressed. Meanwhile, the upgraded oil has very low acidity and moisture content, but high heating value and good volatility. The effect of oxidation and reduction pretreatment of the oil-soluble fraction before SEAWOSE was also investigated. By hydrogen peroxide oxidation, the aldehydes are firstly converted into acids and subsequently esterified to esters, consequently without char formation. The upgraded oil is high quality, less than 4% in moisture, higher than 30 MJ/kg in heating value and less than 2 KOH mg/g in acidity.