响应面法优化油菜秸秆真空热解液化工艺及生物油分析1

Bio-Oil Analysis and Optimization of Bio-Oil Yield from Vacuum Pyrolysis of Rape Straw Using Response Surface Methodology

以油菜秸秆为原料,采用真空热解系统进行了制取生物油的中心组合实验研究,以热解终温、体系压力和升温速率为实验因子,生物油产率为实验指标,利用响应面法(RSM)对制备生物油的工艺参数进行了优化,并对在最优条件下制取的生物油进行了理化特性和化学组成分析。研究结果表明,热解终温、体系压力和升温速率对生物油产率有显著影响,热解终温和升温速率之间的交互作用显著;获得最佳热解液化工艺条件为:热解终温490.0℃、体系压力5.0 k Pa、升温速率20.0℃·min-1,在此条件下,生物油产率可达41.65%。与预测值42.00%较为接近。油菜秸秆真空热解所得生物油的含水量为33.85%,热值为18.65 MJ·kg-1,常温下的运动黏度为4.16 mm2·s-1,密度和p H值分别为1.14g·cm·3和2.32;生物油成分较为复杂,其中多种有机物可被进一步提取用作化工原料;生物油中羧酸、醛、酮类等腐蚀性和不稳定组分含量较高,需对其进一步精制,以提高其稳定性。

Bio-oil yield from rape straw vacuum pyrolysis was optimized. Pyrolysis temperature, reactor pressure and heating rate were selected as independent variables and the response surface methodology （RSM） was employed to obtain maximum bio-oil yield. Moreover, the physical properties and composition of the bio-oil produced under optimal conditions were analyzed. The results show that pyrolysis temperature,reactor pressure and heating rate have obvious effects on bio-oil yield, and pyrolysis temperature and heating rate have a significant interaction. The optimal conditions for bio-oil yield were obtained at pyrolysis temperature of 490.0℃, system pressure of 5.0 kPa and heating rate of 20.0℃ .min^-1. Confirmation runs gave 41.65% of bio-oil yield compared to 42.00% of predicted value. Water content and high heat value of the bio-oil were 33.85% and 18.65 MJ.kg^- 1 respectively, and its dynamic viscosity at room temperature, density and pH value were 4.16 mm^2.s^-1, 1.14 g·cm^-3 and 2.32, respectively. The bio-oil obtained from rape straw is a complex mixture. It is highly-oxygenated with a great amount of organics, which mainly include aldehydes, ketones, carboxylic acids, alcohols and aromatics. Some organic compounds could be further extracted as industrial raw materials. Further study on upgrading of bio-oil from vacuum pyrolysis of rape straw should be performed in future.