原料预处理对橡胶籽壳热裂解特性的影响

Study on pyrolysis characteristic of pre-treated rubber seed shell

为探讨水洗、酸洗以及熔盐等预处理方法对生物质热裂解特性的影响,以橡胶籽壳为原料,使用去离子水(H2O)和质量分数分别为5%、10%和15%的盐酸(HCl)、硫酸(H2SO4)、甲酸(HCOOH)、混合酸溶液(HCl+HCOOH,VHCl∶VHCOOH=1∶1)、KCl以及NaOH对橡胶籽壳进行预处理,采用热重分析法考察了预处理对橡胶籽壳热裂解特性及综合特性指数的影响。结果表明:水洗及酸洗可使橡胶籽壳的热解主反应区热重和微分热重曲线向高温侧移动,最大失重速率和最大失重温度升高,而熔盐则降低;HCl和HCOOH以及HCl+HCOOH溶液浓度对橡胶籽壳热裂解特性的影响较小,而H2SO4浓度的影响显著,并随浓度升高而增大;酸洗有利于橡胶籽壳中挥发分的析出,可以脱除秸秆内的部分钾盐,3种酸脱钾盐的作用依次为H2SO4>HCl>HCOOH;热裂解热性综合特性指数受水洗和酸洗影响显著,并随酸浓度升高而变化。

In order to investigate the influence of pre-treatment methods such as water wash, acid wash and molten salt on biomass pyrolysis characteristic,rubber seed shell was selected as biomass feedstock.Deionized water,hydrochloric acid,sulfuric acid and methanoic acid and mixed acid as well as KCl and NaOH,whose mass fractions were 5%,10%and 15%,respec-tively,were used to wash rubber seed shell,and the thermal decomposition behaviors and com-prehensive index of rubber seed shell pyrolysis were analyzed. At the sametime,the kinetic pa-rameters were studied. The results showed that water wash and acid wash can make thermo-gravimetric analysis and derivative thermogravimetric analysis curves of rubber seed shell pyrol-ysis shift to higher temperature section,and the maximum weight loss rate and temperature in-creased,but the melted salt was decreasing. The impacts of the concentration of hydrochloric ac-id and methanoic acid were negligible,but that of sulfuric acid was significant which became obvious with the increasing concentration. Acid wash was in favor of the emission of volatile matters contained in rubber seed shell,and can eliminate the sylvite.The ability order of three acids was as follows：sulfuric acid,hydrochloric acid and methanoic acid. The thermal compre-hensive characteristic index of pyrolysis decreased after rubber seed shell was pretreated,and changed with the acid concentration.