Study of small methanol conversion system for biomass resources

未利用的生物质资源和固体废物中的有机物一旦转化为液体燃料，就可以用作机动车的液体燃料。这些燃料的利用有利于减少化石燃料的消耗和全球变暖。在此背景下，开展了利用生物质衍生材料建立小型热化学甲醇生产系统的基础研究。首先，利用基于化学平衡的热力学方法对生物质热解、制氢、制一氧化碳进行了研究。其次，采用高压进料的流动反应器对甲醇合成进行了动力学分析，产物用气相色谱仪进行了分析。最后，提出了一种新的甲醇生产发动机。该发动机依靠往复式压缩机和往复式膨胀机的组合。结果表明：生物质干热裂解产生的气体需要加水才能获得合成甲醇的混合气体。预测了各种气体混合物在热解过程中固体碳的形成。实验确定了在普通铜锌催化剂上甲烷合成的最佳条件。甲醇的产率在250℃时达到最大值，与反应器内的压力无关，并且随着压力的增加而增加。在正确的停留时间，收益率可能高达70%。分析表明，甲醇生产发动机有可能实现高压和能量回收。

Unused biomass resources and organic substance in solid wastes may be utilized as liquid fuels for motor vehicles once they are converted into liquid fuels. The utilization of such fuels favors reducing consumption of fossil fuels and global warming. With this background, fundamental studies were carried out to build a small thermo-chemical methanol production system that used biomass-derived materials. At first, pyrolysis of biomass and production of hydrogen and carbon monoxide were dealt with using thermodynamics based on chemical equilibrium. Second, kinetic analysis was made for methanol synthesis using a flow reactor in which model gases were fed at a high pressure, the products being analyzed by gas chromatograph. Last, a new methanol production engine was proposed. This engine relies on the combination of reciprocating compressors and reciprocating expanders.Obtained results are summarized as follows : Gas produced by pyrolysis of dry biomass requires water addition to obtain gas mixture for methanol synthesis. Solid-carbon formation during pyrolysis is predicted for a variety of the gas mixtures. Optimum conditions for methane synthesis are experimentally determined for the case of ordinary Cu-Zn catalyst. Yield of methanol reaches maximum at 250℃ irrespective of the pressure in the reactor and increases as the pressure increases. At a correct residence time, the yield may reach as high as 70%. Analysis shows the likelihood of the methanol production engine that may afford to achieve a high pressure and energy recovery.