酢酸発酵によるリグノセルロースからの先進エタノール生産 Advanced Ethanol Production with Acetic Acid Fermentation from Lignocellulosics

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Abstract

<p>酢酸発酵によるリグノセルロースからの先進エタノール生産プロセスを開発した。2段階加圧熱水によりリグノセルロースをC6糖およびC5糖,これら糖類の過分解物,リグニン由来物質などへと分解し,嫌気性条件下で酢酸発酵する。発酵には混合微生物を用い,回分または流加培養によりNaOH(Ca(OH)<sub>2</sub>も可)でpHを6.5~7.0に制御しながら発酵する。得られた酢酸ナトリウムはバイポーラ電気透析により酢酸に変換し,最大200 g/Lまで濃縮してルイス酸担持触媒(Ru–Sn/TiO<sub>2</sub>)により水素化し,バイオエタノールを得る。アルコール発酵法では,乾物1トンのスギより200~300 Lのバイオエタノールが生産されるのに対し,本プロセスでは2倍のエタノールが得られた。また,アルコール発酵法に比べてエネルギー回収率は高く,かつCO<sub>2</sub>排出原単位は低く,環境負荷低減のためのCO<sub>2</sub>削減に本プロセスが有効であることが明らかとなった。</p>

<p>A novel process of bioethanol production from lignocellulosics was developed by acetic acid fermentation followed by hydrogenolysis of acetic acid to ethanol. This process includes a two-step hot-compressed water treatment of lignocellulosics to C6 and C5 sugars, decomposed products and lignin-derived compounds. In the subsequent fermentation, most of these products are to be anaerobically fermented into acetic acid in form of sodium acetate by free and/or immobilized co-culturing system (<i>Clostridium thermocellum</i> and <i>C. thermoaceticum</i>) by batch or fed-batch fermenter with pH controlled by NaOH or Ca(OH)<sub>2</sub> to be 6.5-7.0. The obtained acetate aqueous solution was then converted and concentrated into acetic acid up to 200 g/L by bipolar membrane electrodialysis. The acetic acid was then converted to bioethanol without emitting CO<sub>2</sub> via hydrogenolysis with Lewis acid-supported catalyst (Ru–Sn/TiO<sub>2</sub>). To evaluate a potential of this process, it was compared with the conventional alcoholic fermentation process, and found that, although conventional process can produce only 200-300 L bioethanol from one dried ton of Japanese cedar, this process can produce double in amount. In addition, energy recovery is higher than the conventional process, with CO<sub>2</sub> emission unit (kg/GJ) being lower. Consequently, this process can be promising to reduce CO<sub>2</sub> so as to mitigate environmental loading.</p>

Journal

  • Journal of the Japan Petroleum Institute

    Journal of the Japan Petroleum Institute 62(5), 199-204, 2019

    The Japan Petroleum Institute

Codes

  • NII Article ID (NAID)
    130007700278
  • NII NACSIS-CAT ID (NCID)
    AA11590615
  • Text Lang
    ENG
  • ISSN
    1346-8804
  • NDL Article ID
    029966966
  • NDL Call No.
    Z17-177
  • Data Source
    NDL  J-STAGE 
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