低碳合成气生物转化及产乙醇发酵工艺探索  

Bioconversion of low-carbon syngas to ethanol and the process development

作　　者：方崇 刘云云 徐惠娟[2] 周雨 邱雨心 巨苗苗 FANG Chong;LIU Yunyun;XU Huijuan;ZHOU Yu;QIU Yuxin;JU Miaomiao(School of Mechanical&Electrical Engineering,Shaanxi University of Science&Technology,Xi’an 710016,Shaanxi,China;CAS Key Laboratory of Renewable Energy,Guangzhou Institute of Energy Conversion,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;Institute of Marine Biology,Shantou University,Shantou 510632,Guangdong,China)

机构地区：[1]陕西科技大学机电工程学院,陕西西安710016 [2]中国科学院广州能源研究所,中国科学院可再生能源重点实验室,广东广州510640 [3]汕头大学海洋生物研究所,广东汕头510632

出　　处：《化工进展》2024年第11期6111-6118,共8页Chemical Industry and Engineering Progress

基　　金：国家重点研发计划(2019YFB1503904);陕西省自然科学基础研究计划面上项目(2021JM-382)。

摘　　要：在碳中和大目标下,生物质气化合成气(主要成分为CO、CO_(2)和H_(2))的资源化利用受到广泛关注,将合成气转化为燃料乙醇具有碳减排和能源生产的双重功效。针对化学催化转化过程存在合成气不能被完全利用的问题,采用生物法对其尾气(低碳合成气)进行进一步利用,以提高合成气的利用率。本文从气体底物、发酵工艺等方面对乙醇梭菌(Clostridium autoethanogenum)发酵产乙醇过程进行了研究。结果表明:在合成气发酵中,菌株会优先利用CO,之后再利用CO_(2)和H_(2),CO和H_(2)消耗的比值为0.99±0.12,产物中乙醇与乙酸的摩尔比为0.78±0.10;以100%CO为底物时,CO消耗与CO_(2)生成的比值为1.72±0.21,乙醇与乙酸的摩尔比为1.00±0.11。木糖-合成气共发酵时菌株对木糖的利用比较缓慢,与合成气发酵相比,菌体浓度较高,但乙醇浓度较低。培养基中添加乙酸钠浓度为4g/L时对菌株活性没有影响,高浓度(≥12g/L)则对菌株生长产生明显的抑制作用。3L搅拌罐式反应器的发酵实验显示,当发酵过程出现“酸崩溃”时,菌株的产乙醇代谢受到抑制,导致乙醇产量低;在菌株对数生长后期降低发酵温度可有效避免“酸崩溃”,发酵得到的最高乙醇浓度为3.46g/L,最高乙醇与乙酸的摩尔比达到2.01,最大乙醇产率达到0.35g/(L·d)。上述研究结果可为Clostridium autoethanogenum发酵产乙醇过程工艺优化提供参考。As an effort to achieve carbon neutrality,utilization of biomass gasification-based syngas(mainly consisting of CO,CO_(2),and H_(2))has been extensively studied.Conversion of syngas to fuel ethanol has the dual effects of carbon emission reduction and energy production.Since syngas can not be completely converted in chemical catalytic process,the tail gas produced,known as low-carbon syngas,is considered to be further utilized by biological process.In this study,fermentation of Clostridium autoethanogenum for ethanol production was investigated from the aspects of gaseous substrate and fermentation technology.Results showed that Clostridium autoethanogenum preferentially consumed CO other than CO_(2) and H_(2)in syngas fermentation,the ratio of CO consumption to H_(2) consumption was 0.99±0.12,and the molar ratio of ethanol and acetic acid achieved was 0.78±0.10;when 100%CO was used as substrate,the ratio of CO consumption to CO_(2) production was 1.72±0.21,and the molar ratio of ethanol and acetic acid was 1.00±0.11.During the process of xylose-syngas co-fermentation,xylose was consumed slowly,and compared to syngas fermentation,the cell density increased,but ethanol concentration was lower.Cell activities were not affected when 4g/L of sodium acetate was added in the medium,while significant inhibition on cell growth was observed under higher concentrations(≥12g/L).Fermentation results in the 3L stirred-tank reactor showed that the ethanol yield was low once“acid crash”happened,while lowering temperature at the late logarithmic phase of cell growth could prevent“acid crash”.Consequently,the maximum ethanol concentration obtained was 3.46g/L,maximum ethanol and acetic acid molar ratio was 2.01,and the highest ethanol yield was 0.35g/(L∙d).This study provided references for the process optimization of ethanol production from low-carbon syngas via Clostridium autoethanogenum fermentation.

关 键 词：合成气 燃料乙醇 气体发酵 乙酸 乙醇梭菌 

分 类 号：TK6[动力工程及工程热物理—生物能]