NSERC-DFG SUSTAIN: Biological and electrochemical process design for biocatalytic CO2 conversion

生物催化转化工艺为可持续循环经济做出了有希望的贡献，因为与现有工艺相比，操作条件温和，生物催化剂培养简单，而且有可能实现原料气的完全转化，而不需要进行必要的昂贵的循环管理。与传统的以淀粉为原料的发酵工艺相反，合成气发酵使用气态的C1-底物和off对原料具有极大的fl灵活性。发酵反应是由一种化学自养微生物催化的，未来过程链的最终产品可能是燃料、化学品、脂类和蛋白质等高价值化学品。厌氧产乙酸菌是一种可能用于气体发酵的微生物，它们已经得到了充分的研究，并已成功地在工业中试和工业装置上用于厌氧合成气发酵。厌氧产乙酸菌能够通过所谓的伍德-永达尔途径，通过二氧化碳的fi氧化产生乙酸酯或乙醇作为中间体。该项目涉及一种新型的电-生物混合过程的开发、估计器和控制设计，以及将二氧化碳转化为高价值产品的优化。这将包括在试验台上实施这些概念。为此，它旨在结合来自德国KIT Karlsruhe和加拿大安大略省女王大学的相关合作伙伴的专业知识。本次调查的一个主要目标是提高整体流程效率。重要的影响因素是合成气的组成、气体流量、pH、反应器中的细胞密度和工艺压力。要整合电化学过程，为二氧化碳转化提供一种混合解决方案，其中可以使用电化学来控制原料成分。催化研究所已经建立了桑德拉试验台，其中包括用于发酵微生物永达梭菌的连续操作的搅拌槽反应器，KIT将作为实验概念验证。由于液相的停留时间较长以及微生物可能的适应过程，在该生物系统中建立固定状态的过程是缓慢的。因此，对反应堆运行进行纯粹的经验优化是非常耗时的。持续控制包括反应堆运行的适当估计器或软测量概念，以实现与总碳fi氧化等有意义的目标相关的最佳运行条件，将有助于大幅缩短反应堆运行时间，同时提供有关系统的有价值的信息，这是未来新技术基于知识的扩大所迫切需要的。

Biocatalytic conversion processes represent a promising contribution to a sustainable circular economy due to mild operating conditions compared to existing processes, simple biocatalyst cultivation, and the possibility to reach a complete conversion of the feed gas without necessary expensive loop management. In opposite to traditional fermentation processes that are based on starch feedstock, synthesis gas fermentation uses gaseous C1-substrates and offers great flexibility regarding the feedstock. The fermentation reaction is catalyzed by a chemolithoautotrophic microorganism, and the final products of a future process chain could be high value chemicals like fuels, chemicals, lipids and proteins. Anaerobic acetogens are possible microorganisms used for gas fermentation, and they are well investigated and already successfully in use at industrial pilot scale and commercial plants for anaerobic syngas fermentation. Anaerobic acetogens are able to produce acetate or ethanol as intermediates through the fixation of CO2 via the so-called Wood-Ljungdahl pathway. This project deals with the development, the estimator and control design, and the optimization of a novel novel electro-bio hybrid process for the conversion of CO2 to high-value products. This will include the implementation of the concepts at a test-rig. For this, it aims to combine the expertise of the involved partners from KIT Karlsruhe, Germany and Queen’s University, Ontario, Canada. A major goal of this investigation is to increase the overall process efficiency. Important contributing factors are composition of the synthesis gas, gas flow rate, pH, cell density in the reactor and process pressure. Electrochemical processes are to be integrated to provide a hybrid solution to CO2 conversion in which the electrochemistry can be used to control feed composition. The SANDRA test-rig, which includes a continuously operated stirred tank reactor for the fermentation of the microorganism Clostridium ljungdahli, has been set up by the Institute of Catalysis Research and Technology of KIT will serve as experimental proof-of-concept. Establishment of a stationary state in this biological system is slow due to the long residence time of the liquid phase and possible adaptation processes of the microorganisms. The purely empirical optimization of reactor operation is therefore extremely time-consuming. Continuous control involving suitable estimator or soft-sensor concepts of reactor operation to achieve an optimal operating condition with respect to a meaningful objective such as total carbon fixation, would help to drastically reduce reactor operating times while providing valuable information about the system, which is desperately needed for a future knowledge-based scale-up of the new technology.