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

与现有工艺相比，生物催化转化工艺具有温和的操作条件，简单的生物催化剂培养，以及无需昂贵的循环管理即可实现原料气的完全转化的可能性，因此对可持续循环经济做出了有希望的贡献。与基于淀粉原料的传统发酵工艺相反，合成气发酵使用气态c1底物，并且在原料方面提供了很大的灵活性。发酵反应由一种化能自养微生物催化，未来工艺链的最终产物可能是高价值的化学品，如燃料、化学品、脂质和蛋白质。厌氧醋酸菌是一种可能用于气体发酵的微生物，对其进行了充分的研究，并已成功地在工业中试规模和商业工厂用于厌氧合成气发酵。厌氧醋酸菌能够通过所谓的Wood-Ljungdahl途径固定二氧化碳，从而产生醋酸盐或乙醇作为中间体。该项目涉及开发，估计和控制设计，并优化一种新颖的新型电-生物混合工艺，用于将二氧化碳转化为高价值产品。这将包括在试验台实施这些概念。为此，它旨在结合来自德国KIT Karlsruhe和加拿大安大略省皇后大学的相关合作伙伴的专业知识。这项调查的一个主要目标是提高整个过程的效率。重要的影响因素是合成气的组成、气体流速、pH、反应器内的细胞密度和工艺压力。电化学过程将集成为二氧化碳转化提供混合解决方案，其中电化学可用于控制饲料成分。由KIT催化研究和技术研究所建立的SANDRA试验台，包括一个连续操作的搅拌槽反应器，用于发酵微生物ljungdahli梭菌，将作为概念的实验证明。由于液相的停留时间长以及微生物可能的适应过程，该生物系统中稳态的建立较慢。因此，对反应堆操作进行纯粹的经验优化是极其耗时的。持续控制包括反应器运行的适当估计器或软传感器概念，以实现相对于有意义的目标（如总碳固定）的最佳运行条件，将有助于大幅减少反应器运行时间，同时提供有关系统的有价值信息，这对于未来基于知识的新技术的扩展是迫切需要的。

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.