Investigating the Phase Equilibria of Branched Alcohol/Water/Salt Mixtures

支链醇比甲醇和乙醇更适合生产燃料添加剂和生物燃料，因为它们的性质与汽油相似。然而，由于通过蒸馏纯化的成本较高，它们在生物精炼厂中的大规模生产目前在经济上不可行。向发酵液中添加一些盐降低了醇与发酵液的亲和力，促进了纯化。因此，需要这些电解质系统的相行为来设计具有成本效益的纯化操作。拟议的研究有以下目标，其目的是解决关键差距的基本理解的热力学支链醇/水/盐的混合物，以推进建模工具的开发，用于生物精炼厂的净化操作的设计和模拟。 目标1-使用从液-液平衡（LLE）研究收集的数据开发数据验证的活度系数模型：向醇/水混合物中加入一些盐，迫使醇从混合物中分离出来。然而，所需的液液平衡数据来阐明的混合物的热力学是稀缺的，可用的模型是相关的，而不是预测。建议收集支化醇/水/盐混合物在一定温度和压力范围内的液液平衡数据，以研究其热力学，并将其纳入基于活度系数的模型中。 目标2-使用从汽液平衡（VLE）研究中收集的数据开发数据验证的混合模型：向醇/水混合物中添加一些盐增加了醇的相对挥发性，从而促进其通过蒸馏从混合物中分离。然而，支化醇/水/盐混合物的汽液平衡数据是稀缺的。建议研究盐对这些混合物的汽液平衡的影响，并开发一个立方状态方程/活度系数混合模型。 目标3-提出一种基于状态方程的建模方法：立方加缔合（e-CPA）状态方程（EoS）的电解质版本有可能应用于模拟支化醇/水/盐混合物在相图中的相行为。然而，该EoS不能产生液液平衡的精确相组成，并且没有在高压下的数据上进行测试。建议开发适合于生物精炼应用的合适的基于e-CPA的方法。这项研究的结果将使生物精炼厂运营商能够设计具有成本效益的纯化操作，以生产燃料级支链醇。加拿大将受益于更具竞争力和更环保的生物炼制。此外，还有两名硕士和一名博士。学生将获得适合在工业界和学术界工作的背景和培训。

Branched alcohols are more suitable to produce fuel additives and biofuels than methanol and ethanol because their properties are similar to those of gasoline. However, their production at large scale in biorefineries is currently not economically viable because of the higher cost of purification through distillation. The addition of some salts to the fermentation broth reduces the affinity of the alcohol with the broth, facilitating the purification. Therefore, the phase behaviour of these electrolyte systems is required for designing cost-efficient purification operations. The proposed research has the following objectives, which aim to address critical gaps in the fundamental understanding of the thermodynamics of branched alcohols/water/salt mixtures to advance in the development of modelling tools for the design and simulation of purification operations in biorefineries. Objective 1-Develop a Data-Validated Activity Coefficient Model Using Data Collected from Liquid- Liquid Equilibrium (LLE) Studies: The addition of some salts to an alcohol/water mixture forces the alcohol to separate off the mixture. However, the LLE data required to shed light on the thermodynamics of the mixture are scarce and available models are correlative rather than predictive. It is proposed to collect LLE data for branched alcohol/water/salt mixtures over a range of temperatures and pressures to investigate its thermodynamics, and to incorporate it into an activity coefficient-based model. Objective 2- Develop a Data-Validated Hybrid Model Using Data Collected from Vapor-Liquid Equilibrium (VLE) Studies: The addition of some salts to an alcohol/water mixture increases the relative volatility of the alcohol facilitating its separation from the mixture by distillation. However, VLE data for branched alcohol/water/salt mixture are scarce. It is proposed to investigate the effect of the salt on the VLE of these mixtures and to develop a Cubic Equation-of-State/Activity Coefficient hybrid model. Objective 3- Propose an Equation-of-State-Based Modelling Methodology: The electrolyte version of the Cubic Plus Association (e-CPA) equation of state (EoS) has the potential to be applied to model the phase behaviour of branched alcohol/water/salt mixtures across the phase diagram. However, this EoS does not produce accurate phase compositions for LLE and has not been tested on data at high pressure. It is proposed to develop a suitable e-CPA based methodology suitable for biorefinery applications. The results from this research will allow biorefinery operators to design cost-effective purification operations to produce fuel-grade branched alcohols. Canada will benefit from more competitive and greener biorefineries. In addition, two M.Sc. and one Ph.D. students will receive background and training suitable for careers in the industry and academia.