Abstract:

The impact of CO₂ on the climate is getting more and more serious. Converting it into formic acid can simultaneously realize resource utilization and carbon emission reduction. The current research of CO₂ hydrogenation to formic acid is mainly to find high-performance catalysts, and process design is also indispensable for the industrialization of formic acid, but the process design of CO₂ electrocatalytic hydrogenation to formic acid has not been reported yet. Using natural gas whose main components are H₂ and CO₂ to produce hydrogen pressure swing adsorption desorption gas as raw materials, a process of gas membrane separation coupled with CO₂ electrocatalytic hydrogenation to produce 30000 t of formic acid per year was designed and simulated in Unisim Design process simulation software. Then the sensitivity analysis method was used to optimize the membrane electrode area, cathode potential, H₂ membrane area, CO₂ membrane area, distillation column pressure and reflux ratio. The unit cost of formic acid under the optimal scheme is 6.37 CNY/kg, which is 31.88% higher than the traditional Kemiral-Leonard (KL) process, but the proposed process can reduce 33300 t CO₂ per year, which has important environmental significance. Finally, through cost analysis, three effective solutions are proposed from the three aspects of reactor life, cost and electricity price, which can reduce the production cost of formic acid to that of the traditional KL process.

Key words: reactor, CO₂ electrocatalysis, mathematical modeling, process simulation, optimal design

摘要：

CO₂对气候影响越来越严重，将其转化为甲酸能够同步实现资源化和碳减排。当前CO₂加氢制甲酸的研究主要在于寻找高性能催化剂，而过程设计对甲酸实现工业化也不可或缺，但是CO₂电催化加氢制甲酸的过程设计尚未见报道。利用主要成分为H₂和CO₂的天然气制氢变压吸附解吸气为原料，设计了气体膜分离耦合CO₂电催化加氢年产3万吨甲酸的工艺，并在Unisim Design流程模拟软件中进行了模拟。随后利用灵敏度分析法对反应器中膜电极面积、阴极电势、H₂膜面积、CO₂膜面积、精馏塔压力和回流比等参数进行优化，在最优方案下甲酸的单位质量成本为6.37 CNY/kg，比传统的Kemiral-Leonard（KL）工艺高31.88%，但是所提出的工艺可以实现减排3.33万吨/年的CO₂，具有重要的环境保护意义。最后通过成本分析，从反应器的寿命、成本和电价三个方面提出三种有效的解决方案，可以将甲酸生产成本降低到传统KL工艺的生产成本。

关键词: 反应器, CO₂电催化, 数学模型, 过程模拟, 优化设计