Abstract This article presents a novel heat-management approach for CO2 valorization to synthetic natural gas based on free convection to the environment, without requirements of heat-exchange services. With this aim, a reactor channel was built (d = 4.6 mm, L = 250 mm) and tested at different conditions of inlet temperatures, gas hourly space velocities and pressures using an active nickel/ceria-based catalyst. After experimentation, a CFD model was developed, validated and employed for an efficient sensitive analysis of the most suitable reaction conditions. The simulation criteria were obtaining high CO2 conversion level and restricting overheating to avoid catalyst and reactor degradation. Then, the optimal conditions found by CFD modelling were successfully validated at lab-scale. The CO2 conversion level experimentally obtained was 93%, by using a decreasing temperature profile in the range of 830–495 K, operating at a pressure of 5 atm and a gas hourly space velocity of 11,520 h−1. The proposed reactor configuration guarantees an efficient heat management along the reactor channel by using feasible conditions of pressure, temperature and flowrate for its implementation in small-scale applications, where the use of the exothermic heat is less profitable.

中文翻译：

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基于自由对流的 CO2 甲烷化热管理洞察

摘要 本文提出了一种新的热管理方法，用于将 CO2 转化为合成天然气，该方法基于与环境的自由对流，无需热交换服务。为此，建造了一个反应器通道（d = 4.6 mm，L = 250 mm），并使用活性镍/二氧化铈基催化剂在入口温度、气时空速和压力的不同条件下进行测试。经过实验，CFD 模型被开发、验证并用于对最合适的反应条件进行有效的灵敏分析。模拟标准是获得高 CO2 转化水平并限制过热以避免催化剂和反应器退化。然后，通过 CFD 建模找到的最佳条件在实验室规模上得到了成功验证。实验获得的 CO2 转化率为 93%，通过使用 830-495 K 范围内的递减温度曲线，在 5 个大气压的压力和 11,520 h-1 的气时空速下运行。所提议的反应器配置通过使用可行的压力、温度和流速条件来保证沿反应器通道的有效热管理，以在小规模应用中实施，其中放热的使用利润较低。