Abstract:

The utilization rate of CO₂ and H₂ raw materials is an important factor affecting the process economy of CO₂ hydrogenation to methanol. The influences of catalyst type, temperature, pressure, space velocity and H₂/CO₂ feed ratio on CO₂ conversion and methanol selectivity, and the influences of process conditions on the loss of carbon and hydrogen in gas and liquid phase were discussed, respectively. A cycle process for CO₂ hydrogenation to methanol was proposed by introducing the stripping unit to recover the dissolved CO₂ from liquid phase. The effects of purge gas on carbon and hydrogen utilization and process economy were studied to determine the optimal rate of purge gas. The results showed that the loss of dissolved CO₂ was negligible after stripping separation and the loss of carbon and hydrogen mainly depended on the purge gas. The equipment investment cost decreased gradually with the increase of the purge gas flowrate while the unit production cost firstly decreased and then increased. The utilization rate of CO₂ and H₂ were respectively 98.9% and 65.9% when the flow rate ratio of purge to feed was set as 1%. Compared with the traditional process, the proposed process had an effective utilization of raw materials. This study provides a feasible path for efficient conversion of CO₂ hydrogenation to methanol.

Key words: carbon dioxide, methanol, process simulation, process analysis, optimization design

摘要：

原料CO₂和H₂利用率是影响CO₂加氢制甲醇过程经济性的重要因素。本文讨论了催化剂类型、温度、压力、空速和H₂/CO₂进料比等因素对CO₂转化率和甲醇选择性的影响以及工艺条件对气液相中碳氢损失的影响，提出了利用汽提方式回收液相中溶解CO₂的循环工艺，并分析了弛放量对碳氢利用率与工艺经济性的权衡关系，确定了最佳的弛放率。结果表明：经过汽提之后，液相中溶解的CO₂损失已可忽略不计，碳氢损失主要取决于气相弛放；随着弛放气流量的增大，设备投资费用逐渐减小，而单位生产成本先减小后增大；在弛放率为1%的条件下，与传统工艺流程相比，含汽提的CO₂加氢制甲醇循环工艺的CO₂利用率为98.9%，H₂利用率为65.9%，具有较高的原料利用率。本研究为CO₂加氢制甲醇高效转换提供了一条可行路径。

关键词: 二氧化碳, 甲醇, 过程模拟, 过程分析, 优化设计