Abstract A kinetic model has been established for the direct synthesis of dimethyl ether (DME) from syngas and CO2 feeds. The kinetic parameters have been determined fitting the experimental results obtained using a CuO‑ZnO‑MnO/SAPO‑18 (CZMn/S) bifunctional catalyst in a fixed‑bed isothermal reactor, under a wide range of operating conditions: 250–350 °C; 10–40 bar; CO2/CO molar ratio in the feed, between 0 and 1; H2/COX molar ratio in the feed, 3/1 and 4/1; space time, from 1.25 gcath(molC)−1, up to 20 gcath(molC)−1; time on stream, up to 30 h. The model considers the kinetic equations of the individual reactions of methanol synthesis from CO and CO2, the dehydration of methanol to DME, the water gas shift reaction (WGS) and the formation of paraffins, along with the deactivation kinetics. The attenuation of the reaction rates of methanol and paraffins synthesis has been considered by the competitive adsorption of CO2 and H2O in the metallic sites with respect to the adsorption of CO (more reactive than CO2 in the synthesis of methanol). The deactivation by coke has been quantified by a kinetic equation dependent on the concentrations of methanol and DME, and the attenuation of the deactivation by the competitive adsorption of CO2 and H2O has also been considered in this equation. The kinetic model allows predicting satisfactorily the evolution with time on stream of the concentration of the components in the reaction medium (methanol, DME, unreacted CO and CO2, and paraffins formed as by‑products). In addition, the model has been used to simulate the reactor, determining the effect of the reaction conditions on the conversion of CO2. This conversion, in contrast to the yield of DME, increases with increasing CO2 concentration in the reactor feed.

中文翻译：

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在 CuO-ZnO-MnO/SAPO-18 催化剂上直接合成二甲醚的动力学模型和 CO2 转化率评估

摘要 建立了由合成气和 CO2 原料直接合成二甲醚 (DME) 的动力学模型。动力学参数已确定，拟合使用 CuO-ZnO-MnO/SAPO-18 (CZMn/S) 双功能催化剂在固定床等温反应器中获得的实验结果，在广泛的操作条件下：250–350 °C ; 10–40 巴；进料中CO2/CO摩尔比，在0到1之间；进料中H2/COX摩尔比，3/1和4/1；时空，从 1.25 gcath(molC)−1，到 20 gcath(molC)−1；在线时间，最长 30 小时。该模型考虑了从 CO 和 CO2 合成甲醇、甲醇脱水为 DME、水煤气变换反应 (WGS) 和石蜡形成的各个反应的动力学方程，以及失活动力学。CO2 和 H2O 在金属位点的竞争吸附相对于 CO 的吸附（在甲醇合成中比 CO2 更具反应性）已经考虑了甲醇和石蜡合成反应速率的衰减。焦炭的失活已通过依赖于甲醇和 DME 浓度的动力学方程进行量化，并且该方程中还考虑了 CO2 和 H2O 的竞争吸附对失活的衰减。动力学模型可以令人满意地预测反应介质中组分（甲醇、二甲醚、未反应的 CO 和 CO2 以及作为副产物形成的石蜡）浓度随时间的变化。此外，该模型已被用于模拟反应堆，确定反应条件对 CO2 转化率的影响。与 DME 的产率相反，这种转化率随着反应器进料中 CO2 浓度的增加而增加。