Abstract Direct synthesis of dimethyl ether from syngas over mixed catalysts constitutes a novel route aimed to replace the traditional two-step process. Many previous studies about this one-step process showed that catalyst deactivation is unavoidable. The present study wants to characterize the deactivation of CuO/ZnO/Al2O3 and γ-Al2O3 mechanical mixtures, and develop a deactivation model for predicting catalyst performance in presence of deactivation. It was demonstrated that water adsorbs over the γ-Al2O3 surface, blocking its active sites and causing a sharp conversion drop (mainly observed during the first hours on stream). This effect was reversible and could be avoided by increasing temperature (270 °C or above). The other deactivation mechanism was the deposition of carbonaceous species over the catalyst surface. A deactivation model was proposed and fitted to the experimental data.

中文翻译：

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在CuO/ZnO/Al 2 O 3 和γ-Al 2 O 3 机械混合物上从合成气直接合成二甲醚的催化剂失活

摘要 合成气在混合催化剂上直接合成二甲醚是一种旨在取代传统两步法的新途径。许多先前关于这一一步过程的研究表明，催化剂失活是不可避免的。本研究希望表征 CuO/ZnO/Al2O3 和 γ-Al2O3 机械混合物的失活，并开发失活模型以预测失活情况下的催化剂性能。结果表明，水会吸附在 γ-Al2O3 表面，阻塞其活性位点并导致转化率急剧下降（主要在运行的最初几个小时内观察到）。这种影响是可逆的，可以通过提高温度（270°C 或更高）来避免。另一种失活机制是含碳物质在催化剂表面上的沉积。