Conversion of methanol to dimethyl ether (MTD) has known to be one of the main routes for the production of a clean bio-fuel, i.e., dimethyl ether (DME). However, efficient, selective, and stable catalyst is highly required for production of DME especially at relatively low temperature. Herein, aluminum phosphate nanocatalysts were fabricated by a co-precipitation method in the presence of triethylamine (TEA) as a surfactant. Thermal, structural, spectroscopic, morphological and texture properties of the catalysts were characterized by thermal analyses (TG–DTA), X-Ray diffraction (XRD), Fourier transform infrared (FTIR), high resolution transmission electron microscopy (HR-TEM) and N₂-sorption analyses. In addition, the acidity of these catalysts was evaluated by isopropyl alcohol dehydration and chemisorption of basic probes. Results of acidity and pyridine-TPD indicated that these catalysts possessed Brϕnsted acidic sites of weak and intermediate strengths. The results of catalytic activity demonstrated that aluminum phosphate nanocatalyst (AP₁T₁) calcined at 400 °C exhibited the best catalytic performance for methanol dehydration into DME with a conversion of 100% and a 100% selectivity at 250 °C. In addition, this catalyst (AP₁T₁) exhibits a unique behavior where its catalytic performance only decreases by 10% upon increasing the % of methanol in the reacting feed to 35%. Moreover, it possessed excellent long-term stability with almost the same efficiency after a period of 120 h. The observable catalytic activity of these catalysts was well linked to the catalyst acidity and the activation energy.

Graphic Abstract

中文翻译：

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超声制备的AlPO4纳米催化剂对甲醇选择性生产二甲醚的催化性能

已知将甲醇转化为二甲醚（MTD）是生产清洁生物燃料即二甲醚（DME）的主要途径之一。然而，特别是在相对较低的温度下，高效，选择性和稳定的催化剂对于DME的生产是非常需要的。在此，在三乙胺（TEA）作为表面活性剂的存在下，通过共沉淀法制备磷酸铝纳米催化剂。通过热分析（TG-DTA），X射线衍射（XRD），傅里叶变换红外（FTIR），高分辨率透射电子显微镜（HR-TEM）和N ₂吸附分析。另外，这些催化剂的酸度通过异丙醇脱水和碱性探针的化学吸附来评估。酸度和吡啶-TPD的结果表明，这些催化剂具有弱和中等强度的布朗斯台德酸性位。催化活性的结果表明，在400°C煅烧的磷酸铝纳米催化剂（AP ₁ T ₁）表现出甲醇脱水成DME的最佳催化性能，在250°C时的转化率为100％，选择性为100％。此外，该催化剂（AP ₁ T ₁）表现出独特的行为，其中当将反应进料中甲醇的百分比提高到35％时，其催化性能只会降低10％。此外，它具有出色的长期稳定性，在120小时后几乎具有相同的效率。这些催化剂的可观察到的催化活性与催化剂的酸度和活化能密切相关。

图形摘要