The thermodynamics on the direct synthesis of dimethyl carbonate (DMC) from CO₂ and CH₃OH was calculated and analyzed. Using Y(NO₃)₃·6H₂O as the precursor, a series of Y₂O₃ were prepared through the one-pot calcination method, which were employed to catalyze DMC synthesis. The decomposition temperature of Y(NO₃)₃·6H₂O was measured by thermogravimetric analysis, and Y₂O₃ was obtained after the precursor calcination at desired temperatures, denoted as Y₂O₃-T (°C). The catalysts were characterized by X-ray diffraction, Brunauer–Emmett–Teller method, transmission electron microscopy, NH₃/CO₂ temperature-programmed desorption, and X-ray photoelectron spectroscopy to detect the crystal phase, surface property, particle size, acidity–basicity amounts, and oxidation state, respectively. The characterization results indicated that Y₂O₃-750 can favor the formation of moderate acidic and basic sites and facilitate the activation of CO₂ and CH₃OH. The catalytic performance evaluation was experimentally investigated, and Y₂O₃-750 owned the highest DMC yield of 1.02 mmol/g·cat under 90 °C, 8 MPa, and 6 h, which also exhibited reliable recycle ability.

中文翻译：

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氧化钇与二氧化碳和甲醇直接合成碳酸二甲酯的热力学研究

计算和分析了由CO ₂和CH ₃ OH直接合成碳酸二甲酯（DMC）的热力学。以Y（NO ₃）₃ ·6H ₂ O为前驱体，通过一锅法煅烧制备了一系列Y ₂ O ₃，用于催化DMC的合成。Y的分解温度（NO ₃）₃ ·6H ₂是通过热重分析测得的O，和Y ₂ ö ₃在期望的温度，表示为Y前体煅烧后，获得₂ ö ₃ - Ť（°C）。通过X射线衍射，Brunauer-Emmett-Teller方法，透射电子显微镜，NH ₃ / CO _2程序升温脱附和X射线光电子能谱对催化剂进行表征，以检测晶体相，表面性质，粒度，酸度。 -碱度和氧化态。表征结果表明，Y ₂ O ₃ -750可促进中等酸性和碱性位点的形成，并促进CO ₂和CH ₃ OH的活化。实验研究了催化性能评价，并采用了Y ₂ O ₃-750在90°C，8 MPa和6 h下具有1.02 mmol / g·cat的最高DMC产率，并且还具有可靠的循环能力。