Effects of post-thermal treatments of ball-milled boron nitrides on solid base catalysis
Effects of post-thermal treatments of ball-milled boron nitrides on solid base catalysis
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DOI：
10.1016/j.cattod.2019.11.007
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发表时间：
2020-08
期刊：
影响因子：
5.3
通讯作者：
Atsushi Takagaki
中科院分区：
文献类型：
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作者：
Atsushi Takagaki
研究了球磨六方氮化硼作为固体碱催化剂。球磨后的氮化硼在真空或空气中加热，用于Knoevenagel冷凝。通过x射线衍射、氮气吸附、热重质谱、傅里叶变换红外光谱和x射线光电子能谱等测试表明，真空热处理对晶体结构和表面组成等理化性质几乎没有改变，而空气热处理由于B2O3的形成而使其性质发生了明显的变化。随着疏散温度的升高，基本站点的数量增加。排出后的氮化硼在40 °C的条件下使苯甲醛与丙二腈的Knoevenagel缩合反应产率适中。煅烧后的氮化硼的活性随煅烧温度的不同而不同。球磨后的氮化硼，在300 ℃下煅烧的活性最高。催化活性与碱量和比表面积无直接关系，表明酸碱双官能团在球磨氮化硼催化剂的Knoevenagel缩合反应中起重要作用。
Ball-milled hexagonal boron nitride was investigated as a solid base catalyst. The ball-milled boron nitrides were heated in a vacuum or air and used for Knoevenagel condensation. Measurements by X-ray diffraction, nitrogen adsorption, thermogravimetry-mass spectrometry, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy indicated that the heat treatment under vacuum hardly changed the physicochemical properties including crystal structure and surface composition whereas the heat treatment in air significantly altered the properties due to the formation of B2O3. The number of basic sites increased with the increase of the evacuation temperature. The boron nitrides after evacuation gave moderate product yield for Knoevenagel condensation of benzaldehyde with malononitrile at 40 °C. The boron nitrides after calcination showed different activity, dependent on the calcination temperature. The boron nitride after ball-milling, followed by calcination at 300 °C exhibited the highest activity. The catalytic activity was not directly related to the base amount and the surface areas, suggesting that acid-base bifunctionality plays an important role in Knoevenagel condensation using the ball-milled boron nitride catalysts.