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首页> 外文期刊>Catalysis science & technology >Improving mass-transfer in controlled pore glasses as supports for the platinum-catalyzed aromatics hydrogenation
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Improving mass-transfer in controlled pore glasses as supports for the platinum-catalyzed aromatics hydrogenation

机译：改善受控孔玻璃中的质量转移，作为对铂催化芳香族剂的支撑

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The liquid-phase hydrogenation of toluene and other alkyl substituted benzene derivatives with different critical diameters was investigated over Pt-catalysts supported on spherical controlled pore glasses (CPGs) as model supports at 373 K in the batch mode. The effect of mass-transfer within the catalyst pores was studied by varying the pore width (4, 10, and 80 nm) and average grain size (18-150 mu m) of the Pt/CPG catalysts. For toluene hydrogenation, internal mass-transfer limitations were absent (effectiveness factor >90%) only for catalysts with particle sizes below 25 mu m and pore widths <= 10 nm or with a pore width of 80 nm and particle sizes around 75 mu m, respectively. Effective diffusion coefficients obtained from initial reaction rates via the Thiele concept, e.g., 2.8 x 10(-10) m(2) s(-1) for toluene over the catalyst with 10 nm pore width, were an order of magnitude lower than when determined by PFG-NMR. This difference was explained in terms of transport resistances such as surface barriers affecting the diffusivity assessment via the Thiele concept, while PFG-NMR measures intraparticle diffusion only.
机译：甲苯和其他烷基取代的苯衍生物的液相氢化研究了不同临界直径的苯衍生物，该模型在批处理模式下在373 K下支撑在球形控制孔玻璃（CPG）上的PT催化剂。通过改变PT/CPG催化剂的孔宽度（4、10和80 nm）和平均晶粒尺寸（18-150 MU M），研究了催化剂孔内质量转移的作用。对于甲苯氢化，对于粒度低于25 mu m且孔宽度 90％）仅为90％> 90％）。 ， 分别。从初始反应速率获得的有效扩散系数，例如，甲苯在具有10 nm孔隙宽度的催化剂上的2.8 x 10（-10）m（-10）m（2）s（-1）的数量级低于催化剂。由PFG-NMR确定。这种差异是用传输电阻（例如通过Thiele概念影响扩散率评估的表面屏障）来解释的，而PFG-NMR仅测量颗粒内扩散。

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