Nepryahin Artjom, Fletcher Robin S, Holt Elizabeth M, Rigby Sean P
1Present Address: Department of Chemical and Environmental Engineering, University of Nottingham, University Park, Nottingham, NG7 2RD UK.
2Johnson Matthey, P.O. Box 1, Belasis Avenue, Billingham, Cleveland, TS23 1LB UK.
Adsorption (Boston). 2016;22(7):993-1000. doi: 10.1007/s10450-016-9806-9. Epub 2016 Aug 13.
Determining structure-transport relationships is critical to optimising the activity and selectivity performance of porous pellets acting as heterogeneous catalysts for diffusion-limited reactions. For amorphous porous systems determining the impact of particular aspects of the void space on mass transport often requires complex characterization and modelling steps to deconvolve the specific influence of the feature in question. These characterization and modelling steps often have limited accuracy and precision. It is the purpose of this work to present a case-study demonstrating the use of a more direct experimental evaluation of the impact of pore network features on mass transport. The case study evaluated the efficacy of the macropores of a bidisperse porous foam structure on improving mass transport over a purely mesoporous system. The method presented involved extending the novel integrated gas sorption and mercury porosimetry method to include uptake kinetics. Results for the new method were compared with those obtained by the alternative NMR cryodiffusometry technique, and found to lead to similar conclusions. It was found that the experimentally-determined degree of influence of the foam macropores was in line with expectations from a simple resistance model for a disconnected macropore network.
确定结构-传输关系对于优化作为扩散受限反应的多相催化剂的多孔颗粒的活性和选择性性能至关重要。对于无定形多孔体系，确定孔隙空间特定方面对质量传输的影响通常需要复杂的表征和建模步骤，以解卷积所讨论特征的具体影响。这些表征和建模步骤的准确性和精度往往有限。本工作的目的是展示一个案例研究，该研究演示了对孔网络特征对质量传输影响进行更直接实验评估的应用。该案例研究评估了双分散多孔泡沫结构的大孔在改善质量传输方面相对于纯介孔体系的功效。所提出的方法涉及将新型集成气体吸附和压汞法扩展到包括吸附动力学。将新方法的结果与通过替代的核磁共振低温扩散测量技术获得的结果进行了比较，发现得出了相似的结论。结果发现，通过实验确定的泡沫大孔的影响程度与针对不连续大孔网络的简单阻力模型的预期一致。
