Modelling of pore structure evolution during catalyst deactivation and comparison with experiment
Modelling of pore structure evolution during catalyst deactivation and comparison with experiment
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DOI：
10.1016/j.ces.2010.07.027
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发表时间：
2010-10
影响因子：
4.7
通讯作者：
Peter I. Chigada;Jiawei Wang;B. Al-Duri;J. Wood;S. Rigby
中科院分区：
文献类型：
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作者：
Peter I. Chigada;Jiawei Wang;B. Al-Duri;J. Wood;S. Rigby
超临界流体通常被提议作为延长非均相催化剂寿命的手段，所述非均相催化剂通过固体碳质沉积物（通常称为“焦炭”）的沉积而失活。这是因为与气态相比，超临界状态的更高密度允许在焦炭可以积聚并抑制传质之前溶解和去除焦炭前体和焦炭。然而，该方法对所实现的催化剂寿命延长的影响强烈地取决于催化剂载体的孔隙空间的性质，因为这决定了质量传输速率和颗粒对孔堵塞的敏感性。为了优化在超临界条件下运行催化过程的设计，能够预测传质速率和结构演变之间的相互作用至关重要。以前的工作忽略了非均相催化剂的空隙空间的全部复杂性，但在模型中捕获这一点对于充分理解焦化过程中空隙空间的演变至关重要。在这项工作中，一种新的结构模型，捕捉控制质量传输和结构演化的空隙空间的关键特征已被采用。各种反应方案的模拟，捕捉真实的反应途径的重要方面，再加上质量传输，使结构演化的特定轨迹的预测是可以预期的。这些模拟已与超临界条件下的真实的催化剂的结构演变的实验观察进行了比较。模拟与实验的比较，使验证的结构模型和特定的反应方案中使用的模拟。
Supercritical fluids are often proposed as a means of extending the lifetimes of heterogeneous catalysts that deactivate by deposition of solid carbonaceous deposits, often called ‘coke’. This is because the higher density of the supercritical state, compared to the gaseous state, permits the dissolution and removal of coke precursors and coke, before coke can build up and inhibit mass transfer. However, the impact of this process on the extension of catalyst lifetime achieved depends strongly upon the nature of the pore space of the catalyst support, as this dictates the rates of mass transport and the susceptibility of the pellet to pore blockage. In order to optimise the design for running a catalytic process under supercritical conditions, it is vital to be able to predict the interaction between mass transport rates and structural evolution. Previous work has neglected the full complexity of the void space of heterogeneous catalysts, but capturing this in the model is essential to fully understand the evolution of that void space during coking. In this work, a novel structural model that captures the key features of the void space that control mass transport and structural evolution has been employed. Simulations of various reaction schemes, capturing the important aspects of the real reaction pathways, coupled with mass transport, have enabled the prediction of the particular trajectories of structural evolution to be expected. These simulations have been compared with experimental observations of the structural evolution of a real catalyst under supercritical conditions. A comparison of simulation with experiment has enabled a validation of the structural model and particular reaction scheme used in the simulations.