Abstract This work studies the heterogeneous conversion of naphthalene over different chars at 800 °C and 900 °C with gas residence times ranging from 0.05 s to 0.15 s. The aim was to analyse the role of the pore size distribution and surface composition on the catalytic activity of the char during batch experiments with a steady gas flow doped with naphthalene. The char samples were produced by steam activation using the same parent material (a pyrolysed Colombian coal). The activation aimed at generating chars with increasing porosities but similar surface composition. An ash-leached char was also prepared to investigate the role of the ash-forming elements on the char activity. The evolution of the naphthalene conversion in the gas phase and the pore size distribution of the char were measured during the tests. The initial naphthalene conversion and the char deactivation rate were seen to be strongly influenced by the concentration of alkali and alkaline earth metallic (AAEM) elements in the char. In absence of AAEM elements, the char surface was rapidly deactivated due to the depletion of surface oxo-groups produced during the char activation. The steam activation of unleached chars does not influence their inherent surface reactivity but significantly enhances the amount of surface area available for tar conversion. A linear correlation between the reaction rate coefficient and the mesopore surface area was determined for the chars with similar surface composition but different pore size distribution.

中文翻译：

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炭内部结构和组成对萘非均相转化的影响

摘要 本工作研究了萘在 800 °C 和 900 °C 下在不同炭上的多相转化，气体停留时间为 0.05 s 至 0.15 s。目的是分析孔径分布和表面组成对在掺有萘的稳定气流的批量实验中炭催化活性的作用。使用相同的母体材料（一种热解的哥伦比亚煤）通过蒸汽活化生产炭样品。活化旨在产生孔隙率增加但表面成分相似的炭。还准备了灰浸炭以研究成灰元素对炭活性的作用。在测试期间测量了气相中萘转化的演变和炭的孔径分布。初始萘转化率和炭失活率被认为受炭中碱金属和碱土金属 (AAEM) 元素浓度的强烈影响。在没有 AAEM 元素的情况下，由于炭活化过程中产生的表面氧代基团的消耗，炭表面会迅速失活。未浸出炭的蒸汽活化不会影响其固有的表面反应性，但显着增加了可用于焦油转化的表面积量。对于具有相似表面组成但不同孔径分布的炭，确定了反应速率系数与中孔表面积之间的线性相关性。