The fast deactivation caused by serious formation of coke is a major challenge in catalytic isomerization of endo-tetrahydrodicyclopentadiene (endo-THDCPD) into exo-tetrahydrodicyclopentadiene (exo-THDCPD) over the HY zeolite. In order to suppress the coke formation for the isomerization process, the conventional HY zeolite was modified with Pt at 0.3 wt %. Then, the hydroisomerization of endo-THDCPD into exo-THDCPD was evaluated over a fixed-bed reactor. The catalytic stability of Pt/HY was greatly enhanced in comparison to that of the HY zeolite. The Pt/HY catalyst provided 97% endo-THDCPD conversion and 96% selectivity for exo-THDCPD without deactivation after 100 h. Moreover, the formation mechanism of coke on the HY zeolite during the isomerization process was proposed based on the results of the coke analysis. It was indicated that the coke was generated from the oligomerization and condensation of olefin species, which originated from the β-scission reaction or hydride transfer reaction of intermediates. The lower coke formation over Pt/HY was attributed to the lower amount of coke precursors, which could be hydrogenated by activated H₂ over Pt sites. Therefore, Pt on Pt/HY and H₂ were two crucial factors in efficiently enhancing the catalytic stability of the HY zeolite for this isomerization reaction.

中文翻译：

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内-四氢二环戊二烯在 Pt/HY 上高效加氢异构化为外-四氢二环戊二烯

由严重的焦炭形成引起的快速失活是在 HY 沸石上将内型四氢二环戊二烯( endo- THDCPD)催化异构化为外型四氢双环戊二烯( exo- THDCPD)的主要挑战。为了抑制异构化过程中的焦炭形成，传统的 HY 沸石用 0.3 wt% 的 Pt 改性。然后，在固定床反应器上评估了内型-THDCPD加氢异构化为外型-THDCPD。与 HY 沸石相比，Pt/HY 的催化稳定性大大提高。Pt/HY 催化剂提供了 97% 的内型-THDCPD 转化率和 96% 的外型-THDCPD 选择性-THDCPD 100 小时后未失活。此外，根据焦炭分析结果，提出了异构化过程中HY沸石上焦炭的形成机理。表明焦炭是由烯烃类的低聚和缩合生成的，该反应来源于中间体的β-裂解反应或氢化物转移反应。Pt/HY 上焦炭的形成较少归因于焦炭前体的量较少，其可以通过 Pt 位点上的活化 H ₂进行氢化。因此，Pt/HY 上的 Pt 和 H ₂是有效提高 HY 沸石对该异构化反应的催化稳定性的两个关键因素。