We report for the first time Pd nanoparticles (NPs) supported on natural halloysite as catalysts for selective production of p-cymene from waste tire pyrolysis (WTP). The catalysts were prepared by dispersing Pd NPs on either the inner (PdHin, 3.4 nm) or outer surface (PdHout, 1.6 nm) of halloysite nanotubes to produce different acid–base properties. The performance of these catalysts for WTP was studied by micropyrolysis coupled to mass spectrometry (Py-GC/MS) between 400 and 500 °C and for discrete times (2, 12, 20, and 40 s). PdHin exhibited twice the selectivity (42%) of PdHout, which was attributed to its higher acidity (1.74 mequiv g^–1) and its bifunctionality established between the support’s acidity and the Pd⁰ sites. From discrete time-dependent experiments, we estimated activation energies for waste tire conversion (72.8 kJ/mol) and p-cymene production on PdHin (101.0 kJ/mol) under a kinetically controlled regime (Biot ∼3.1, Py^I ≫1, and Py^II ≫1).

中文翻译：

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天然埃洛石负载钯催化快速热解废轮胎的价值

我们首次报告了负载在天然埃洛石上的 Pd 纳米粒子 (NPs) 作为催化剂，用于从废轮胎热解 (WTP) 中选择性生产对伞花烃。通过将 Pd NPs 分散在埃洛石纳米管的内表面（PdHin，3.4 nm）或外表面（PdHout，1.6 nm）以产生不同的酸碱特性来制备催化剂。这些催化剂用于 WTP 的性能通过微热解与质谱联用 (Py-GC/MS) 在 400 至 500°C 和离散时间（2、12、20 和 40 秒）进行研究。PdHin 的选择性 (42%) 是 PdHout 的两倍，这归因于其较高的酸度 (1.74 mequiv g ^–1 ) 及其在载体酸度和 Pd ⁰之间建立的双功能性网站。从离散时间相关的实验中，我们估计废轮胎转换活化能（72.8千焦/摩尔）和p上PdHin（101.0千焦/摩尔）动力学控制制度下（比奥-cymene生产~3.1，PY^我»1，和Py ^II ≫1)。