Catalytic pyrolysis has been used to upgrading the quality of pyrolytic liquids. Herein, we report a comprehensive study on the catalytic pyrolysis of waste tires using Ni/SiO₂ as catalysts. The analyses were carried out by combining thermogravimetry (TGA), TGA interfaced to a Fourier transform infrared spectrometer (TGA–FTIR), and pyrolysis coupled to gas chromatography/mass spectrometer (Py–GC/MS) techniques. During waste tire decomposition, the main functional groups detected in the FTIR were alkenes, aromatics, and heteroatoms-containing groups such as nitrogen, sulfur, and oxygen. Meanwhile, by Py–GC/MS were identified mainly D,L-limonene, isoprene, benzene, toluene, xylenes (BTX), and p-cymene. The Py–GC/MS experiments at three different temperatures (350, 400, and 450 °C) suggested an effect of the catalyst on product distribution. The Ni catalyst promoted cyclization reactions and subsequently aromatization, leading to an improved vapors composition. The use of iso-conversional kinetic models along with master plots allows proposing a multiple-step reaction mechanism, which was well described by the Avrami–Erofeev, Random Scission, and truncated Sestak–Berggren models. The values of activation energies show differences for the catalyzed and uncatalyzed pyrolysis (111.0 kJ mol⁻¹ and 168.4 kJ mol⁻¹), validating the effectivity of Ni/SiO₂. Finally, the thermal Biot (> 1) and Py^I and Py^II numbers (10^–3 < Py^I < 10^–1 and 10^–2 < Py^II < 10^–3) confirms that the process is being occurred between the kinetic and the convection-limited regimes.

Graphic Abstract

中文翻译：

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使用 Ni/SiO2 催化剂进行废轮胎热解的热行为、反应途径和动力学意义

催化热解已被用于提升热解液体的质量。在此，我们报告了使用 Ni/SiO ₂催化热解废轮胎的综合研究作为催化剂。这些分析是通过结合热重分析 (TGA)、TGA 与傅里叶变换红外光谱仪 (TGA-FTIR) 连接以及热解与气相色谱/质谱仪 (Py-GC/MS) 技术相结合来进行的。在废轮胎分解过程中，FTIR 检测到的主要官能团是烯烃、芳烃和含杂原子的基团，如氮、硫和氧。同时，通过 Py-GC/MS 主要鉴定了 D,L-柠檬烯、异戊二烯、苯、甲苯、二甲苯 (BTX) 和对伞花烃。在三个不同温度（350、400 和 450 °C）下的 Py-GC/MS 实验表明催化剂对产物分布的影响。Ni 催化剂促进了环化反应和随后的芳构化，从而改善了蒸气组成。等转化动力学模型和主图的使用允许提出多步反应机制，Avrami-Erofeev、Random Scission 和截断的 Sestak-Berggren 模型对此进行了很好的描述。催化和未催化热解的活化能值显示差异 (111.0 kJ mol^-1和 168.4 kJ mol ^-1 )，验证了 Ni/SiO ₂的有效性。最后，热 Biot (> 1) 和 Py ^I和 Py ^II数（10 ^–3  < Py ^I  < 10 ^–1和 10 ^–2  < Py ^II  < 10 ^–3）证实该过程发生在动力学和对流限制制度。

图形摘要