Using tungstophosphoric acid-modified CeO2, TiO2, and SiO2 catalysts to promote secondary reactions leading to aromatics during waste tire pyrolysis

OSORIO-VARGAS, PAULA; LICK, ILEANA D.; PIZZIO, LUIS R.; ALEJANDRO, SERGUEI; CASAS-LEDÓN, YANNAY; POBLETE, JORGE; CASELLA, MÓNICA L.; ARTEAGA-PÉREZ, LUIS E.

Molecular Catalysis

Elsevier

Año: 2022 vol. 531

2468-8231

The synthesis of catalysts for upgrading waste tire pyrolysis oils (TPO) into marketable products such as fuels, solvents or fine chemicals is a major challenge. Herein, the effect of CeO2, SiO2, and TiO2 catalysts containing tunsgtophosphoric acid (TPA) on the selectivity to aromatics (benzene, toluene, and xylenes viz. BTXs) and p-cymene was studied for the first time. Modifying TiO2 with 1% and 10% TPA allowed modulating the oxide’s acidity, resulting in a ratio of Lewis acid sites and strong Brønsted acid sites that favored the target compound formation. The 1%TPA catalyst enhanced the p-cymene production (Sp-cymene = 56.3%). In contrast, 10%TPA promoted BTX formation (SBTX= 26%) over p-cymene (Sp-cymene = 6.5%) due to its greater content of Brønsted acid sites. The selectivity of SiO2 and CeO2-based catalysts to these aromatic compounds was in the same order as the uncatalyzed reaction. The p-cymene is mainly formed from secondary reactions of isomerization of limonene to other terpenes (terpinolene, α-terpinene, and γ-terpinene) and the subsequent ring dehydrogenation with an activation energy of 62.3 kJ mol-1. The BTXs were kinetically favored on 10%TPATi catalyst with an Ea = 112 kJ mol-1. The study was performed in a fixed bed Pyr-GC/MS system under kinetically controlled regime.