Tuning the product distribution during the catalytic pyrolysis of waste tires: The effect of the nature of metals and the reaction temperature

OSORIO-VARGAS, PAULA; MENARES, TAMARA; LICK, DANIELA; CASELLA, MONICA L.; ROMERO, ROMINA; JIMÉNEZ, ROMEL; ARTEAGA-PÉREZ, LUIS E.

CATALYSIS TODAY

ELSEVIER SCIENCE BV

Año: 2020

0920-5861

Metal catalysts based on Ni, Co, and Pd supported on SiO2 were evaluated in the catalyticpyrolysis of waste tires using pyrolysis experiments coupled to gas chromatography/massspectrometry (Py?GC/MS) and thermogravimetric analysis coupled with Fourier TransformInfrared spectrometer (TGA?FTIR) techniques. The effect of temperature and the nature ofmetals on the product distribution and reaction pathways was determined. Catalytic pyrolysispromoted aromatization and cracking reactions at particularly low temperatures ca. 350 °C,leading mainly to the formation of alkenes (isoprene), aromatic terpenes (p-cymene),aliphatic terpenes (d,l-limonene), and other aromatic compounds such as benzene, toluene,and xylenes (BTX). The Pd/SiO2 catalyst was the most selective toward aromatic compounds(around 40%), owing to its well-known hydrogenation/dehydrogenation capacity, while C?C bond cleavage reactions, leading to alkenes, were more favored on the Ni/SiO2 andCo/SiO2 catalysts. In all cases, high selectivity to limonene and isoprene was observed at lowtemperature. Above 400 °C, no significant differences in product distribution were observedbetween catalyzed and uncatalyzed pyrolysis. Herein, selectivity toward high-valuehydrocarbons (i.e., d,l-limonene, isoprene, BTX, and p-cymene) during the catalyticpyrolysis of waste tires was tuned by the nature of the supported transition metals (i.e., Ni,Co, Pd) and the reaction temperature (e.g.,