Thermal Behavior, Reaction Pathways and Kinetic Implications of Using a Ni/SiO2 Catalyst for Waste Tire Pyrolysis

Abstract

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.

Pyrolysis and Oxidation of Waste Tire Oil: Analysis of Evolved Gases

“…Waste car tires are quickly becoming a menace of global proportions with more than 25.7 million tons of waste generated annually out of which 35% is not recycled or recovered in any shape or form. 1 Waste tires are typically aggregated and due to their low volume density and high void ratio, consume a relatively large space in landfills or dumping grounds. One of the several options to use waste tires is through producing pyrolysis oil, which is a liquid fraction obtained from their pyrolysis.…”

“… 2 The use of waste tire oil (WTO) needs to be perceived in the broad context of the concept of circular economy, which is essential to move toward the new paradigm in sustainability. 1 The tires that are typically dumped in landfills can help meet some of the energy needs, which is evaluated as part of the current work. When looking at any recycling opportunity, it is imperative to understand the net gain in energy obtained in reusing the resource as compared to dumping it in landfills or incinerators.…”

“…One of the several options to use waste tires is through producing pyrolysis oil, which is a liquid fraction obtained from their pyrolysis . The use of waste tire oil (WTO) needs to be perceived in the broad context of the concept of circular economy, which is essential to move toward the new paradigm in sustainability . The tires that are typically dumped in landfills can help meet some of the energy needs, which is evaluated as part of the current work.…”

Catalytic Cracking of Waste Tires using Nano‐ZSM‐5/MgAl‐LDO

“…Around 25.7 million tons of tires are wasted every year, of which only 65% are reused in some form of recycling or recovery. [ 1 ] Most of tires consist of natural rubber ( cis ‐1,4‐polyisoprene rubber: NR), synthetic rubber (styrene‐butadiene rubber: SBR and/or polybutadiene rubber: BR) as well as auxiliary agents including vulcanizing agents, accelerators, aging retardants, and carbon black. [ 2 ] The complex composition of tires brings some challenges to their recycling.…”

“…Thermal pyrolysis is a particularly efficient way to deal with high volumes of tires and eliminate long‐standing stockpiles because it is generally technically straightforward to implement on a large scale. [ 1–3 ] At the same time, it can produce some useful chemical products, such as toluene widely used in the production of pesticides, dyes, surfactants and solvents, and limonene commonly used in the preparation of industrial solvents, resins, and adhesives. [ 4–6 ] In addition, light hydrocarbons can also be obtained by thermal pyrolysis of waste tires, which can be used not only as the main component of fuel but also as the starting materials for other chemicals.…”