Cobalt-Iron-Manganese Catalysts for the Conversion of End-of-Life-Tire-Derived Syngas into Light Terminal Olefins

Influence of Specific Power on the Solid and Liquid Products Obtained in the Microwave-Assisted Pyrolysis of End-of-Life Tires

In this work, chemical recycling as an alternative to conventional end-of-life treatments was studied. Two different types of end-of-life tires (ELT), truck tires and mix tires (50:50 mixture of passenger car and truck tires), were pyrolyzed in a batch microwave reactor. The influence of specific power (10, 20, and 30 W/g) on mass distribution was analyzed. The maximum liquid yield was attained at 10 W/g, while the maximum gas yield is obtained at 30 W/g. Liquid fractions were characterized by gas chromatography/quadrupole mass spectrometry (GC/qMS) to identify the main components, and major compounds were quantified. In all samples, limonene (3.76 ± 0.31–6.80 ± 2.37 wt. %) and BTEX (3.83 ± 0.20–1.19 ± 2.80 wt. %) were the main components. Major limonene concentration is obtained in oil produced from truck ELT while higher yields of aromatic compounds are obtained from mix ELT. The maximum BTEX concentration is obtained at 10 W/g being toluene the main compound with a concentration of 2.07 ± 0.42 and 4.63 ± 1.29 for truck and mix ELT, respectively. The separation and purification of these compounds will confer important value to these fractions. Higher yields of the solid fraction are produced when mix tires are pyrolyzed due to the higher concentration of ash in this type of ELT. Recovered carbon black was characterized by measuring the surface area.

Automotive wastes

A review of the literature from 2018 related to automotive wastes is presented. Topics include solid wastes from autobodies, batteries, tires, and vehicle electronics, in addition to sustainable building materials. Treatment and control of automotive pollution is also discussed, as well as potential toxicological and health risks. PRACTITIONER POINTS: Life cycle analyses and sustainable development automotive components were a key focus of the 2018 literature. Automobiles have been identified as point sources for air and water pollution. Research into energy consumption, emissions control, and catalytic converter behavior was conducted to mitigate the impact of automobile emissions. Potential non-point source control measures were identified. These included biological and chemical degradation of pollutants, as well as adsorption of heavy metals.

Cobalt-Iron-Manganese Catalysts for the Conversion of End-of-Life-Tire-Derived Syngas into Light Terminal Olefins

Co‐Fe‐Mn/γ‐Al₂O₃ Fischer–Tropsch synthesis (FTS) catalysts were synthesized, characterized and tested for CO hydrogenation, mimicking end‐of‐life‐tire (ELT)‐derived syngas. It was found that an increase of C₂‐C₄ olefin selectivities to 49 % could be reached for 5 wt % Co, 5 wt % Fe, 2.5 wt % Mn/γ‐Al₂O₃ with Na at ambient pressure. Furthermore, by using a 5 wt % Co, 5 wt % Fe, 2.5 wt % Mn, 1.2 wt % Na, 0.03 wt % S/γ‐Al₂O₃ catalyst the selectivity towards the fractions of C₅₊ and CH₄ could be reduced, whereas the selectivity towards the fraction of C₄ olefins could be improved to 12.6 % at 10 bar. Moreover, the Na/S ratio influences the ratio of terminal to internal olefins observed as products, that is, a high Na loading prevents the isomerization of primary olefins, which is unwanted if 1,3‐butadiene is the target product. Thus, by fine‐tuning the addition of promoter elements the volume of waste streams that need to be recycled, treated or upgraded during ELT syngas processing could be reduced. The most promising catalyst (5 wt % Co, 5 wt % Fe, 2.5 wt % Mn, 1.2 wt % Na, 0.03 wt % S/γ‐Al₂O₃) has been investigated using operando transmission X‐ray microscopy (TXM) and X‐ray diffraction (XRD). It was found that a cobalt‐iron alloy was formed, whereas manganese remained in its oxidic phase.