Reduction of Metal Oxides by Pyrolysis of Waste Polymers

Öz

This review evaluates the effectiveness of gaseous products derived from the pyrolysis of waste polymers (polyethylene (PE), polypropylene (PP), high-density polyethylene (HDPE) and waste tires) in reducing metal oxides (cobalt(III) oxide (Co₃O₄), nickel(II) oxide (NiO), bismuth(III) oxide (Bi₂O₃) and copper(II) oxide (CuO)). Owing to the high energy consumption and environmental impact of conventional reduction techniques, utilizing pyrolytic gases as an alternative reducing atmosphere is critical for sustainability and resource recovery. Experimental studies conducted using horizontal tube furnace systems have demonstrated that gas mixtures obtained from waste polymers — comprising mainly H₂, CH₄, C₂H₄ and aromatic hydrocarbons — can effectively reduce these metal oxides at relatively low temperatures. This review comparatively evaluates parameters influencing reduction efficiency, such as temperature, reactant ratio, heating rate, and gas composition, and provides detailed evaluations of product phases and microstructures through XRD, SEM, and EDS analyses. The findings reveal novel opportunities for waste management and sustainable metallurgy, establishing pyrolytic gases as a promising solution at scientific and industrial levels.

Anahtar Kelimeler

• Metal Oxide
• Pyrolytic Gas
• Reactive Atmosphere
• Reduction Process
• Sustainable Metallurgy
• Waste Polymer.

Atık Polimerlerin Pirolizi ile Metal Oksitlerin İndirgenmesi

Öz

Bu inceleme, atık polimerlerin (polietilen (PE), polipropilen (PP), yüksek yoğunluklu polietilen (HDPE) ve atık lastikler) pirolizinden elde edilen gaz halindeki ürünlerin metal oksitleri (kobalt(III) oksit (Co₃O₄), nikel(II) oksit (NiO), bizmut(III) oksit (Bi₂O₃) ve bakır(II) oksit (CuO)) indirgenme etkinliğini değerlendirmektedir. Geleneksel indirgeme tekniklerinin yüksek enerji tüketimi ve çevresel etkisi nedeniyle, pirolitik gazların alternatif indirgeme atmosferi olarak kullanılması, sürdürülebilirlik ve kaynak geri kazanımı için kritik öneme sahiptir. Yatay tüp fırın sistemleri kullanılarak yapılan deneysel çalışmalar, H₂, CH₄, C₂H₄ ve aromatik hidrokarbonlardan oluşan atık polimerlerden elde edilen gaz karışımlarının, bu metal oksitleri nispeten düşük sıcaklıklarda etkili bir şekilde indirgenebildiğini göstermiştir. Bu derleme, sıcaklık, reaktan oranı, ısıtma hızı ve gaz bileşimi gibi indirgeme verimliliğini etkileyen parametreleri karşılaştırmalı olarak incelemekte ve XRD, SEM ve EDS analizleri yoluyla ürün fazları ve mikro yapılar hakkında ayrıntılı değerlendirmeler sunmaktadır. Bulgular, atık yönetimi ve sürdürülebilir metalurji için yeni fırsatlar ortaya koyarak, pirolitik gazları bilimsel ve endüstriyel düzeyde umut verici bir çözüm olarak ortaya koymaktadır.

Anahtar Kelimeler

• Metal Oksit
• Pirolitik Gaz
• Reaktif Atmosfer
• İndirgeme Prosesi
• Sürdürülebilir Metalurji
• Atık Polimer

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