Valorization of waste waxed corrugated cardboard via pyrolysis for recovering wax

Abstract

Corrugated cardboard (CCB) comprises a substantial portion of municipal solid waste, of which ~5% is wax coated CCB (WCCB) to enhance its performance. WCCB cannot be recycled, making it a suitable resource to recover wax and produce char. The WCCB was characterized for its extractable wax, lignin, and carbohydrate contents and by thermogravimetric analysis to study its thermal degradation behavior. WCCB was preliminarily examined by pyrolysis‐gas chromatography–mass spectrometry to determine product composition. WCCB samples were then pyrolyzed in auger and tube reactors at 450, 500, and 550°C, and their pyrolysis wax‐oil and char products characterized. WCCB and char were subjected to proximate, ultimate, surface area, analyses. The highest char yield was 36% at 450°C, and the highest wax‐oil yield was 53% at 550°C in the tube reactor. The wax‐oil fraction contained mainly alkanes, alkenes, and dienes (C9–C36), and chain length decreased with pyrolysis temperature. This wax fraction could be recovered and used as bunker fuel (C12–C40) or further converted to diesel (C10–C20).

Catalytic Upgrading of Pyrolysis Wax Oil Obtained from Waxed Corrugated Cardboard Using Zeolite Y Catalyst

“…Al Maadeed et al also recorded a reduction in crystallinity of polyolefin blends HDPE and LLDPE due to the increased wax addition in their study. This conforms to the high wax yield and low crystallinity seen in previous studies and in the DSC results. , The presence of shorter chain hydrocarbons obtained at higher pyrolysis temperatures suggested that the wax oil samples might be viable options for producing cleaner fuels. , …”

“…The minor and major peaks also depict the solid–solid phase and solid–liquid phase transition for the wax oil samples, respectively. , An increase in the pyrolysis temperature from 450 to 500 °C resulted in a slight increase in wax oil major melting peak temperature from 51.3 to 52.2 °C. The melting peak temperature decreased to 47.7 °C for WO550 yielding shorter-chain hydrocarbons, which have a lower melting point . Shorter-chain hydrocarbons exhibit a higher melting enthalpy and lower melting temperature. , This is consistent with studies that show the melting point of waxes decreases with a decreased number of carbon atoms…”

“…The liquid products of thermal and catalytic pyrolysis of the extracted wax and wax oil samples were analyzed by GC-MS. The authors have reported in their earlier work that the wax oil samples were mixtures of long-chain alkanes, alkenes, and dienes as well as oxygenated compounds such as levoglucosan . The thermal pyrolysis process resulted in a mixture of alkanes and olefins with varying chain length (C 6 –C 39 ) and a small proportion of aromatic hydrocarbons (0.0–5.4%) (Figures S1 and S2; Table ).…”

“…The wax oil samples were the products of waxed cardboard pyrolysis at three different temperatures of 450, 500, and 550 °C in an auger reactor. The details of the pyrolysis and solvent extraction process are outlined in the authors’ previous work . The wax oil samples were named WO450, WO500, and WO550 according to their original pyrolysis temperature (450, 500, and 550 °C).…”

“…The pyrolysis wax oil products contained mainly alkanes, alkenes, and dienes (C 9 –C 36 ), and the chain length decreased with pyrolysis temperature. The results suggested that this wax fraction could be recovered and used as bunker fuel (C 12 –C 40 ) or further converted to diesel (C 10 –C 20 ) via catalytic (hydrocracking) upgrading …”