No 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).

This study evaluates the potential of recycling polystyrene (PS) plastic wastes via a fixed bed (batch) slow pyrolysis reactor. The novelty lies in examining the reactor design, conversion parameters, and reaction kinetics to improve the process yield, activation energy, and chemical composition. PS samples were pyrolyzed at 475–575 °C for 30 min under 10–15 psi. Process yield and product attributes were evaluated using different methods to understand PS thermal degradation characteristics better. The results show that PS decomposition started within 2 min from all temperatures, and the total decomposition point of 97% at 475 °C at approximately 5 min. Additionally, analytical results indicate that the average necessary activation energy is 191 kJ/mol. Pyrolysis oil from PS was characterized by gas chromatography–mass spectrometry. The results show that styrene was produced 57–60% from all leading oil compounds (i.e., 2,4-diphenyl-1-butene, 2,4,6-triphenyl-1-hexene, and toluene), and 475 °C has the major average of conversion effectiveness of 91.3%. The results show that the reactor temperature remains the main conversion parameter to achieve the high process yield for oil production from PS. It is concluded that pyrolysis provides a sustainable pathway for PS waste recycling and conversion to value-added products, such as resins and polymers. The proposed method and analytical results are compared with earlier studies to identify directions for future studies.

The cell wall compositional (lignin and polysaccharides) variation of two sweet sorghum varieties, Della (D) and its variant REDforGREEN (RG), was evaluated at internodes (IN) and nodes (N) using high-performance liquid chromatography (HPLC), pyrolysis−gas chromatography-mass spectrometry (Py-GCMS), X-ray diffraction (XRD), and two-dimensional (2D) 1 H− 13 C nuclear magnetic resonance (NMR). The stalks were grown in 2018 (D1 and RG1) and 2019 (D2 and RG2) seasons. In RG1, Klason lignin reductions by 16−44 and 2−26% were detected in IN and N, respectively. The analyses also revealed that lignin from the sorghum stalks was enriched in guaiacyl units and the syringyl/guaiacyl ratio was increased in RG1 and RG2, respectively, by 96% and more than 2-fold at IN and 61 and 23% at N. The glucan content was reduced by 23−27% for RG1 and by 17−22% for RG2 at internodes. Structural variations due to changes in both cellulose-and hemicellulose-based sugars were detected. The nonacylated and γ-acylated β−O−4 linkages were the main interunit linkages detected in lignin. These results indicate compositional variation of stalks due to the RG variation, and the growing season could influence their mechanical and lodging behavior.

About 5% of all corrugated cardboard is coated with wax to enhance performance under humid conditions. Waxed cardboard is unrecyclable. The authors have previously shown that the wax can be effectively recovered using pyrolysis. The main compounds found in wax oil obtained from pyrolysis of waxed cardboard were alkanes, alkenes, and dienes (C 9 to C 36 ). In this work, recovered wax and wax oil samples were thermally and catalytically pyrolyzed on a custom-made small tubular batch reactor, and the resultant liquid products were analyzed (GCMS, FTIR, and ESI-MS) against gasoline to evaluate their performance as a transport fuel. The products of thermal pyrolysis of the samples are mainly composed of dienes and short-chain olefins, oxygenated compounds, and minor amounts of aromatic compounds. Their functional groups resembled those found in paraffin. The analyses revealed that the liquid products of catalytic pyrolysis had chemical and functional group profiles similar to gasoline (e.g., methylbenzenes). The addition of zeolite Y as the catalyst facilitated the conversion of long-chain hydrocarbons to short-chain alkanes and aromatics. The monomer-to-oligomer ratio of the liquid products also increased significantly after catalytic pyrolysis.