Pyrolysis

About: Pyrolysis is a research topic. Over the lifetime, 34918 publications have been published within this topic receiving 833524 citations.

Valorization of packaging plastic waste by slow pyrolysis

Abstract: Low and high-density polyethylene (LDPE and HDPE) and polypropylene (PP) are three most common polyolefins profusely used as packaging materials and abundantly found in the plastic waste stream. These plastic waste samples were collected from household waste and converted into plastic derived oil (PDO) by low temperature (300 °C to 400 °C) slow pyrolysis (long isothermal holding time) in a semi-batch reactor. The PDO samples obtained had shown variation in their compositions and fuel properties based on the pyrolysis temperature. PDO from the pyrolysis of PP has high octane number (∼92) and low viscosity. Noticeably, the PDO samples obtained at low temperature pyrolysis are lighter with low viscosity, high octane number and having high calorific values. 1H NMR analysis revealed that the oil samples mostly consist of paraffinic and olefinic hydrocarbons. Simulated distillation (SimDist) of PDO indicated that the liquid products resemble the characteristic closer to middle distillate of petroleum fraction having very low pour point and flash point. The temperature with long pyrolysis time also influenced the evolved gas composition and yield. Trace amount of hydrogen, carbon monoxide and carbon dioxide were present in the gaseous product along with various hydrocarbon gases ranging from C1–C5. The degradation mechanism follows end chain scission which produces monomer units whereas random scission results most of the hydrocarbon products. Subsequent reactions like radical recombination and inter or intra molecular hydrogen transfer results in the formation of most of the olefinic components.

Elucidating the Nature of Fe Species during Pyrolysis of the Fe-BTC MOF into Highly Active and Stable Fischer–Tropsch Catalysts

Abstract: In this combined in situ XAFS, DRIFTS, and Mossbauer study, we elucidate the changes in structural, electronic, and local environments of Fe during pyrolysis of the metal organic framework Fe-BTC toward highly active and stable Fischer–Tropsch synthesis (FTS) catalysts (Fe@C). Fe-BTC framework decomposition is characterized by decarboxylation of its trimesic acid linker, generating a carbon matrix around Fe nanoparticles. Pyrolysis of Fe-BTC at 400 °C (Fe@C-400) favors the formation of highly dispersed epsilon carbides (e′-Fe2.2C, dp = 2.5 nm), while at temperatures of 600 °C (Fe@C-600), mainly Hagg carbides are formed (χ-Fe5C2, dp = 6.0 nm). Extensive carburization and sintering occur above these temperatures, as at 900 °C the predominant phase is cementite (θ-Fe3C, dp = 28.4 nm). Thus, the loading, average particle size, and degree of carburization of Fe@C catalysts can be tuned by varying the pyrolysis temperature. Performance testing in high-temperature FTS (HT-FTS) showed that the initial turnover fr...

Copyrolysis of Biomass with Phosphate Fertilizers To Improve Biochar Carbon Retention, Slow Nutrient Release, and Stabilize Heavy Metals in Soil

Abstract: Two phosphate fertilizers, triple superphosphate (TSP) and bone meal (BM), were premixed with sawdust and switchgrass biomass for pyrolytic biochar formation. Carbon retention, P release kinetics, and capacity of biochar for stabilizing heavy metals in soil were evaluated. Results show that TSP and BM pretreatment increased carbon retention from 53.5–55.0% to 68.4–74.7% and 58.5–59.2%, respectively. The rate constants (k2) of P release from the TSP- and BM-composite biochars are 0.0012–0.0024 and 0.89–0.91, respectively, being much lower than TSP and BM themselves (0.012 and 1.79, respectively). Copyrolysis with phosphate fertilizers enhanced biochar capability for stabilizing metals in soil significantly, especially the BM-composite biochar which increased Pb, Cu, and Cd stabilization rates by up to about 4, 2, and 1 times, compared to the pristine biochars. During the pyrolysis process, Ca(H2PO4)2 in TSP converted to Ca2P2O7 and reacted with biomass carbon to form C–O–PO3 or C–P, leading to greater carb...