Lost foam casting (LFC) generates substantial hazardous air pollutants during the intense pyrolysis of expandable polystyrene (EPS) foam upon contact with high-temperature molten metal. Conventional thermogravimetric studies, conducted at far lower heating rates than actual LFC conditions, may misrepresent both reaction kinetics and product hazards. This work employed a self-developed wireless-powered thermobalance and wire-mesh reactor to investigate EPS pyrolysis under realistic ultra-fast heating (~22800 °C/min), with systematic comparisons to conventional slow pyrolysis. The apparent activation energy under fast pyrolysis dropped to 19–32 kJ/mol, approximately 85% lower than the 165–179 kJ/mol observed under slow pyrolysis, indicating a transition of the overall rate-limiting step rather than a weakening of intrinsic chemical bonds, and distinct kinetic compensation lines confirmed a genuine mechanistic shift. Fast pyrolysis substantially amplified PAH formation compared with slow pyrolysis, an effect attributable to the combined differences in heating rate and vapor residence time between the two reactor systems. The peak area of 2-phenylnaphthalene reached 4.72% at 600 °C versus only 1.83% under slow heating, indicating that conventional assessments significantly underestimate LFC occupational exposure risks. Regarding mitigation, Fe/ZSM-5 reduced total PAH content to 2.5% at 600 °C, outperforming Ni/ZSM-5 and ZSM-5, while introducing 7–21% O2 into the carrier gas nearly eliminated PAHs. These findings provide apparent kinetic parameters that better represent real LFC heating conditions for LFC optimization and a dual-strategy framework for source-level pollution abatement.
Polyolefin elastomer (POE) is increasingly used as an encapsulant in photovoltaic modules, yet its pyrolysis mechanism remains insufficiently understood. In this study, calorific value analysis, Py-GC/MS, TG-FTIR-GCMS, thermogravimetric and kinetic analysis, and ReaxFF molecular dynamics are integrated to establish a cross-scale interpretation of photovoltaic POE pyrolysis. Under the tested conditions, POE underwent near-complete conversion at 500 °C. Py-GC/MS and TG-FTIR-GCMS reveal a hydrocarbon-dominated product feature. The FWO, SKAS, and DAEM methods yielded average apparent activation energies of ~ 200 kJ/mol. ReaxFF MD trajectory analysis identified homolysis and recombination, β-scission, hydrogen transfer, and radical addition as reaction pathways involved in POE pyrolysis. The simulated trajectories and changes in bond populations supported a two-stage interpretation of POE pyrolysis, with the initial stage dominated by C–C bond cleavage and the subsequent stage showing an increased contribution from C–H bond cleavage. These findings provide a mechanistic basis for thermal delamination and indicate the energy recovery potential of POE in end-of-life photovoltaic modules.
Growing energy demand and supply constraints have renewed interest in oil shale, but reaction-front dynamics and channeling during in-situ conversion remain poorly understood. This study experimentally investigates topochemical heat (TSA) conversion using a two-dimensional high-temperature, high-pressure apparatus with a prefabricated 2-mm fracture between oil shale slabs (φ380 mm). Experiments at 3, 5, and 7 MPa assess pyrolysis through product, gas, thermal, and post-reaction analyses (SEM, TG/DTG, Rock-Eval, and XRD). Results show that reaction pressure governs the evolution of high-conductivity channels from local inception to full connectivity. As reaction pressure rises from 3 to 7 MPa, inter-well peak temperature increases from 762.8 ℃ to 1087.8 ℃, while oil recovery drops from 59.8% to 34.2% and energy efficiency decreases from 1.83 to 0.71, below unity at 7 MPa. Channel coalescence diverts injected air, with produced-gas O2 exceeding 5% and residual organic carbon in unconverted zones reaching 43.3% of raw values. Field observations at shallow (Nong'an, 70 m) and medium–deep (Fuyu, 500 m) formations confirm the channeling mechanism, explaining the "gas-only, no-oil" failure under high-pressure, wide-spacing conditions. These findings guide injection and well-pattern optimization to suppress preferential flow and promote uniform front propagation for energy-efficient in-situ oil shale exploitation.
The synergistic interaction during the co-pyrolysis of plastics and biomass remains a critical focus for optimizing thermochemical conversion processes. This study systematically investigates the co-pyrolysis behavior and underlying mechanisms of polyethylene (PE) mixed with two distinct biomass components: cellulose and xylan. Thermogravimetric analysis, in-situ visual observations, gas chromatography/mass spectrometry (GC/MS), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and higher heating value (HHV) measurements were comprehensively employed to evaluate the mixtures. In the PE/cellulose system, cellulose particles underwent independent decomposition within the molten PE matrix. Although a physical matrix effect dominated—where the molten PE physically trapped cellulose-derived intermediates (e.g., levoglucosan)—minor chemical interactions via secondary volatile cracking also subtly contributed to the pyrolytic pathway. Conversely, the PE/xylan system proceeded through a repetitive cycle of melting and decomposition, establishing a unique "Bi-molten" state. The chemical interaction induced by this molten xylan significantly altered the pyrolysis mechanism of PE. These interactions in both systems promoted the carbonization of the respective residues, modifying their final properties and leading to the formation of amorphous carbonized residues with higher heating values (HHVs) than the theoretically calculated values. These findings provide crucial insights into the microscopic interactions that govern the high-efficiency co-pyrolysis of mixed waste streams.
The decommissioning of wind turbine blades is rapidly escalating as a global challenge, driven by the urgent need for sustainable energy transitions. The inherent cross-linked structure of thermosetting epoxy resins, which serve as the primary matrix material in these blades, severely impedes conventional recycling routes, resulting in low‑value recovery and significant environmental liabilities. In this study, pure bisphenol-A epoxy resin is employed as a model compound to represent the resin matrix of wind turbine blades, enabling controlled and reproducible investigation of the fundamental pyrolysis chemistry under concentrated solar irradiation. In this study, this knowledge gap is addressed through a systematic experimental investigation using a purpose‑built solar simulator coupled with a fixed‑bed reactor. The effects of the solar simulator’s input electric power (ranging from 650 W to 950 W, corresponding to a peak radiative flux density of 347 kW/m2 at 950 W) and the addition of mineral‑based catalysts including CaO, dolomite, and K2CO3, as well as transition metal catalysts Ni and Co, on product distribution, gas composition, and solid residue characteristics are systematically investigated; gas yields and composition are quantified, while solid residues are characterized by FTIR and SEM. The results demonstrate that increasing electrical input power markedly enhances total gas yields by up to 85.6% and promotes hydrogen production, accompanied by progressive aromatization and deoxygenation of the solid carbonaceous residues, as evidenced by FTIR and SEM analyses. Catalytic experiments reveal distinct functionalities: CaO significantly boosts H2 yield to 31.6 mL at a loading of 0.9 g through in‑situ CO2 capture and water‑gas shift promotion, while dolomite preferentially enhances CO production to 51.6 mL, yielding the highest total gas output among the mineral/alkali-metal catalysts (104.6 mL). Notably, Co emerges as the most effective catalyst, achieving a total gas yield of 125 mL, which represents a 4.6‑fold increase over the non‑catalytic baseline, with H2 and CO fractions reaching 44% and 34% respectively, and with markedly reduced visible tar deposition. These findings elucidate the coupled thermal‑radiative‑catalytic mechanisms governing solar‑driven epoxy resin pyrolysis, establishing a robust scientific foundation for the design of efficient solar‑powered recycling strategies for end‑of‑life wind turbine blades and advancing the principles of circular economy in renewable energy infrastructure.
