ChemEngineering

The transition toward a sustainable society is fundamentally reshaping chemical engineering [...]

Coal tar wash oil degradation during industrial benzene recovery alters both the absorbent’s performance and the liquid-phase rheology. This study introduces an integrated rheological and quantum-chemical framework to evaluate the non-ideal flow behavior of light and heavy wash oils (fresh and operational) diluted with 0–30 vol.% benzene. Compositional changes were monitored via GC–MS, while viscosity non-ideality was quantified using relative viscosity deviations (η_%) and characteristic empirical parameters (φ_1max). Quantum-chemical calculations revealed stronger interactions between benzene and the polycyclic aromatic and heterocyclic compounds enriched in heavy operating oil, consistent with a lower (φ_1max) for heavy oil (0.23) compared to light oil (0.34–0.37). This multi-method approach provides a sensitive, phenomenological diagnostic probe for monitoring absorbent degradation, supporting operational decisions regarding wash oil regeneration or replacement in industrial scrubbing units.

Perovskite oxides have emerged as a versatile class of functional materials owing to their structural flexibility, tunable defect chemistry, mixed ionic–electronic conductivity, and excellent thermal stability. These characteristics make them attractive for engineering applications in heterogeneous catalysis, solid oxide fuel cells (SOFCs), oxygen separation membranes, and sustainable energy conversion. This review critically analyzes recent advances in the crystal structure, physicochemical properties, defect chemistry, synthesis strategies, and engineering applications of bulk perovskite oxides and related Ruddlesden–Popper phases. Conventional and advanced synthesis methods, including solid-state, sol–gel, Pechini, hydrothermal, solution combustion, and spray pyrolysis approaches, are compared with respect to compositional homogeneity, microstructure, oxygen vacancy formation, scalability, and functional performance. The review demonstrates that the performance of perovskite materials is governed by the interplay between crystal structure, defect chemistry, synthesis route, and oxygen mobility. Recent developments in methane reforming, catalytic oxidation, SOFC electrodes, oxygen separation membranes, and perovskite–fluorite nanocomposites highlight the broad engineering potential of these materials. Despite significant progress, challenges remain in achieving long-term structural stability, reproducible large-scale synthesis, and precise defect engineering. Future research should focus on sustainable manufacturing strategies, nanocomposite design, and data-driven materials optimization to accelerate the development of next-generation functional perovskite materials.