Phase-evolving inorganic mineral matrices for product-selective pyrolysis of biomass-rich organic solid wastes

Product formation during pyrolysis of biomass-rich organic solid wastes is usually interpreted through temperature, residence time, and reactor configuration, while inorganic mineral matrices are considered less consistently. This review develops an interpretive phase-evolution framework that links the initial mineral assemblage and its condition-dependent transformation to surface functions accessible to pyrolysis vapors and the resulting product responses. Here, product selectivity is used at two distinct levels: partitioning among liquid, gas, and char, and preferential distribution of a defined product family or component within one phase. Relative compositional enrichment is not equated with an increase in absolute yield. Ca-bearing and related alkaline-earth matrices, waste-derived multi-oxide residues, natural minerals, and transition-metal oxides are compared in terms of phase transformation, accessible acid base and redox sites, pore structure, and vapor-solid contact. Representative studies associate Ca-bearing matrices with reported decreases in acidic oxygenates and shifts in gas composition toward H 2 -, CO-, and CH 4 -rich products; these responses are consistent with basic deoxygenation, cracking, and carbonate–oxide chemistry. For N-rich feedstocks, however, nitrogen partitioning among NH 3 /HCN, oil-phase N-containing compounds, and char-N needs to be evaluated independently of deoxygenation. Studies of red mud and steel slag further report oxygenated-vapor restructuring and atmosphere-dependent carbon redistribution within mixed-oxide environments. Natural minerals and transition-metal oxides further show that calcination history and oxide identity affect phenolic, aromatic, and gas-oriented responses. Mineral-assisted pyrolysis should therefore be assessed by phase evolution, accessible surface function, product-family response, matrix lifetime, and spent-solid safety rather than nominal composition or precursor cost alone.