Evaluation of theoretical and experimental mass transfer limitation in steam reforming of phenol-PET waste to hydrogen production over Ni/La-promoted Al₂O₃ catalyst

Theoretical and experimental approaches were achieved to estimate the presence of mass transfer limitations using Ni/La-co-promoted Al₂O₃ catalyst for selective reaction from polyethylene terephthalate (PET) plastic waste via steam reforming process. The catalysts were prepared by impregnation method and were characterized using, BET, TPD-CO₂, TPR-H₂, SEM-EDX, TGA and DTA. The internal and external diffusions were indicated in the experimental technique, by changing the catalyst pellet size (d_p) and feed flow rate (ml/min). Dimensionless parameters in the theoretical method such as Thiele modules (φ₁), effectiveness factor (η), and overall effectiveness factor (Ω) were evaluated. From the experimental results, due to the decreasing of PET-Phenol conversion (from 89 to 76%) at different pellet size, internal mass transfer limitation was indicated. In addition, the theoretical approaches of internal mass transfer limitation was observed in PET-Phenol reaction for all catalyst pellet sizes due to effectiveness factor less than 1 (η ≠ 1). This is shown that experimental results are in complete agreement with the theoretical approach. The presence of external and internal diffusion for all catalytic pellet sizes also confirmed from the overall effectiveness factor evaluation (Ω).