Optimization of Process Parameters and Product Distribution in Catalytic Co-Pyrolysis of Durian Waste over Fly Ash-Derived Heterogeneous Catalyst

Abstract

The catalytic co-pyrolysis of durian peel and fly ash offers a sustainable route for simultaneous biomass and industrial waste valorization. This study aims to optimize process parameters and evaluate their effects on product distribution using fly ash as a low-cost heterogeneous catalyst. Experiments were conducted at temperatures of 400–600 °C with a fixed reaction time of 50 min, while varying feedstock composition ratios (durian peel:fly ash = 0:1, 1:0, 2:1, 3:2, 1:1, 1:2). Response Surface Methodology (RSM) and ANOVA were applied to assess the significance of process variables and their interactions. The models obtained were statistically significant (p ≤ 0.001) with non-significant lack-of-fit, confirming their reliability. Bio-oil yield was mainly influenced by the quadratic effect of fly ash concentration (p < 0.0001), while biochar yield was governed by the quadratic effect of temperature (p < 0.0001). Gas yield was significantly affected by temperature, interaction effects, and quadratic terms. Product distribution showed that gas was the dominant fraction (80–95%), followed by biochar (10–20%) and bio-oil (1–10%). Increasing temperature favored gas production, whereas moderate catalyst loading slightly enhanced bio-oil yield. These findings demonstrate the effectiveness of fly ash as a catalyst and highlight an optimized, cost-effective pathway for converting waste into valuable energy products.