Multiple Reaction Networks Involved in CO₂ Oxidative Dehydrogenation of Butane to Olefins and Syngas: A Thermodynamic Analysis

The CO₂ oxidative dehydrogenation of butane (CO₂ ODHB) to olefins offers a pathway for utilizing CO₂ in producing value-added chemicals. This study conducted a thermodynamic process analysis using Aspen Plus software V9 via the minimization of Gibbs free energy approach. This provides insight into the effect of thermodynamic parameters on CO₂ ODHB, which is currently lacking in the literature. The operation was carried out with a CO₂/C₄H₁₀ ratio of (0.1–5.0), temperature (100–1100 °C), and pressure (0–50 bar) to study their effects on conversion and selectivity. There was a high conversion of butane for all CO₂/C₄H₁₀ feed ratios, even at low temperatures below 400 °C. However, butadiene selectivity decreases as the ratio increases, indicating that CO₂ promotes side reactions. The selectivity reaches its maximum at temperatures between 400 and 500 °C. Thus, operating with lower CO₂/C₄H₁₀ ratios and temperatures above 400 °C is preferable for this process. Pressure has a negative effect on both the selectivity and conversion, making atmospheric pressure optimal for the process. The result when compared with the literature shows that for a CO₂/C₄H₁₀ feed ratio of 2.0, the selectivity of butadiene was 27.4%, which corresponds to a value of 25% found in this study, which is an indication of strong agreement between the model and the experimental data.