Enhanced gasification of waste plastics for hydrogen production: experiment and simulation

The quality of hydrogen produced from waste plastic steam gasification is compromised by CO₂ and tar. While the use of CaO for CO₂ adsorption and tar catalytic cracking has been explored, the impact of the heat released during CaO carbonation on hydrogen production has not been sufficiently studied. This work investigates the role of Fe-doped CaO in enhancing hydrogen production and tar removal during gasification. Aspen Plus is used to evaluate the impact of CaO carbonation heat on hydrogen generation via waste plastic steam gasification. Experimental results show that, at 700 °C and 20 vol% H₂O, the H₂ concentration and yield increase to 67.9 vol% and 288.6 mL/g, respectively, with a liquid production rate of 17 % when Ca₉₀Fe₁₀/PE mass ratio is 2.0. In simulations, with the gasifier operating at 700 °C and maintaining thermal equilibrium, H₂ molar percentage is 58.5 % for an O₂ inflow of 13.03 kg/h. At 700 °C and Ca₉₀Fe₁₀/PE mass ratio of 2.2, the heat generated by the CO₂ adsorption reaction of CaO is 76.51 MJ/h and requires 6.9 kg/h of O₂ and the molar percent of H₂ is 80.76 %. To achieve material circulation, 0.8 kg/h of CH₄ is combusted in the calciner to regenerate CaO, consuming 3.2 kg/h of O₂. Overall, O₂ consumption for the entire cycle is reduced by 2.93 kg/h, compared to processes without CaO.