Optimization Study of Catalytic Co-gasification of Rubber Seed Shell and High Density Polyethylene Waste for Hydrogen Production Using Response Surface Methodology

Abstract

Experimental studies on the production of hydrogen (H₂) gas from catalytic co-gasification of mixtures of plastic high density polyethylene (HDPE) derived from municipal solid waste (MSW) and biomass rubber seed shell (RSS) are conducted in a non-isothermal thermogravimetric analysis (TGA) equipment coupled with mass spectrometer (MS). A commercial nickel is selected as the catalyst in this process. The main objective of the present study is to assess the combined effect of the operating parameters such as temperature, HDPE particle size, RSS particle size, and percentage of plastics in the mixtures on the response variable i.e. production of H₂ from the system. The steam generated by the superheater at temperature of 110 °C is injected at flowrate of 0.005 mL min⁻¹ meanwhile argon gas is supplied at flowrate of 100 mL min⁻¹ into the TGA-MS system. The steam to feedstock and catalyst to feedstock ratio of 1 and 0.1 are used respectively. A central composite design (CCD) based on response surface methodology (RSM) is used for the experimental design. The studies are carried out at temperature of 500–900 °C, HDPE particle size range of 0.125–0.625 mm, RSS particle size of 0.125–0.625 mm and percentage of HDPE in the mixture of 10–40 wt% on the response variable of H₂ production. The optimum process parameter for maximum H₂ production in the system is determined.