Process Feasibility for Converting the Waste Plastics to Hydrogen and Methanol

Hydrogen and methanol are among the most vital fuels and chemicals nowadays. Hydrogen is considered as clean fuel because it produces zero carbon emissions. Comparably, methanol is regarded as a low-carbon alternative fuel. The resources of the two fuels are mainly crude oil, coal, and natural gas. Alternative sources of the two fuels are highly needed to meet the increasing energy demand. On the other hand, plastic waste is also a pollutant and drastically affects the environment. Thermochemical recycling and processing of plastic waste could lead to hydrogen and methanol production. Two comparative models have been developed in Aspen Plus to produce hydrogen and methanol from the waste plastics. In base model (case 1), the waste plastic is first gasified using steam as a gasification agent and the produced syngas containing H₂, CO, and CO₂ is introduced to the water gas shift unit to maximize hydrogen production. Finally, the CO₂ was captured to recover the pure hydrogen. In the alternative model (case 2), the integration between plastic gasification and steam methane reforming (SMR) is proposed to increase the syngas yield while minimizing the overall process energy requirements. The two cases have been technically and economically evaluated to determine the best case. The results showed that the process efficiency of case 2 is higher than base case by 3%. The case 2 also showed a potential to reduce the fuel production cost by 51.8% as compared to case 1. The CO₂ specific emissions in case 2 are reduced by 34% as compared to case 1. Overall, it has been seen that integrating the SMR process with plastic gasification for the dual hydrogen and methanol production is less energy intensive and represents better project feasibility.