A Review on the Conversion of Synthetic Gas to LPG over Hybrid Nanostructure Zeolites Catalysts

Technoeconomic Feasibility of Hydrogen Production from Waste Tires with the Control of CO2 Emissions

The worldwide demand for energy is increasing significantly, and the landfill disposal of waste tires and their stockpiles contributes to huge environmental impacts. Thermochemical recycling of waste tires to produce energy and fuels is an attractive option for reducing waste with the added benefit of meeting energy needs. Hydrogen is a clean fuel that could be produced via the gasification of waste tires followed by syngas processing. In this study, two process models were developed to evaluate the hydrogen production potential from waste tires. Case 1 involves three main processes: the steam gasification of waste tires, water gas shift, and acid gas removal to produce hydrogen. On the other hand, case 2 represents the integration of the waste tire gasification system with the natural gas reforming unit, where the energy from the gasifier-derived syngas can provide sufficient heat to the steam methane reforming (SMR) unit. Both models were also analyzed in terms of syngas compositions, H₂ production rate, H₂ purity, overall process efficiency, CO₂ emissions, and H₂ production cost. The results revealed that case 2 produced syngas with a 55% higher heating value, 28% higher H₂ production, 7% higher H₂ purity, and 26% lower CO₂ emissions as compared to case 1. The results showed that case 2 offers 10.4% higher process efficiency and 28.5% lower H₂ production costs as compared to case 1. Additionally, the second case has 26% lower CO₂-specific emissions than the first, which significantly enhances the process performance in terms of environmental aspects. Overall, the case 2 design has been found to be more efficient and cost-effective compared to the base case design.

Simulation and Modelling of Hydrogen Production from Waste Plastics: Technoeconomic Analysis

The global energy demand is expected to increase by 30% within the next two decades. Plastic thermochemical recycling is a potential alternative to meet this tremendous demand because of its availability and high heating value. Polypropylene (PP) and polyethylene (PE) are considered in this study because of their substantial worldwide availability in the category of plastic wastes. Two cases were modeled to produce hydrogen from the waste plastics using Aspen Plus®. Case 1 is the base design containing three main processes (plastic gasification, syngas conversion, and acid gas removal), where the results were validated with the literature. On the other hand, case 2 integrates the plastic gasification with steam methane reforming (SMR) to enhance the overall hydrogen production. The two cases were then analyzed in terms of syngas heating values, hydrogen production rates, energy efficiency, greenhouse gas emissions, and process economics. The results reveal that case 2 produces 5.6% more hydrogen than case 1. The overall process efficiency was enhanced by 4.13%. Case 2 reduces the CO2 specific emissions by 4.0% and lowers the hydrogen production cost by 29%. This substantial reduction in the H2 production cost confirms the dominance of the integrated model over the standalone plastic gasification model.