Process Integration of Urea Production with Methane Pyrolysis for Reduced Carbon Emissions

The increasing global population is expected to drive a surge in fertilizer demand in the future. However, traditional ammonia-urea production methods, such as steam methane reforming (SMR), contribute significantly to greenhouse gas (GHG) emissions. The purpose of this study was to mitigate CO₂ emissions during an unbalanced plant load of ammonia and urea, which leads to a CO₂ vent. The introduction of methane pyrolysis (MP) enabled the continuous production of ammonia and urea while concurrently generating marketable solid carbon black as a co-product. A detailed SMR-ammonia production plant was simulated using Aspen Plus v11 software. The MP unit was then integrated into SMR by splitting the natural gas feed after the sulfur removal unit. Several schemes were conducted to find the most preferable scenario for the industries. The schemes vary in the splitting ratio of natural gas feed to SMR and MP. Techno-economic analysis from this study demonstrates favorable results when incorporating methane pyrolysis into current SMR-ammonia-urea plants. This includes a significant reduction in CO₂ emissions by 71.70% compared to the base case. In a scenario with a carbon black revenue of $0.5/kg and a carbon tax of $20/ton-CO₂e, diverting 15% of the natural gas feed into a methane pyrolysis integration unit could yield an extra annual profit of up to $1.6 million.