Overview of Alternative Ethylene Production Feedstock and Their Contaminants - Part I

The steam cracking process, a significant contributor to global greenhouse gas emissions, is undergoing a substantial transformation in the sourcing of feedstocks for ethylene production. The exploration of alternative feedstocks offers a promising avenue to diversify raw material inputs and reduce environmental impacts in the near future. For Part I of this paper, we consider the following alternative feedstocks:

• Renewable naphtha from HEFA (Hydrotreated Esters and Fatty Acids).
• Plastic pyrolysis oil
• Fischer-Tropsch products as a feed (derived from biomass or other sources).

This transition raises concerns regarding the impact of contaminants and impurities in both the hot and cold sections of the ethylene process from these alternative feedstocks.

This consortium paper provides an overview of biomass and circular economy-based pathways for ethylene production. It includes block flow diagrams and descriptions of each process. The potential for integration into brownfield petrochemical plants is also discussed. The paper offers commentary on the composition, characteristics, and potential contaminants associated with these alternative feedstocks, emphasizing their implications for product quality, process efficiency, and environmental considerations. Key aspects discussed include the presence of impurities such as tar, sulfur, halogens, oxygenates, nitrogen compounds, filler materials, and heavy metals, which can be derived from various alternative feedstock sources and may impact catalyst performance and downstream processing