PTQ Q1 2024 Issue

highest activity ZSM-5 results in reduced additive con- sumption for a similar or higher propylene yield. Since ZSM-5 can only crack gasoline-range molecules, using a large amount of ZSM-5 additive results in a dilution of the base catalyst activity and lower conversion of feed- stock into gasoline olefin precursors. The main benefit then of using a high-activity additive is to minimise the dilution of the base catalyst activity vs the use of a lower- activity ZSM-5 additive. To maximise propylene, Grace recommends using high-activity ZSM-5 additives from its OlefinsUltra family of additives or its newest innovation in ZSM-5 technology, Zavanti additives. In summary, refiners are adopting a variety of strate - gies to increase butylene and propylene from the FCC, depending on their specific hardware constraints, down - stream handling limits, and regional economics. FCC cata- lysts and additives are key elements of the strategy as well, given the flexibility they offer and the dynamic nature of the FCC unit operation. A Ezequiel Vicent, Senior Application Engineer and Consulting Lead, OLI Systems The dual focus on increasing butylene production and pro - pylene production is being met with ZSM-5 technology and a propane/propylene (PP) splitter (50-300 MMUSD). Refiners on the US West Coast and the Gulf of Mexico are best positioned to take advantage of an increase in the production of butylene and propylene. However, market

drivers and asset characteristics will dictate the extent of the benefit realised. Increasing the production of propane, propylene, and butylene can be achieved by introducing additives to the FCC catalyst, the zeolite ZSM-5. This ZSM-5 will help in the cracking and production of butylene and propylene. The butylene will be used at the alkylation (sulphuric or HF acid) unit to produce alkylate, a gasoline-range material almost void of contaminants and aromatic components and makes an excellent blending component in the gaso - line pool. Whenever there is insufficient butylene or a market need for increased alkylate, propylene can also be added to the alkylation unit. However, the propylene can be cleaned at a PP split- ter and further refined to either chemical-grade propylene (92-95 mass% propylene) or polymer-grade propylene (99.5 mass% and greater). If a refinery does not have a PP splitter as an asset, the butylene/propylene or propane/propylene mix can be sent to the gas plant and recovered as ‘refinery gas’, which can be later used as fuel to the various furnaces in the refinery. The investment to design and install a PP splitter at a refin - ery is not small. Pre-C OVID estimates put the total cost of the project at around 300 million US dollars (2019) on the West Coast (California) and around 50 to 100 million US dol - lars (2019) in the Gulf. The three-to-one ratio difference is due to labour and materials costs on the West Coast.

PTQ Q1 2024