On catalysis

MIP is the English abbreviation for maximizing the production of heteroalkanes. This technology is a riser modification technique developed specifically for catalytic cracking units in order to reduce the olefin content in catalytic gasoline to below 35% and meet relevant **standards. It aims to maximize the production of isoparaffins. A key feature of this process is the use of a new type of tandem riser that includes two reaction zones: the first reaction zone is primarily used for primary cracking reactions, with high reaction intensity; after a short residence time, the fluid moves on to the lower part of the second reaction zone, which has an expanded diameter. In the second reaction zone, measures such as expanding the diameter and using low-temperature catalysts are employed to reduce the flow rates of the hydrocarbon stream and the catalyst, as well as to lower the reaction temperature in this zone, thereby meeting the requirements regarding space velocity. This approach facilitates increased hydrogen transfer and isomerization reactions, while simultaneously controlling secondary cracking reactions to an appropriate level. Under the combined action of secondary cracking and hydrogen transfer reactions, the amount of olefins in gasoline is significantly reduced, while the octane rating of gasoline remains essentially unchanged. An additional quenching gasoline nozzle was installed above the original feed nozzle, and a low-pressure distribution plate along with a rapid separation unit (VQS) were placed at the bottom of the second reaction zone; the original rapid separation unit was removed. The reaction temperature in the first reaction zone is 500–505°C, while it is 485–490°C in the second reaction zone. The CRMI-2 catalyst is used, which enables the olefin content in the catalyzed gasoline to be reduced to around 30%. The yield of light products from the plant can also increase slightly, but the consumption of 1.0 MPa steam rises, and the solid content in the oil slurry increases as well.

Currently, MIP is outdated; the newer version is MIP-CGP. It allows for reduced olefins in gasoline while producing more propylene, but it requires specialized catalysts. This technology, developed by the Petroleum Science Research Institute, features two reaction zones in the riser system, and it has been widely adopted by Sinopec.