Refiners need the flexibility to operate with a dynamic feedstock of varying quality as well as the flexibility to produce a wide range of products to meet market demands. Many refiners in North America have an economic incentive to produce higher LPG olefins to feed their alkylation units in order to increase the octane value of the refinery gasoline pool. In this paper, we will discuss light olefins and gasoline octane fundamentals and will present Grace’s novel catalytic solutions towards increasing C4 olefins and gasoline octane in a fluid catalytic cracking (FCC) unit. Furthermore, we will provide commercial examples to illustrate the value generated from these novel technologies. Within traditional FCC technologies, refiners employ zeolite Y modification, commonly via lowering the zeolite unit cell size, to decrease hydrogen transfer thus leading to higher light olefins yields. However, lower zeolite unit cell size is achieved by reducing zeolite rare earth stabilization, which decreases the acid site density of the zeolite, leading to lower activity per unit of zeolite. Addition of ZSM-5 to the catalyst also increases the yield of LPG olefins via scavenging of gasoline olefins formed on Y zeolite, however, traditional ZSM-5 additives favor the formation of propylene over butylene, which is not as desirable for alkylation. In recent years, Grace has commercialized a new catalyst technology ,ACHIEVE®400, and a butylene-selective additive, GBA™. These solutions are superior at producing high value alkylation feedstock, shifting product yields toward higher butylene to propylene ratios and rendering high-octane FCC gasoline. ACHIEVE®400 incorporates isomerization activity within the catalyst particle by using two different types of zeolites – a traditional Y zeolite and a specially tuned pentasil zeolite. Incorporation of isomerization activity into the particle itself results in a more desirable yield pattern than the use of a traditional FCC additive. The ACHIEVE®400 catalyst leads to both an improved butylene-to-propylene ratio and a higher-octane FCC gasoline relative to ZSM-5 additives. Overall, ACHIEVE®400 increases the yield of FCC butylene, keeping the alkylation unit full and increasing refinery pool octane. In addition to ACHIEVE®400, Grace has recently launched a novel butylene-selective additive, GBA™. GBA™ is a tool that refiners can use as needed to fill their alkylation units in order to take advantage of short-term economic opportunities.

Novel catalytic approach towards C4 olefins and gasoline octane in fluid catalytic cracking

255th National Meeting (2018)

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