PTQ Q3 2024 Issue

1.5

0% ZSM - 5 dose 3% ZSM - 5 dose 6% ZSM - 5 dose

MFT-1 MFT-2

1.4

1.3

C= / C= decreases with increased ZSM - 5 dose

1.2

1.1

0.9

MFT tailored for highest C= / C= ratio

0.8

0.7

Conversion (wt%)

Figure 1 Propylene to butylene selectivity of traditional ZSM-5 vs specialty MFT zeolite

Europe, Middle East, and Africa, BASF, Melissa Mastry, Director, Global Technology and Technical Services, BASF Multiple strategies can be utilised to increase FCC gasoline octane. First, increasing the octane of the ‘as-produced’ naphtha is an obvious choice, either by formulating a base catalyst with reduced hydrogen transfer to preserve high octane molecules, adding ZSM-5 additives also, or a com- bination of both. Of course, process condition adjustments, such as increasing reactor outlet temperature (ROT), can also increase the as-produced octane. Second, producing high octane blending components is another common choice. The desired blending component is alkylate, having a RON value typically ranging between 92 and 98 (a function of feedstock used between – C₃, C₄, or C₅). Historically, refiners have used an olefins additive, includ - ing ZSM-5, in FCC units to capture value from the mar- ket’s demand for increased light olefins for alkylation and higher-octane gasoline components. The ZSM-5 zeolite is designed to selectively crack gasoline-range molecules into propylene (C₃=) and, to a lesser extent, butylenes (C₄=). In general, C₄= alkylate has a higher road octane ([RONC + MONC] / 2) value than C₃= alkylate, and C₄= alkylate is less cost intensive to produce. As an example, alkylate made from C₃= and isobutane can have a road octane of up to 92, whereas alkylate from C₄= can have a road octane of up to 98. Therefore, C₄= alkylation is the preferred method for most refiners operating alkylation units. Since ZSM-5 zeolite tends to generate more propylene than butylenes (see Figure 1 ), there are strong incentives for FCCs, which feed to alkylation units, to increase C₄=/C₃= selectivity through the base catalyst technology to generate higher-octane alkylate species. FCC catalysts can be tuned to effect such change. Recent technical advancements have made this even more possible, with some refiners having taken it upon themselves to expand their alkylation units to fully utilise the benefits that improved technologies can offer. Fourtune and Fourtitude FCC catalysts for vacuum gasoil (VGO) and resid applications, respectively, utilise BASF’s Multiple Framework Topologies (MFT) technology (Figure 1) to maximise butylenes yield and selectivity over propylene.

The multiple zeolite frameworks have optimised acid site density and strength to ensure selective butylenes yield over propylene, as well as enhanced porosity to reduce dif- fusion limitations and minimise saturation reactions. The mechanism behind the success of such butylenes-maxi - mising catalysts involves both generation and preservation (avoiding saturation) of C₄ olefins while preserving high- octane molecules in the gasoline range. Fourtune and Fourtitude catalysts have been used in multiple commercial FCC units with stand-out performance in C₄=/C₃= selectivity (up to 1% volume increase in butyl - enes yield at constant propylene yield) and FCC naphtha octane for gasoline blending (up to 2 RONC increase) com- pared to alternative suppliers in unit operating data. These changes have allowed refiners to increase their refinery gasoline octane by two methods: improved octane of FCC- generated naphtha and an increase in alkylate production. Fourtune and Fourtitude are marks of BASF. A Jignesh Fifadara, Evonik Catalysts, Global Business Executive, HPC Catalysts and Sustainability, Evonik There are several methods to increase the octane rating of gasoline. However, each has its own advantages and limi- tations. Some of the methods include:  Blending of higher-octane components (alkylates, isomerates, or reformates) with lower-octane gasoline to increase gasoline pool octane rating. v Blending with an alcohol-based additive (ethanol) since it has higher octane ratings than gasoline and can be blended in certain proportions. w Addition of aromatics (benzene, toluene, and xylene) in small amounts, which have higher octane ratings compared to straight-chain hydrocarbons. x Investment in an isomerisation process that converts straight-run hydrocarbons into branched chain hydrocar- bons, which typically have higher octane ratings. y Addition of fuel additives focused on boosting octane can also be utilised but can be restrictive due to environ- mental concerns. z Optimising catalyst systems within an FCC gasoline hydrotreater to minimise octane loss while operating at higher severities to meet sulphur specifications.

PTQ Q3 2024