PTQ Q2 2022 Issue

the blend, typically by around 1 psi (7 kPa) for both E10 and E20 blends. This impact will place a greater rel- ative premium on low RVP compo- nents in the gasoline pool. Petrochemicals integration A further factor influencing the Indian gasoline market is the pro- gression towards greater integra- tion of refining and petrochemicals, where optimal molecule manage- ment is key to maximising value. In an integrated scheme, a portion of naphtha is cracked in a steam cracker or high severity catalytic cracker to maximise olefins yield, and aromatics from reformate and FCC light naphtha are recovered for petrochemicals use. 12 Removing aromatic compounds from the gas- oline pool in this way will have a negative impact on volume, octane, and RVP of the pool, while cracking naphtha to produce light olefins fur - ther decreases the volume of blend stock available. Meeting demand and specifications With tightening emissions standards and increasing gasoline consump- tion, the demand for high octane, clean burning gasoline blend stocks will require focused investments in the near term. As reformate and naphtha are increasingly redirected to petrochemicals production, Indian refiners should look for alternative routes to produce high octane, low RVP components. One such oppor- tunity lies within the butane-buty- lene fraction (BBF) product from the FCC unit. The olefinic content of this stream can be readily utilised to produce ethers and alkylate, both of which are ideal premium gasoline blend stocks: • Alkylate is produced via the alkyl- ation of isobutane with light olefins, most commonly butylene, gener- ating a high octane, clean burning, and low RVP product. • Common ethers include methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE), with clear RON of 117 and 118, produced from etherification of isobutylene with methanol and ethanol, respectively. While only two MTBE units and two alkylation units are listed in published data for India, there are

24.4

4.8

Isooctene 3.1

MTBE

Alkylate

FCC BBF

Stream or product name

Alkylate 1-butene

MTBE

Isooctene

n-butane

i-butane i-butene

trans-2-butene

cis-2-butene

Figure 4 Potential utilisation of FCC butane-butylene fraction

around 20 FCC units in the coun- try, representing an opportunity to increase production of octane enhancers. By contrast, there are around 50 FCC units in Europe, of which over 80% have associ- ated etherification and/or alky - lation capacity to meet EN228 specifications. Figure 4 illustrates the potential gasoline products to be produced from a typical 20 MT/h FCC BBF stream via dimerisation of isobu- tylene, etherification with metha - nol, or alkylation with isobutane. MTBE and ETBE exhibit high blending RON, typically 119 and 120, respectively, depending on the gasoline matrix. Isooctene, the product of isobutylene dimerisa-

tion, has a high blending RON of 124, based on a 10% blending vol- ume. Alkylate, with a RON rating of around 97, can be produced in larger volumes because it utilises all C 4 olefins and isobutane, mak - ing it a good component to add high octane volume to the gaso- line pool. Make-up isobutane for alkylate production is typically sourced from the saturated gas plant, with additional volumes pro- duced through C 4 isomerisation, if required. Etherification and alkylation tech - nologies can be used in series to provide the largest octane contribu- tion. Figure 5 illustrates the potential products from sequential production of MTBE and alkylate, with the alky-

Alkylate MTBE

18.2

n-butane i-butane 1-butene trans-2-butene cis-2-butene i-butene

4.8

FCC BBF

MTBE & Alkylate

Stream or product name

Figure 5 Maximise octane contribution from FCC butane-butylene fraction

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