Catalysis 2024 Issue

is well below 0.5 wt%. The chemical CO₂ contribution is therfore an order of magnitude less than FCC or PDH. • Hybrid product recovery section: The inclusion of cryo - genic distillation for ethylene recovery and conventional distillation for propylene and butylene recovery offers signif - icant heat integration capabilities not typically found in a pol - ymer-grade propylene or polymer-grade ethylene operation. Catalyst development Catalyst studies began in 2017, utilising the Chemical Process Engineering Research Institute (CPERI) laboratories in Thessaloniki, Greece. The catalyst development work was initially carried out in a microactivity test (MAT) reactor with many catalyst formulations, including multiple zeolite and alumina types and sources, each with various metal types and levels. The catalysts were tested fresh and with incre - mental deactivation severities. The bulk of the testing was carried out at end-of-life con - ditions to achieve near-constant olefin selectivities as the catalyst ages. Gasolfin carried out approximately 300 indi - vidual tests before selecting the final few catalyst formula - tions. These catalysts were then advanced to the pilot plant phase. The final catalysts were tested for approximately 100 days of pilot plant operations. The feedstocks selected for these tests were pentane, hexane, octane, light straight run (LSR), full range naphtha (FRN), and FCC naphtha. Ease of cracking Gasolfin has created a catalyst system to efficiently convert all naphtha boiling-range hydrocarbons, excluding aromat - ics, into light olefins. The catalyst produces ethylene, pro - pylene, and butylene with a total olefin yield of 60-88 wt%. There are no higher molecular weight byproducts produced, such as diesel or heavier. The ethylene-to-propylene-to-bu - tylene product ratio (EPB ratio) is feedstock dependent. Paraffinic feeds such as LSR and FRN present an EPB ratio of 21:50:29, while olefinic feeds such as FCC naphtha pres - ent an EPB ratio of 18:49:33. More than 25 commercially derived feedstocks have been cracked at CPERI’s Thessaloniki, Greece, laboratory. These feeds include pentanes, LSR, medium straight run (MSR), FRN, light FCC naphtha (LCN), full range FCC naphtha (HCN), pyrolysis naphtha (PN), Fischer-Tropsch naphtha (FTN), bio-naphtha (BN), and various petrochemical inter - mediate streams. The petrochemical intermediate streams

Feed PIONA conversion

Unsaturated naphthene

75 74 73 60 59 48

Normal olefin

Iso-olefin

Normal paraffin

Saturated naphthene

Isoparaffin

Table 1

included various paraffinic naphthas, olefinic naphthas, oxy - genated naphthas, and naphtha streams bearing a mix of both olefinic and oxygenated components. The EPB ratios of these streams were all consistent with the typical ranges stated above. The ease of cracking is directly related to the composition and molecular weight of the feeds. In general, the order of cracking is unsaturated naphthenes and olefins > oxygen- bearing molecules > saturated naphthenes and normal par - affins > isoparaffins. Table 1 presents the average conversion levels for cracking FCC naphtha over the Gasolfin catalyst. Naphtha cracking proceeds efficiently up to undecane (C11), at which point steric hindrances begin to affect reac - tion rates. Higher molecular weight molecules crack faster than low molecular weight molecules. Pentane cracking follows the following order: Pentenes > isopentane > nor - mal pentane. Butane is the lightest molecule cracked by the Gasolfin catalyst, while C11 is the heaviest. Not all refiners have sufficient alkylation capacity to pro - cess the additional butylene produced by a Gasolfin unit. Additionally, many refiners operating in Europe and Asia do not possess alkylation units. The Gasolfin catalyst efficiently converts butylene, enabling further conversion to light olefin. Inovacat recommends recycling the mixed butane stream (C₃/C₄ column bottoms) back to the feed for alkyla - tion capacity-limited refineries. The butane selectivity for the Gasolfin catalyst converting LSR feed is about 21.8 wt%. The typical composition of the butane stream is 5% isobutane, 13% normal butane, and 82% butylene. A butylene cracking operation yields approx - imately 24.7 wt% ethylene and 75.3 wt% propylene. Such an operation enables a Gasolfin operation to be profitable in a refinery without (additional) alkylation capacity. The catalyst is not poisoned by sulphur. However, it is

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Catalysis 2024