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Nov-2019

Catalyst responds to cold flow challenges (TIA)

A Greek refiner needed to expand exports of automotive diesel oil beyond the saturated market in Greece.

Phillip Parker
ExxonMobil Catalysts and Technology Licensing
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Article Summary
Northern markets, especially nearby Balkan countries, offered opportunities for ultra low sulphur diesel (ULSD) exports, if the refiner could meet the more stringent cold flow specifications. While specifications in Greece required cold filter plugging point (CFPP) of -5°C in winter and +5°C in summer, northern Balkan markets demanded -15°C or even lower during cold months.

At the refinery, engineers used additives to reduce cloud and pour points, as well as CFPP, but still could not profitably meet specifications. The refiner contacted ExxonMobil Chemical Company’s Catalyst and Licensing business unit seeking a solution to help them profitably produce ULSD for export.

Solution
After analysing the challenge, ExxonMobil engineers recommended installing a bed of MIDW catalyst in the heavy atmospheric gas oil (HAGO) hydrotreater, which was designed to accommodate the installation (see Figure 1). MIDW technology uses a proprietary shape-selective catalyst for isomerisation to convert normal paraffins to isoparaffins.

Utilising a drop-in solution, MIDW is easily integrated with other technologies and existing plant equipment at diesel producing refineries.
ExxonMobil suggested one minor modification to the reactor, including adding a treat gas quench line and a quench nozzle in the inter-bed area to allow for quenching during warm months. The MIDW catalyst was loaded in sour mode, replacing less than one-third of the hydrodesulphurisation catalyst.

Result
The MIDW catalyst technology helped the refiner achieve its goal of producing high quality ULSD that meets cold flow specifications in northern markets. The MIDW catalyst enabled the refinery to produce CFPP at -15°C to -20°C, with the aid of additives, opening new markets in the Balkans. The catalyst cycle exceeded 1000 normalised days (see Figure 2).

By reaching new, northern markets that previously had been closed, the refiner achieved significant profits, exporting more than 30% of diesel production as ULSD instead of as lower value heating oil. MIDW technology helped improve the refiner’s profitability.

This short case study originally appeared in PTQ's Technology In Action feature - Q4 2019 issue.

For more information: Phillip.j.parker@exxonmobil.com

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