Ecofining™ hydroprocessing technology

Ecofining™ from UOP LLC/Eni is another feedstock-flexible catalytic hydroprocessing technology that converts a wide range of vegetable oils and other biologically-derived feedstocks (waste) into a Green Diesel fuel with high cetane values (80-90 range), good cold-flow properties and low emissions [81-83]. The Green Diesel process is a two-stage process: (i) hydrodeoxygenation (HDO) of vegetable oils (using a UOP (Ni, Mo) catalyst); and (ii) isomerisation of n-paraffins (using an Eni PMG catalyst). Figure 15.21 shows a simplified process flow diagram. Feedstock is routed to the catalytic reactor where it is combined with hydrogen, brought to reaction

15.21 Simplified Ecofining™ Green Diesel process flow diagram.

temperature, and then converted by a series of optimised hydrodeoxygenation, decarboxylation and hydroisomerisation reactions to a branched paraffin-rich diesel fuel. Water and COx formed by deoxygenation according to

are separated from the fully deoxygenated liquid hydrocarbon product, which is then fractionated to remove a small amount of light-fuel by-product. Excess hydrogen provided to the reactor is recovered and recycled to the reactor to maintain a minimum required hydrogen partial pressure. Make­up hydrogen is added to the process to balance both chemical consumption and solution losses. Process hydrogen requirements and product yields are shown in Table 15.20. The primary product is paraffinic diesel and co­products include propane and naphtha. Product carbon number distribution and selectivity of oxygenate conversion to H2O and COx is controlled by the choice of catalyst and reaction conditions. Diesel yield depends on both feedstock type and operating severity and varies from 88 to about 99 vol% depending on the level of hydroisomerisation required to achieve product cloud point specification.

A range of vegetable oil feedstocks has been processed in pilot plants, including SBO, RSO and PMO, while other potential feedstocks such as tallow and greases are under evaluation. Palm oil requires substantially less hydrogen than rapeseed or soybean oil due to the lower olefin content. Pilot-plant tests have shown that there is no measurable catalyst deactivation after over 2000 h on-stream.

Table 15.20 shows some performance parameters of the Green Diesel

Table 15.20 Performance parameters of Green Diesel process (after ref. [83])

Feedstock.

• Vegetable oil

• Hydrogen

Products.

• Naphtha/kerosene

• Propane

• Green diesel

process. Green Diesel has excellent fuel properties, and is very similar to diesel produced via Fischer-Tropsch processes. On the basis of an LCA study [83] the product is superior to both petrodiesel and biodiesel and an excellent blending component. Green Diesel has a lower environmental impact and lower climate active CO2 production than FAME. The eco-compatibility in terms of kg active CO2/kg fuel is more favourable for Green Diesel (0.9 kg/ kg) than for biodiesel (1.6-2.3 kg/kg) or petrodiesel (3.8 kg/kg) (see also Fig. 14.8). The environmental impact of FAME production is higher due to the methanol feedstock requirement. Methanol is produced from natural gas through a very energy intensive process with high environmental burdens. Fossil energy consumption in the Ecofining™ process is reduced by 84-90% for green diesel produced from SBO or PMO, respectively, when H2 is produced internally from the light-fuel by-products rather than from fossil resources. Green Diesel thus has the potential to displace more petroleum resources per energy content in the fuel compared to biodiesel.

As in all refinery processes, the primary factor in the Green Diesel process economics is the feedstock costs. The process is economically competitive and sustainable. Process economics is assured for palm and soy oil (at US$420/ MT and US$560/MT, respectively; May 2007) for crude oil prices of US$52 and US$67/bbl, respectively. With the provision of a US$1/gal subsidy for renewable diesel produced in the US, a new unit processing soybean oil can be paid back in 1 year at a crude oil price of US$39/bbl.

UOP LLC’s Ecofining™ process has been licensed to Eni SpA, Livorno (Italy), Ecofining’s co-developer, and to Galp Energia (Sines, Portugal). Both 330 kt/yr plants are expected to be on stream by early 2010.

UOP LLC/DARPA have developed renewable energy technology to convert vegetable and algal oils to fuels for military jets (Jet Propellant 8 or JP-8).

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