FT diesel

Synthetic FT diesel fuels can have excellent autoignition characteristics. The FT diesel is composed of only straight-chain hydrocarbons and has no aromatics or sulfur. Reaction parameters are temperature, pressure and H/CO ratio. FT product composition is strongly influenced by catalyst composition the yield of paraffins is higher with cobalt catalytic ran and the yield of olefins and oxygenates is higher with ironcatalytic ran. 

Table 3.9 Properties of Fischer-Tropsch (FT) diesel and No. 2 diesel fuels...

When we produce synthetic liquid fuel, such as Fischer-Tropsch (FT, diesel) oil from coal, heat is necessary for the coal gasification process to produce synthetic gas (syn gas, CO+HJ and additional hydrogen is necessary to adjust the hydrogen content in the syn gas for the subsequent FT synthesis... 

The concept of this process is shown in Figure 6. The carbon in biomass which is fixed by photosynthesis from atmospheric C02 is converted into i) solid carbon (various kinds of charcoal, carbon and graphite) for use as materials or for storage, which is a stable state of carbon element ii) synthetic fuels such as FT diesel oil, DME or hydrogen, which can replace fossil fuels as carbon neutral alternate fuels (Hori, 2007, 2007a, 2007b). 

In this process, carbon from biomass is converted to gases (CO, CO2) by high temperature (above 800 °C). The produced CO2 can react with hydrogen to directly produce methane, but also other different products, such as diesel, and other chemicals such as 1-alkenes in the presence of catalysts (Dry, 1999). This process has been used to produce Fischer-Tropsch diesel (FT diesel). 

The combination of high value outputs, scale-effects and flexibility in general, may lead to a very efficient, cost-effective and clean overall system. Cost-effective means that the electricity produced has to compete with electricity from coal. For fair comparison the cost of clean electricity generation must be considered with a similarly low environmental burden. For instance, costs for removal or storage of the emitted carbon dioxide from coal plants have to be included. For electricity this inches an allowable cost price of 0.05 Euro/kWh. This value is the EU strategic goal and seems achievable for large advanced systems [5] where electrical efficiencies between 50 and 60% can be obtained [6]. In the case of the produced liquid fuels, cost-effective means that the cost price must correspond to the cost prices of fossil fuels, which will be used in the future in cars with low or very low emissions. For the liquid fuels FT diesel is taken as example and the cost price would have to be 0.34 Euro/litre (of diesel). 

The production of Fischer-Tropsch liquids (diesel) is today the optimal route for producing energy carriers from biomass. The FT diesel is directly applicable in the existing infrastructure and is free from sulphur and aromatics in contrast to fossil diesel. For the demonstration of integrated systems ECN focuses on two lines of development (1) large-scale dedicated installations for imported biomass and (2) small- to medium scale installations for local biomass and residues. 

No mention was made that any lubricants produced from Fischer-Tropsch liquids were utilized. However, during the period 1943 to 1945, diesel fuel used by both the Navy and Army contained FT liquids. The FT diesel oil, most of which was obtained from the Miike Synthetic Oil Plant at Omuta, was utilized by the Navy by blending with 90% of Tarakan oil, to meet diesel fuel specifications. The Army used about 50% of the FT diesel oil production as fuel for diesel engines in tanks. 

As mentioned above, high-quality diesel can be obtained via FT processing. High cetane numbers of > 70 are reached and the fuel is almost free of sulphur, nitrogen or aromatic contaminants. Furthermore, engine tests revealed low NOx, CO, hydrocarbons and particulate emissions. Compared to fossil diesel, FT diesel shows superior characteristics and can be employed instead of, or in blends with, fossil diesel without modification of engines and gas station systems. 

Currently, the attention is focused on the synthesis of both liquid biofuels - mainly FT-diesel products and methanol - and gaseous synthetic fuels such as dimethyl ether (DME) and substitute natural gas (SNG, which is addressed in this chapter) the main parameters (pressure, temperature, type of catalyst, H2/CO ratio) governing the different synthesis pathways of these fuels are reported in reference [4],... 

Syngas platform biorefinery for Fischer—Tropsch (FT) diesel and phenols from straw... 

Figure 2.32 Oryx GTL plant in Qatar, 34,000 bpd FT diesel. Oxygen plant Air Produets Syngas Topsoe FT synthesis Sasol Hydroeraeking Chevron. The plant is designed in two lines (17,000 bpd). Reprodueed with the permission of Oryx GTL.

Among the few options that exist for producing motor biofuels with commercial potential, the gasification of biomass to obtain Fischer-Tropsch (FT) diesel has received growing attention in recent years, as it offers a way of refining a clean and potentially carbon-neutral motor fuel that is directly usable in vehicles (Hamelinck, Faaij, den Uil, Boerrigter, 2004). 

The amount of FT diesel that can be produced from forest residues was determined by... 

Table 18.7 Emission reduction factors for BTL-FT diesel fuel and different emission reduction technologies (negative values indicate a reduction of emission)...

---