Upgrading of Fischer-Tropsch (FT) biowaxes to second-generation biofuels via hydroprocessing is the final step for increasing the fuel amount of the overall biomass conversion route: gasification of lignocellulosic biomass, FT synthesis, and hydroprocessing. The typical FT product portfolio consists of high molecular weight paraffinic waxes as the main product and FT fuels in the diesel and naphtha boiling range. OMV's objective and contribution to the project focus on achieving coprocessing of FT biowaxes with fossil feedstock using existing hydrotreating plants of crude oil refineries. Various test runs have been examined with a conventional refining catalyst under mild conditions (380-390°C, 5.8 MPa; WHSV, 0.7-1.3 h −1 ) in a pilot plant.Pure FT biowax is converted to gases, fuels, and an oil/ waxy residue in a fixed-bed reactor with a porous catalyst layer technology. The presence of hydrogen in the reaction chamber reduces the fast deactivation of the catalyst caused by the formation of a coke layer around the catalyst particle surface and saturates cracked hydrocarbon fragments.Another approach is the creation of synthetic biodiesel components with excellent fuel properties for premium fuel application. Basically, premium diesel fuel differs from standard diesel quality by cetane number and cold flow properties. Hydroprocessed synthetic biodiesel (HPFT diesel) has compared to conventional diesel advantages in many aspects. Depending on the catalyst selected, premium diesel quality can be obtained by shifting cold flow operability properties of HPFT fuels to a range capable even under extreme cold conditions. In addition, a highquality kerosene fraction is obtained to create bio jet fuels with an extremely deep freezing point, as low as −80°C. The isomerization degree, as well as the carbon number distribution of high paraffinic profile, and the branching degree have a major impact on the cold flow properties and cetane number. FT diesel has, compared to HPFT diesel, a slightly higher derived cetane number (DCN>83) and a cloud point of −9°C, whereas HPFT diesel reaches values as low as −60°C. Although the HPFT naphtha obtained consists of high amounts of isoparaffins, the RON/ MON values are comparable to fossil straight-run naphtha. The reason is that the branching degree of isoparaffins from the naphtha fraction is not sufficiently high enough to reach the typical octane number values of gasoline products delivered at filling stations. Assuming the goal of launching a premium biodiesel or biokerosene fuel to the market, these hydroprocessed synthetic biofuels from FT biowaxes are ideal blending components.

The present study describes the application of Fischer Tropsch biowaxes as a feedstock in a pilot-scale hydroprocessing unit at operating conditions very similar to industrial size hydrotreating plants of traditional refineries. The project focus on a future coprocessing of biowax/gasoil blends due to produce bio-products derived from lignocellulosic biomass: crack gases, naphtha, kerosene, diesel and a residual product. Hydro-processing plants operating at mild cracking conditions support the production of high amounts in middle distillates at reduced coke formation. Premium bio-diesel and bio-kerosene with excellent cold flow properties are the main objective of the investigations. Various test runs with different hydrotreating catalysts have been conducted due to determine the influence of waxy feedstock on catalyst behavior and product distribution. Depending on the catalyst selected, the fixed bed reactor streamed by hydrogen operates under specified cracking condition defined by the following parameters: reactor temperature, hydrogen pressure and weight hourly space velocity (WHSV). Test runs with selected catalysts -isodewaxing (IDW), hydro-desulphurization (HDS) and the catalytic deparaffination (CDP) catalyst -have been executed at constant process conditions in order to compare the product spectrum and properties of product groups. Highest amounts of bio-diesel and bio-kerosene with excellent cold flow properties can be obtained with the IDW catalyst. This NiW-based catalyst with special additives generates cleaved and reshaped molecular fragments via skeletal isomerisation increasing the isoparaffin content of naphtha and middle distillates. Further investigations with this catalyst type have been executed due to determine the catalyst aging effect in a separate long term test run. The loss of cracking severity during operation of the catalyst can be observed by a steady decline in conversion. Unsaturated hydrocarbons such as olefins and diolefines in the bio-feedstock support the formation of a coke layer on the catalyst surface resulting in reinforced deactivation. As the consequence naphtha and finally the crack gases and the kerosene fraction are shifted to higher molecular fragments increasing the diesel and residue yield. Physicochemical properties of the product groups obtained during the test run vary and especially the cold flow properties from the diesel and kerosene fraction degrade significant. Balancing the conversion decline of the catalyst in operation can be realized by increasing the reactor temperature and the hydrogen pressure, but the effect is time limited.