Transport fuels from two-stage coal liquefaction

Abstract

Four Spanish lignites and their vitrinite concentrates were evaluated for coal liquefaction. Correlationships between the content of vitrinite and conversion in direct liquefaction were observed for the lignites but not for the vitrinite concentrates. The most reactive of the four coals was processed in two‐stage liquefaction at a higher scale. First‐stage coal liquefaction was carried out in a continuous unit at Clausthal Universität at a temperature of 400°C at 20 MPa hydrogen pressure and with anthracene oil as a solvent. The coal conversion obtained was 75.41% being 3.79% gases, 2.58% primary condensate and 69.4% heavy liquids. A hydroprocessing unit was built at the Instituto de Carboqumica for the second‐stage coal liquefaction. Whole and deasphalted liquids from the first‐stage liquefaction were processed at 450°C and 10 MPa hydrogen pressure, with two commercial catalysts: Harshaw HT‐400E (Co‐Mo/Al2O3) and HT‐500E (Ni‐Mo/Al2O3). The effects of liquid hourly space velocity (LHSV), temperature, gas/liquid ratio and catalyst on the heteroatom liquids, and levels of 5 ppm of nitrogen and 52 ppm of sulphur were reached at 450°C, 10 MPa hydrogen pressure, 0.08 kg H2/kg feedstock and with Harshaw HT‐500E catalyst. The liquids obtained were hydroprocessed again at 420°C, 10 MPa hydrogen pressure and 0.06 kg H2/kg feedstock to hydrogenate the aromatic structures. In these conditions, the aromaticity was reduced considerably, and 39% of naphtas and 35% of keroseno fractions were obtained.

Hydrogenation process of the tar obtained from the pyrolisis of brown coal

“…Multiple facilities of the kind are operated in a pilot scale particularly in Europe and the USA. Moreover, the prognoses suggest that coal will be one of the fuels that will replace crude oil in future [2,12,31]. As far as the liquefying processes are concerned, the most appropriate coal is such coal that contains high amount of hydrogen (brown coal and lignite) and high amounts of reactive maceral groups (vitrinite and exinite).…”

“…The objective of the coal liquefying processes is production of fuel oil, diesel and naphtha from coal (which products have predominantly been produced from crude oil). On industrial scale, the technologies of liquefying of coal had been used in particular before and during the World War II in Germany, where multiple facilities of the kind had been operated [2,23]. The first technology of direct liquefying had been made operational in 1927 in Leuna (Bergius Process -IG Farben).…”

A review on coal-to-liquid fuels and its coal consumption

“…Liquid yields can be in excess of 70% of the dry weight coal, with overall thermal efficiencies of 60-70% [22,23]. The resulting liquids are of much higher quality, compared to pyrolysis, and can be used unblended in power generation or other chemical processes as a synthetic crude oil (syncrude).…”

Brown coal tar hydrotreatment

“…At the same time ash content is also removed. The objective of the coal liquefying processes is production of fuel oil, diesel and naphtha from coal (which products have predominantly been produced from crude oil scale, the technologies of liquefying of coal had been used in particular before and during the World War II in Germany, where multiple facilities of the kind had been operated [2,26]. The first technology of direct liquefying had been made operational in 1927 in Leuna (Bergius Process -IG Farben).…”

“…Multiple facilities of the kind are operated in a pilot scale particularly in Europe and the USA. Moreover, the prognoses suggest that coal will be one of the fuels that will replace crude oil in future [2,12,35].…”