Patent GB-494834-A (GB)
Title: Improvements in or relating to the extraction of bituminous or brown coal and like solid carbonaceous materials with solvents at high temperatures
IPC: C10G1/00
Filed: 1937-02-01
Abstract: In the pressure extraction of solid carbonaceous materials with solvents followed by destructive hydrogenation of the extract obtained, the extraction agent employed comprises a fraction boiling between 170 to 260 DEG  C. and containing 5-40 per cent cresols by weight which has been obtained from the products produced by destructive hydrogenation of a previous extract.  The heavy residues from the hydrogenation process are preferably recycled as pasting agent for further initial material to be extracted, the said residues being collected as liquids without substantial cooling from the hot reaction products issuing from the reaction vessel.  The extraction is carried out at 250-470 DEG  C. and under pressures of 20-500 atmos. for 30 to 60 mins. in the presence of catalysts, e.g. metal halides, and if desired in presence of limited amounts of hydrogen. Naphthalene may be added to the used hydrogenation extract to increase the content of tetrahydronaphthalene or may be removed therefrom by distillation. In the example, 435 kgs. ground bituminous coal are pasted with 700 kgs. solvent comprising 420 kgs. tetrahydronaphthalene, 140 kgs. naphthalene, and 140 kgs. cresols, and the paste is extracted at 410-430 DEG  C. at pressures increasing from 80 to 105 atmos.; 300 kgs. pressure extract and 700 kgs. extraction agent are obtained, the latter comprising 280 kgs. <PICT:0494834/III/1> <PICT:0494834/III/2> <PICT:0494834/III/3> is mixed with 555 kgs. of pasting oil comprising sludgy residues obtained from the hot catchpot of a previous hydrogenation and which contains already as catalyst 5-7 per cent of iron oxide obtained as a residue from the chemical disintegration of bauxite by sodium carbonate.  The mixture is destructively hydrogenated at 470-480 DEG C. under a pressure of 650 atmos. and a product is obtained comprising 70 kgs. gases and 11 kgs. water and liquid products which are topped to remove gasoline boiling below 190 DEG  C. The fraction boiling between 190 and 225 DEG  C. is recovered and 700 kgs. of this fraction comprising 420 kgs. tetrahydronaphthalene, 140 kgs. naphthalene, and 140 kgs. cresols are separated and used as extracting agent for fresh coal.  The remainder of this fraction is mixed with the gasoline fraction and subjected to a refining hydrogenation at 475 DEG  C. tetrahydronaphthalene, 280 kgs. naphthalene, and 140 kgs. cresols (one-third of the tetrohydronaphthalene is thus converted into naphthalene).  The mixture of extract and extracting agent and 50 atmos. pressure in presence of a stationary catalyst comprising tungsten disulphide, and a final product comprising 70 kgs. gases, 11 kgs. water, 112 kgs. gasoline (octane number 92) and 177 kgs. fuel oil (viscosity, 1,5 Engler at 20 DEG  C. and pour point, 50 DEG  C.) is obtained.  The method of operation is shown diagrammatically in Fig. 1, while in Fig. 2 the process is modified by separating by distillation the tetrahydronaphthalene and cresol from the extract prior to the hydrogenation stage.  The separation may be carried out before or after the hot residues have been added to the extract.  A further modification is shown in Fig. 4, according to which the separated solvent with or without addition or removal of naphthalene is subjected to hydrogenation prior to re-use as solvent. Specification 283,545, [Class 91], is referred to.