Patent GB-471482-A (GB)
Title: Improvements in the manufacture and production of low boiling liquid hydrocarbons from the gases obtained in the dry distillation of fuels
IPC: C07C2/00
Filed: 1936-03-02
Abstract: Liquid hydrocarbons, mainly not boiling higher than 360 DEG  C., are produced by passing gases obtained by the dry distillation of fuels, such as mineral coals, brown coals, peat, wood, pitches and asphalts, together with the normally liquid hydrocarbons or part thereof contained in the gases over or through acid catalysts at a temperature suitable for the conversion.  The liquid hydrocarbons formed, together with those originally present, are removed from the gases.  Catalysts specified are sulphuric, phosphoric, phosphorous and pyrophosphoric acids, sulphur trioxide, phosphorus pentoxide, alkyl-and arylsulphonic acids such as benzene- or naphthalene-sulphonic acids, esters of sulphuric or phosphoric acid, such as glycerine monophosphoric acid, the acid salts or acid-reacting neutral salts of these acids with alkalies, alkaline earths, earths or heavy metal oxides, and the acid-reacting salts of the halogen hydracids, as for example, tin, aluminium or titanium chloride, or mixtures thereof.  These substances are preferably applied to carriers such as pumice stone, active carbons, coke, silicon carbide, chamotte, sillimanite, &c.  The catalysts may also be used in the form of suspensions, for example, phosphorus pentoxide in oils such as hydrogenated washing oil.  Different catalysts may be arranged one behind the other, or the same catalyst in several stages may be used.  Suitable temperatures range from 0 to 300 DEG  C., and atmospheric or increased pressure may be used.  Impurities in the gases, e.g. ammonia, hydrogen sulphide, cyanogen, organic sulphur compounds may be removed from the gases prior to passage over the catalyst.  For example, the ammonia may be removed by washing with sulphites, whereupon the gas is heated to 575 DEG  C. and led, after the addition of air, over the catalyst to oxidize the hydrogen sulphide to sulphur dioxide.  The gas is cooled to 200 DEG  C. and the residual ammonia, or that formed from the cyanogen is removed by 25 per cent sulphuric acid.  After passage over the acid catalyst for formation of the liquid hydrocarbons, the gas is cooled and simultaneously freed from sulphur dioxide by means of ammonium sulphite solution led in a cycle.  The liquid hydrocarbons may be removed from the gases by freezing out at atmospheric or increased pressure, or by leading the gases over active carbon or silica gel, or preferably through washing oil.  The liquid hydrocarbons have an unsaturated character, and may be purified by washing with dilute sulphuric acid or by hydrogenation.  In examples, (1) brown coal low temperature carbonization gas is freed from benzine to such an extent that 3 grams/cubic metre are present in the gas, desulphurized, and passed at 100 DEG  C. over a catalyst consisting of a mixture of sulphuric and phosphoric acids applied to coke. Liquid hydrocarbons are obtained by cooling the gas; (2) coke oven gas freed from tar, ammonia and sulphur is dehydrated and compressed to 5 ats., and passed at 100 DEG  C. over a catalyst consisting of a mixture of aluminium phosphate and phosphoric acid applied to pumice stone. Benzene formed together with that originally present is separated by cooling to 20 DEG  C.; (3) low temperature carbonization gas, freed from hydrogen sulphide, is treated at 0 DEG  C. with 60 DEG  B<\>ae. sulphuric acid.  A pale yellow oil collects on the acid, and more separates on dilution.  The oil is washed with soda solution and water.  By strong cooling and oil washing of the treated gas, further liquid hydrocarbons are obtained.  Specifications 291,137, [Class 2 (iii)], and 437,188 are referred to.  According to the Provisional Specification, the normally liquid hydrocarbons present in the gases may be removed therefrom prior to the treatment with the acid catalysts.ALSO:In a process wherein liquid hydrocarbons are produced by passing gases obtained by the dry distillation of fuels, together with the normally liquid hydrocarbons or part thereof contained in the gases, over or through acid catalysts, a catalyst consisting of a suspension of phosphorus pentoxide in oils, such as hydrogenated washing oil, may be used.