Benzole recovery

In an agreement signed by the War Ministry, represented by Mauclere (deputy managing director of the Service des Poudres), starting on 1 November 1915, Schneider et Cie was to supply the Ministry with 90 tonnes of benzene and 30 tonnes of toluene recovered from its benzol recovery plant in Creusot. Once this initial delivery was complete, further consignments of at least 28 tonnes a month were to be... 

As indicated by the analysis, benzene is by far the most abundant compound in the light oil. For this reason the total liquid recovered is sometimes referred to as benzol. The marketable benzene products of specified purity are also referred to as benzol (e.g.. 1° benzol, industrial benzol, etc.), and the word toluol has the same significance with regard to toluene. Carbon disulfide can also be removed from the gas stream during the light oil recovery operation, and, in some installations, which are specifically designed for this service, carbon disulfide removal is of equal importance to benzol recovery. 

Properties of Typical Petroleum and Coal-tar Oils Used for Benzol Recovery... 

Designed primarily for benzol recovery. fDesigned primarily for carbon disulfide recovery. Source Silver and Hopton, 1942... 

Naphthalene is adequately removed in the oil-washing operation for benzol recovery, and a separate naphthalene removal step is not required if benzol is recovered. This type of operation is shown in the overall coke byproduct recovery flow diagram (Figure 16-25) where residual naphthalene in the gas from the final cooler is removed by the light oil scrubber. However, in some cases it is advantageous to remove naphthalene in a separate step before the gas is processed for the removal of benzol and other impurities. This is usually accomplished hy oil washing. 

Proof of the existence of benzene in the light oil derived from coal tar (8) first estabHshed coal tar and coal as chemical raw materials (see Eeedstocks, COAL chemicals). Soon thereafter the separation of coal-tar light oil into substantially pure fractions produced a number of the aromatic components now known to be present in significant quantities in petroleum-derived Hquid fuels. Indeed, these separation procedures were for the recovery of benzene—toluene—xylene (BTX) and related substances, ie, benzol or motor benzol, from coke-oven operations (8) (see BTX processing). 

Continuing further with the recovery aspects from coke oven gas reference may be drawn to the recovery of light oil (crude benzol). In a typical process used, the coke oven gas (from which benzol is to be recovered) after removal of tar, ammonia etc. is passed through the benzol scrubber where the benzol vapours are scrubbed by wash oil flowing countercurrent to the gas. Benzolised wash oil is then pumped to the recovery section where the crude benzol, absorbed in the wash oil is stripped off by steam. The steam vapour mixture, com-... 

For many years benzene (benzol) was made from coal tar, but new processes that consist of catalytic reforming of naphtha and hydrodealkylation of toluene are more appropriate. Benzene is a natural component of petroleum, but it cannot be separated from crude oil by simple distillation because of azeotrope formation with various other hydrocarbons. Recovery is more economical if the petroleum fraction is subjected to a thermal or catalytic process that increases the concentration of benzene. 

Figure 4.3 shows the flow diagram of the recovery of benzole from coke oven gas by distillation. 

In 1883, Viktor Meyer first detected thiophene in coke-oven benzole, where it is present in concentrations of around 1%. (Because of the close relationship between thiophene and benzene, Meyer took the name kryptophen ( hidden in benzene ) into consideration.) Recovery of thiophene from coke-oven benzole, which is possible by the reaction of thiophene with concentrated sulfuric acid to thiophenesulfonic acid, is not used industrially since the synthesis is more economical. 

Field test data showing the effects of natural gas composition and flow rate are given by Enneking (1966). The use of adsorption to recover hydrocarbons from gas streams at refineries and petrochemical plants is described by Cantrell (1982). The recovery of benzol (a benzene-rich light oil) from manufactured and coke-oven gas streams was formerly an important application of activated carbon adsorption, but is no longer considered significant. A typical benzol removal installation is described by Howell (1943) and Walker et al. (1944). Hydrocarbon recovery processes are not described in detail herein because of their similarity to solvent recovery processes and the fact that they are intended primarily for recovery, not gas purification. 

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