US2039798A - Treatment of hydrocarbon oils - Google Patents

Description

Patented May 5, 1936 UNITED STATES 2,039,798 TREATMENT OF HYDROCARBON orLs PATENT OFFICE -Vladimir Ipatiefi, Chicago, 111., assignor to Universal Oil Products Company, Chicago, Ill.,- a corporation of Delaware No Drawing. Application February 11, 1933, I

Serial No. 656,371

1 Claim. (01. 260-168) crackingdistillation of primary crude oils, those produced by the rerunning of these primary fractions and also motor fuels resulting from the cracking of heavier and less valuable portions of crude petroleums.

In a more specific sense the invention has reference to a process of treatment by means of which the sulfur content of sulfuric acid. treated hydrocarbon products is efficiently reduced by means of a specific treating reagent.

Owing to the adoption of high compression ratios in automobile engines to increase. their thermodynamic eiiiciency, a demand has been made upon the petroleum refining and other industries which furnish hydrocarbon motor fuels,-

for fuels of a high anti-knocking or slow-burning character. The cracking process which generally produces both unsaturated hydrocarbons and cyclic (including aromatic) hydrocarbons due to the dehydrogenating character of the decomposition reactions is employed quite generally to meet the demand for a high anti-knock motor fuel. However, complete control of the proportion of aromatics to olefins is not possible as the character of the charging oil varies with the type of crude oil from which they are produced, and

when intensive cracking conditions are employed in an effort to increase the amount of aromatics and hence the anti-knock value, undesirably large losses inlgas and coke are encountered and frequently the amount of olefins, particularly those of a highly unsaturated and unstable character, increases roughly in proportion to theincrease in aromatics. I

In order to conserve and stabilize the olefins produced in the cracking of heavy oils for the production of motor'fucl, processes are employed in which they are caused to combine chemically with other hydrocarbons of an aromatic,-naphtheme or paraflinic character in the presence of various catalysts which are effective in accelerating the rate of combination. In using sulfuric acid for this purpose there is evidence to indicate that intermediate compound formation occurs whereby sulfuric acid esters are formed on the one hand by direct addition of olefins to sulfuric acid and sulphonic acids on the other hand are produced by reactions analogous to the formation of benzene sulphonic acid from benzol. Further reaction between the esters and sulphonic acids thus initially formed results in the formation of alkylated hydrocarbons and a partial regeneration of the sulfuric acid.

The following equations typify the general character of the reactions taking place between olefins and aromatics in the presence of a sulfuric acid catalyst:

0 CoHo 00 3-021 1 Propyl- Benzol Mono-isoene ptopyl benzol H130 2CzHe CuHu Cu 4'( sH1):

Propyl- Benzol Di-iso-propyl one benzol upon the strength of the acid and the temperature, both increasing strength of acid and increasing temperature favoring the formation of polysubstituted products;

The above equations typifying reactions between a particular olefin and benzolmay be err-- tended not only to include the interaction between any olefin and any aromatic but also to reactions between various olefins on the one hand and naphthenic and parafiinic hydrocarbons on the other hand. Thus, in contacting a straight run or cracked gasoline fraction with the olefincontaining gases from'a cracking process in the presence of sulfuric acid, a certain amount of alkylation occurs as evidenced by the increase in anti-knockvalue and the proximate analysis of the. products. In. such cases,- however, there is undoubtedly some concurrent polymerization atingconditions, a certain amount of these esters dissolvesin the -oil and is difficult to remove therefrom either by further sulfuric acid treatment or by the use of alkalies; and extended washing. If the esters are not removed the sulfur content of the product istoo high to meet commercial specifications and if 'redistillation is resorted to it is necessary to keep below a certain temperature by use of steam orvacuum to avoid decomposition of the esters and contamination of the overhead product with sulfuri compounds of a more or less-indeterminate character though they are apparently a mixture of organic sulfur compounds comprising sulfur ethers, sulphoe acids and sulfoxy compounds. In distilling with steam a certain amount of hydrolysis-of the esters occurs and altogether the treatment of such A specific example of the results obtainable by products becomes a problem of some importance.

Inone specific embodiment the present invention comprises treatment of synthetic hydrocarbon mixtures produced by interacting olefins and other hydrocarbons in the presence of sulfuric acid by phosphoric acid to desulfurize them and produce other refining effects. The invention further comprises the use of graded mixtures of sulfuric and phosphoric acids for the same purpose. v a

The following equation shows the reaction which occurs between propylene (representing an olefin) and sulfuric acid:

Mono-propyl ester oi sulfuric acid Propylone The compound shown on the right of the equation typifies a number of esters of similar structure which as previously stated may remain dissolved in a liquid hydrocarbon mixture produced by synthetic reactions betweenoleflns and other hydrocarbons in the presence of sulfuric acid. According to the process of the present invention the hydrocarbon liquid containing such dissolved compounds is treated with phosphoric acid or the above mentioned graded mixtures of phosphoric and sulfuric acids, the course of the main'reactions, being evidently somewhat as follows:

on p on so o=r-on on I OCrHr Monop l Phosphoric esteroi ffm io acid ester of phosphorlc acid equation are evidently soluble in the phosphoric acid employed in the treatments, at least upto a high concentration since as will be shown later a large quantity of hydrocarbon mixture containing sulfuric acid esters may be treated before the equilibrium is reversed and the treating efficiency of the acid drops below an economical point.

The prosphoric acid ester remaining dissolvedo=rori OH Phosphoric acid Iso-propyl alcohol shown which may comprise a series of compounds not capable of hydrolysis. The proportion of such compounds will depend to a large extent on the nature of the reacting constituents which formed the synthetic hydrocarbon mixture in the presence of sulfuric acid.

The compounds on the right hand side of the a treatment comprised within the scope of the invention will be of assistance in showing its value in connection with the treatment of hydrocarbon oil mixtures containing sulfuric acid esters and other organic products of sulfuric acid treat-v ment.

The stock treated may have been produced as a result of treating a paraflinic straight run gasoline with olefin-containing gases from an oil cracking plant in the presence of sulfuric acid. This stock may have a total sulfur content of 1.34% and at the same time have the approximate boiling range for motor fuel and not be distillable without decomposition of the sulfur compounds to an extent which gives a percentage of sulfur in theoverhead product greatly in excess-of that allowed in commercial gasoline.

'Ihis gasoline stock may be treated with about 1% by volume of 89% phosphoric acid at a temperature of 50 C. The run may be made by treating successive 20% portions of the oil with the same acid, this method of operation simulating 'counterilow treatment. The sulfur content of the combined oil portions may be less than 0.05% and after separation from the phosphoric acid sludge it may be distilled to produce a water white color and gum stable gasoline suitable for marketing. The 1% by volume of phosphoric acid used corresponds to the use of about 6 pounds of acid per barrel of stock treated which is a reasonable and practical figure when considered from an economic standpoint. When using sulfuric acid of commercial grade in treating cracked distillates or other hydrocarbon products five pounds perbarrel is considered a very mild treatment.

A further yield of gasoline is recoverable by treating the phosphoric acid sludge with steam and also an amount of isopropyl alcohol approximately equivalent to the sulfuric acid esters corresponding to the 1.34 sulfur content, the alcohol being obtained by neutralizingand again distillirig the sludge.

The process is therefore shown as a valuable adjunct to synthetic processes in which oleiins in the presence of sulfuric acid catalyst are caused the process is also applicable to the treatment of sulfuric acid treated products from any source such as acid treated cracked naphthas to remove therefrom the sulfuric acid esters which tend to decompose on redistillation of the naphtha and increase the sulfur content of the overhead gasoline aswell as diminish the yield of boiling point products by inducing polymerization reactions among the unsaturated components.

The foregoing specification and example will serve their respective purposes of developing the character of the invention in showing its commercial value, but neither is to be considered as imposing undue, limitations upon its generally broad scope. i

I claim as my invention:

In the alkylation of aromatic hydrocarbons by reaction thereof with olefin gases-in the presence of sulphuric acid as a catalyst and wherein there acid.

VLADIMIR IPA'I'IEFF.

is produced a hydrocarbon liquid containing dis-