Isobutane in the presence

Alkylation of isobutylene and isobutane in the presence of an acidic catalyst yields isooctane. This reaction proceeds through the same mechanism as dimerization except that during the last step, a proton is transferred from a surrounding alkane instead of one being abstracted by a base. The cation thus formed bonds with the base. Alkylation of aromatics with butylenes is another addition reaction and follows the same general rules with regard to relative rates and product stmcture. Thus 1- and 2-butenes yield j -butyl derivatives and isobutylene yields tert-huty derivatives. 

Alkylation is one of the refining processes in which light olefin molecules are reacted with isobutane (in the presence of either sulfuric or hydrofluoric acid) to produce a desirable gasoline component called alkylate. 

HF alkylation an alkylation process whereby olefins (C3, C4, C5) are combined with isobutane in the presence of hydrofluoric acid catalyst. 

Alkylation A refinery process for producing high-octane components consisting mainly of branched chain paraffins. The process involves combining light olefins with isoparaffins, usually butene and isobutane, in the presence of a strong acid catalyst such as hydrofluoric or sulfuric acid. 

Problem 6.60 Ethylene is alkylated with isobutane in the presence of acid (HF) to give chiefly (CH,),CHCH(CH,)2, not (CHiljCCHjCH,. Account for the product. 

Use of Catalysts Containing Transition Metal Cations. Ethyl -ene being alkylated over certain zeolite catalysts reacts specifically. Ethylene can not, however, be alkylated with Isobutane In the presence of H2SO., because of the formation of stable ethylsulphates. We examined the Isobutane - ethylene alkylation over crystalline aluminosilicates and found that those catalysts containing RE and/or Ca In combination with transition metal cations were most active. The alkylation has resulted In not hexanes as would be expected, but an alkylate containing octane Isomers as the major product (about 80%). Moreover, the product composition was similar to that obtained from n-butene over CaREY. The TMP-to-DMH ratios were 7.8 and 7.1 respectively. 

Although no specific analysis was made to Identify sec-butyl sulfate in the acid phase, there seems little doubt that this sulfate was the reaction product obtained in the n-butene runs. First, the n-butenes and acid reacted on essentially a 1 1 molar basis only a slight excess of acid was needed In all cases. Of Interest, formation of butyl sulfates has also been reported to occur In conventional alkylation reactors (13). Second, the reaction product was similar 1n many respects as compared to sec-propyl sulfate the product was unstable at higher temperatures and 1t reacted with isobutane in the presence of sulfuric aicd to form alkylate (9). Third, the reaction products from all three n-butenes alkylated in identical manners as will be discussed later (9). Fourth, McCauley (14) has shown that butyl fluorides can be formed and are quite stable at low temperatures such as used here he had contacted HF with n-butenes. 

More than 30 runs were made In which sec-butyl sulfate was reacted with Isobutane In the presence of sulfuric acid. Variables Investigated Included the following ... 

Diolefins also occur in relatively small concentrations in olefin feed streams. Their concentration increases as cracking severity increases, such as in fluid coking. As in the case of ethylene, the butadienes do not appear to react with isobutane in the presence of strong sulfuric acid. The dienes are believed to form reaction products, most of which are acid soluble, and if this general premise is accepted the fresh acid make-up rate for a dilution range of 98.5 to 90.0% (wt.) can be calculated to be 2465 pounds of acid per barrel of butadiene. Industry practice is to use rates in the range of 1890 to 4200 pounds per barrel. 

Problem 6.6 When ethylene is alkylated by isobutane in the presence of acid, there is obtained, not neohexane, (CH3)3CCH2CH3. but chiefly 2,3-dimethylbutane. Account in detail for the formation of this product. 

Oxidation of all the saturated paraffin hydrocarbons up to isobutane in the presence of chlorine was found to result in the preferential reaction of the oxygen with the carbon to give carbon dioxide and of the chlorine with hydrogen to give hydrochloric acid gas.1- ... 

An oxidation of alkanes by molecular oxygen, which is catalyzed by N-hydroxyphthalimide (NHPI) combined with Co(acac) ( =2,3) or transition metal salts, has been described by Ishii and coworkers (see a review [33] and original papers [34] in some cases NHPI also efficiently catalyzes the oxidation in the absence of metal derivatives [35]). For example, the oxidation of isobutane in the presence of catalytic amounts of NHPI and Co(acac)2 under an air atmosphere in benzonitrile at I(X) °C gave terf-butyl alcohol (yield 84%) as well as acetone (13%) [34d], The co-catalytic effects of various metal compounds are compared in Table IX.2. The proposed mechanism of the Ishii oxidation reaction involves hydrogen abstraction from isobutane (or any other compound with reactive C-H bonds) by the phthalimidooxyl radical (PINO) (Scheme IX. 4) [34d]. 

Figure 9. Pyrolysis of isobutane in the presence of HCl or HBr. Variations of the relative magnitude of the two stoichiometries vs. initial concentration of additive YH.

Alkylation is the reaction of an olefin with an isoparaffin (usually isobutane) in the presence of a catalyst (either 98 percent sulfuric acid or 75 to 90 percent hydrofluoric acid) under controlled temperatures and pressures to produce high octane compounds known as alkylate. These products are separated in a settler where the acid is returned to the reactor and the al late is farther processed. This hydrocarbon stream is scrubbed with caustic soda to remove acid and organically combined sulfur before passing to the fractionation section. Isobutane is recirculated to the reactor feed, the alkylate is drawn off from the bottom of the debutanizer, and the normal butane and propane are removed from the process. 

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