Butanes alkylation

Figure 13.42 Mechanism for/-butane alkylation with 2-butylene and 1-butylene.

Table 13.5 Steps for i-butane alkylation with 2-butylene to make TMP.

Tetramethylbutane 36 was not formed when n-butane and. sec-butyl cation were reacted. The isomer distribution of the octane isomers for typical butyl cation-butane alkylations is shown in Table 5.7. 

Torok and co-workers312 have reported the one-pot synthesis of /V-arylsulfonyl heterocycles through the reaction of primary aromatic sulfonamides with 2,5-dimethoxytetrahydrofuran. When triflic acid is used in catalytic amount, IV-arylsulfonylpyrroles are formed (Scheme 5.34). Equimolar amount of triflic acid results in the formation of N- ary I s u I fo n y I i n do I e s, whereas /V-arylsu Ifonylcar-bazoles are isolated in excess acid (Scheme 5.34). In the reaction sequence 1,4-butanedial formed in situ from 2,5-dimethoxytetrahydrofurane reacts with the sulfonamide to give the pyrrole derivative (Paal-Knorr synthesis). Subsequently, one of the formyl groups of 1,4-butanal alkylates the pyrrole ring followed by a second, intramolecular alkylation (cyclialkylation) step. 

Alkylation in the petroleum industry, a process by which an olefin (e.g., ethylene) is combined with a branched-chain hydrocarbon (e.g., iso-butane) alkylation may be accomplished as a thermal or as a catalytic reaction. 

This decomposition mirrors the decentralization of the control problem. The recommended procedure is to apply model reduction to individual units, and then to couple together these reduced models. The technique will be applied to a case study the 5o-butane alkylation plant. 

In the following ehapter, the application of the model reduction with process knowledge for the dynamic optimization will be presented. This will be done by means of a case study the Ao-butane alkylation plant. 

Figure 2. The proposed plantwide control stmcture for the /50-butane alkylation plant.

Table 1. The model reduction of the iio-butane alkylation plant...

Bala S, Tang S, Aaron MS (2009) Improved i-butene/iio-butane alkylation with acidic ionic liquids and tunable acid/ionic liquid mixtures. J Catal 268 243—250... 

Recently, Clark and Subramaniam conducted a similar reaction, 1-butene/iso-butane alkylation, in SCCO2 with USY zeolite as the catalyst [55]. The utilization of SCCO2 was considered mainly to lower the reaction temperature, as the high reaction temperatures in other supercritical phase systems could have increased the cracking and coking reactions. 

Liquefied gas fractions (propane, propylene, butanes, butenes) that will be able to provide feedstocks to units of MTBE, ETBE, alkylation, dimerization, polymerization after sweetening and/or selective hydrogenation. 

The C4H9 alkyl groups may be derived either from the unbranched carbon skele ton of butane or from the branched carbon skeleton of isobutane Those derived from butane are the butyl (n butyl) group and the 1 methylpropyl (sec butyl) group... 

Alkyl substituents stabilize a carbonyl group m much the same way that they sta bilize carbon-carbon double bonds and carbocations—by releasing electrons to sp hybridized carbon Thus as then heats of combustion reveal the ketone 2 butanone is more stable than its aldehyde isomer butanal... 

When usiag HF TaF ia a flow system for alkylation of excess ethane with ethylene (ia a 9 1 molar ratio), only / -butane was obtained isobutane was not detectable even by gas chromatography (72). Only direct O -alkylation can account for these results. If the ethyl cation alkylated ethylene, the reaction would proceed through butyl cations, inevitably lea ding also to the formation of isobutane (through /-butyl cation). 

Isomerization. Isomerization is a catalytic process which converts normal paraffins to isoparaffins. The feed is usually light virgin naphtha and the catalyst platinum on an alumina or zeoflte base. Octanes may be increased by over 30 numbers when normal pentane and normal hexane are isomerized. Another beneficial reaction that occurs is that any benzene in the feed is converted to cyclohexane. Although isomerization produces high quahty blendstocks, it is also used to produce feeds for alkylation and etherification processes. Normal butane, which is generally in excess in the refinery slate because of RVP concerns, can be isomerized and then converted to alkylate or to methyl tert-huty ether (MTBE) with a small increase in octane and a large decrease in RVP. 

Isomerization. Stmctural isomerization of / -butane to isobutane is commercially useful when additional isobutane feedstock is needed for alkylation (qv). The catalysts permit low reaction temperatures which favor high proportions of isobutane in the product. The Butamer process also is well known for isomerization of / -butane. 

Propane and light ends are rejected by touting a portion of the compressor discharge to the depropanizer column. The reactor effluent is treated prior to debutanization to remove residual esters by means of acid and alkaline water washes. The deisobutanizer is designed to provide a high purity isobutane stream for recycle to the reactor, a sidecut normal butane stream, and a low vapor pressure alkylate product. 

The value of butylenes ia the United States is determined by their value ia alkylation of isobutane to high octane gasoline. Table 11 shows how the chemical use of ethylene, propylene, butylenes, and butanes varied between 1983 and 1988 and their corresponding price swiags. 

Although benzene prices have escalated in recent years, a concurrent need for butenes for use in alkylates for motor fuel has also increased and butane prices have also escalated. As a result, a search for alternative feedstocks began and Amoco Chemical Co. commercialized a process in 1977 to produce maleic anhydride from butane. A plant in JoHet came on-stream in 1977 with a capacity of 27,000 t/yr (135,136). No new plants have been built in the United States based on butenes since the commercialization of butane to maleic anhydride technology. In Europe and particularly in Japan, however, where butane is in short supply and needs for butenes as alkylation feed are also much less, butenes may become the dominant feedstock (see Maleic anhydride). 

Reactions of carbon nucleophiles with organohalogen compounds have great diversity for the construction of now carbon-carbon bonds. The intriguing synthon, ethoxyethynylsodium, is generated and alkylated in 1-ETHOXY-1-BUTANE. Following an alkylation of propynylsodium, a vinyl halide is generated in a stereoselective manner... 

After reaction at 200 - 250 F and 350 psig the reactor effluent is stripped to remove recycle HCl. The stripper bottoms is cooled and caustic washed to remove remaining traces of HCl. The product can then be sent to the alkylation plant for fractionation or a tower provided in the isomerization plant for fractionation of isobutane and recycle of unconverted normal butane back to isomerization. 

The demand for aviation gasoline during World War II was so great that isobutanc from alkylation feedstock was insufficient. This deficiency was remedied by isomerization of abundant normal butane into isobutane using the isomerization catalyst aluminum chloride on alumina promoted by hydrogen chloride gas. 

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