2- Butenes Upgrading

Blending with LLDPE is used to upgrade the properties and improve the processing of conventional LDPE. For example, by adding 25% of ethylene—1-butene LLDPE resin with I2 of 0.5 to conventional LDPE resin, the dart impact strength of 75 p.m film is increased from 490 to 560 g, the puncture strength from 41 to 49 J /mm (770-920 ft-lbf/in.), and the tear strength from 43 to 63 N /mm (246—360 ppi). CompositionaHy uniform VLDPE resins are used in blends with HDPE, commodity LLDPE, and polypropylene (PP) (70,71,89). 

The indium-mediated aqueous Barbier-type reaction of crotyl bromide with benzaldehyde shows no diastereo-selectivity. However, the use of preformed crotylindium sesquibromide in DMF affords. sy/z-l-phenyl-2-methyl-3-buten-l-ol (ca. 40% de) after aqueous acidic workup. At 22 °G in DMF prior to workup, a greater relative proportion of //-intermediate is decomposed as compared to its yy/z-diastereomer. The resultant kinetic diastereoselection upgrades the syn anti ratio to 99 1 with a concomitant drop in overall yield (Scheme 14).127... 

Application To produce polymer-grade propylene plus either an isobutylene-rich stream or MTBE by upgrading low-value pyrolysis C4 cuts or butene-rich streams via selective hydrogen and Meta-4 processes. This process is particularly profitable when butadiene markets are weak and propylene demand is strong. 

Once the diolefms are removed, the problem of subsequent processing of the C4. cuts resides essentially in the separation of l>butene or isobutene. Two principal methods are available, depending on whether the goal is to produce one or the other of these two components to meet the relevant specihcations. The remaining product, which is necessarily impure, then requires supplementary treatment to be upgradable. 

Depending on the method used to separate isobutene or butene-1, and in accordance with the deared application for the remainiag components the Q cuts initially available, supplonentary treatments may exhibit a range of complexity. Hence it may or may not be possible, both for technical and ecopomic reasons, to incorporate them in the extraction facilities that ser e as a basis for the upgrading schemes selected. In certain cases, in fact, one of the primary separation processes already examined can be used as an auxiliary for another technology, that is also designed as an initial step. 

Several processes are used to upgrade the C4 fraction. The isobutydene contained in the C4 cut is removed by reaction with methanol to produce MTBE. The remaining n-butenes in the C4 cut can be alkylated with isobutane catalyzed by liquid HE or H2SO4 or isomcrized into isobutylene in the presence of acid catalysts. 

Dimersol E is used to upgrade C2 + C3 fuel gas. Co-oligomerization of ethylene and propene leads to a gasoline stream very similar to the Dimersol G product. Mixed butenes are also obtained with Dimersol E (from ethylene dimerization). They can be used in paraffinic alkylation or to make propene through a subsequent cross-metathesis reaction with ethylene. 

Axens Isobutane, Isobutylene, 2-Butenes, Butene-1 C Cut Upgrading C s from steam crackers via hydrogenation processes >100 2010... 

Mixed C4 streams, containing butadiene, butenes, and butanes, are co-produced in steam-cracking processes. These streams contain valuable components, which can be either processed in situ or extracted purely. A typical composition of a steam-cracker C4 cut is shown in Fig. 3.1. Maximizing its value is a major objective for most petrochemical companies. Therefore, a variety of techniques exists for upgrading the C4 streams by removal of pure C4 components and conversion of low-value streams to higher-value products. 

GVL 73, itself a potential biofuel, is also a starting material for pentanoate esters ( valeric biofuels ) that have been shown to have outstanding fuel properties [213]. GVL-derived pentanoic acid 80 can be catalytically upgraded by decarboxylative ketonization to 5-nonanone 81, which can then be variously processed to nonane 82 and other hydrocarbons [214, 215], GVL has also been converted to butenes over a silica-alumina catalyst, which are then oligomerized on H-ZSM-5 or Amberlyst-70 to give a mixture of Cg-Cie alkenes that can be hydrogenated to drop-in fuels (Scheme 27) [216]. 

IFP [(Institut Francais du Petrole)—Axens] was the first to operate an ionic liquid pilot plant [43]. Since the mid-1970s, IFP developed the Dimersol process (Dimersol-G, and -X) that upgrades light olefins by dimerization (respectively, propene and butenes) to the more valuable branched hexenes and octenes, respectively in high yield (Figs. 20.16 and 20.17) [44]. 

C4 streams are one of the by-products from the manufacture of ethylene, and contain a mixture of butadiene, butenes, and butanes. The projected growth for ethylene is much higher than that for butadiene, and a growing surplus of butadiene is expected to reach 1.36 million tons in 1998. Dow s technology apparently offers a profitable alternative for ethylene producers to upgrade crude butadiene (from C4 streams) into more valuable styrene. 

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