Olefin-paraffin mixture

Silver fluorocomplexes are also used ia the separation of olefin—paraffin mixtures (33), nitration (qv) of aromatic compounds (34), ia the synthesis of (9-bridged bicycHcs (35), pyrroles (36), cyclo-addition of vinylbromides to olefins (37), and ia the generation of thioben2oyl cations (38). 

Another type of gas exchange process, developed to the pilot plant stage, is separation of gaseous olefin/paraffin mixtures by absorption of the olefin into silver nitrate solution. This process is related to the separation of olefin/paraffin mixtures by facilitated transport membranes described in Chapter 11. A membrane contactor provides a gas-liquid interface for gas absorption to take place a flow schematic of the process is shown in Figure 13.11 [28,29], The olefin/paraffin gas mixture is circulated on the outside of a hollow fiber membrane contactor, while a 1-5 M silver nitrate solution is circulated countercurrently down the fiber bores. Hydrophilic hollow fiber membranes, which are wetted by the aqueous silver nitrate solution, are used. 

Absorption of olefin from olefin/paraffin mixtures has been scaled up to the pilot plant scale, and a number of successful trials were performed in the early 1990s. Separation factors of 200 or more were obtained, producing 99.7 % pure ethylene. However, slow degradation of the silver nitrate solution is a problem, and a portion of the recirculating degraded silver nitrate solution must be bled off and replaced with fresh solution continuously. Boundary layer problems on the liquid side of the membrane are also a serious issue in these devices [21]. 

Separation of liquid olefin/paraffin mixtures Removal of 2-chlorophenol Ethanol removal from aqueous solutions Separation of cephalosporin C from fermentation broth Separation of penicillin G from aqueous streams Enrichment of amino acids... 

The olefins ethylene and propylene are highly important synthetic chemicals in the petrochemical industry. Large quantities of such chemicals are used as feedstock in the production of polyethylene, polypropylene, and so on [31]. The prime source of lower olefins is the olefin-paraffin mixtures from steam cracking or fluid catalytic cracking in the refining process [32]. Such mixtures are intrinsically difficult to... 

Description Linear paraffins are fed to a Pacol reactor (1) to dehydrogenate the feed into corresponding linear olefins. Reactor effluent is separated into gas and liquid phases in a separator (2). Diolefins in the separator liquid are selectively converted to mono-olefins in a DeFine reactor (3). Light ends are removed in a stripper (4) and the resulting olefin-paraffin mixture is sent to a Detal reactor (5) where the olefins are alkylated with benzene. The reactor effluent is sent to a fractionation section (6, 7) for separation and recycle of unreacted benzene to the Detal reactor, and separation and recycle of unreacted paraffins to the Pacol reactor. A rerun column (8) separates the LAB product from the heavy alkylate bottoms stream. 

In membrane separation of the olefin/paraffin mixture, the predominant selective separation of the olefin is evident. First, the olefin molecule is smaller in size compared to the respective paraffin. Specifically, C—C distance in paraffins is 0.1534 nm, whereas the C=C distance in olefins is 0.1337 nm. Atoms of carbon in paraffins feature sp hybridization and free rotation around C—C bonds. Atoms of olefins feature sp hybridization. The rigid C=C bond impedes internal rotation in the olefin molecule and makes it flat. It is therefore clear why olefin molecules are smaller in size compared to paraffin and why the diffusion coefficients of olefins in polymers would be higher than those of paraffins. Second, the presence of unsaturated bonds in olefin molecules makes them capable of specific interactions with the membrane matrix. Efforts to take advantage of these capabilities resulted in the development of an important field of research facilitated transport. 

Application Separation of pure olefins from olefinic/paraffinic mixtures via extractive distillation using a selective solvent. BUTENEX is the Uhde technology to separate light olefins from various feedstocks, which include ethylene cracker and FCC sources. 

The membranes containing AgBr nanocomposites were also tested for the separation of olefin/paraffin mixtures. The incorporation of AgBr nanocomposites in... 

The chlorination of paraffins first produces a so-called chloro-oil , which contains around 30% alkyl chlorides and 70% paraffins. The chloro-oil is dehydro-chlorinated in a dehydrochlorination column, with a bottom temperature of around 300 °C. The resulting olefin/paraffin mixture is mixed with a larg molar excess of benzene and fed into the reactor, which is fitted with a powerful stirrer and cooling pipes. Here, the benzene is alkylated in the presence of hydrogen fluoride at a temperature below 50 °C. The reaction product is then separated into two layers in a separation vessel the upper layer, the crude alkylate, is split by distillation into benzene, an inter-cut, paraffin, alkylbenzene and a higher-boiling tail product. The hydrogen fluoride, which is present in the lower layer, is recirculated. 

---