ETBE Process

The column operates at 7.5 atm pressure and a reflux ratio of 2.94. The catalyst holdup on the reactive trays is 1000 kg. The bottoms stream contains ETBE with a purity of 

DESIGN OF MTBE AND ETBE REACTIVE DISTILLATION COLUMNS 

IRORK(NIUORK),NSTAGE, IHLBAS,IHVBAS,NREAL, KPHI, 

REAL 8 HLDLIQ,TIMLIQ,HLDVAP,TIMVAP,TZERO, + FT 

All commercial etheriflcation technologies use similar operating conditions but different plant layouts (number and type of reactors) according to the isobutene required conversion [8]. 

In this plant configuration, the C4 feedstock is mixed with ethanol and passed through the first reaction stage (one or more reactors with intermediate cooling) where the synthesis is carried out under mild temperature conditions. The reactor effluent is then fractionated in a first separation tower to recover the produced ether as a bottom stream and a mixture of unconverted isobutene, C4 and ethanol (azeotropic concentration) as overhead stream. 

This stream is first sent to the second reaction stage (one or more reactors) and then to the second fractionation column. 

The bottom of this tower, a mixture of C4 and ether produced in the second stage, is recycled to the first column while the overhead stream (C4 and ethanol) is sent to the alcohol extraction tower. In this column, ethanol is removed by counter-current washing with alcohol-free water while C4 raffinate, isobutene-free, is sent to battery limits. The stream water/ethanol is finally sentto an additional fractionation tower where the ethanol-free water, recovered as bottom stream, is recycled to the washing tower, and the overhead ethanol/water azeotropic stream is recycled to the reaction stages. 

When a higher C4 raffinate purity is required it is possible to perform a more efficient removal of oxygenates (mainly DEE) by including an additional distillation tower or an oxygen removal unit (ORU) based on molecular sieves. 

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Application The Uhde (Edeleanu) ETBE process combines ethanol and isobutene to produce the high-octane oxygenate ethyl tertiary butyl ether (ETBE). 

Commercial plants The Uhde (Edeleanu) proprietary ETBE process has been successfully applied in two refineries, converting existing MTBE units. Another MTBE plant is in the conversion stage. 

Owing to thermodynamic and kinetic constraints it is very important in the ETBE process to choose the right reactor. 

ETBE Process. An article by Sneesby et al. provides a description of the conventional ETBE process. There are two reactors in series, the first operating at 90 °C and the second at 50-60 °C. The lower temperature in the second reactor gives a higher equilibrium constant because the reaction of ethanol and isobutene to produce ETBE is exothermic. 

Ethers, such as MTBE and methyl / fZ-amyl ether (TAME) are made by a catalytic process from methanol (qv) and the corresponding isomeric olefin. These ethers have excellent octane values and compete on an economic basis with alkylation for inclusion in gasoline. Another ether, ethyl tert-huty ether (ETBE) is made from ethanol (qv) and isobutylene (see Butylenes). The cost and economic driving forces to use ETBE vs MTBE or TAME ate a function of the raw material costs and any tax incentives that may be provided because of the ethanol that is used to produce it. 

Some isopentane is dehydrogenated to isoamylene and converted, by processes analogous to those which produce methyl /-butyl ether [1634-04-4] (MTBE) to /-amyl methyl ether [994-05-8] (TAME), which is used as a fuel octane enhancer like MTBE. The amount of TAME which the market can absorb depends mostly on its price relative to MTBE, ethyl /-butyl ether [637-92-3] (ETBE), and ethanol, the other important oxygenated fuel additives. 

Ethyl er -Butyl Ether. Ethanol can react with isobutylene to form ETBE much the same way as methanol is now processed into MTBE, methyl tert-huty ether (see Ethers). 

CDETHEROL A process for making ethers (MTBE, TAME, ETBE) from alcohols. Combines the Etherol process with catalytic distillation. 

S. Davis., UOP Ethermax Process for MTBE, ETBE, and TAME Production , Handbook of Petroleum Refining Processes - second ediUon, 13.9-13.12, (1997). 

The most important application of RD today seems to be the production of ethers such as methyl tertiary butyl ether (MTBE), ethyl tertiary butyl ether (ETBE), and tertiary amyl methyl ether (TAME), which are widely used as modem gasoline components. Figure 7, upper part, shows a traditional process for MTBE production, which is a strongly exothermic reaction. The disadvantages of that process can be avoided if the reaction and separation take place within the same zone of the reactor (Figure 7, lower part). 

The ether process combines an alcohol with an iso-olefin. In the United States, a weight percentage of oxygenate (2 wt.%) content is mandated for reformulated gasoline (RFG). The most common oxygenate currently used is methyl tertiary butyl ether (MTBE). Methanol and the iso-olefin form of isobutylene are reacted to form MTBE. Other alcohols, such as ethanol, may be reacted with iso-butylene to form ethyl tertiary butyl ether (ETBE). Methanol can be reacted with iso-amylene, another iso-olefin, to form tertiary amyl-methyl ether (TAME). Of all the mentioned ethers, MTBE is the one most widely used as a gasoline-blending component.16... 

ETBE is recovered as the bottoms product of the distillation unit. The ethanol-rich C4 distillate is sent to the ethanol recovery section. Water is used to extract excess ethanol and recycle it back to process. At the top of the ethanol/water separation column, an ethanol/water azeotrope is recycled to the reactor section. The isobutene-depleted C4 stream may be sent to a raffinate stripper or to a molsieve-based unit to remove oxygenates such as DEE, ETBE, ethanol and tert-butanol. 

CDTECH/Snamprogetti SpA ETBE Mixed C4 hydrocarbons High-conversion catalytic distillation process for ETBE using C4s and ethanol 5 2000... 

UOP Ether FCC raffinate and steamcracking butadiene Ethermax process produces MTBE, ETBE or TAME 39 1997... 

The competitiveness of the oxidation of isobutene compared to the conventional acetone cyanohydrin route (Equation 33) is not only related to its performance and better environmental standards but has to contend with the demands of other users for isobutene, particularly for MTBE and ETBE production. In fact the predominant methacrylic acid process is still the hydrolysis of acetone cyanohydrin however, the change of mood on the use of MTBE in gasoline blends in the USA, could signal a future shift of isobutene availability making it a more attractive feedstock for methacrylic acid production. 

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