Processes MaxEne

The UOP MaxEne process for the separation of n-paraffins from branched and cyclic hydrocarbons found in full-range naphtha is based on the well established. 

Unlike the gasoline Molex process that employs a iso-butane and n-butane desorbent mixture, the MaxEne process employs a heavy desorbent system. A heavy desorbent system means that the bottom product from both the Sorbex extract and raffinate frachonation columns is desorbent while the feed components are recovered as overhead products. In the MaxEne process case, heavy normal paraffin such as n-dodecane is employed as the desorbent though desorbents as light as n-decane and as heavy as n-tetradecane are possible candidates too. 

Another UOP zeolitic process that produces petrochemical feedstocks is the MaxEne process (27). The MaxEne process, another member of the Sorbex family of processes, separates C5 to Cn full-range naphtha into an extract stream containing more than 90 wt-% normal paraffins and a raffinate stream containing over 99 wt-% non-normals, namely isoparaffins plus naphthenic and aromatic hydrocarbons. The high normal-paraffin content of the extract makes it a preferred feedstock for a naphtha steam cracker, and the absence of normal paraffins in the raffinate makes it a preferred feedstock for catalytic reforming. 

The addition of a MaxEne process to the flow scheme provides several benefits, beginning with an increase in throughput of 18%. With this higher feed rate, the MaxEne extract stream matches the capacity of the cracker, 34.1 weight units. However, the MaxEne extract is a preferable feed for the cracker because of its high normal paraffin content. Consequently, the yield pattern from the cracker, in Table 4.12, is improved. Olefins increase by 15%, with ethylene increasing by almost 50%. In addition, LPG increases by 32%. 

Foley T.D., Greer D.W. and Pujado P.R., MaxEne Process Increased Ethylene Yield in Naphtha Crackers (AIChE Spring National Meeting, Houston, 2001). 

Application The MaxEne process increases the ethylene yield from naphtha crackers by raising the concentration of normal paraffins (n-paraffins) in the naphtha-cracker feed. The MaxEne process is the newest application of UOP s Sorbex technology. The process uses adsorptive separation to separate C5-Cn naphtha into a rich n-paraffins stream and a stream depleted of n-paraffins. 

MaxEne A process for increasing the yield of propylene from naphtha crackers without increasing that of propylene. A version of the Sorbex process is used to separate the normal paraffins from the branched paraffins before the cracker. Developed and offered by UOP in 2000, but not reported to have been licensed by 2005. 

Liquid Phase Separation. UOP have pioneered several small-scale processes to fractionate mixtures of liquids. The Parex process was introduced in 1971 and by 2001 71 units were running conunercially. The MX-Sorbex process was introduced in 1998 and so far 5 units have been commerciahzed. Very recently, in 2001, UOP introduced a new Sorbex process, MaxEne, to increase the ethlene yield from Naphtha Crackers. Examples of these are listed in Table 30. 

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