Gasoline Molex™ process

The gasoline Molex process is the first of three processes since it separates the lowest molecular weight feed of the three Molex normal paraffin separahon processes. Gasoline Molex was developed to optimize a Refiner s octane pool by extracting low octane value normal paraffins (specifically C5, 5) from naphtha. In a typical refinery flow scheme, a gasoline Molex unit is integrated with a catalyhc isomeriza-hon unit (Penex unit) which converts the Molex unit s extracted normal paraffins into desired iso-paraffins. These iso-paraffins are desirable because they possess higher octane value than their linear counterpart. 

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. 

The naphtha processed by a gasoline Molex unit typically has a Enger distillation (D86) with an initial boiling point (IBP) of 26°C and end point (EP) of 82°C. Table 8.3 lists the typical components found in naphtha with their corresponding calculated research octane numbers (RON) and shows why nCs and nCc are undesirable in a gasoline pool due to their low RON value [8]. 

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