Isomerization
Overview
Hengye offers adsorbents for isomerization processes to remove water and sulfur from the process stream. The resulting purified isomerization stream can then enter the isomerization reactor to allow the conversion of normal paraffins to isoparaffins. Isomerization is the process of converting normal paraffins into isoparaffins, which offer a higher value than their normal counterparts. Normal paraffins have a linear structure, which can be rearranged to create branches, thus forming isomers that have the same number of carbons, but have a different geometric structure.
Butane Isomerization
Normal butane (n-butane) is converted into isobutane (i-butane), which will then be used in alkylation units. Before n-butane can be isomerized, first it is dehydrated and sulfur is removed to create a cleaner butane stream. Hydrogen is added to the purified stream to suppress dehydrogenation and the formation of coke. The stream is then processed in the isomerization reactor where normal paraffin chains are converted into isoparaffins chains. The butane mixture that is produced will then enter the fractionator, also known as a deisobutanizer, to separate normal butane from the desired isobutane stream.
Pentane and Hexane Isomerization
Normal pentane (n-C5) and normal hexane (n-C6) are converted into isopentane (i-C5) and isohexane (i-C6) for use in gasoline blending because the isomerization process increases the octane rating of these compounds. To process n-C5 and n-C6 into isomers, the feedstock is dehydrated and desulfurized, mixed with organic chloride and hydrogen, then heated. The addition of hydrogen to the stream will suppress dehydrogenation and coking. The stream is then introduced to catalysts that cause benzene and olefins to hydrogenate. Next, the stream enters the isomerization reactor where the conversion of normal paraffins to isoparaffins occurs in the presence of catalysts. After isomerization, the stream is cooled and separated into recycled hydrogen gas and a liquid product stream, known as isomerate. To finish processing the isomerate, caustic and water is used to wash the stream, acid is used to strip the stream, and then the stream is stabilized before being stored or used in the gasoline blending pool.
Products for Isomerization
Before normal butane, n-pentane, and n-hexane can be isomerized water and sulfur compounds must first be removed.