Pentene Azeotropic distillation

Another type of problem may also arise from the formation of azeotropes, w ose boiling points are close to that of isoprene. This is the case of cydopentadiene, whose separation, like that of piperylene, should normally take place by simple distillation, but wUch produces azeotropes with n-pentane (35J Q, 2butenes (38 Q and ds 2-pentene (36,9 C). 

Water can be removed from methanol by a membrane of polyvinyl alcohol cross-linked with polyacrylic acid, with a separation factor of 465.204 A polymeric hydrazone of 2,6-pyridinedialdehyde has been used to dehydrate azeotropes of water with n- and /-propyl alcohol, s- and tort butyl alcohol, and tetrahydrofuran.205 The Clostridium acetobutylicum which is used to produce 1-butanol, is inhibited by it. Pervaporation through a poly(dimethyl-siloxane) membrane filled with cyclodextrins, zeolites, or oleyl alcohol kept the concentration in the broth lower than 1% and removed the inhibition.206 Acetic acid can be dehydrated with separation factors of 807 for poly(4-methyl-l-pentene) grafted with 4-vinylpyridine,207 150 for polyvinyl alcohol cross-linked with glutaraldehyde,208 more than 1300 for a doped polyaniline film (4.1 g/m2h),209 125 for a nylon-polyacrylic acid membrane (5400 g/m2h), and 72 for a polysulfone.210 Pyridine can be dehydrated with a membrane of a copolymer of acrylonitrile and 4-styrenesulfonic acid to give more than 99% pyridine.211 A hydrophobic silicone rubber membrane removes acetone selectively from water. A hydrophilic cross-linked polyvinyl alcohol membrane removes water selectively from acetone. Both are more selective than distillation.212... 

The chemically inert components in the C5 feed stream include isopentane, n-pentane, 1-pentene, and 2-pentene. These components are not inert from the standpoint of phase equilibrium. Essentially all of these chemically inert components go out the top of the reactive distillation column as azeotropes with methanol. Isopentane (iCs) is the major C5 component. We illustrate the phase equilibrium by looking at the binary system iCs and methanol. 

---