20.1 Introduction

• •  In this lecture, we discuss the process technology for isoprene and oxoprocessing.

•  Isoprene is prepared using propylene and is an important commodity for polymerization reactions and products.

•  Oxoprocessing involves reaction between olefins and synthesis gas at high pressure to yield aldehydes. The aldehydes can be subsequently subjected to hydrolysis to obtain short as well as long chain alcohols.

•  We first present the process technology associated to isoprene manufacture

20.2 Isoprene

20.2.1Reactions

• •  Isoprene is manufacture from propylene using three consecutive reactions. These are

• •  Dimerization of propylene to obtain 2-methyl-1-pentene

• 

 

• •  Isomerization of 2-methyl-1-pentene to obtain 2-methyl-2-pentene



 

• •  Pyrolysis of 2-methyl-2-pentene to obtain isoprene along with methane as a side – product.



 

•  Since three reactions are involved that have distinct operating conditions as well as catalyst requirements, the process involves a series of reactor-separator-recycle networks.

•  We therefore, consider presenting all these cases separately so that the process can be well understood.

20.2.2.Dimerization reaction

• • Catalyst is tripropyl aluminium.

• A solvent carrier is used that enables the recovery of the catalyst from the product stream.

• Operating conditions are 150 – 200°C and 200 atms.

20.2.3 Isomerization reaction

• • The reaction requires an acid catalyst on porous carrier.

• Operating conditions are 150 – 300°C and normal pressure conditions.

20.2.4 Pyrolysis reaction

• • HBr catalyst is used.

• Operating conditions are 650 – 800°C and normal pressure.