Page 177 - CW E-Magazine (14-1-2025)

Special Report

converted to fatty aldehydes and then to While 1-hexene is present in the C6 comonomers, plasticizers, synthetic
fatty alcohols, which are precursors to stream of a steam cracker, extraction is motor oils, lubricants, automotive addi-
plasticizers and detergents. not viable due the presence of many tives, surfactants, paper sizing agents,
co-boilers and contamination. 1-Hexene and in a wide range of specialty appli-
It takes roughly 1.04-1.07 tonnes of is therefore commercially produced by cations.
ethylene to generate 1 tonne of LAO. the oligomerisation of ethylene.
Ethylene makes up nearly 70% of the C4, C6, and C8 LAOs are prima-
operating cost of preparing LAOs. Researchers at the University of rily consumed as comonomers in the
Wisconsin (Madison, USA) have deve- production of linear low-density poly-
The majority of 1-butene produced loped a method for producing LAOs ethylene (LLDPE), with C4 and C6
in the world comes from on-purpose cheaply from biomass. In the process, also finding use in high-density poly-
separation from the mixed C4 streams an inexpensive solid acid catalyst is ethylene (HDPE). These comonomer
particularly of steam cracker raffinate. used in a reaction that converts the are typically added in proportions of up
The C4 fractions boil too closely for carboxylic acids and lactones present to 8-10% for LLDPE, 2-3% for HDPE,
separation by simple distillation, and in the feedstock. The catalyst features and up to 20-30% for specialty-grade
the dominant process involves first the Lewis acid catalytic sites and no pre- polyethylenes.
separation of butadiene by reactive dis- cious metal components(2).
tillation, followed by the conversion of The use of 1-octene as a co-mono-
isobutylene to methyl tert-butyl ether Applications mer for LLDPE accounts for about 56%
(MTBE), and then the reactive distil- LAOs are important chemical inter- of its global consumption. Another signi-
lation of 1-butene. Technologies for mediates, widely used in several ficant use is for production of a linear
isomerisation of 2-butene to 1-butene industrial and consumer products accor- aldehyde via the oxo synthesis (hydro-
are also commercially available for ding to carbon number and chemical formylation) to give the C9 aldehyde
licensing, and allow for enhanced reco- structure. LAOs or their derivatives (nonanal). Oxidation of this aldehyde
very of the valuable co-monomer. are used extensively as polyethylene gives the short-chain fatty acid nonanoic

Table 1: Applications of some important LAOs acid, while hydrogenation gives the
fatty alcohol, 1-nonanol, which is used
Alpha-olefin Applications as a plasticizer for PVC. Smaller uses
1-Butene (C-4) Chemicals, polymers. for 1-octene include for making surfac-
1-Hexene (C-6) Polymers. tants and lubricants.
1-Octene (C-8) Flavour & fragrance, lubricants, polymers. C8 LAOs, along with C10, C12, and
1-Decene (C-10) Flavour & fragrance, lubricants, polymers, surfactants. sometimes a blend of these, is conver-
1-Dodecene (C-12) Lubricants, chemicals, surfactants. ted through oligomerization to produce
1-Tetradecene (C-14) Lubricants, chemicals, surfactants. poly alpha olefins (PAOs), which serve
1-Hexadecene (C-16) Lubricants, paper chemicals, surfactants. as base stocks for synthetic lubricants.
Linear alcohols in the C12-C16 range are
1-Octadecene (C-18) Lubricants, paper chemicals, surfactants. mainly used to produce alcohol ethoxy-

Table 2: Applications of LAOs
Category Main Applications

Polymer applications High density polyethylene (HDPE), linear low-density polyethylene (LLDPE).

Surfactants Alpha olefin sulfonate (AOS), Detergent alcohols, Linear
alkyl benzene sulfonates, Amine derivatives, Alkane sulfonates.

Synthetic fluids Polyalphaolefins (PAO), Polyol esters, Alkyl aromatics.

Additives Plasticiser alcohols, Alkyl succinic anhydrides, Polyvinylchloride lubricants & stabilisers, Silane.

Chemical Weekly January 14, 2025 177

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