2-EHA, also known as Octanol is one of the isomer of the Oxo Alcohols. The term “oxo-alcohols” is used to describe alcohols obtained from the “oxo process,” which involves reaction of olefins and synthesis gas (a mixture of hydrogen & carbon monoxide), to produce aldehydes, which are converted to alcohols. Since a major application of oxo-alcohols is for making plasticisers, they are also referred to as plasticiser alcohols. The list includes
- n-Butanol (NBA)
- 2-Ethylhexanol (2-EHA)
- 2-Propylheptanol (2-PH)
- Isononyl alcohol (INA)
- Isodecyl alcohol (IDA).
In addition, several higher alcohols are also produced from different olefins using the oxo process.
2-EHA is a clear, colourless, flammable, and high-boiling liquid with low volatility and with a characteristic odour. It is miscible with most organic solvents, but has very limited miscibility with water.
2-EHA readily forms esters with various acids. The major application of 2-EHA is in the manufacture of di-(2-ethylhexyl) phthalate, more commonly known as dioctyl phthalate (DOP), which, in turn, is extensively used as a plasticiser in the manufacture of flexible PVC products such as like cables, footwear, sheets, films etc.
It is also used in the production of 2-ethylhexyl acrylate, which finds application in emulsion paints, adhesives, surface coatings, paper and textile processing. The other applications of 2-EHA relate to nitrate esters, lube and fuel additives, surfactants, stabilizers, solvent extraction, oil floatation, agricultural chemicals, engine machinery lubrication etc.
2-EHA is usually stored in closed steel storage tanks protected against excess sunlight and heat, and provided with sprinkling devices. Small quantities are packed in 220-litre steel drums.
It is transported in steel rail and road tankers, as well as ISO tanks.
Typical specifications of 2-EHA
Oxo-alcohols, in general, are produced by the oxo-process, more formally known as hydroformylation. This is the reaction of an olefin with mixture of carbon monoxide (CO) and hydrogen(H2) (synthesis gas or syngas) to give an aldehyde. Subsequent hydrogenation of the aldehydes leads to oxo-alcohols.
The oxo-process is used to produce different alcohols via the respective aldehydes using different olefin feedstock. Although there are several versions of processes to produce aldehydes from olefins, using different catalysts, the hydrogenation steps to produce oxo-alcohols from aldehydes, are similar for most manufacturers.
Propylene is used as raw material to produce NBA, 2-EHA and IBA by reaction with synthesis gas. The first step – hydroformylation to convert propylene to a mixture of aldehydes – is common to all three oxo-alcohols. Further processing to obtain the individual alcohols, differs slightly.
During hydroformylation step, a mixture of two aldehydes – n-butyraldehyde&isobutyraldehyde – is obtained. This mixture is either separated initially, and the individual aldehydes isomers hydrogenated to the respective alcohols; or the mixture of isomeric aldehydes is hydrogenated directly and the NBA and IBA product mix separated by distillation.
The technology can also be used to produce higher alcohols such as C11 to C14 from olefins produced from Fischer-Tropsch synthesis.
2-ethyl hexanol is used to make 2-Ethylhexyl acrylate, which is used as a raw material in the manufacture of emulsion polymers for latex surface coatings, enamels, pressure-sensitive adhesives, construction materials, acrylic rubber and emulsions.
2-Ethylhexyl acrylate polymers display a range of properties depending on the selection of monomer and reaction conditions. Copolymers can be prepared from acrylic acid & its salts, amides & esters, and with methacrylates, acrylonitrile, maleic acid esters, vinyl acetate, vinyl chloride, vinylidene chloride, styrene, butadiene, unsaturated polyesters, drying oils etc. It is also used as an intermediate to produce a variety of derivatives.
It is also used to make 2-Ethylhexyl methacrylate (2-EHM) used as an acrylic monomer to produce polymers with many applications.
2-EHA is used as a solvent in a variety of lacquers and coatings – automotive, industrial, can, coil, marine etc. It is the solvent of choice when slow evaporation is desired. It is used as a low volatility ingredient in solvent blends for the dyestuffs and coatings industries, e.g., in printing and stamp-pad inks, dipping lacquers, etc., as also some disinfectants and insecticidal sprays.
- 2-EHA, in the form of esters of dicarboxylic acids, glycols and polyacrylates, is used in lubricants.
- It is used as flow & gloss improver in baking finishes.
- It is an additive in dispersing and wetting agents for pigment pastes.
- 2-EHA is used as a feedstock for the manufacture of ethoxylates and herbicides (e.g., 2-ethylhexyl esters of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)).
- 2-Ethylhexyl sulphate is used as a surfactant for electrolytes.
- 2-Ethylhexyl esters of trialkylphosphite can be used as thermal stabilizers and antioxidants in plastics.
- 2-EHA is an excellent defoaming agent in almost all aqueous systems, in photographic, varnish, rubber latex, textile printing, paper and ceramic industries. In these applications, especially in textile and paper industries, very low proportions of 2-EHA, ~0.1 %, are required.
Andhra Petrochemicals Ltd. (APL) is the only producer of oxo-alcohols in India and accounts for just 32% of the market. It produces NBA, IBA and 2-EHA. As on today, the company has 73,000-tpa of capacity at its facility in Visakhapatnam, in the state of Andhra Pradesh. The facility began its operations in 1994 with an initial capacity of 30,000-tpa. The plant uses oxo process technology provided by Davy Process Technology. Over the years, the company enhanced its production capacity to 73,000-tpa. APL invested about $65-mn(Rs. 320-crore) in the expansion.
Trend in the production of 2-EHA by APL is given in Table 2. As can be seen production has increased from 47,000 tons in 2010-11 to 78,700 tons in 2017-18 thereby registering CARG of 7.7% during the period of last 8 years.
Production of 2-EHA by Andhra Petrochemicals
The local production of 2EHA is insufficient to meet the demand and hence huge quantities of EHA are imported into the country. Table 3 provides the details of imports and consumption of 2EHA in the country. While Table 4 provides details of countrywise imports of 2EHA during last two years.
Table 3: Production, Imports and Consumption of 2-EHA in India
Table 4: Sourcewise import of 2-EHA during last two years
Germany, Netherland, Singapore, Malaysia and USA are the major suppliers of 2EHA to India. The consumption of 2EHA in India has grown from 76,117 tons in 2010-11 to 115,129 tons in 2017-18 thereby registering CARG of 6.2% during the period of last 8 years. Another point worth noting is that the consumption of 2-EHA in the year 2015-16 and 2016-17 was a little over 1.50 lakhs and this has come down to 1.15 lakh tons. This is understood due to substitution of 2-EHA by Iso Nonyl Alcohol in many applications due to economic reasons. It is understood for industry sources that Iso Nonyl Alcohol to the tune of 5,000 tons per month is imported into India. This has resulted in lower consumption of 2-EHA.
Consumption pattern of 2EHA
The major application of 2-EHA is in the manufacture of plasticisers (DOP), which in turn is used to make flexible PVC. Other smaller volume plasticisers include dioctyl terephthalate (DOTP), dioctyl maleate (DOM), dioctyladipate (DOA), etc. The advantage of DOTP is that there are no safety issues (unlike DOP) and the raw materials are available in plenty. The market for this is still small, but is expected to gather momentum in the next 3-5 years.
The other major application that has emerged during last 2-3 years is in the manufacture of 2-EHN, which is used as fuel additive (to raise cetane number of diesel fuels). Deepak Nitrite Ltd. and Kutch Chemicals, Panoli are the two producers engaged in making 2-EHN. Other applications of 2-EHA include use in paints, lubes, pharma, solvents, etc.
DOP consumes around 75% of the total consumption of 2-EHA while Fuel additive consumes 24% of the total consumption and the balance 1% is shared by other uses.
The demand for 2-EHA is expected to grow between 8 to 10% per annum driven by the growth in the PVC industry, plasticisers and growth in fuel additive markets.
Bharat Petroleum Corporation Ltd. (BPCL), as a part of its Integrated Refinery Expansion Project (IREP), is putting up a petrochemical complex at Kochi. The proposed complex consists of three major process units: acrylic acid, oxo-alcohols and acrylates. About 329-ktpa of products will be manufactured from 250-ktpa of propylene. Of the total capacity 2-EHA will be produced at around 47,000-tons. The project is scheduled for completion by end of March 2019.