Linear alkyl benzene
Linear alkylbenzene is a family of organic compounds with the formula C6H5CnH2n+1. Its appearance is colourless oily liquid and has a density 0.8628 g cm-3 and boiling point of 282-302 °C. Linear alkylbenzene (LAB), the material used to produce LAS, is derived exclusively from petroleum derivatives: benzene and linear paraffins.
Linear alkylbenzenes (LAB) are compounds that have significant commercial importance. Linear alkylbenzene sulfonate (LAS) compounds made by sulfonation of linear alkylbenzene are used in the manufacture of detergents and other products.
Because linear alkylbenzenes are more easily biodegradable than branched alkylbenzenes, linear alkylbenzenes have essentially replaced branched alkylbenzenes in detergents and other products. In particular, linear alkylbenzenes with long alkyl chains, such as chains having about 10 to about 14 carbons, are commonly used.
However, linear alkylbenzenes with longer chains and with shorter chains also are commercially important. Linear alkylbenzenes often are made by alkylation of benzene with olefins. Positional isomers, such as 2-phenyl, 3-phenyl, 4-phenyl, 5-phenyl, and the like, result from this alkylation of benzene with long chain olefins.
The distribution of the phenyl along the alkyl chain produces different products.
Historically, linear alkylbenzenes are manufactured commercially using classic Friedel-Crafts condensation employing catalysts such as aluminum chloride, or by using strong acid catalysts such as hydrogen fluoride, for example, to alkylate benzene with olefins.
In 1995, a solid bed alkylation process, the Detal® process, using a solid non-corrosive acid catalyst was introduced. While such methods produce high conversions, the selectivity to the 2-phenyl isomer typically is about 30 percent or less.
Linear alkylbenzenes with a high percentage of the 2-phenyl isomer are highly desired because such compounds when sulfonated have long tails that provide enhanced solubility and detergent properties.
Huntsman Corporation, CEPSA Quimica, S.A., Quimica Venoco, CA, Sasol North America and Repsol-YPF, Jin Tung Petrochemical, Unggul Indah Cahaya and Reliance Industries Ltd. (RIL) are some of the leading producers of LAB in the world.
Indian industry made a modest beginning in 1978 with the commissioning of first LAB plant at Vadodara. Subsequently Reliance Industries Ltd (RIL), Tamil Nadu Petrochemicals Limited (TPL) and Nirma Ltd. set up facilities for manufacture of LAB. Indian Oil Corporation Ltd (IOC) commissioned a plant of capacity of 120 KTA in August 2004.
The 2016-17 capacity of LAB in India is projected at 570 KTA with demand pegged for 2016-17 at 579 KTA.
Growth in household detergents is driving demand for linear alkylbenzene produced from kerosene-derived normal paraffins.
Linear alkylbenzene sulfonates (LAS) for laundry detergents, light-duty dishwashing liquids, industrial cleaners, for household cleaners.
Some LAB also find minor use as solvent and binder in speciality applications, for e.g.: cable oil, ink industry, paint, insulating and electricity.
Linear Alkyl Benzene:
LAB is mainly produced from n-paraffins, from kerosene (typically in the C10-C13 range), and benzene. Conventional technologies are based on hydrofluoric acid (HF) or aluminum chloride alkylation.
HF's share of global capacity will decrease, as proposed new capacity is based on the Detal process from US-based UOP, developed jointly with Spain's CEPSA. Detal abolished the use of liquid HF, reducing capital and investment costs.
UOP is the world's leading supplier of LAB process technology. Most of the olefins for the LAB production are produced by UOP’s PACOL catalytic dehydrogenation process. This process produces a stream that is approximately 15 percent “internal” olefins, which is more than adequate for alkylation since it is a fast and exothermic reaction. The process is non-polluting and produces no waste streams; similarly the catalyst used is noncorrosive and requires no special handling.
The PEP process was first commercialized in 1995 and more than 10 units have been licensed. UOP provides a single source of technology supply which simplifies project execution and optimizes unit integration with an upstream n-Paraffins complex. Typically, linear alkylbenzenes are manufactured commercially using classic Friedel-Crafts condensation or catalysis with strong acid to alkylate benzene with olefins.