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Linear alkyl benzene by na b
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Linear alkyl benzene |
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Business,Business News,Business Opportunities
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History & Applications
Hydrotreated kerosene is the feedstock for high purity linear paraffins which are subsequently dehydrogenated to linear olefins. The resulting linear mono-olefins are reacted with benzene in the presence of a catalyst to produce linear alkylbenzene. Linear alkylbenzene is sulfonated to produce linear alkylbenzene sulfonate (LAS), a biodegradable surfactant detergent. LAS replaced dodecylbenzene sulfonates which have slower biodegradation rates. There are currently challenges to the dominance of LAS from detergent alcohol derivatives.
Hydrogen fluoride (HF) and aluminum chloride (AlCl3) are the two major catalysts for benzene alkylation with linear mono-olefins (C1016). The HF-based process became commercially dominant; however, the risk of releasing HF (a poisonous substance) into the environment became a concern particularly after the Clean Air Act Amendment. In 1995, a solid catalyst system (the DETAL process) became available. The process eliminates catalyst neutralization and HF disposal. Consequently, most LAB plants built since then have utilized this process.
Production
There are five main routes to prepare linear alkylbenzene:
The HF/n-paraffins process involving dehydrogenation of n-paraffins to olefins, and subsequent reaction with benzene using hydrogen fluoride as catalyst. This process accounts for the majority of the installed LAB production in the world. It includes a PACOL Stage where n-paraffins are converted to mono-olefins (typically internal mono-olefins), a DEFINE Unit whose primary function is to convert residual diolefins to mono-olefins, a PEP Unit which is essentially an aromatic removal unit - introduced before the alkylation step to improve LAB yield and quality, an Alkylation Step where mono-olefins, both internal and alpha olefins, are reacted with benzene to produce LAB in the presence of HF catalyst.
The DETAL process involving dehydrogenation of n-paraffins to olefins, and subsequent reaction with benzene using a fixed bead catalyst. This is newer technology and has several of the stages depicted in the HF/n-paraffins process, but it is principally different in the benzene alkylation step, during which a solid-state catalyst is employed. There is a developing transalkylation (TA) stage to the Detal process wherein any higher alkylated benzenes (HAB) are contacted with additional benzene over a transalkylation catalyst.
The Friedel-Crafts alkylation process involves chlorination of n-paraffins to monochloroparaffins followed by benzene alkylation with aluminum chloride (AlCl3) catalyst. This is one of the oldest commercial routes for the production of LAB.
Purchased olefins reacted with benzene in the presence of HF or AlCl3 catalyst
Chlorination of n-paraffins to monochlorinated paraffins followed by dechlorination to produce olefins and subsequent benzene alkylation (no longer commercially used)
Each of the LAB processes creates LAB products with different product and application features. Important product characteristics include the bromine index, sulfonatability, amount of 2-phenyl isomers (2-phenylalkane), amount of tetralin content, amount of non-alkylbenzene components, and the linearity of the product.
It is worth noting that production of n-paraffins often occurs as part of an integrated LAB plant where the producers start from kerosene as raw material. The UOP process for producing normal paraffin includes a kerosene prefractionation unit, a hydrotreating unit and a Molex unit. The ExxonMobil Chemical technology includes a recovery process and can produce LAB grade n-paraffins from most medium to low sulfur kerosene without the use of a hydrotreater stage upstream. A desulfurization process is needed to reduce the sulfur content of some n-paraffins.
Commercial Aspects
The Asia Pacific region accounts for nearly half of the global capacity. North America and West Europe capacity has been reduced in recent years.
Environmental Effects
LAB has been subject to concern about its effect on the environment and human health. European Council Regulation (EC) 1488/94 led to it being extensively evaluated. The life-cycle analysis considered the emissions and resulting environmental and human exposures. Following the exposure assessment, the environmental risk characterization for each protection target in the aquatic, terrestrial and soil compartment was determined. For human health the scenarios for occupational exposure, consumer exposure and human exposure indirectly via the environment have been examined and the possible risks identified.
The report concludes that there are no concerns for the environment or human health. There is no need for further testing or risk reduction measures beyond those currently practiced. LAB was therefore de-classified and was removed from Annex 1 in the 28th ATP (Directive 2001/59).
References
^ a b c Linear alkylbenzene 07/08-S7 Report, ChemSystems, February 2009.
^ ""UOP Linear Alkylbenzene (LAB) Complex"". http://www.uop.com/objects/18%20LAB.pdf. Retrieved 22. DEC 2009.
^ European Council Regulations (EC) 1488/94
External links
Material Safety Data Sheet
Integrated LAB complex
Categories: Aromatic hydrocarbonsHidden categories: Chemical pages needing a CAS Registry Number I am Components Electronic suppliers writer, reports some information about blow film extrusion , plastic film extruders.
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