Description

Linear alkylbenzene (LAB) has emerged as the dominant detergent intermediate since the early 1960s driven by the environmental need to produce biodegradable detergents. The commercial development of LAB focused on the extraction of high purity linear paraffins derived from hydrotreated kerosene feedstock. Initially, these linear paraffins were dehydrogenated, at less than complete conversion, to linear internal mono-olefins. The dehydrogenation effluent, a mixture of olefins and paraffins, was used to alkylate benzene using hydrofluoric acid as the catalyst to produce linear alkylbenzenes. The conversion of the olefins to alkylbenzenes facilitated the separation of the unreacted linear paraffins by fractionation and their recycle to the dehydrogenation process. The resulting linear alkylbenzene product became the synthetic detergent intermediate for the production of linear alkylbenzene sulfonate (LAS), a major biodegradable synthetic surfactant. LAS remains the dominant workhorse surfactant but its position in North America and Western Europe is constantly challenged by detergent alcohol derivatives. Commercially, in the past, there were two major catalysts for the alkylation of benzene with higher alpha or internal mono-olefins (C10-C16 detergent range olefins), hydrogen fluoride, HF, and AlCl3. The HF-based process became more prevalent than ones based on aluminum chloride. However, with the introduction of a solid catalyst system in 1995 by UOP, commercially known as the Detal process, which eliminates the problem of catalyst neutralization and disposal of HF, the LAB industry has adopted the solid catalyst-based process as the "preferred process". In fact, since 1995, most of the new LAB plants that have come on stream have employed the Detal process. At the same time, most commercial plants based on AlCl3 catalysts have shut down. In fact, there are only three plants worldwide currently employing aluminum chloride catalyst. LAB is produced commercially via the following routes: Dehydrogenation of n-paraffins to internal olefins followed by alkylation with benzene using a hydrofluoric acid (HF) catalyst. This process is licensed by UOP and currently accounts for 75 percent of the installed LAB capacity worldwide. Dehydrogenation of n-paraffins to internal olefins followed by alkylation with benzene using a fixed-bed of acidic, non-corrosive solid catalyst. This process, jointly developed by CEPSA and UOP, licensed by UOP, is referred as the Detal process and is the most novel among the commercial processes. New plants are expected to employ this technology. Chlorination of n-paraffins to form monochloroparaffins. The monochloroparaffins are subsequently alkylated with benzene in the presence of an aluminum chloride (AlCl3) catalyst. This process is practiced by two producers - Sasol and Wibarco (BASF) at two plants worldwide. Chlorination of n-paraffins to form chlorinated paraffins. The chlorinated paraffins are subsequently dehydrochlorinated to olefins (both alpha and internal). These olefins subsequently undergo benzene alkylation in the presence of an aluminum chloride catalyst. This process is however no longer commercially employed. A few plants, originally dedicated for the production of branched alkylbenzene (BAB) from propylene tetramer feedstock, have been converted to production of LAB by reacting purchased olefins - typically a mix of internal and alpha olefins - with benzene in the presence of a hydrofluoric acid (HF) catalyst. There are only three plants worldwide using this process - Quimica Venoco in Venezuela, Shell and Karbochem in South Africa. Most LAB plants can employ internal or alpha olefins as feedstock in the alkylation process but typically that is not economical. The inclusion of alpha olefins is occasionally practiced when either n-paraffins are not available or when an LAB producer wants to exceed the production capability of the plant and achieve incremental production on a temporary basis. LAB Worldwide Capacity by Process As shown, the majority of commercial LAB production worldwide is currently based on HF catalyst, which currently accounts for 79 percent of the worldwide installed capacity. The Detal Process, which currently has 11 percent of the worldwide capacity, is currently the process of choice in the industry and is expected to gain a growing share of the market as new supply is likely to employ this process. The HF Olefin process is traditionally not the most economical but still practiced by a handful of companies - Shell, Karbochem and Quimica Venoco (Venezuela). There are only 3 plants left worldwide employing the aluminum chloride route. Of these 3 plants, Sasol owns two - one in Baltimore and one in Porto Torres. BASF (Wibarco) operates the third aluminum chloride plant. However, Sasol had indicated that with its new Detal unit that came on stream at the end of 2001 at Augusta, the Porto Torres plant will eventually be closed. Furthermore, the Baltimore plant was upgraded in fall 2001 to include a PACOL unit, but still alkylates with AlCl3. This new report by Nexant/ChemSystems assesses the relative merits of the various approaches to make LABs, compares the production economics, and projects supply/demand out to 2012.