Although its application to pharmaceutical manufacturing is a relatively recent development, one of the earliest applications for Simulated Moving Bed (SMB) chromatography was in the petrochemical industry. The use of SMB chromatography in the petrochemical industry goes back several decades. The technique, which offers a method for continuous chromatography, is useful for large-scale separation of isomers.

SMB chromatography utilizes a series of identical chromatography columns and a network of valves that continually switch the columns at which influent enters the system and effluent exits the system to effectively simulate the movement of the packed bed of chromatographic media counter to the flow of the mobile liquid phase. This design allows for continuous chromatographic separations and, at industrial scales, requires much less solvent and stationary phase media than conventional batch chromatography systems, thus providing huge operational cost savings.

By far, the largest application in the petrochemical industry for SMB chromatography is the isolation of para-xylene. Para-xylene is one of three isomers of xylene, all three of which have different chemical properties, but are not separable using traditional refining distillation methods. Crystallization is the traditional method of separation, but is generally slower and more expensive than SMB chromatography for larger scales. Derivatives of para-xylene are used in the production of polyester. SMB chromatography is also utilized to produce meta-xylene, which is used to make PET (polyethylene terephthalate) bottles.

The first SMB systems for para-xylene production were developed and installed in the early 1970s, and there are now well over 100 such units in operation. Smaller units can produce tens of thousands of tons of para-xylene annually, although most recent and pending installations are on the high end, with capacities of well over one million tons of para-xylene per year.

The worldwide market for SMB chromatography for the petrochemical industry will be about $85 million in 2009, including system construction, services and chromatographic media. Although the combination of a deep recession and a dramatic crash in oil prices has led the petroleum industry to slash spending, the effect on the industry’s demand for SMB chromatography systems has been muted. The lead time from initial order to the completion of a typical SMB system for xylene separation is typically between 18 months and three years, and therefore demand is very slow to respond to rapid variations in macroeconomic factors. Much of the new demand is coming from locations such as China, Korea and Middle Eastern countries due to refinery construction. However, upgrades and expansions of existing refineries in the US and Europe, as well as service requirements, continue to drive demand in those regions as well.

SMB in the Petrochemicals

Market at a Glance:

Leading Suppliers

• UOP (Honeywell)

• Axens (IFP)

• Knauer

Leading Applications

• Para-xylene

• Meta-xylene

Instrument Cost

• $2–$100 million