Discovered over 40 years ago, this catalytic process is used for making oxo alcohols – the chemical building block of solvents, plastics and other chemicals
Johnson Matthey's Process Technologies business, together with our licence partner The Dow Chemical Company, lead the way in the Low Pressure Oxo
Commercialisation of the Low Pressure Oxo SM Process dates back to the 1970s and the formation of a three-way collaboration between The Power Gas Corporation Ltd (a former name of Davy Process Technology, which Johnson Matthey acquired in 2006), Union Carbide Corporation (now a subsidiary of The Dow Chemical Company) and Johnson Matthey & Co. Ltd. (now Johnson Matthey Plc).
A key step in the process involves a hydroformylation reaction which converts propylene to butyraldehyde using a catalyst. Since the 1940s cobalt based catalysts had been used but were not ideal. They delivered only poor conversion of the propylene and low selectivity to butyraldehyde in cumbersome plants operating a high pressure.
So could platinum group metal catalysis improve this?
Back in the 1960s Union Carbide had demonstrated the promise for rhodium complexes as hydroformylation catalysts at low pressure. Meanwhile, independent research by Professor Geoffrey Wilkinson at Imperial College, London, supported by Johnson Matthey, seemed to reproduce and complement Union Carbide's findings.
Johnson Matthey in turn approached The Power Gas Corporation who drew on its strong background in process engineering to investigate the commercial potential for a low pressure route to butyraldehyde.
Three heads are better than one
Following the publication of patents by Union Carbide and Johnson Matthey, the three parties realised they had a common interest and so in 1971, they launched a joint development programme to convert the laboratory rhodium catalysed chemistry into a commercial process.
A process employing a rhodium based homogenous catalyst was developed for the production of aldehydes from a mixture of carbon monoxide and hydrogen (known as syngas) at significantly lower pressure and temperature requirements compared to conventional cobalt catalysed processes. The new technology, named the Low Pressure (LP) Oxo SM Process, possessed an array of economic advantages; more efficient conversion, lower temperature and pressure, reduced capital costs and lower operating costs.
The first commercial plant employing the LP Oxo SM Process to produce butyraldehydes was successfully opened in 1976 and this technology now accounts for the majority of the world's butyraldehyde production.
Continued investment in R&D
Since commercialisation there has been continued development of the technology including improvements in product separation, catalyst deactivation, reactivation of spent catalyst and other advances to streamline the process further.
Today, plants using the LP Oxo SM Process boast many benefits – they are easy to operate, have low environmental impact and require low maintenance. Their relatively simple flowsheet, moderate design conditions and absence of exotic materials of construction mean low investment costs for plant operators too.
In the years since the LP Oxo SM Process was introduced it has been recognised as one of the best known applications of industrial scale chemistry using rhodium and has transformed the manufacturing ability of the petrochemical sector dramatically. Supported by good market demand for oxo products and the continued research and development from all collaborators, the LP OxoSM Process seems set to play an important role in industrial hydroformylation applications for many years to come.
LP Oxo SM is a service mark of The Dow Chemical Company.