https://doi.org/10.1595/205651317X695875 Johnson Matthey Technol. Rev., 2017, 61, (3), 246–256 JOHNSON MATTHEY TECHNOLOGY REVIEW www.technology.matthey.com Industrial Low Pressure Hydroformylation: Forty-Five Years of Progress for the LP OxoSM Process A long standing collaboration between Johnson Matthey and Dow continues to sustain the high standing of their oxo technology through innovative solutions to address the changing needs of the global oxo alcohol market By Richard Tudor Introduction Retired, Reading, UK The LP OxoSM Process is the rhodium-catalysed Atul Shah* hydroformylation process in wide use today in a variety Johnson Matthey, 10 Eastbourne Terrace, London, W2 of industrial applications. These applications have been 6LG, UK developed, co-marketed and licensed as a cooperation between affiliates of The Dow Chemical Company *Email: [email protected] (‘Dow’) and Johnson Matthey or their predecessors, for over 45 years. The LP OxoSM Process first made an impact in the 1970s when its technical elegancy, environmental Since the mid-1970s when the ‘Low Pressure Oxo’ footprint and economics attracted huge attention by process (LP OxoSM Process) was first commercialised, the world’s producers of normal butyraldehyde for it has maintained its global position as the foremost conversion to the plasticiser alcohol 2-ethylhexanol oxo process, offering particular appeal to independent (2EH). producers of commodity plasticisers facing increasing regulatory pressure. The story of this important The Early Dominance of Cobalt Catalysis industrial process is told from its early beginnings when laboratory discoveries by independent groups of Hydroformylation is the reaction of an unsaturated researchers in USA and UK revealed the remarkable olefinic compound with hydrogen and carbon ability of organophosphine containing rhodium monoxide to yield an aldehyde. In the case of the compounds to catalyse the hydroformylation reaction, widely practised hydroformylation of propylene, the and describes how its development, exploitation olefin (usually present in chemical or polymer grade and continuing industrial relevance came about by propylene) is reacted with a mixture of hydrogen and collaboration between three companies: The Power- carbon monoxide (in the form of synthesis gas), to Gas Corporation, which later became Davy Process produce two aldehyde isomers (normal butyraldehyde Technology before becoming part of Johnson Matthey; and iso-butyraldehyde) according to Equation (i): Union Carbide Corporation, which became a wholly owned subsidiary of The Dow Chemical Company; and 2CH3CH=CH2 + 2CO + 2H2 → Johnson Matthey. CH3CH2CH2CHO + (CH3)2C(H)CHO (i) 246 © 2017 Johnson Matthey https://doi.org/10.1595/205651317X695875 Johnson Matthey Technol. Rev., 2017, 61, (3) The hydroformylation reaction was first reported become a winner of the Nobel Prize for Chemistry) at by Dr Otto Roelen of Ruhrchemie AG, Germany, in Imperial College London, UK, found independently that 1938 and was given by German researchers the rhodium compounds containing organophosphines description of ‘oxo’ synthesis. Alcohols synthesised could catalyse the hydroformylation reaction at mild by the hydrogenation of aldehydes produced from temperatures and pressures and with high selectivity hydroformylation tend therefore to be called oxo to linear aldehydes (2, 3). Wilkinson’s research alcohols. Roelen’s discovery was to lay the foundation was supported by the precious metal refiner and for bulk organometallic chemistry and the application processor Johnson Matthey who supplied rhodium of homogeneous catalysis on an industrial scale. He through a loan scheme inaugurated in 1955 that did originally employed as a catalyst a mixture containing much to foster university research in platinum group cobalt, thorium and magnesium oxide that was metals chemistry in the UK and overseas. Wilkinson commonly used for Fischer-Tropsch synthesis and later later proposed that the rhodium complex responsible speculated that cobalt hydridocarbonyl (HCo(CO)4) for catalysing hydroformylation reactions was was the catalytically active species. He realised that tris(triphenylphosphine)rhodium(I) carbonyl hydride the catalytic mechanism was homogeneous in nature (RhH(CO)(PPh3)3) and that high selectivities to normal (for example (1, 2)). The Second World War hindered aldehyde could be achieved using a large excess of Ruhrchemie’s attempts to complete the construction of phosphine ligand (for example (4, 5)). In the late 1960s a first industrial oxo plant for producing fatty alcohols Johnson Matthey and The Power-Gas Corporation from Fischer-Tropsch olefins, and in the following decided to seek worthwhile opportunities to collaborate years Ruhrchemie commercialised a number of in research projects. The Power-Gas Corporation was a hydroformylation processes using homogeneous full services engineering and construction contractor of cobalt catalyst for use in the production of detergent considerable international repute with a strong process and plasticiser alcohols. By the end of the 1960s engineering base, and had recently restructured its most plants were using the ‘classic’ cobalt process research and development activities meaning it was employing HCo(CO)4, operating at very high pressures looking for process development projects. By early 1970, in the range of 200 to 450 bar and temperatures The Power-Gas Corporation had broadly confirmed in between 140ºC and 180ºC, although a modification of its Stockton-on-Tees laboratory Wilkinson’s proposition this catalyst, cobalt hydridocarbonyl trialkylphosphine that high n:i ratios can be obtained with a large excess (HCo(CO)3PR3), had been commercialised enabling of phosphine. Further encouraged by preliminary the hydroformylation of propylene to occur at about process engineering evaluation work, The Power-Gas 50 bar. This phosphine modified cobalt catalyst also Corporation concluded in a 1970 letter to Johnson gave improved selectivity to the preferred normal Matthey that a proposition for a low pressure propylene butyraldehyde, the isomer ratio (normal:branched hydroformylation process using a homogeneous aldehyde or ‘n:i ratio’) being about 7:1 rather than the rhodium based catalyst would be “economically 3:1 that was typical of the classic cobalt process. To this attractive when compared with what we currently know day, cobalt catalysts are still being used industrially of processes as they are operated today”. By the in some hydroformylation applications, especially in middle of the year, Johnson Matthey and The Power- the manufacture of detergent alcohols from long chain Gas Corporation had entered into a new, but far more olefins produced by ethylene oligomerisation and the wide-reaching collaboration aimed at developing a production from butene dimers and propylene trimer commercial, licensable hydroformylation process of the plasticiser alcohols iso-nonyl alcohol (INA) and initially directed at the conversion of propylene to iso-decyl alcohol (IDA) respectively. 2EH. The agreement was followed by co-ordinated programmes of further research, testing and studies The Beginnings of the LP OxoSM Process of reaction kinetics in the laboratories of both companies. The Power-Gas Corporation did process In the 1960s researchers at the chemicals producer scale-up work and process designs based on predicted Union Carbide Corporation (now a wholly owned optimum reaction conditions. Johnson Matthey subsidiary of The Dow Chemical Company, USA) investigated how it would manufacture commercial in Charleston, West Virginia, USA, and a group led quantities of a suitable rhodium catalyst precursor and by the late Professor Sir Geoffrey Wilkinson (later to also economically manage the recovery of rhodium 247 © 2017 Johnson Matthey https://doi.org/10.1595/205651317X695875 Johnson Matthey Technol. Rev., 2017, 61, (3) from used catalyst. Based on information describing modified rhodium catalyst discovered by Union Carbide Union Carbide Corporation’s activity found in literature Corporation and proposed by Wilkinson. Union Carbide searches, Johnson Matthey and The Power-Gas Corporation took the precaution of building a pilot plant Corporation decided to visit Union Carbide Corporation at Ponce so that operating data could be available in the USA in October 1970. It became evident from during the construction of the main plant. The choice early discussions that Union Carbide Corporation had of location meant the catalyst could be tested using the made significant progress on the experimental front commercial feedstocks that were to be used in full-scale but also that Wilkinson’s results complemented the operations. Data from the pilot plant tests calibrated the Union Carbide Corporation findings. After confidential process engineering design of the commercial plant disclosures had been made between them, three that was being carried out by Davy Powergas (another independent companies in different, but overlapping, name change!) in London. Following its decision to fields found they had mutual and complementary build a butyraldehyde plant, Union Carbide Corporation interests and contributions to make in developing decided to fast-track an ethylene hydroformylation potentially revolutionary chemical technology: project at Texas City, USA. The plant started operations • Union Carbide Corporation: A chemicals producer in April 1975 ahead of the Ponce plant, which started having experience in the operation of cobalt oxo in January 1976. The commissioning of both