Published April 1988
This, the third supplement to PEP Report 21, covers the progress in oxo alcohol technology since Report 21B, which was issued in 1978. It includes hydroformylation, aldol condensation, hydrogenation, and related operations.
Three types of catalysts are used commercially for hydroformylation, namely, rhodium/phosphine, cobalt carbonyl, and cobalt/phosphine. Oil-soluble rhodium/phosphine catalysts have largely replaced the conventional cobalt carbonyl catalyst in the production of the n-butyral- dehyde intermediate from propylene. Recently, Ruhrchemie replaced a cobalt carbonyl catalyst with a water-soluble rhodium/phosphine catalyst in one of its units. The rhodium/phosphine process is more selective to the normal (as opposed to the iso) butyraldehyde at low temperature and low pressure than is the cobalt carbonyl process. A typical normal/iso ratio for the rhodium/phosphine process is around 9:1. The n-butyraldehyde is converted to n-butanol or 2-ethylhexanol through hydrogenation or aldol condensation/hydrogenation.
Cobalt carbonyl catalysts are not generally limited to the production of the aldehyde precursors of C6-C13 alcohols. Two U.S. producers, however, still use these catalysts to produce butyraldehydes in normal/iso ratios of 2:1 to 4:1 (Badische and Eastman).
The cobalt/phosphine catalyst, which enables hydroformylation and hydrogenation to be performed in a single step, is used exclusively by Shell--for n-butanol, 2-ethylhexanol, and C9-C15 alcohols. The cobalt/ phosphine catalyst also entails lower reaction temperatures and pressures than the cobalt carbonyl catalyst does. It provides a normal/iso ratio of 8:1.
This report presents and evaluates several oxo processes for manufacturing n-butyraldehyde, n-butanol, 2-ethylhexanol (2-EH), isodecyl alcohols, and C12-C15 primary linear alcohols. The Ziegler process and those processes making alcohols from natural products are covered in PEP Report 163.
