According to the invention, there is provided a process for ameliorating a liquid organic feedstock containing at least one undesired oxygenated organic compound, which process comprises admixing the liquid organic feedstock, a liquid alcohol and a hydroxide; and allowing the hydroxide to react with the undesired oxygenated organic compound, to form a salt of the undesired organic compound.

While any liquid organic feedstock containing, eg contaminated with, the undesired oxygenated organic compounds, can in principle be used, the Applicant believes that the process of the invention will find particular application in the treatment of a liquid organic feedstock comprising oxygenated organic compounds. Thus, the liquid organic feedstock may be that obtained by hydroformylating

an olefin-rich feedstock, eg a Fischer-Tropsch derived olefinic product. Such a liquid organic feedstock thus is aldehyde and/or alcohol based. Typically, it comprises alcohols having from 8 to 17 carbon atoms, ie C8 to C17 alcohols. When the feedstock is Fischer-Tropsch derived, it can, for example, be the product from a reactor such as that commonly known as a Synthol reactor. The unwanted oxygenated organic compounds can be esters, aldehydes and/or organic acids, but the principal unwanted compounds are normally esters in such a hydroformylation derived feedstock.

The liquid alcohol which is admixed with the liquid organic feedstock preferably has fewer carbon atoms than the alcohol(s) in the feedstock, and may have from 1 to 5 carbon atoms. In particular, the liquid alcohol may be methanol, ethanol or propanol.

The hydroxide may be a hydroxide of a metal of Group IA, Group IIA or Group IIB of the Periodic Table of Elements.

Preferably, the metal of the metal hydroxide is sodium, potassium, rubidium, cesium, barium or calcium. In particular, the metal hydroxide may be sodium hydroxide, due to its high solubility in the preferred alcohols, its high reactivity and its relatively low cost.

The reaction of the hydroxide with the undesired oxygenated organic compound will thus take place in a reaction zone provided by a suitable vessel or reactor. The liquid alcohol and the hydroxide can be added separately to the vessel, but are preferably added as a premixture.

The esters are transformed by an irreversible hydrolysis reaction (1) involving the hydroxide: RCOOR' + MOH , RCOO-M+ + R'OH (1) wherein R and R' are hydrocarbon radicals, and M is a metal of Group IA, Group IIA or Group IIB.

The liquid alcohol in the first instance acts as a solvent for the hydroxide. However, it was surprisingly found that the alcohol also reacts with the hydroxide to form small amounts of an alkoxide in accordance with reaction (2): MOH + R"OH , R"O-M+ + H2O (2) wherein M is as hereinbefore defined, and R" is a hydrocarbon radical.

The Applicant has further surprisingly found that the alkoxide, ROM, is a catalyst for the hydrolysis reaction (1) If desired, the salts of the unwanted compounds and excess hydroxide and alkoxide can be removed from the treated liquid organic feedstock. It will form part of a heavy tail of the organic feedstock and can be removed, eg by means of distillation, if required.

The process may also include separating the liquid alcohol from the treated feedstock, eg by means of a stripper.

The reaction temperature may be between 200C and 1000C, typically about 75"C. The pressure in the vessel may be atmospheric pressure. The retention time of the feedstock in the vessel will be sufficient for reaction (1) to be completed, and may thus be between 5 and 20 minutes.

The relative proportions of the liquid organic feedstock, the hydroxide and the liquid alcohol will depend on the amounts of esters present in the organic feedstock.

However, typically the volumetric proportion of feedstock to liquid alcohol can be in the range 5:1 to about 10:1, eg about 6:1.

Similarly, the proportion of hydroxide used will depend on the quantities of unwanted esters in the feedstock, but can typically be in the range of 0,5g per 100mE feedstock and 5g per 100me feedstock, eg about 2g of hydroxide per 100me feedstock.

The invention will now be described by way of non-limiting example and by way of the following simplified flow diagram of a process according to the invention for ameliorating a liquid organic feedstock.

In the drawing, reference numeral 10 generally indicates a process according to the invention for ameliorating a liquid organic feedstock containing undesired oxygenated organic compounds.

The process 10 includes a caustic make-up vessel 12, with a methanol flow line 14 leading into the vessel 12. A caustic or sodium hydroxide make-up flow line 16 also leads into the vessel 12. A flow line 18 leads from the vessel 12 to an ester transformation reactor 20. A liquid organic feedstock flow line 22 also leads into the reactor 20, while a treated feedstock withdrawal line 24 leads from the reactor 20 to a stripper 26. A methanol recycle line 28 leads from the top of the stripper 26 to the vessel 12,

while a treated feedstock or product withdrawal line 30 leads from the bottom of the stripper 26.

In use, a feedstock comprising C11 to C14 alcohols and obtained from the hydroformylation of SYNTHOL (trademark) products as described in, for example, PCT/GB96/01563 which is hence incorporated herein by reference, is fed into the vessel 20 along the flow line 22, together with a premix of methanol and sodium hydroxide entering the vessel 20 along the flow line 18. The vessel 20 is sized such that the retention time of the feedstock in the vessel is between 5 and 20 minutes. Unwanted esters in the organic feedstock react in accordance with reaction (1), to be transformed into their corresponding salts, with reaction (1) being assisted by the alkoxide formed in accordance with reaction (2). Thus, in the process 10, M of reaction (1) is Na, while R" of reaction (2) is CH3. It will be appreciated that only small quantities of the methanol react with the sodium hydroxide to form the alkoxide. Due to the high efficiency of the process of the invention for transforming the esters into their corresponding salts, the reaction conditions in the vessel 20 are moderate. Thus, the temperature in the reactor can be controlled at about 750C, and the vessel 20 can operate at atmospheric pressure.

The process 10 was demonstrated on laboratory scale by means of the following non-limiting example.

EXAMPLE A C12-13 oxo alcohol liquid feedstock, as produced in accordance with Example 10 of our co-pending PCT/GB96/01563 was used as feedstock in this example. It was thus

obtained by the hydroformylation of a Fischer-Tropsch derived olefinic product. 300me of the feedstock was placed in a 500mE round bottom flask equipped with a condenser. The feedstock was heated up to about 700C by means of a hot plate, and l,5g of sodium hydroxide, dissolved in 50me methanol and preheated to 650C, was added to the organic feedstock. The mixture was stirred by means of a magnetic stirrer, while the temperature was maintained at 750C by means of the condenser. After 10 minutes, the methanol was flashed off, and the C12l3 alcohol separated from its heavy tail (and thus also from the sodium salts of the esters which had formed) by means of vacuum distillation. The feedstock sample was then analyzed for esters with the following results: Cur13 alcohol sample before ester removal Esters = 2,5mgKOH/g C12l3 alcohol sample after ester removal Esters = 0,02mgKOH/g It was thus surprisingly found that in the process of the present invention, which uses a liquid alcohol as a solvent for sodium hydroxide rather than water which is used as a solvent in known processes for removal of esters from organic feedstocks, the retention time was drastically shortened to between 5 and 20 minutes. In the known processes, the retention times can be up to 3 to 5 hours.

Furthermore, the operating conditions in the process according to the invention are much milder with the reaction temperature being approximately 750C compared to a reaction temperature of about 100"C in the known processes. Still further, the process is more economical to operate, since substantially less sodium hydroxide is

required than in the known processes. For example, in the process of the invention, typically 6g of sodium hydroxide dissolved in 200me of methanol can be used to treat lkg of organic feed. In contrast, in known processes, 100g of sodium hydroxide dissolved in 500my of water, is typically required to treat the same quantity of feedstock. Further, no caustic waste water is generated with the process according to the invention, whereas large quantities are produced in the known processes. Still further, the use of an alcohol as opposed to water results in a 1-phase system with no associated mixing difficulties in the reaction vessel, giving rise to the very short retention times. The alcohol can also be recycled leading to little alcohol wastage.