The present invention relates to catalysts for purification of gaseous condensate and oil fractions from mercaptans and can be used in oil-processing and in petrochemical industry.
Usually oxidation of mercaptans is performed by oxygen or air at room or elevated temperature in the presence of homogenous or heterogeneous catalyst based on a transitional metal:2RSH+½02→RSSR+H20
Mercaptans are extracted from organic phase by strongly alkali aqueous solutions, in which at elevated temperature and pressure catalytical oxidation of mercaptans takes place, and as a catalyst salts from metals of alternating valency (Fe, Co, Ni, V, Mn, Cr) in the form of simple or complex compositions, more often phatocyanites (as disclosed for example in European patent no. 394571, German patent 3008284 and others). The catalysts of this type provide sufficiently complete removal of mercaptans. Their common disadvantage is not sufficient availability and high cost of phatocyanites, which leads to making the process of purification expensive. Moreover, the necessity to conduct the process in strongly-alkli medium leads to a significant corrosion of equipment and worsening of the properties of oil pipelines.
It is known that phtalocyanines in catalytical compositions can be replaced with other compounds of transitional metals.
A catalyst are known based on metallo-organic derivatives of metals of VIA, VIIA, and VIII groups with general formula Mea(R)x(CO)y where R is aromatic ligand, for example benzol or its alkyl derivatives, antrazen, benzpirin, phenanthren (U.S. Pat. No. 3,053,756). Disadvantages of such catalysts include their low stability, high cost and toxicity.
A catalyst for oxidating demercaptanization of carbohydrates is known which is a helate complex of a transitional metal with bi, tri, or tetra dentant ligand, containing at least one amide group (French patent 2,573,087). In particular, replaced 2-(alkyl(aryl, alkylary))-aminocarboxypyriditines and others even more complicated compounds are utilized. As a metal it can be Co, Fe, Cu, Ni, Mn. The disadvantage is a low stability of the catalyst and use for its manufacture of expensive and scarce components.
Also, catalysts of oxidating demercaptanization are known-complexes of copper with tetracyantiophenol and tetracyandentin (French patent 2591610). These catalysts provide high degree of purification, but their practical use is questionable because their very high cost and scarce availability of the components.
A method of oxidative demercaptanization are known which is performed by oxidation of mercaptans with oxygen of air in presence of helate complexes of a transitional metal (Co, Fe, Cu, Ni, Mn) with polydentan ligand from the class of amides, in particular from aminocarboxyperidines (French patent 2573087). The main disadvantage of the method with the use of this catalyst is high cost of its components.
A heterogeneous catalyst is described, based on complexes of copper with amino derivatives (aminoalcohols, aminoacids, amines) applied on a mineral carrier or activated coal (European patent 996500). The disadvantage of this catalyst is a low content of active phase on the surface of the carrier, which inevitably leads to a significant consumption of the heterogeneous catalyst.
The closest solution to the present invention is disclosed in U.S. patent no. In accordance with this patent, a catalyst of alkali-free purification of oil fractions from mercaptans is proposed, which contains a copper oxide, a complex of copper with nitrogen-containing compound of amines, aminoalcohols, aminoacids, or amids and an inert carrier. The disadvantage of this method is a complex technology for producing catalyst and a high consumption of the carrier, which makes the catalyst quite expensive.