CROSS REFERENCE TO RELATED APPLICATIONS

This is a national stage application of International Application No. PCT/EP2016/081922, filed 20 Dec. 2016, which claims benefit of priority to European Patent Application No. 15201753.9, filed 21 Dec. 2015.

FIELD OF THE INVENTION

The present invention relates to a method for preparing a hydrogenation catalyst or catalyst precursor thereof comprising a catalytically active material and a carrier material. The present invention relates to a catalyst particle and catalyst precursor thereof obtainable by said method. The present invention relates to a process for preparing hydrocarbons wherein said catalyst is used.

BACKGROUND TO THE INVENTION

The catalytic preparation of hydrocarbons from synthesis gas, i. e. a mixture of carbon monoxide and hydrogen, is well known in the art and is commonly referred to as Fischer-Tropsch synthesis.

Catalysts suitable for use in a Fischer-Tropsch synthesis process typically contain a catalytically active metal of group 8, 9 or 10 of the Periodic Table of the Elements (Handbook of Chemistry and Physics, 89th edition, CRC Press, 2008-2009) supported on a refractory oxide, such as alumina, titania, zirconia, silica or mixtures of such oxides. In particular, iron, nickel, cobalt and ruthenium are well known catalytically active metals for such catalysts. Reference may be made to EP-A-398420, EP-A-178008, EP-A-167215, EP-A-168894, EP-A-363537, EP-A-498976 and EP-A-71770, optionally in combination with one or more metal oxides and/or metals as promoters selected from zirconium, titanium, chromium, vanadium and manganese, especially manganese. Such catalysts are known in the art and have been described for example, in the specifications of WO 9700231A and U.S. Pat. No. 4,595,703. CN 104 174 400, US 2012/083540, U.S. Pat. No. 5,945,459, US 2011/301024 and LEI SHI ET AL: “Studies on surface impregnation combustion method to prepare supported Co/SiO catalysts and its application for Fischer-Tropsch synthesis”, (APPLIED CATALYSIS A: GENERAL, ELSEVIER SCIENCE, AMSTERDAM, NL, vol. 435, 6 Jun. 2012 (2012-06-06), pages 217-224, XP028425865, ISSN: 0926-860X, DOI: 10.1016/J.APCATA.2012.06.007) disclose methods involving impregnation.

Catalysts can be prepared by obtaining a metal hydroxide, carefully oxidising it to the metal oxide and then placing it in the appropriate reactor where it is reduced to the metal in situ.

CN 104 174 400 discloses a method of manufacturing a Fischer-Tropsch catalyst based on impregnating a carrier material.

The first step of the process according to US 2012/083540 entails providing Fe(II) carboxylate in solution. This solution may be formed by means of a dissolution step wherein a source of iron, Fe(0), is dissolved in a suitable solution, preferably an acidic solution, preferably an aqueous solution including one or more carboxylic acids, in order to convert iron in the zero oxidation state to Fe(II) carboxylate in solution where the iron is in an oxidation state of two.

U.S. Pat. No. 5,945,459 discloses a preparation of a catalyst, in which a preformed particulate refractory inorganic solids support is impregnated with a compound, or salt, of a catalytic metal. Similarly, US 2011/301024 discloses a preparation method based on impregnation.

There is a continuous interest in finding catalysts for use in the Fischer-Tropsch synthesis which provide an improved activity and/or an improved selectivity in the conversion of carbon monoxide into valuable hydrocarbons, in particular hydrocarbons containing 5 or more carbon atoms (“C5+ hydrocarbons” hereinafter), and which minimise the formation of methane, which is a hydrocarbon carbon frequently considered as being of lower value.

SUMMARY OF THE INVENTION

A method has been found which provides for an improved hydrocarbon synthesis catalyst and precursor thereof. Said catalysts have a higher C5+ selectivity and activity.

The present invention provides for an improved catalyst.

Accordingly, the present invention provides for a method for preparing a hydrogenation catalyst comprising a catalytically active material and a carrier material, wherein:an acidic solution comprising metal ions of a metal selected from the IUPAC group 8, 9 or 10 metals, preferably cobalt;a suspension comprising the carrier material;an alkaline solution; and said method comprising a step d.:d. Mixing the acidic solution, the suspension and the alkaline solution causing the cobalt to precipitate in the presence of the carrier material, obtaining a mixture comprising a precipitate;

wherein at least the alkaline solution comprises a conjugated base of a carboxylic acid and/or the suspension comprises a carboxylic acid or a conjugated base thereof, preferably step d. is preceded by step a., b., and/or c. in which the acidic solution, the suspension and the alkaline solution are prepared, respectively.

The present invention provides for a precursor of a hydrogenation catalyst and a catalyst obtained from said precursor. Said precursor comprises a metal salt of a group 8, 9 or 10 metal, preferably cobalt(II) on a carrier material wherein the precursor after calcination comprises crystallites of metal oxides having an average crystallite size of maximally 8 nm as measured with XRD.

