Catalyst And Process For Selective Production Of Lower Hydrocarbons C1-C5 From Syngas With Low Methane And Co2 Production (SABIC)

CATEGORY: CATALYST-FISCHER TROPSCH 
Catalyst And Process For Selective Production Of Lower Hydrocarbons C1-C5 From Syngas With Low Methane And Co2 Production (SABIC)
United States Patent Application 20150321972
November 12, 2015
Applicant: Saudi Basic Industries Corporation
Abstract
The present invention relates to a catalyst composition comprising cobalt manganese oxide which is modified with silicon in the form of a hydrophilic silica, the catalyst further comprises at least one of lanthanum, phosphorus, Fe, Zr, and Zn, and optionally one or more basic elements selected from the group consisting of alkali metal, alkaline earth metal, and transition metal. Furthermore, a method for preparing the catalyst composition and a process for producing aliphatic and aromatic hydrocarbons using the catalyst composition are provided.
BACKGROUND
[0001] Gaseous mixtures comprising hydrogen (H.sub.2) and carbon monoxide (CO) can be converted into a hydrocarbon product stream by a catalytic process known as Fischer-Tropsch synthesis (F-T synthesis). The most common catalysts useful in F-T synthesis ("F-T catalysts") are based on Fe and/or Co, although Ni- and Ru-based catalysts have also been described (see e.g. U.S. Pat. No. 4,177,203; Commereuc (1980) J. Chem. Soc., Chem. Commun. 154-155; Okuhara (1981) J. Chem. Soc., Chem. Commun. 1114-1115). Generally, Ni-based catalysts are relatively more selective for producing methane whereas Co-, Fe- and Ru-based catalysts are more selective for hydrocarbons having at least two carbon atoms (C.sub.2+ hydrocarbons). Moreover, the selectivity for C.sub.2+ hydrocarbons can be increased by decreasing the H.sub.2:CO ratio, decreasing the reaction temperature and decreasing the reactor pressure.
[0002] It has been previously described that unsupported cobalt-manganese oxide catalysts can be used as an F-T catalyst having an improved selectivity for C.sub.3 hydrocarbons and a suppressed CH.sub.4 selectivity (see Van der Riet (1986) J. Chem. Soc. Chem. Commun 798-799 and Keyser (1998) Applied Catalysis 171:99-107). The unsupported cobalt-manganese oxide composition suitable for use as F-T catalyst was produced by a process comprising the steps of co-precipitating cobalt and manganese oxides from cobalt- and manganese-comprising solution, calcining the precipitate to form a calcined catalyst precursor and reducing the calcined catalyst precursor to obtain the cobalt-manganese oxide catalyst composition (see Colley (1988) Ind. Eng. Chem. Res. 27:1339-1344). It was found that the catalyst precursor comprised the mixed spinels Co.sub.2MnO.sub.4 and Co.sub.2Mn.sub.2O.sub.4. Reduction of the catalyst precursor resulted in an unsupported catalyst composition comprising metallic Co, MnO and a certain amount of mixed spinels Co.sub.2MnO.sub.4 and Co.sub.2Mn.sub.2O.sub.4.
[0003] It was the disadvantage of the prior art that F-T synthesis of hydrocarbon products result in a mixture of undesired products and less desired olefin products. A major drawback of conventional unsupported cobalt-manganese oxide F-T catalysts is their relatively low activity resulting in a relatively low syngas conversion rate.
[0004] It was an object of the present invention to provide an improved Fischer-Tropsch catalyst (F-T catalyst) having superior catalyst activity while maintaining high hydrocarbon selectivity and low carbon dioxide (CO.sub.2) and methane (CH.sub.4) selectivity. In another aspect, it was an object of the present invention to provide an improved process for producing a higher yield of ethylene and propylene from syngas in addition to value added products, such as 1-hexene and 1-butene.
SUMMARY
[0005] The present invention relates to a catalyst composition comprising cobalt manganese oxide which is modified with silica in the form of a hydrophilic silica, the catalyst further comprises at least one of lanthanum, phosphorus, Fe, Zr and Zn and optionally one or more basic elements selected from the group consisting of alkali metal, alkaline earth metal and transition metal. Furthermore, a method for preparing said catalyst composition and a process for producing aliphatic and aromatic hydrocarbons using said catalyst composition is provided.
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