Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Metal – metal oxide or metal hydroxide
Reexamination Certificate
2000-08-11
2003-10-28
Silverman, Stanley S. (Department: 1754)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Metal, metal oxide or metal hydroxide
C502S232000, C502S240000, C502S263000, C502S303000, C502S324000, C502S325000, C502S335000, C502S337000, C502S340000, C502S341000, C502S342000, C502S343000, C502S345000, C502S346000, C502S349000, C502S355000
Reexamination Certificate
active
06638889
ABSTRACT:
THIS INVENTION relates to a process for producing hydrocarbons from a synthesis gas, and to catalysts. It relates in particular to a method of treating a catalyst support to form a modified catalyst support, to a modified catalyst support thus formed, to a method of forming a catalyst from the modified catalyst support, to a catalyst thus obtained; to a process for producing hydrocarbons, and to hydrocarbons thus produced.
According to a first aspect of the invention, there is provided a method of treating a catalyst support, which method comprises introducing onto and/or into an untreated catalyst support which is partially soluble in an aqueous acid solution and/or a neutral aqueous solution, Si, Zr, Cu, Zn, Mn, Ba, Co, Ni and/or La as a modifying component which is capable, when present in and/or on the catalyst support, of suppressing the solubility of the catalyst support in the aqueous acid solution and/or the neutral aqueous solution, thereby to form a protected modified catalyst support which is less soluble or more inert in the aqueous acid solution and/or the neutral aqueous solution, than the untreated catalyst support.
The catalyst support may, in particular, be in particulate form. The modifying component is thus present, in the modified catalyst support particles, on the particle surfaces and/or in internal support frameworks of the particles, ie the modifying component is chemically bonded to the particle surfaces and/or to support frameworks of the particles. For example, the modifying component may be chemically bonded to OH (hydroxy groups) on the support surfaces or via the formation of spinel structures with the support.
In principle, any commercially available catalyst support which is partially soluble in an aqueous acid solution and/or in a neutral aqueous solution, can be used. Examples of untreated catalyst supports that can be used are alumina (Al
2
O
3
), titania (TiO
2
) and magnesia (MgO). When the catalyst support is alumina, any suitable alumina support can, in principle, be used. For example, the alumina support may be that obtainable under the trademark Puralox SCCa 5/150 from CONDEA Chemie GmbH. Puralox SCCa 5/150 (trademark) is a spray-dried alumina support. Similarly, when the catalyst support is titania, any suitable titania support can, in principle, be used. For example, the titania support may be that obtainable under the trademark Degussa P25.
The introduction of the modifying component onto and/or into the catalyst support may include contacting a precursor of the modifying component with the catalyst support, for example, by means of impregnation, precipitation or chemical vapour deposition. Such modifying component precursors include compounds, e.g. salts or alkoxides, containing the modifying component or elements, viz Si, Zr, Cu, Zn, Mn, Ba, Co, Ni, and/or La.
In one embodiment of the invention, the modifying component precursor may, in particular, be a silicon-based modifying component precursor, e.g. an organic silicon compound or agent, so that the modifying component is silicon (Si) The organic silicon compound may be tetra ethoxy silane (‘TEOS’) or tetra methoxy silane (‘TMOS’).
When a silicon-based modifying component precursor is used with an alumina catalyst support, it may then be used in a quantity such that the silicon level in the resultant protected modified catalyst support is at least 0.06 Si atoms per square nanometer of the untreated or fresh support, preferably at least 0.13 Si atoms per square nanometer of the fresh support, and more preferably at least 0.26 Si atoms per square nanometer of the fresh support.
The upper limit of the modifying component, e.g. silicon, in the protected modified catalyst support may be set by parameters such as the degree of acidity imparted to the support by the modifying component and/or the porosity of the protected modified catalyst support and/or by the average pore diameter of the protected modified catalyst support. Preferably, the average pore diameter of the protected modified catalyst support as hereinafter described is at least 12 nm, as disclosed in South African Patent No. 96/2759, which is hence incorporated herein by reference thereto. Additionally, if an objective is to obtain, from the protected modified catalyst support, a catalyst having a composition of 30 g Co/100 g Al
2
O
3
, the untreated Al
2
O
3
catalyst support, and also the protected modified catalyst support, must have a pore volume of at least 0.43 ml/g, as discussed hereinafter with reference to Table 2. The upper limit of the modifying component, e.g. Si, in the protected modified catalyst support is thus to be selected in such a manner that the geometry, e.g. the average pore diameter and porosity, of the protected modified catalyst support is not detrimentally effected to an appreciable extent. If the support acidity is negatively influenced by the modifying component, e.g. as may be the case when silicon is used as the modifying component, then the upper limit of the modifying component in the protected modified support can, instead, be set by the modifying component level at which the support acidity becomes unacceptable.
Thus, when spray-dried Puralox SCCa 5/150 (trademark) alumina is used as the untreated or fresh catalyst support, sufficient silicon-based modifying component precursor is used such that the upper limit of silicon in the resultant protected modified catalyst support is 2.8 Si atoms
m
2
of fresh catalyst support, preferably 2.5 Si atoms
m
2
of fresh catalyst support.
Instead, when spray-dried Puralox SCCa 5/150 (trademark) alumina is used as the untreated catalyst support (ie having a surface area of ca 150 m
2
/g and a pore volume of ca 0.5 ml/g implying an average pore diameter of ca 13 nm), then the maximum level of silicon may be set in accordance with Table 1.
TABLE 1
Characteristics of silicon modified supports
B.E.T. derived geometries
Silicon level of modified
of modified and calcined Al
2
O
3
and calcined Al
2
O
3
Pore
Surface
Average pore
(Si atoms
m
2
volume
area
diameter
of fresh support)
(ml/g)
(m
2
/g)
(nm)
1
0.48
155
13
2.5
0.48
158
12
2.8
0.44
162
11
7.0
0.39
157
10
14.8
0.25
136
7
The organic silicon compound or agent may be dissolved in an impregnation solvent, which is typically an organic solvent capable of dissolving the silicon compound, such as ethanol, acetone or propanol. The catalyst support may be admixed with the resultant solution to form a treatment mixture. The treatment mixture may be maintained at an elevated temperature for a period of time to impregnate the modifying agent into and/or onto the catalyst support. The elevated temperature may be at or near the boiling point of the impregnation solvent. The impregnation may be effected at atmospheric pressure, and the period of time for which the impregnation is effected may be from 1 minute to 20 hours, preferably from 1 minute to 5 hours. The excess solvent or solution may then be removed, to obtain a modified catalyst support. The removal of the excess solvent or solution may be effected under a vacuum of 0.01 to 1 bar(a), more preferably 0.01 to 0.1 bar(a), and at temperature equal to the boiling point of the solvent, e.g. using known drier equipment, fitted with a mixing device, and of which the jacket temperature is thus higher than the solvent boiling point.
The method may include calcining the silicon-containing modified catalyst support, to obtain the protected modified catalyst support. The calcination of the modified catalyst support may be effected at a temperature from 100° C. to 800° C., preferably from 450° C. to 550° C., and for a period of from 1 minute to 12 hours, preferably from 1 hour to 4 hours.
Calcination after support modification is necessary to decompose organic groups and to obtain the protected modified support. An optimized calcination time can be obtained by infra-red analysis of the modified support after calcination.
In another embodiment of the invention, the modifying component precursor may be an inorganic cobalt compound so that the
Barradas Sean
Caricato Elsie Adriana
Loosdrecht Jan Van De
Van Berge Peter Jacobus
(Sasol Technology (Proprietary) Limited)
Silverman Stanley S.
Strickland Jonas N.
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