1. A catalyst containing an active phase comprising at least one metal of group VIIIB selected from cobalt, nickel, ruthenium and iron deposited on an oxides support comprising alumina, silica, phosphorus and at least one simple spinel MAl2O4 or mixed spinel MxM\u2032(1-x)Al2O4 which is or is not partial, wherein M and M\u2032 are separate metals selected from the group formed by magnesium (Mg), copper (Cu), cobalt (Co), nickel (Ni), tin (Sn), zinc (Zn), lithium (Li), calcium (Ca), caesium (Cs), sodium (Na), potassium (K), iron (Fe) and manganese (Mn) and in which x is between 0 and 1, the values 0 and 1 being themselves excluded.
2. A catalyst according to claim 1 wherein said support is a phosphorus-containing silica-alumina or a phosphorus-containing silica-containing alumina in which spinel is included.
3. A catalyst according to claim 1 wherein the silica content of said support is between 0.5% by weight to 30% by weight with respect to the total weight of the support.
4. A catalyst according to claim 1 wherein the phosphorus content of said support is between 0.1% by weight and 10% by weight of said element with respect to the weight of the support.
5. A catalyst according to claim 1 wherein the spinel content is between 3 and 50% by weight with respect to the weight of the support.
6. A catalyst according to claim 1 wherein the content of metal M or M\u2032 is between 1 and 20% by weight with respect to the weight of the support.
7. A catalyst according to claim 1 wherein M is cobalt or nickel in the case of a simple spinel and M is cobalt and M\u2032 is magnesium or zinc in the case of a mixed spinel.
8. A catalyst according to claim 1 wherein the metal of group VIIIB is cobalt.
9. A catalyst according to claim 1 wherein the content of metal of group VIIIB is between 0.5 and 60% by weight with respect to the weight of the catalyst.
10. A catalyst according to claim 1 wherein the alumina from which the support is prepared has a specific surface area of between 50 m2g and 500 m2g, a pore volume measured by mercury porosimetry of between 0.4 mlg and 1.2 mlg and a monomodal pore distribution.
11. A catalyst according to claim 1 wherein the support further comprises a simple oxide selected from titanium oxide, ceria and zirconia, alone or as a mixture.
12. A catalyst according to claim 1 wherein the catalyst further comprises at least one dopant selected from a noble metal of groups VIIB or VIIIB, an alkali metal element or an alkaline-earth element or an element of group IIIA.
13. A process for the preparation of a catalyst according to claim 1 comprising the following steps:
a) an oxides support comprising alumina and silica is provided,
b) said oxides support comprising alumina and silica is impregnated with an aqueous or organic solution of a phosphorus precursor, followed by drying and calcination so as to obtain a support comprising alumina, silica and phosphorus,
c) the support comprising alumina, silica and phosphorus is impregnated with an aqueous or organic solution comprising at least one salt of metal M or M\u2032 selected from the group formed by magnesium (Mg), copper (Cu), cobalt (Co), nickel (Ni), tin (Sn), zinc (Zn), lithium (Li), calcium (Ca), caesium (Cs), sodium (Na), potassium (K), iron (Fe) and manganese (Mn) followed by drying and calcination at a temperature of between 700 and 1200\xb0 C. so as to obtain a simple spinel MAl2O4 or a mixed spinel MxM\u2032(1-x)Al2O4 which is or is not partial, in which M and M\u2032 are separate metals and x is between 0 and 1, the values 0 and 1 being themselves excluded, and
d) the oxides support comprising alumina, silica, spinel and phosphorus is impregnated with an aqueous or organic solution comprising at least one salt of metal from group VIIIB selected from cobalt, nickel, ruthenium and iron, followed by drying and calcination at a temperature of between 320\xb0 C. and 460\xb0 C. so as to obtain said catalyst.
14. A Fischer-Tropsch process for the synthesis of hydrocarbons comprising bringing a catalyst according to claim 1 into contact with a charge comprising synthesis gas under a total pressure of between 0.1 and 15 MPa at a temperature of between 150 and 350\xb0 C. at an hourly space velocity of between 100 and 20000 volumes of synthesis gas per volume of catalyst and per hour with an H2CO molar ratio in the synthesis gas of between 0.5 and 4.
15. A Fischer-Tropsch process according to claim 14 which is used in a reactor of slurry bubble column type.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An optical system, comprising:
a) at least two optical elements, at least one of which being a movable optical element,
b) a computer for calculating a target position for the at least one movable optical element such that, in the target position, the total perturbation of the at least two optical elements which is made up of polarization-dependent perturbations and polarization-independent perturbations of the at least two optical elements, is minimized;
c) an actuator for moving the at least one movable optical element to the target position calculated by the computer.
2. The optical system of claim 1, comprising a sensor for determining for at least one of the at least two optical elements a polarization-dependent perturbation and for determining for at least one of the at least two optical elements a polarization-independent perturbation.
3. The optical system of claim 1, wherein the polarization-dependent perturbation includes stress birefringence.
4. The optical system of claim 2, wherein at least one of the at least two optical elements consists of a crystalline material, and wherein a determination of a polarization-dependent perturbation of the at least one of the at least two optical elements comprises a determination of the position of at least one crystal axis.
5. The optical system of claim 1, in which the at least one movable optical element is configured to be rotated about its axis of symmetry.
6. The optical system of claim 1, in which the at least one movable optical element is configured to be linearly displaced.
7. The optical system of claim 1, in which the at least one movable optical element is configured to be displaced transversely to an optical axis of the optical system.
8. The optical system of claim 1, in which the at least one movable optical element is configured to be tilted relative to an optical axis of the optical system.
9. A photolithographic exposure apparatus comprising the optical system of claim 1.
10. A photolithographic exposure apparatus, comprising at least two optical elements being in a relative position such that the total perturbation of the at least two optical elements which is made up of polarization-dependent perturbations and polarization-independent perturbations is minimized.