Silica containing alumina supports, catalysts made therefrom and processes using the same

1. A method of preparing a catalyst support comprising:

(a) forming a first aqueous slurry of alumina by mixing an aqueous alkaline solution and an aqueous solution of a first aluminum compound at pH in the range of from about 6 to about 11 while maintaining the first aqueous slurry at a temperature ranging from about 45° C. to 70° C. so as to precipitate seed alumina and form a first aqueous alumina containing slurry;

(b) increasing a temperature of the first aqueous alumina containing slurry by at least 3° C. within a range of from about 48° C. to 80° C. to provide a second aqueous slurry;

(c) adding to said second aqueous slurry an aqueous solution of an aluminum compound and an aqueous alkaline solution at a second pH in the range of from about 6 to 11 while maintaining the second aqueous slurry at a temperature ranging from about 48° C. to 80° C. to precipitate alumina and form a second aqueous alumina containing slurry;

(d) filtering and washing the second aqueous alumina containing slurry to obtain alumina particles;

(e) reslurrying the alumina particles in an aqueous solution to obtain a third alumina containing slurry;

(f) heating the third alumina containing slurry at a temperature ranging from about 60° C. to about 90° C.;

(g) adding a silica containing compound to the heated slurry in an amount sufficient to provide at least about 0.1 wt % silica in the final alumina composition;

(h) optionally, peptizing the silica containing alumina slurry;

(i) filtering and drying the slurry to obtain a silica containing alumina;

(j) extruding the silica containing alumina to form an extrudate; and

(k) calcining the extrudate at a temperature ranging from about 400° C. to about 900° C. to obtain a catalyst support comprising precipitated alumina powder containing at least about 0.1 wt % silica.

2. A method of preparing a catalyst support comprising:

(a) forming a first aqueous slurry of alumina by combining an aqueous slurry containing a silica containing compound in an amount sufficient to provide at least about 0.1 wt % silica in the final catalyst support, with an aqueous alkaline solution and an aqueous solution of a first aluminum compound at pH in the range of from about 6 to about 11 while maintaining the first aqueous slurry at temperature ranging from about 45° C. to 70° C. so as to form a precipitated alumina containing silica to form a first aqueous alumina containing slurry;

(b) increasing a temperature of the first aqueous alumina containing slurry by at least 3° C. within a range of from about 48° C. to 80° C. to provide a second aqueous slurry;

(c) adding to said second aqueous slurry an aqueous solution of a second aluminum compound and an aqueous alkaline solution at a second pH in the range of from about 6 to 11 while maintaining the second aqueous slurry at a temperature ranging from about 48° C. to 80° C. to precipitate alumina and form a second aqueous silica containing alumina slurry;

(d) filtering and washing the second aqueous silica containing alumina containing slurry to obtain silica containing alumina;

(e) optionally, peptizing the silica containing alumina slurry;

(f) filtering and drying the slurry to obtain a silica containing alumina;

(g) extruding the silica containing alumina to form an extrudate; and (h) calcining the extrudate at a temperature ranging from about 400° C. to about 900° C. to obtain a catalyst support comprising precipitated alumina powder containing at least about 0.1 wt % silica.

3. A method of preparing a catalyst support comprising:

(a) forming a first aqueous slurry of alumina by mixing an aqueous alkaline solution and an aqueous solution of an aluminum compound at pH in the range of from about 6 to about 11 while maintaining the first aqueous slurry at temperature ranging from about 45° C. to 70° C. so as to precipitate seed alumina and form a first aqueous alumina containing slurry;

(b) increasing a temperature of the first aqueous alumina containing slurry by at least 3° C. within a range of from about 48° C. to 80° C. to provide a second aqueous slurry;

(c) adding to said second aqueous slurry an aqueous solution of a second aluminum compound and an aqueous alkaline solution at a second pH in the range of from about 6 to 11 while maintaining the second aqueous slurry at a temperature ranging from about 48° C. to 80° C. to precipitate alumina and form a second aqueous alumina containing slurry; and

(I):

(i) washing the second aqueous alumina containing slurry;

(ii) heating the second aqueous alumina containing slurry at a temperature ranging from about 60° C. to about 90° C.;

(iii) adding a silica containing compound to the slurry in an amount sufficient to provide at least about 0.1 wt % silica in the catalyst support of (I)(vii);

(iv) optionally, peptizing the silica containing alumina slurry;

(v) filtering and drying the slurry to obtain a silica containing alumina;

(vi) extruding the silica containing alumina to form an extrudate; and

(vii) calcining the extrudate at a temperature ranging from about 400° C. to about 900° C. to obtain a catalyst support comprising precipitated alumina powder containing at least about 0.1 wt % silica; or

(II):

(w) spray drying the second aqueous alumina containing slurry to obtain alumina particles;

(x) contacting the spray dried alumina particles with a silica containing compound in an amount sufficient to provide at least about 0.1 wt % silica in the catalyst support of (II) (z);

(y) extruding the silica containing alumina to form an extrudate; and

(z) calcining the extrudate at a temperature ranging from about 400° C. to about 900° C. to obtain a catalyst support comprising precipitated alumina powder containing at least about 0.1 wt % silica.