Catalyst containing phosphorous and a process hydrotreatment...

Details Catalyst containing phosphorous and a process hydrotreatment... Catalyst containing phosphorous and a process hydrotreatment...

1999-05-12

2001-12-25

Griffin, Steven P. (Department: 1754)

Mineral oils: processes and products

Refining

Sulfur removal

C208S213000, C208S244000, C208S243000, C502S211000, C502S213000, C502S305000, C502S314000, C502S321000, C502S322000, C502S325000, C502S332000

Reexamination Certificate

active

06332976

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention concerns a catalyst for hydrotreatment of a hydrocarbon petroleum feed, comprising cobalt, molybdenum and phosphorous.
Hydrotreatment of petroleum cuts is gaining importance in refining, both with the increasing necessity for converting ever heavier fractions and with the increasing severity of specifications for the finished products.
This state of affairs arises from the economic importance of maximally upgrading imported crudes with ever-increasing heavy fractions which have both a relative deficit of hydrogen in those heavy fractions or lighter fractions produced from them, and contain a large quantity of heteroatoms such as sulphur and nitrogen.
In general, hydrotreatment is the purification of hydrocarbon petroleum cuts without significant modification of the backbone defined by the carbon atoms. Thus it includes eliminating heteroatoms such as sulphur and nitrogen, eliminating metals, and partial or complete hydrogenation. When this proves to be necessary, the petroleum cut is hydrotreated then freed of the products formed which means that a purified petroleum cut can be recovered.
The “severity” of hydrotreatment is directly linked to the operating conditions. The term “operating conditions” means the nature of the feed, the total pressure in the reaction zone, the partial pressures of the various compounds, the reaction temperature, the hourly space velocity and the hydrogen flow rate. In general, the heavier the feed, the more difficult it is to convert, the more severe are the operating conditions, i.e., the pressures, temperature and hydrogen flow rate are higher and the hourly space velocity is lower.
2. Related Art
The closest known prior art is Sherwood, EP 0 526 988 A2. Sherwood describes the following catalyst:
1.6-6.0% wt GVIII metal oxide (NiO or CoO preferably NiO)
10.0-25.0% wt GVI metal oxide (Mo O
3
preferred)
1.0-6.0% wt P
2
O
5
, 1.5-3.0% preferred having
a surface of 160-210 m
2
/g
Total Pore Volume (TPV) of 0.5-0.65 cc/g
diameters 100-130 Å: 70.0-85.0% TPV
>160 Å<7.5% TPV
>250 Å<4.0% TPV
Sherwood has prepared CoMoP catalyst B (Table II of the Sherwood publication) with 3.3% Co., 15.2% MoO
3
and 1.5% P
2
O
5
having a surface of, 182 m
2
/g and an average pore diameter of 120 Å and a TPV of 0.579 cc/g.
The following table summarizes the pore size distribution of Sherwood's catalysts, particularly CoMoP and NiMoP.
TABLE 1
Sherwood's Catalyst pore size distribution of Catalysts A and B.
Pore Size (Å)
NiMoP (Ex. A) in % TPV
CoMoP (Ex. B) in % TPV
<100
12.8
11.2
<130
90.1
85.4
<160
94.2
96.2
100-130
78.1
74.2
100-160
81.4
85.0
>120
43.7
50.2
>130
9.2
14.6
>160
5.9
3.8
>250
3.9
2.2
SUMMARY OF THE INVENTION
Our research on a variety of supports with a variety of compositions has led us to the discovery that, surprisingly, alumina based catalyst containing, expressed as the oxide content by weight, 2-10% by weight of cobalt oxide CoO, 10-30% by weight of molybdenum oxide MoO
3
and 4-10% of phosphorous oxide P
2
O
5
and which preferably has particular physico-chemical characteristics, has a hydrotreatment activity which is far superior to those of prior art formulations.
The matrix used is alumina based (at least 50% by weight of alumina) and is preferably essentially constituted by alumina.
The catalyst is characterized in that the phosphorous content, expressed as the percentage by weight of phosphorous pentoxide P
2
O
5
, with respect to the finished catalyst, is in the range 4.0% to 10.0%, preferably in the range 4.5% to 8.0% and more preferably in the range 5.6% to 8.0% or 5.6% to 6.5%. It is characterized in that the cobalt content, expressed as the percentage by weight of cobalt oxide CoO with respect to the finished catalyst, is in the range 2.0% to 10.0%, preferably in the range 3.5% to 7.0% and more preferably in the range 3.5% to 5.5%. It is characterized in that the molybdenum content, expressed as the percentage by weight of molybdenum oxide MoO
3
with respect to the finished catalyst, is in the range 10% to 30%, advantageously in the range 10% to 18.9%, preferably in the range 15.0% to 18.9% and more preferably in the range of 16.0% to 18.5%.
The catalyst is also characterized by:
BET Surface Area:
The BET surface area, measured on the finished catalyst, is in the range 100 to 300 m
2
/g, preferably in the range 120 to 250 m
2
/g and more preferably in the range 130 to 240 m
2
/g.
CSH:
The Shell crushing strength, termed CSH, measured on the finished catalyst, is more than 1.4 MPa and preferably more than 1.6 MPa.
Average Pore Diameter:
The average pore diameter is measured from the pore distribution profile obtained using a mercury porosimeter. From the pore distribution curve, the derivative curve can be calculated. This derivative curve passes through one or more maxima, the abscissa of which gives the pore diameter. The catalyst claimed is such that the maximum is/are obtained for a pore diameter or diameters in the range 80 Å to (10 Å=1 nm), preferably in the range 95 Å to 110 Å, more preferably in the 100 Å to 110 Å.
Pore Volume of Pores Below 80 Å:
The pore volume of pores with a diameter of less than 80 Å is at most 0.05 ml/g, or less than 10% Total Pore Volume (TPV), preferably at most 0.035 ml/g and more preferably at most 0.025 ml/g.
Pore Volume of Pores Over 140 Å:
The pore volume of pores with a diameter of over 140 Å is less than 0.08 ml/g, or less than 22% TPV, preferably less than 0.06 ml/g and more preferably less than 0.05 ml/g. There are practically no pores of over 250 Å, more generally their pore volume is less than 10% of the TPV, or more preferably less than 8%.
Pore Volume of Pores in the Range 80 Å to 140 Å:
The pore volume of pores with a diameter in the range 80 Å to 140 Å is in the range 0.20 ml/g to 0.80 ml/g, preferably in the range 0.30 ml/g to 0.70 ml/g and 20-60% of the total pore volume is in pores with a diameter 100-130 Å.
Table II below summarizes the pore size distribution of the catalyst of the present invention.
TABLE II
General pore size distribution of the catalyst of the present invention.
Pore Size (Å)
% Total Pore Volume (TPV)
ml/g
 <80 Å
<10%
≦0.05
<100 Å
20-70%
 80-100 Å
20-60%
100-130 Å
20-60%
>140 Å
<22%
<0.08
 80-140 Å
0.20-0.80
>160 Å
<12%
>250 Å
<10%
The catalyst of the present invention can be prepared using any one of the methods which are known to the skilled person.
The hydrogenating element is introduced during mixing or after forming (as is preferred).
Forming is followed by calcining, the hydrogenating element being introduced before or after calcining. Preparation is finished in all cases by calcining at a temperature of 250° C. to 600° C.
One preferred method consists of mixing a moist alumina gel for several tens of minutes then passing the paste obtained through a die to form extrudates with a diameter which is preferably in the range 0.4 to 4 mm.
The catalyst also comprises a hydrogenating function. The hydro-dehydrogenating function is provided by molybdenum or cobalt. It can be introduced into the catalyst at various stages in the preparation and in various ways.
It may be introduced partially or completely on mixing with the gel of the oxide selected as the matrix, the remaining hydrogenating element(s) being introduced after mixing, more generally after calcining.
Molybdenum is preferably introduced simultaneously with or after the cobalt, whatever the method of introduction.
It is preferably introduced by one or more ion exchange operations carried out on the calcined support using solutions containing the precursor salts of the metals.
It can be introduced by one or more operations for impregnating the formed and calcined support with a solution of one or more precursors of cobalt oxide while the molybdenum oxide precursor(

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