Nickel molybodtungstate hydrotreating catalysts (law444)

Details Nickel molybodtungstate hydrotreating catalysts (law444) Nickel molybodtungstate hydrotreating catalysts (law444)

2000-03-03

2001-10-09

Myers, Helane E. (Department: 1764)

Mineral oils: processes and products

Refining

Nitrogen contaminant removal

C208S25400R

Reexamination Certificate

active

06299760

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to new hydrodenitrogenation (HDN) catalysts. More particularly this invention relates to the decomposition product of nickel (ammonium) molybdotungstates and their use as catalysts in HDN processes.
BACKGROUND OF THE INVENTION
As the supply of low sulfur, low nitrogen crudes decrease, refineries are processing crudes with greater sulfur and nitrogen contents at the same time that environmental regulations are mandating lower levels of these heteroatoms in products. Consequently, a need exists for increasingly efficient desulfurization and denitrogenation catalysts.
In one approach, a family of compounds, related to hydrotalcites, e.g., ammonium nickel molybdates, has been prepared. Whereas X-ray diffraction analysis has shown that hydrotalcites are composed of layered phases with positively charged sheets and exchangeable anions located in the galleries between the sheets, the related ammonium nickel molybdate phase has molybdate anions in interlayer galleries bonded to nickel oxyhydroxide sheets. See, for example, Levin, D., Soled, S. L., and Ying, J. Y., Crystal Structure of an Ammonium Nickel Molybdate prepared by Chemical Precipitation, Inorganic Chemistry, Vol. 35, No. 14, p. 4191-4197 (1996). The preparation of such materials also has been reported by Teichner and Astier, Appl. Catal. 72, 321-29 (1991); Ann. Chim. Fr. 12, 337-43 (1987), and C. R. Acad. Sci. 304 (II), #11, 563-6 (1987) and Mazzocchia, Solid State Ionics, 63-65 (1993) 731-35.
Now, when molybdenum is partially substituted for by tungsten, an amorphous phase is produced which upon decomposition and, preferably, sulfidation, provides enhanced hydrodenitrogenation (HDN) catalyst activity relative to the unsubstituted (Ni—Mo) phase.
SUMMARY OF THE INVENTION
In accordance with this invention, an amorphous nickel molybdo tungstate composition is produced and exhibits enhanced hydrodenitrogenation (HDN) activity as compared to known catalyst. In essence, at least a portion but not all of the molybdenum in a nickel-molybdate system is replaced by tungsten, that is the molar ratio of molybdenum to tungsten is at least 0.01/1 and less than 0.95/1.
The composition can be further described as a bulk mixed metal oxide useful as an HDN catalyst and preferably sulfided prior to use as a catalyst, of the formula:
(Ni)
b
(Mo)
c
(W)
d
O
z
wherein the molar ratio of b: (c+d) is 0.5/1 to 3/1, preferably 0.75/1 to 1.5/1, more preferably 0.75/1 to 1.25/1;
The molar ratio of c:d is preferably >0.01/1, more preferably >0.1/1, still more preferably 1/10 to 10/1, still more preferably 1/3 to 3/1, most preferably substantially equimolar amounts of Mo and W, e.g., 2/3 to 3/2; and z=[2b+6(c+d)]/2.
The essentially amorphous material has a unique X-ray diffraction pattern showing crystalline peaks at d=2.53 Angstroms and d=1.70 Angstroms.
The mixed metal oxide is readily produced by the decomposition of a precursor having the formula:
(NH
4
)
a
(Ni)
b
(Mo)
c
(W)
d
O
z
wherein the molar ratio of a:b is ≦1.0/l, preferably 0-1; and b, c, and d, are as defined above, and z=[a+2b+6(c+d)]/2. The precursor has similar peaks at d=2.53 and 1.70 Angstroms.
Decomposition of the precursor may be effected at elevated temperatures, e.g., temperatures of at least about 300° C., preferably about 300-450° C., in a suitable atmosphere, e.g., inerts such as nitrogen, argon, or steam, until decomposition is substantially complete, i.e., the ammonium is substantially completely driven off. Substantially complete decomposition can be readily established by thermogravimetric analysis (TGA), i.e., flattening of the weight change curve.


REFERENCES:
patent: 4824821 (1989-04-01), Lopez et al.
patent: 4857496 (1989-08-01), Lopez et al.
patent: 2030444 (1995-03-01), None
Levin, D., Soled, S.L., and Ying, J.Y., Crytsal Structure of an Ammonium Nickel Molybdate prepared by Chemical Precipitation, Inorganic Chemistry, vol. 35, No. 14, pp. 4191-4197 (Sep. 1995).*
Teichner and Astier, Appl. Catal. 72, 321-29 and C, R, Acad, Sci, 304 (II), #11, 563-6 (1987) Sep. 1990.*
Mazzocchi, Solid State Ionics, 63-65 (1993) 731-35. Month N/A.

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