Oxide materials and catalyst compositions containing them

Details Oxide materials and catalyst compositions containing them Oxide materials and catalyst compositions containing them

1998-10-28

2001-05-15

Griffin, Walter D. (Department: 1764)

Mineral oils: processes and products

Chemical conversion of hydrocarbons

Cracking

C208S118000, C208S119000, C502S245000, C502S263000, C423S328100, C423S328200

Reexamination Certificate

active

06231751

ABSTRACT:

The present invention relates to oxide materials, a process for their preparation, catalyst compositions containing them and use of the catalyst compositions in a process for catalytically cracking a hydrocarbonaceous feedstock.
Laminar materials that swell or expand in the presence of water and/or appropriate intercalating cations are exemplified by clays, zirconium phosphates and phosphonates, hydroxycarbonates such as hydrotalcite, silicas such as kanemite, magadiite and keniaite, transition metal sulphides, graphite and laminar hydroxides. The individual layers of these materials are linked together by weak bonds such as hydrogen bonds and electrostatic forces which are easily ruptured when the intercalating force or the solvation energy of the cations exceeds the force of attraction between the layers. This is the case for example with sodium montmorillonite which swells in the presence of excess water until the distance between its layers exceeds 10 nm (100 Å). An advantage of such swellable or expandable materials, particularly those having catalytic uses, is that the space between their layers and so their internal surface can be made accessible to reactive molecules, thereby considerably increasing the catalytically active surface area of the material. However, when the intercalated cations in the swollen or expanded laminar material are eliminated by calcination, the laminar material collapses and the original spacing between the layers is re-established.
In order to prevent this collapse between the layers on calcination, it has been proposed in the art to intercalate in the swelled or expanded laminar material some “columns” or “pillars” of thermostable hydroxides and oxides. These columns consist of polymeric hydroxides, for example, of aluminium, silicon, chromium, nickel or zirconium. On calcination, these hydroxides give rise to columns of the corresponding oxides which are anchored in the surface of the layers, keeping them at a certain distance from one another. This stabilises the final product which is known as a “pillared laminar material”. The preparation of a pillared laminar oxide material, in particular MCM-36, is described in detail in Published International Patent Application No. WO 92/11934.
It would be desirable to prepare a calcined, oxide material having an increased active surface area which is not a pillared material.
In accordance with the present invention, there is therefore provided an oxide material having in its calcined form an X-ray diffraction pattern including values substantially as set forth in Table I below:
TABLE I
Relative Intensity,
d (Ångstrom)
I/I
o
× 100
12.49 ± 0.24 
vs
11.19 ± 0.22 
m-s
6.43 ± 0.12
w
4.98 ± 0.10
w
4.69 ± 0.09
w
3.44 ± 0.07
vs
3.24 ± 0.06
w
and an adsorption capacity for 1,3,5-trimethylbenzene at a temperature of 42° C. and a pressure of 173.3 Pa.(1.3 torr) of least 0.50 mmol/g, preferably at least 0.60 mmol/g, more preferably at least 0.70 mmol/g, still more preferably at least 0.80 mmol/g and especially at least 1.00 mmol/g, in particular 1.02 mmol/g.
In this specification, unless otherwise stated, the relative intensities as indicated by the symbols, w, m, s and vs denote respectively weak, medium, strong and very strong and correspond generally to the following values:
w=0-20
m=20-40
s=40-60
vs=60-100
The X-ray diffraction pattern of the oxide material of the invention has substantially no peaks with a relative intensity (I/I
o
×100) greater than about 5 at d-values higher than 15 Ångstrom.
The oxide material according to the present invention is characterised by a high active surface area and a microporous structure. It possesses channels formed by 10-membered atomic rings having a pore diameter of 0.56 nm (5.6 Å), and chalice-shaped cavities that measure 0.8×0.7 nm (8×7 Å) which are open to the outside via 12-membered atomic rings, as indicated by the high adsorption capacity for the bulky molecule 1,3,5-trimethylbenzene. By comparison, MCM-22 zeolite has an adsorption capacity for 1,3,5-trimethylbenzene at a temperature of 42° C. and a pressure of 173.3 Pa (1.3 torr) of 0.25 mmol/g. Similarly, the oxide material of the invention possesses higher adsorption capacities than MCM-22 zeolite for toluene (e.g. 2.10 mmol/g versus 1.46 mmol/g at 42° C. and 1333.2 Pa (10 torr)) and meta-xylene (e.g. 1.58 mmol/g versus 0.79 mmol/g at 42° C. 666.61 Pa (5 torr)).
Adsorption capacities were determined from microcalorimetric measurements of the differential heat of adsorption of an adsorbate (>99% purity) as a function of its uptake on 100 mg samples of oxide material. Conventional volumetric apparatus was used together with a heat-flow microcalorimeter of the Tian-Calvet type (model BT, Setaram, France). Before each experiment, the sample material was heated in an oxygen flow (30 cm
3
/min) up to 450° C. and outgassed overnight at 450° C. in a vacuum less than 1 mPa. Isotherms were determined in the usual way by measuring amounts adsorbed at increasing pressures and the corresponding heat evolved with each dose of adsorbate. The experiments were carried out at a temperature of 42° C.
Preferably the oxide material of the invention comprises the oxides XO
2
and Y
2
O
3
wherein X represents a tetravalent element and Y represents a trivalent element, the atomic ratio X to Y being at least 10.
Preferably X in XO
2
represents at least one tetravalent element selected from silicon and germanium, and is especially silicon.
Preferably Y in Y
2
O
3
represents at least one trivalent element selected from aluminium, boron, iron, chromium and gallium, and is especially aluminium.
A particularly preferred oxide material is one comprising the oxides SiO
2
and Al
2
O
3
, i.e. wherein X represents silicon and Y represents aluminium.
The atomic ratio X to Y may take any value from 10 to infinity but is preferably a value in the range from 10 to 500, more preferably in the range from 10 to 350, still more preferably in the range from 10 to 150 and especially in the range from 10 to 100. Very advantageous results have been obtained when the atomic ratio X to Y is in the range from 15 to 50.
The present invention further provides a process for the preparation of an oxide material according to the invention which comprises, prior to calcination, at least partially delaminating a swollen, layered oxide material having an X-ray diffraction pattern including values substantially as set forth in Table II below:
Table II
Relative Intensity,
d (Ångstrom)
I/I
o
× 100
>32.2
vs
12.41 ± 0.25
w-s
 3.44 ± 0.07
w-s
The swollen, layered oxide material having the X-ray diffraction pattern of Table II is preferably at least partially delaminated using ultrasound techniques.
The swollen, layered oxide material may conveniently be prepared as described in Published International patent application No. WO 92/11934 from a precursor of MCM-22 zeolite as known, e.g., from U.S. Pat. Nos. 4,954,325, 4,992,615, 5,107,047 and 4,956,514. When this precursor is calcined at temperatures in excess of 200° C., it collapses, giving rise to zeolite MCM-22 with a three-dimensional structure.
The MCM-22 precursor may be prepared from a reaction mixture containing an oxide of a tetravalent element (X), e.g. silicon, an oxide of a trivalent element (Y), e.g. aluminium, an organic directing agent (organic template), water and, optionally, sources of alkali or alkaline earth metal (M), e.g. sodium or potassium cation.
Examples of organic templates that may be used include heterocyclic imines (e.g. hexamethyleneimine, 1,4-diazacycloheptane and azacyclooctane), cycloalkyl amines (e.g. aminocyclopentane, aminocyclohexane and aminocycloheptane), adamantane quarternary ammonium ions (e-.g. N,N,N-trimethyl-1-adamantanammonium ions and N,N,N-trimethyl-2-adamantanammonium ions), and mixtures of N,N,N-trimethyl-1-adamantanammonium ions or N,N,N-trimethyl-2-adamantanammonium ions with either hexa

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