US 4,363,718 A · Crystalline chromosilicates and process uses

Abstract

There are provided crystalline chromosilicates, their methods of preparation, and process uses. A first crystalline chromosilicate comprises a molecular sieve material providing a specific X-ray diffraction pattern and having the following composition in terms of mole ratios of oxides: 0.9.+-.0.2[WR.sub.2 O+(1-W)M.sub.2/n O]:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O, wherein R is an alkyl ammonium cation, M is at least one cation having a valence of n, Y is a value within the range of about 4 to about 500, Z is a value within the range of about 0 to about 160, and W is a value that is greater than or equal to 0 and less than or equal to 1. A second crystalline chromosilicate comprises a molecular sieve material providing a specific X-ray diffraction pattern and having the following composition in terms of mole ratios of oxides: 0.9.+-.0.2M.sub.2/n O :Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O, wherein M is at least one cation having a valence of n, Y is within the range of about 4 to about 500, and Z is within the range of about 0 to about 160. The first crystalline chromosilicate is a precursor of the second. There is provided also a process for the conversion of a hydrocarbon stream, which process comprises contacting said stream under hydrocarbon conversion conditions with a catalyst comprising the second crystalline chromosilicate. In addtion, there is provided a process for the isomerization of a xylene feed, which process comprises contacting said feed under isomerization conditions with a catalyst comprising the second crystalline chromosilicate.

Claims30

Dependent claims

A process for the conversion of a hydrocarbon stream, which process comprises contacting said stream under suitable hydrocarbon conversion conditions with a catalyst comprising a crystalline chromosilicate, which chromosilicate comprises a molecular sieve material providing an X-ray diffraction pattern comprising the following X-ray diffraction lines and assigned strengths:

______________________________________ Interplanar Spacing Assigned d, A Strength ______________________________________ 11.15 .+-. 0.2 W 9.96 .+-. 0.2 VS 5.99 .+-. 0.1 VW 5.71 .+-. 0.1 VW 4.97 .+-. 0.1 W 3.85 .+-. 0.07 M 3.82 .+-. 0.07 MS 3.75 .+-. 0.05 M 3.32 .+-. 0.05 VW 1.99 .+-. 0.02 W ______________________________________
and having the following composition in terms of mole ratios of oxides:
0.9.+-.0.2 M.sub.2/n O:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,
wherein M is at least one cation having a valence of n, Y is within the range of about 4 to about 500, and Z is within the range of 0 to about 160.

1 more element

A process for the isomerization of a xylene feed, which process comprises contacting said feed under isomerization conditions with a catalyst comprising a crystalline chromosilicate, which chromosilicate comprises a molecular sieve material providing an X-ray diffraction pattern comprising the following X-ray diffraction lines and assigned strengths:

______________________________________ Interplanar Spacing Assigned d, A Strength ______________________________________ 11.15 .+-. 0.2 W 9.96 .+-. 0.2 VS 5.99 .+-. 0.1 VW 5.71 .+-. 0.1 VW 4.97 .+-. 0.1 W 3.85 .+-. 0.07 M 3.82 .+-. 0.07 MS 3.75 .+-. 0.05 M 3.32 .+-. 0.05 VW 1.99 .+-. 0.02 W ______________________________________
and having the following composition in terms of mole ratios of oxides:
0.9.+-.0.2 M.sub.2/n O:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,
wherein M is at least one cation having a valence of n, Y is within the range of about 4 to about 500, and Z is within the range of 0 to about 160, said chromosilicate having been prepared by the method which comprises:
(1) preparing a mixture containing an oxide of silicon, a compound of chromium, a hydroxide of an alkali metal or an alkaline earth metal, an alkylammonium cation or a precursor of an alkylammonium cation, and water;
(2) maintaining said mixture at suitable reaction conditions to effect formation of said chromosilicate, said reaction conditions comprising a temperature within the range of about 25.degree. C. to about 300.degree. C., a pressure of at least the vapor pressure of water at said temperature, and a reaction time that is sufficient to effect crystallization to crystals of said chromosilicate;
(3) drying said crystals;
and (4) activating said crystals of chromosilicate by heat treating said crystals at a temperature within the range of about 800.degree. F. (427.degree. C.) to about 1,700.degree. F. (927.degree. C.) in the presence of a hydrogen-containing atmosphere, and said mixture that is prepared in step (1) of said method of preparation having ratios of the initial reactant concentrations in the following ranges:
SiO.sub.2 /Cr.sub.2 O.sub.3 :1-500
R'.sub.4 N.sup.+ /(R'.sub.4 N.sup.+ +Na.sup.+ :0.1-1
OH.sup.- /SiO2:0.1-10
H.sub.2 O/OH.sup.- :10-500
wherein R' is an alkyl group and Na.sup.+ represents sodium, any other alkali metal, or an alkaline earth metal.

10 more elements

Dependencies are inferred from the claim text.

Crystalline chromosilicates and process uses

Life of this patent

Crystalline chromosilicates and process uses

Life of this patent

Abstract

Claims30