Silicon/titanium oxide mfi zeolites

Claim 2

A calcined MFI zeolite having the formula: (Si.sub.96-x Ti.sub.x)O.sub.192 wherein x ranges from about 0.1 to 6, said MFI zeolite having a monoclinic crystalline network.

Claim 3

The MFI zeolite as defined by claim 1, having the X-ray diffraction pattern set forth in Table I.

Claim 4

The MFI zeolite as defined by claim 1, comprising from 0.01 to 0.8% by weight of fluorine.

Claim 5

The MFI zeolite as defined by claim 1, devoid of fluorine values.

Claim 6

A process for the preparation of the MFI zeolite as defined by claim 1, comprising (i) formulating an aqueous reaction medium having a pH ranging from 1.5 to 10.5 and which comprises at least one source of silicon oxide, at least one source of titanium oxide, fluoride ions, and a structuring agent, the Ti/Si molar ratio therein ranging from 0.002 to 1.5, the F/Si molar ratio therein ranging from 0.04 to 10, the H 2 O/Si molar ratio therein ranging from 4 to 400, and the structuring agent/Si molar ratio therein ranging from 0.02 to 2; (ii) crystallizing such reaction mixture; and (iii) recovering and calcining the resulting crystalline precipitate at a temperature greater than about 450° C.

Claim 7

The process as defined by claim 5, said Ti/Si molar ratio ranging from 0.01 to 1.

Claim 8

The process as defined by claim 6, said F/Si molar ratio ranging from 0.06 to 6.

Claim 9

The process as defined by claim 7, said H 2 O/Si molar ratio ranging from 6 to 100.

Claim 10

The process as defined by claim 8, said structuring agent/Si molar ratio ranging from 0.04 to 1.

Claim 11

The process as defined by claim 5, said reaction medium including a common source of the silicon oxide and titanium oxide.

Claim 12

The process as defined by claim 5, said structuring agent comprising a tertiary amine having the formula I: ##STR5## wherein R 1 , R 2 and R 3 , which may be identical or different, are each an alkyl group.

Claim 13

The process as defined by claim 11, wherein the formula I, R 1 , R 2 and R 3 are propyl or butyl.

Claim 14

The process as defined by claim 5, said structuring agent comprising a quaternary ammonium salt having the formula II: ##STR6## wherein R 1 , R 2 , R 3 and R 4 , which may be identical or different, are each an alkyl group.

Claim 15

The process as defined by claim 13, wherein the formula II, R 1 , R 2 , R 3 and R 4 are propyl or butyl.

Claim 16

The process as defined by claim 5, said structuring agent comprising a compound having the formula: ##STR7## wherein R 1 , R 2 and R 3 , which may be identical or different, are each an alkyl group.

Claim 17

The process as defined by claim 5, said structuring agent comprising a compound having the formula: ##STR8## wherein R 1 , R 2 , R 3 and R 4 , which may be identical or different, are each an alkyl group.

Claim 18

The process as defined by claim 5, said at least one source of silicon oxide comprising a hydrogel, aerogel, colloidal silica suspension, silicic ester, water soluble silicate, silica derived from a natural or synthetic crystalline compound, or hydrolyzable tetravalent silicon compound.

Claim 19

The process as defined by claim 17, said at least one source of titanium oxide comprising a natural or synthetic titanium oxide or hydroxide, halide, alcoholate, or water soluble titanate salt.

Claim 20

The process as defined by claim 5, said reaction mixture comprising at least one titanium co-mobilizing agent, in a molar ratio relative to silicon, of from 0.01 to 3.

Claim 21

The process as defined by claim 19, said co-mobilizing agent comprising oxalic acid or salt thereof, acetylacetone, or tartaric acid or salt thereof.

Claim 22

The process as defined by claim 5, the fluoride ions in said reaction mixture being derived from hydrofluoric acid, ammonium or amine fluoride, or a hydrolyzable compound releasing fluoride anions.

Claim 23

The process as defined by claim 21, said fluoride ions being derived from titanium fluoride, silicon fluoride, a double ammonium and titanium fluoride, or a double ammonium and silicon fluoride.

Claim 24

The process as defined by claim 5, said reaction mixture having a pH of from 5 to 10.5; a molar ratio of Ti/Si ranging from 1.5 to 0.002; a molar ratio of F/Si ranging from 10 to 0.04; a molar ratio of H 2 O/Si ranging from to 4; and a molar ratio of structuring agent/Si ranging from 2 to 0.02.

Claim 25

A selective adsorbent comprising the MFI zeolite as defined by claim 1.

Claim 26

A catalyst comprising the MFI zeolite as defined by claim 1.

Claim 27

A catalyst support comprising the MFI zeolite as defined by claim 1.