Patent EA-002376-B1 (EA)
Title: Process for production of paraxylene
Inventor: MOHR GARY D
IPC: C07C5/41
Filed: 1997-05-29
Abstract: 1. A process for making para-xylene by reacting toluene with a methylating agent under methylation conditions in the presence of a zeolite bound zeolite catalyst which contains less than 10% by weight of non-zeolitic binder based on the combined weight of first and second zeolite and comprises: (a) crystals of a first intermediate pore size zeolite; and (b) a binder comprising crystals of a second zeolite. 2. The process recited in Claim 1 wherein the second zeolite crystals are intergrown and form at least a partial coating on the first zeolite crystals. 3. The process recited in Claim 1 or 2 wherein the catalyst contains less than 5% by weight of non-zeolitic binder based on the combined weight of first zeolite and second zeolite. 4. The process recited in any preceding Claim wherein the first zeolite crystals have an average particle size greater than 0.1 micron and the second zeolite crystals have an average particle size less than that of the first zeolite crystals. 5. The process recited in Claim 4 wherein the first zeolite crystals have an average particle size of from 1 to 6 microns and/or the second zeolite crystals have an average particle size of from 0.1 to 0.5 microns. 6. The process recited in any preceding Claim wherein the first zeolite and/or the second zeolite is an aluminosilicate zeolite or a gallium silicate zeolite. 7. The process recited in Claim 6 wherein the first zeolite is an aluminosilicate with a silicon dioxide to aluminium oxide mole ratio of from 10:1 to 300:1 or a gallium silicate with a silicon dioxide to gallia oxide mole ratio of from 40:1 to 500:1. 8. The process recited in Claim 6 or 7 wherein the second zeolite is an aluminosilicate with silicon dioxide to aluminium oxide mole ratio greater than 200:1 or a gallium silicate with silicon dioxide to gallia oxide mole ratio greater than 100:1. 9. The process recited in any preceding Claim wherein the structure type of the first zeolite and the second zeolite is independently selected from the group consisting of AEL, MFI, MEL, MTW, MTT, FER, TON and EUO. 10. The process recited in Claim 9 wherein the first zeolite has an MFI structure and/or the second zeolite has an MFI or MEL structure. 11. The process recited in Claim 10 wherein the second zeolite is silicalite or silicalite 2. 12. The process recited in any preceding Claim wherein the catalyst is preparable by aging at elevated temperature a silicon dioxide -bound aggregate containing the crystals of first zeolite in an aqueous ionic solution containing a source of hydroxy ions sufficient to convert the silicon dioxide in the aggregate to the second zeolite. 13. The process recited in any preceding Claim wherein the catalyst is selectivated. 14. The process recited in Claim 13 wherein the catalyst is selectivated with a selectivation agent comprising a silicon compound, preferably hexadimethylsiloxane. 15. The process recited in Claim 13 wherein the catalyst is preselectivated by contacting the catalyst with a toluene stream at a temperature of from 482 to 649 degree C (900 to 1200 degree F), a pressure of from 0.10 to 10.1 MPa (1 to 100 atmospheres) and a weight hourly space velocity of from 0.1 to 20, and wherein the toluene stream optionally further contains hydrogen at a H2/toluene mole ratio of up to 2. 16. The process recited in Claim 15 wherein the mole ratio of hydrogen to toluene in the toluene stream is from 0.1 to 2. 17. The process recited in any of Claims 13 to 16 wherein the catalyst contains at least 2% by weight coke. 18. The process recited in any preceding Claim wherein the methylating agent is methanol, methylchloride, methylbromide, dimethylether or dimethylsulfide. 19. The process recited in any preceding Claim wherein the methylation conditions include a temperature of from 300 degree C to 750 degree C and/or a manometer pressure of from 0.10 MPa to 6.9 MPa (1 atmosphere to 1000 psi) and/or a weight hourly space velocity of from 1 to 200 and/or a molar ratio of methylating agent to toluene of from 0.05 to 5.