Processes for converting aromatic hydrocarbons using passivated reactor

Patent metadata

Field	Value
Publication number	US-11535578-B2
Application number	US-202016820227-A
Country	US
Kind code	B2
Filing date	Mar 16, 2020
Priority date	Mar 28, 2019
Publication date	Dec 27, 2022
Grant date	Dec 27, 2022

Abstract

This disclosure provides improved processes for converting aromatic hydrocarbons, such as benzene/toluene, alkylation, transalkylation, or isomerization. In an embodiment, a process comprises utilizing a passivated reactor to reduce deactivation of a molecular sieve catalyst. Additional measures such as the use of an auxiliary catalyst and/or an elevated reactor pressure may be used to further reduce deactivation of the molecular sieve catalyst.

First claim

What is claimed is:

1. A process for converting aromatic hydrocarbons, the process comprising:
(I) providing a passivated reactor;
(II) providing a conversion catalyst system in the passivated reactor, the conversion catalyst system comprising a molecular sieve catalyst;
(III) feeding a feed comprising aromatic hydrocarbons into the passivated reactor; and
(IV) contacting the feed with the conversion catalyst system under conversion conditions to produce a conversion product mixture effluent,
wherein the step (I) comprises:
(Ia) providing an unpassivated reactor;
(Ib) passivating the unpassivated reactor to obtain the passivated reactor by methods of passivating internal surface of the unpassivated reactor comprising the following:
(Ib.1) forming a layer of a glass material on the internal surface of the unpassivated reactor;
wherein in the step (Ib.1), the glass material is selected from borosilicate glass, aluminosilicate glass, or a combination thereof and the step (Ib.1) comprises coating the internal surface of the unpassivated reactor with particles of the glass material and heating the unpassivated reactor to a temperature ≥600° C.

2. The process of claim 1 , wherein the methods of passivating internal surface of the unpassivated reactor further comprise:
(Ib.2) forming a layer of a refractory material selected from alumina, silica, calcium oxide, magnesium oxide, or a combination thereof on the internal surface of the unpassivated reactor;
wherein the step (Ib.2) comprises coating the interior surface of the unpassivated reactor with particles of the refractory material and heating at a temperature of ≥500° C. for ≥30 minutes.

3. The process of claim 1 , wherein the methods of passivating internal surface of the unpassivated reactor further comprise:
(Ib.3) washing the internal surface of the unpassivated reactor with a passivating liquid;
wherein in the step (Ib.3), the passivating liquid is selected from an aqueous solution of citric acid, nitric acid, or a combination thereof.

4. The process of claim 3 , wherein after the step (Ib.3), the internal surface of the passivated reactor is washed with clean water.

5. The process of claim 1 , wherein the methods of passivating internal surface of the unpassivated reactor further comprise:
(Ib.4) electropolishing the internal surface of the unpassivated reactor;
wherein in the step (Ib.4), the electropolishing is conducted by filling the unpassivated reactor with an electrolyte solution and applying a direct current to the unpassivated reactor.

6. The process of claim 1 , wherein the methods of passivating internal surface of the unpassivated reactor further comprise:
(Ib.5) sulfiding the internal surface of the unpassivated reactor.

7. The process of claim 6 , wherein the step (Ib.5) is carried out after the step (Ib.1).

8. The process of claim 1 , wherein the conversion catalyst system has a deactivation rate of no greater than 0.005% gram of the molecular sieve catalyst per gram of the feed.

9. The process of claim 1 , wherein the conversion catalyst system comprises a hydrogenation metal, and optionally a binder.

10. The process of claim 1 , wherein the passivated reactor is a methylation reactor, a transalkylation reactor, or an isomerization reactor.

11. The process of claim 10 , wherein the passivated reactor is a methylation reactor, the conversion catalyst system is a methylation catalyst system comprising a zeolite, the feed further comprises a methylating agent, the aromatic hydrocarbons comprises toluene and/or benzene, and the conversion product mixture effluent comprises xylenes.

12. The process of claim 11 , wherein the methylation catalyst system is disposed in a fixed bed, the methylating agent comprises methanol and/or dimethyl ether, and the conversion product mixture effluent further comprises toluene and at least one of methanol and dimethyl ether.

13. The process of claim 12 , wherein the conversion product mixture effluent comprises methanol and dimethyl ether, the conversion catalyst system comprises a MWW framework type zeolite, and the conversion conditions comprise a temperature ranging from 200 to 500° C.

14. The process of claim 11 , wherein the conversion catalyst system further comprises an auxiliary catalyst, and the auxiliary catalyst comprises a metal element selected from the Group 2 elements, the Group 3 elements, the lanthanide series elements, the actinide series elements, and mixtures and combinations thereof.

15. The process of claim 11 , wherein a molar ratio of the aromatic hydrocarbon(s) to the methylating agent is R(a/m),

R
⁡
(

a
/
m

)

=

M
⁡
(
tol
)

+

2
·

M
⁡
(
bz
)

M
⁡
(
methano1
)

+

2
·

M
⁡
(
DME
)

,

where M(tol) and M(bz) are the moles of toluene and benzene in the aromatic hydrocarbon(s), respectively, and M(methanol) and M(DME) are the moles of methanol and dimethyl ether in the methylating agent; respectively, and wherein 1≤R(a/m)≤5.

16. The process of claim 11 , wherein the conversion conditions comprise a weight hourly space velocity in a range from 0.5 to 50 hour −1 , based on flow rate of the feed and the weight of the zeolite.

17. The process of claim 11 , wherein the conversion conditions comprise an absolute pressure in the passivated reactor of at least 4400 kPa.

18. A process for converting benzene and/or toluene; the process comprising:
(I) providing a passivated methylation reactor;
(II) providing a fixed bed of a methylation catalyst system in the passivated methylation reactor, wherein the methylation catalyst system comprises a zeolite; wherein the zeolite comprises a MWW framework type zeolite, and the methylation catalyst system further comprises an auxiliary catalyst physically mixed with the zeolite, and wherein the auxiliary catalyst comprises an oxide of one or more of the lanthanide series elements;
(III) feeding a feed comprising an aromatic hydrocarbon and a methylating agent into the passivated methylation reactor, wherein the aromatic hydrocarbon is benzene and/or toluene, and the methylating agent is methanol and/or dimethyl ether; and
(IV) contacting the feed with the methylation catalyst system under conversion conditions effect

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Washburn Seth M
• Chiang Hsu
• Aslam Umar
• Lai Wenyih Frank
• Levin Doron
• Chen Tan-Jen

Classifications

• C07C15/08

  Xylenes · CPC title

• C23C22/78

  Pretreatment of the material to be coated · CPC title

• C07C2529/00

  Catalysts comprising molecular sieves · CPC title

• B01J8/02

  with stationary particles, e.g. in fixed beds · CPC title

• B01J2208/00628

  Controlling the composition of the reactive mixture · CPC title