Process for producing light olefins and aromatics

Patent metadata

Field	Value
Publication number	US-9771529-B2
Application number	US-201414292945-A
Country	US
Kind code	B2
Filing date	Jun 2, 2014
Priority date	Mar 8, 2004
Publication date	Sep 26, 2017
Grant date	Sep 26, 2017

Abstract

A process for producing light olefins and aromatics, which comprises reacting a feedstock by contacting with a catalytic cracking catalyst in at least two reaction zones, wherein the reaction temperature of at least one reaction zone among the reaction zones downstream of the first reaction zone is higher than that of the first reaction zone and its weight hourly space velocity is lower than that of the first reaction zone, separating the spent catalyst from the reaction product vapor, regenerating the separated spent catalyst and returning the regenerated catalyst to the reactor, and separating the reaction product vapor to obtain the desired products, light olefins and aromatics. This process produces maximum light olefins such as propylene, ethylene, etc from heavy feedstocks, wherein the yield of propylene exceeds 20% by weight, and produces aromatics such as toluene, xylene, etc at the same time.

First claim

What is claimed is:

1. A process for producing light olefins and aromatics, comprising the steps of:
(1) reacting a feedstock with a hydrotreating catalyst and hydrogen in a hydrotreating unit under the conditions of a hydrogen partial pressure between about 3.0 MPa and 20.0 MPa, a reaction temperature between about 300° C. and 450° C., a hydrogen/oil ratio between about 300 and 2000 by volume, and a liquid hourly space velocity (LHSV) between about 0.1 h −1 -3.0 h −1 , and separating a reaction effluent to obtain a hydrotreated product and hydrogen, wherein the hydrogen enters a recycle stream that is fed into the hydrotreating unit; and
(2) catalytically cracking in a catalytic cracker the hydrotreated product under conditions of a reaction temperature between about 400° C. and 800° C. and a weight hourly space velocity (WHSV) between about 0.1 h −1 and 750 h −1 ,
wherein the catalytic cracker comprises a first reaction zone, a final reaction zone, and optionally one or more reaction zones disposed between the first reaction zone and the final reaction zone,
wherein the catalytic cracking of the hydrotreated product in Step (2) comprises:

introducing the hydrotreated product and a catalytic cracking catalyst into the first reaction zone;
introducing substantially all effluent from the first reaction zone into a reaction zone downstream from the first reaction zone;
obtaining a spent catalyst and a reaction product stream from the final reaction zone;
separating the spent catalyst from the reaction product stream;
regenerating the spent catalyst to produce a regenerated catalyst;
introducing the regenerated catalyst into the catalytic cracker,
wherein a reaction temperature in a reaction zone downstream from the first reaction zone is higher than that of the first reaction zone,
wherein values of WHSV in the catalytic cracker range from 0.1 h −1 and 750 h −1 and the WHSV of a reaction zone downstream from the first reaction zone is lower than that of the first reaction zone.

2. The process according to claim 1 , wherein the hydrotreating catalyst in the step (1) is a catalyst comprising one or more non-noble metal selected from a group consisting of Group VIB and Group VIII elements supported on a support selected from the group consisting of alumina, an amorphous silica-alumina, and combinations thereof.

3. The process according to claim 2 , wherein said non-noble metal of Group VIB is Mo, W, or both and that of Group VIII is Co, Ni, or both.

4. A process for producing light olefins and aromatics, comprising the steps of:
(1) hydrotreating a feedstock in the presence of hydrotreating hydrogen and a hydrotreating catalyst under the conditions of a hydrogen partial pressure between about 3.0 MPa and 20.0 MPa, a reaction temperature between about 300° C. and 450° C., a hydrogen/oil volume ratio between about 300-2000, and a liquid hourly space velocity (LHSV) between about 0.1 h −1 -3.0 h −1 , and separating a reaction effluent to obtain H 2 , CH 4 , hydrotreated C 2 0 -C 4 0 , hydrotreated naphtha, and a hydrotreated product, wherein the H 2 reaction effluent is reused for reaction with the feedstock;
(2) catalytically cracking the hydrotreated product in a catalytic cracking reactor under conditions of a reaction temperature between about 400° C. and 800° C. and a weight hourly space velocity (WHSV) between about 0.1 h −1 and 750 h −1 , separating spent catalyst from a reaction product vapor, and stripping and regenerating the spent catalyst for reuse, separating a reaction product vapor to obtain H 2 , CH 4 , catalytic cracking C 2 = -C 3 = , catalytic cracking C 2 0 -C 3 0 , catalytic cracking C 4 -C 5 , catalytic cracking naphtha, LCO, and heavy cycle oil (HCO), and cycling the C 4 -C 5 , LCO, and HCO into the catalytic cracking reactor;
(3) steam cracking the hydrotreated C 2 0 -C 4 0 and hydrotreated naphtha of step (1) and catalytic cracking C 2 0 -C 3 0 of step (2) in a steam cracking unit under a temperature between about 700° C.-1000° C. to produce a stream cracking product and separating the stream cracking product to obtain H 2 , CH 4 , steam cracking C 2 = -C 3 = , steam cracking C 2 0 -C 3 0 , steam cracking C 4 -C 5 , steam cracking naphtha, and fuel oil, wherein the steam cracking C 4 -C 5 are cycled to the catalytic cracking reactor;
(4) selectively hydrogenating the catalytic cracking naphtha of step (2) and the steam cracking naphtha of step (3) to produce a hydrogenated naphtha, and separating the hydrogenated naphtha in a solvent extraction unit to obtain an aromatics stream and an extraction raffinate, and feeding the extraction raffinate to the steam cracking unit for steam cracking,
wherein the catalytic cracker comprises a first reaction zone, a final reaction zone, and optionally one or more reaction zones disposed between the first reaction zone and the final reaction zone,
wherein the catalytic cracking of the hydrotreated product in Step (2) comprises:
introducing the hydrotreated product and a catalytic cracking catalyst into the first reaction zone;
introducing substantially all effluent from the first reaction zone into a reaction zone downstream from the first reaction zone,
wherein a reaction temperature in a reaction zone downstream from the first reaction zone is higher than that of the first reaction zone, and
wherein a WHSV of a reaction zone downstream from the first reaction zone is lower than that of the first reaction zone.

5. The process according to claim 4 , wherein the conditions for steam cracking in step (3) include a residence time for reaction between about 0.05 seconds and 0.6 seconds, and a steam to oil ratio between about 0.1-1.0 by weight.

6. The process according to claim 4 , wherein the conditions for selective hydrogenation of step (4) include a hydrogen partial pressure between about 1.2 MPa and 8.0 MPa, a reaction temperature between about 150° C. and 300° C., a hydrogen to oil ratio between about 150 and 600 by volume, and a LHSV between about 1 h −1 and 20 h −1 .

7. The process according to claim 4 , wherein a solvent in the solvent extraction unit of step (4) is one selected from the group consisting of sulfolane, N-methyl pyrrolidone, diethyl glycol ether, triethyl glycol ether, tetraethyl alcohol, dimethyl sulfoxide, and N-formyl morpholine, and mixtures thereof.

8. The process according to claim 4 , wherein the temperature for the solvent extraction in step (4) is about 80° C.-120° C. and a solvent to feed ratio is about 2-6 by volume.

Assignees

• China Petroleum & Chem Corp
• Res Inst Petroleum Processing Sinopec

Inventors

• Long Jun
• Da Zhijian
• Li Dadong
• Wang Xieqing
• Shu Xingtian
• Zhang Jiushun
• Nie Hong
• Xie Chaogang
• Zhang Zhigang
• Wang Wei

Classifications

• C10G2300/44

  Solvents · CPC title

• C10G2400/20

  C2-C4 olefins · CPC title

• C07C4/06

  Catalytic processes {(C07C4/025 takes precedence)} · CPC title

• C10G69/02

  plural serial stages only · CPC title

• C10G2300/1074

  Vacuum distillates · CPC title