Reverse flow reactors having low maldistribution parameter while containing asymmetric feeds, methods of using same, and pyrolysis products made from same

Patent metadata

Field	Value
Publication number	US-11279884-B2
Application number	US-201917041012-A
Country	US
Kind code	B2
Filing date	Apr 9, 2019
Priority date	Apr 20, 2018
Publication date	Mar 22, 2022
Grant date	Mar 22, 2022

Abstract

Reverse flow reactor (RFR) apparatuses exhibiting asymmetric feed profiles and improved flow distribution during heating mode and/or pyrolysis mode operation, and methods of using same to transform a hydrocarbon feed into a pyrolysed hydrocarbon product are disclosed. The RFR apparatus includes an RFR body with a reaction zone having at least one bed. The RFR body has a central vertical axis and is flanked by first and second void spaces. The method utilizes at least two oxygen-containing feeds, a combustion fuel feed, a purge feed, and a hydrocarbon pyrolysis feed. The RFR apparatus can cycle between an exothermic heating mode (heated to ≥700° C. while maintaining a pressure drop across the reaction zone of ≤100 kPag), a purge mode (purging oxygen using <6 bed volumes of purge gas while maintaining a pressure drop of ≤35 kPag), and an endothermic pyrolysis mode (feeding pyrolysis hydrocarbons through the reaction zone to form pyrolysis products, while maintaining a pressure drop across the reaction zone of ≤70 kPag).

First claim

What is claimed is:

1. A method of transforming a hydrocarbon feed into a pyrolysed product in a reverse flow reactor (RFR) apparatus exhibiting an asymmetric heating feed profile and a low maldistribution parameter, the method comprising:
providing an RFR apparatus comprising an RFR body, a reaction zone located within the RFR body, at least two oxygen-containing feeds, a combustion fuel feed, a purge feed, and a pyrolysis feed which comprises hydrocarbon, at least 60 mol % of which comprise C 2+ hydrocarbon compounds, wherein (i) the reaction zone has a central vertical axis and is flanked by first and second void spaces and (ii) the reaction zone includes at least one bed having the form of a monolith having a plurality of discrete passages extending axially therethrough;
operating the RFR apparatus to cycle between an exothermic heating mode, a purge mode, and an endothermic pyrolysis mode so as to attain substantially hydrocarbon pyrolysis products;
in the heating mode, heating the reaction zone to a temperature of at least 700° C. by reacting the combustion fuel feed with the oxygen-containing feeds while maintaining a pressure drop across the reaction zone of about 15 psig or less;
in the purge mode, purging oxygen from the reaction zone using less than 6 bed volumes of the purge feed and under conditions sufficient to maintain a pressure drop across the reaction zone of about 5 psig or less; and
in the pyrolysis mode, exposing the hydrocarbons in the pyrolysis feed to a temperature and flow conditions and for a time sufficient to pyrolyse the hydrocarbons to form the pyrolysis products, while maintaining a pressure drop across the reaction zone of 10 psig or less,
wherein the heating mode is operated under conditions such that the maldistribution parameter is at 5% or less, and such that a ratio of the pressure drop across the reaction zone to an average axial kinetic energy density of the feeds within the first and second void spaces is at least 10.

2. The method of claim 1 , wherein the RFR apparatus further contains a catalyst to facilitate conversion of the hydrocarbons in the pyrolysis feed to form the pyrolysis products.

3. The method of claim 1 , further comprising purifying the pyrolysis products to reduce a concentration of one or more first pyrolysis products and/or to enhance a concentration of one or more second pyrolysis products, thereby forming a pyrolysis product.

4. The method of claim 1 , wherein the pyrolysis mode is operated under conditions such that the maldistribution parameter is at 10% or less, and such that a ratio of the pressure drop across the reaction zone to an average axial kinetic energy density of the feeds within the first and second void spaces is at least 10.

5. The method of claim 1 , wherein less than 15 mol % of the hydrocarbons in the pyrolysis feed comprise C 1 hydrocarbons, and at least 50 mol % of the hydrocarbons in the pyrolysis feed comprise C 2 hydrocarbons.

6. The method of claim 1 , wherein the heating mode is operated so as to maintain the pressure drop across the reaction zone at 10 psig or less, the maldistribution parameter at 2% or less, and the ratio of the pressure drop across the reaction zone to the average axial kinetic energy density of the feeds within the first and second void spaces between 20 and 40.

7. The method of claim 1 , wherein the heating mode is operated under conditions such that a catalyst located within the reaction zone is at least partially regenerated, thereby reducing a content of coke on the catalyst to less than 5 wt. %.

8. The method of claim 1 , wherein the purging is conducted so as to maintain the pressure drop across the reaction zone at 2 psig or less and to achieve an oxygen level at an outlet of the RFR body of at most 20 ppm in the purge mode, while using 4.5 bed volumes or less of the purge feed.

9. The method of claim 1 , wherein the pyrolysis mode is operated so as to maintain the maldistribution parameter at 5% or less, and the ratio of the pressure drop across the reaction zone to the average axial kinetic energy density of the feeds within the first and second void spaces between 20 and 40.

10. The method of claim 1 , wherein at least two purge feeds and at least two pyrolysis feeds are present, wherein at least one of the purge feeds comprises steam provided in a flow path countercurrent to the pyrolysis feeds through the reaction zone, and wherein the method thus comprises steam cracking of the hydrocarbons in the pyrolysis feed.

11. The method of claim 3 , wherein the one or more second pyrolysis products comprise one or more of ethylene, acetylene, propylene, 1,4-butadiene, benzene, toluene, o-xylene, p-xylene, and naphthalene.

12. The method of claim 3 , wherein the one or more first pyrolysis products comprise methane, ethane, propane, butane, and hydrogen.

13. The method of claim 1 , wherein the RFR body comprises:
a first distributor between the first void space and the reaction zone;
a second distributor between the second void space and the reaction zone; and
a support structure configured to mechanically support the reaction zone and the first and second distributors and disposed adjacent to the second distributor, such that the support structure is between the reaction zone and the second void space.

14. The method of claim 1 , wherein the RFR apparatus comprises:
two or more oxygen-containing feed ports configured to axially feed the at least two oxygen-containing feeds into the first void space of the RFR body and arranged asymmetrically with respect to the central axis;
a pyrolysis feed port configured to axially feed the pyrolysis feed containing the hydrocarbons into the second void space of the RFR body;
a pyrolysis products port configured to axially receive the pyrolysis products from the first void space of the RFR body;
a flue gas port configured to axially receive by-product fluids from the second void space of the RFR body;
two or more purge feed ports, at least one configured to axially feed a first portion of the purge feed into the first void space and at least one configured to axially feed a second portion of the purge feed into the second void space; and
one or more combustion fuel feed ports configured to feed the combustion fuel feed into the reaction zone.

15. The method of claim 14 , wherein the RFR apparatus further comprises:
at least two pyrolysis feed ports arranged asymmetrically with respect to the central axis;
at least two pyrolysis products ports arranged asymmetrically with respect to the central axis; and
at least two flue gas ports arranged asymmetrically with respect to the central axis.

16. The method of claim 13 , wherein a ratio of a volume of the first void space to a volume of the reaction zone is 0.070 or less, and a ratio of a sum of a volume of the second void space plus the support structure volume to the volume of the reaction zone is 0.16 or less.

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Daly Kevin B
• Barrai Federico

Classifications

• C10G9/26 Primary

  with discontinuously preheated non-moving solid material, e.g. blast and run · CPC title

• C07C4/04

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

• B01J2219/2419

  for the reactants · CPC title

• B01J19/2485

  Monolithic reactors · CPC title

• C10B55/02

  with solid materials · CPC title