Claims:WE CLAIM:
1. A process for producing olefins, said process comprising the following steps:
a) heating a feed comprising CO2 and at least one alkane in a reformer, at a first predetermined temperature and at a first predetermined pressure, in the presence of at least one first catalyst, to produce a first stream comprising syngas and unused feed,
wherein the ratio of H2 to CO in said syngas is 1:1;
b) contacting said first stream comprising syngas with at least one second catalyst in a first reactor, at a second predetermined temperature and at a second predetermined pressure, to produce a second stream comprising dimethyl ether (DME), and a first mixture of unconverted syngas and CO2;

c) contacting said second stream comprising DME with a third catalyst in a second reactor, at a third predetermined temperature and at a third predetermined pressure, to produce a third stream comprising olefins, H2O, unconverted DME, and a second mixture of alkanes comprising said at least one alkane; and
d) separating said H2O, said unconverted DME, and said second mixture of alkanes from said third stream in a fractionation column to obtain said olefins.
2. The process as claimed in claim 1, wherein said process comprises separating from said first stream said syngas and said unused feed, in a first separator and recycling said unused feed to said reformer.

3. The process as claimed in claim 1, wherein said process comprises separating from said second stream, said DME and said first mixture of unconverted syngas and CO2 in a second separator; separating said unconverted syngas and said CO2 in a third separator and recycling the separated CO2 to said reformer, and said unconverted syngas to said first reactor.
4. The process as claimed in claim 1, wherein said process steps (a) to (c) are carried out in a single reactor by heating said feed comprising CO2 and said at least one alkane, at said first predetermined temperature and at said first predetermined pressure, in the presence of at least one tri-functional catalyst, to produce said third stream comprising H2O, unconverted syngas, unconverted CO2, unconverted alkane, olefins, and unconverted DME; and
separating said H2O, unconverted syngas, unconverted CO2, unconverted alkane, and unconverted DME from said third stream in said fractionation column to obtain said olefins.

5. The process as claimed in claim 4, wherein said tri-functional catalyst is at least one selected from the group consisting of copper oxide, chromium oxide, zinc oxide, aluminium oxide, zeolites, aluminophosphate molecular sieve, and silicoaluminophosphate (SAPO).

6. The process as claimed in claim 1, wherein said first predetermined temperature is in the range of 300 ºC to 1000 ºC and said first predetermined pressure is in the range of 1 kg/cm2 to 80 kg/cm2.
7. The process as claimed in claim 1, wherein said second predetermined temperature is in the range of 100 ºC to 400 ºC and said second predetermined pressure in the range of 1 kg/cm2 to 60 kg/cm2.
8. The process as claimed in claim 1, wherein said third predetermined temperature is in the range of 200 ºC to 600 ºC and said third predetermined pressure is in the range of 0.5 kg/cm2 to 10 kg/cm2.
9. The process as claimed in claim 1, wherein said first catalyst is at least one selected from the group consisting of compounds of nickel, cerium, and cobalt.
10. The process as claimed in claim 1, wherein said second catalyst is at least one selected from the group consisting of copper oxide, chromium oxide, zinc oxide and, aluminium oxide.
11. The process as claimed in claim 1, wherein said third catalyst is at least one selected from the group consisting of zeolites, aluminophosphate molecular sieve, and silicoaluminophosphate (SAPO).
12. The process as claimed in claim 1, wherein said process comprises recycling said unconverted DME to said second reactor and said mixture of alkanes to said reformer.
13. The process as claimed in claim 1, wherein said olefin is at least one of ethylene and propylene.
14. The process as claimed in claim 1, wherein said alkane is a C1 to C20 alkane.
15. The process as claimed in claim 1, wherein the ratio of the amount of said CO2 to the amount of said alkanes is in the range of 1:1 to 4:1.11.
16. An apparatus for producing olefins; said apparatus comprising:
a. a reformer (R) configured for receiving a feed comprising CO2 and at least one alkane, and heating said feed in the presence of a first catalyst to produce a first stream comprising syngas and unused feed;
b. a first separator (S1) configured for receiving said first stream and separating from said first stream, said unused feed to obtain a stream of syngas;
c. a first conduit (i) for leading said first stream from said reformer (R) to said first separator (S1);
d. a second conduit (ii) for recycling said unused feed from said first separator (S1) to said reformer (R);
e. a first reactor (D) configured for receiving said stream comprising syngas and contacting said stream comprising syngas with a second catalyst to obtain a second stream comprising dimethyl ether (DME) and a first mixture comprising unconverted syngas and CO2;
f. a third conduit (iii) for leading said stream comprising syngas from said first separator (S1) to said first reactor (D);
g. a second separator (S2) configured for receiving said second stream, and separating from said second stream, said first mixture to obtain a stream of DME;
h. a fourth conduit (iv) for leading said second stream from said first reactor (D) to said second separator (S2);
i. a third separator (S3) configured for receiving said first mixture, and separating said unconverted syngas and said CO2 from said first mixture;
j. a fifth conduit (v) for leading said first mixture from said second separator (S2) to said third separator (S3);
k. a sixth conduit (vi) for recycling said unconverted syngas from said third separator (S3) to said first reactor (D);
l. a seventh conduit (vii) for recycling said CO2 from said third separator (S3) to said reformer (R);
m. a second reactor (O) configured for receiving said stream comprising DME and contacting said stream comprising DME with a third catalyst to obtain a third stream comprising olefins, H2O, unconverted DME, and a second mixture of alkanes comprising said alkane;
n. an eighth conduit (viii) for leading said stream comprising DME from said second separator (S2) to said second reactor (O);
o. a fractionation column (Dw) configured for receiving said third stream, and separating said H2O, said unconverted DME, said second mixture of alkanes from said third stream to obtain a stream of olefins;
p. a ninth conduit (ix) for leading said third stream from said second reactor (O) to said fractionation column (Dw);
q. a tenth conduit (x) for recycling said second mixture of alkanes from said fractionation column (Dw) to said reformer (R); and
r. an eleventh conduit (xi) for recycling said unconverted DME and heavies from said fractionation column (Dw) to said second reactor (O).
, Description:FIELD
The present disclosure relates to a process for production of olefins from CO2.
BACKGROUND
Ethylene and propylene are the major olefins globally produced in high volumes by cracking feeds such as ethane, propane, butane, naphtha, gas oil, etc. Propylene is co-produced with gasoline in Fluid Catalytic Cracking (FCC) units. Additionally, Propylene is also produced by Propane Dehydrogenation technology. Furthermore, Ethylene and Propylene are also produced by Methanol to Olefin technology and Coal to Olefins technology with syngas as an intermediate product. Other processes are known for the production of Ethylene and Propylene, however, insignificant volumes of Ethylene and Propylene are produced by these processes.
CO2 emissions are inevitable part of most of the industrial processes that consume fuel. CO2 emissions have considerable negative impact on the atmosphere. Reduction or elimination of CO2 emission would help to reduce the negative impact on the environment. Moreover, converting CO2 to useful syngas and subsequently into chemicals would domicile the Carbon of CO2 into chemicals for long time and reduce the release of CO2 into atmosphere.
Syngas can be used in a variety of applications such as production of methanol, production of dimethyl ether (DME), production of ammonia, production of urea, heating, generation of steam and generation of power.
Syngas comprises hydrogen (H2), carbon monoxide (CO) and CO2. During the production of syngas, the ratio of H2 to CO in syngas varies depending upon the feed used and the reaction conditions maintained while producing syngas. Syngas can be used for producing olefins using a methanol pathway, wherein syngas is converted to methanol, which is further converted to olefins.
One pathway for the production of olefins from CO2 is illustrated in Figure 1. CO2 (1) and methane (2) are fed to a reforming reactor (100), wherein syngas (3) with H2: CO ratio of 1: 1 is produced. Syngas additionally comprises unreacted CO2 and methane. For the production of methanol, syngas comprising 2:1 ratio of H2 to CO is needed. A portion of syngas (3) is introduced into a water-gas shift reactor (50) from the reforming reactor (100), where water is added and a mixture (5) of H2, CO2 and CO is generated. A remaining portion of syngas from the reforming reactor (100) and the mixture (5) from the water-gas shift reactor (50) are then fed to a separator (200). The flow of the mixture (5) and syngas is managed in such a way that syngas after passing through the separator (200) will have H2: CO ratio of 2:1. In the separator (200) CO2 is separated and recycled to the reforming reactor (100). Syngas (6) having H2: CO ratio of 2: 1 is fed to a methanol reactor (300) from the separator (200) to produce a stream (7) comprising methanol. The reaction for producing methanol is depicted herein below:
2H2 + CO = CH3OH (methanol)
The stream (7) from methanol reactor (300) is a mixture of methanol and unconverted syngas, which is then fed to a separation section (400) from the methanol reactor (300). In the separation section (400), the stream (7) is separated into methanol (9) and syngas (8). Syngas (8) is recycled to the methanol reactor (300) and methanol (9) is introduced into a reactor (500), wherein methanol is dehydrogenated to produce a stream (10) comprising olefins, unconverted methanol and DME, light streams, heavy streams and H2O. The stream (10) is introduced into a separator (600) for separating unconverted methanol and DME (11), light streams (12), heavy streams (13) and H2O (4), to obtain olefins (14). The separated H2O (4) and the unconverted methanol and DME can be further utilized in the water-gas shift reactor/section (50) and for the production of olefins (6) respectively.
Syngas produced using CO2 and Methane reforming has a H2: CO ratio of 1:1. Syngas with H2: CO ratio of 1:1 has to be transformed to H2: CO ratio of 2:1 using water-gas shift reaction, wherein CO is reacted with water to generate H2 and CO2.
Other than water-gas shift reactor, additional process equipment is required for complete removal of carbon dioxide from syngas. Also, the amount of energy required to separate carbon dioxide from syngas is more due to significant CO2 in syngas and need of complete removal of CO2. This increases the capital expenditure (CAPEX) and operational expenditure (OPEX) of this pathway of producing olefins.
Moreover, syngas comprising 2:1 ratio of H2 to CO results in the conversion of syngas to methanol at a particular temperature (in the range of 300oC to 400oC) and pressure (in the range of 60 bar to 90 bar) conditions, thereby requiring a reactor for producing methanol. Also, different process equipment like heaters and compressors are required for achieving the specific temperature and pressure conditions in the reactor. This results in a further increase in the capital expenditure (CAPEX) and operational expenditure (OPEX) of this variant of producing olefins.
Therefore, there is a need for producing olefins with reduced CAPEX and OPEX by an alternate process.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows.
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
An object of the present disclosure is to provide a process for conversion of CO2 to syngas and finally to olefins by different routes.
Another object of the present disclosure is to provide a process which consumes less energy along with reduction of process steps.
Yet another object of the present disclosure is to efficiently separate products and appropriately recycle unused feed and products to additional Olefins production.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure relates to a process for producing olefins. The process comprises heating a feed comprising CO2 and at least one alkane in a reformer at a first predetermined temperature and at a first predetermined pressure, in the presence of at least one first catalyst, to produce a first stream comprising syngas and unused feed. The ratio of H2 to CO in syngas is 1:1.
The first catalyst includes, but is not limited to compounds of nickel, cerium and, cobalt.
The first predetermined temperature can be in the range of 300 ºC to 1000 ºC and the first predetermined pressure can be in the range of 1 kg/cm2 to 80 kg/cm2.
The first stream comprising syngas is contacted with at least one second catalyst in a first reactor, at a second predetermined temperature and at a second predetermined pressure, to produce a second stream comprising dimethyl ether (DME), unconverted CO2, and syngas (H2, and CO).
The second predetermined temperature can be in the range of 100 ºC to 400 ºC and the second predetermined pressure can be the range of 1 kg/cm2 to 60 kg/cm2.
The second catalyst includes, but is not limited to copper oxide, chromium oxide, zinc oxide and, aluminum oxide.
Next, the second stream comprising DME is contacted with at least one third catalyst in a second reactor, at a third predetermined temperature and at a third predetermined pressure, to produce a third stream comprising olefins, H2O, unconverted DME, and a second mixture of alkanes comprising at least one alkane.
The third predetermined temperature can be in the range of 200 ºC to 600 ºC and the third predetermined pressure can be in the range of 0.5 kg/cm2 to 10 kg/cm2.
The third catalyst includes, but is not limited to zeolites, aluminophosphate molecular sieve and substituted forms thereof.
Thereafter, H2O, unconverted DME and the second mixture of alkanes are separated from the third stream in a fractionation column to obtain olefins. The separated CO2 and the mixture of alkanes can be recycled for producing syngas.
In one embodiment, the process comprises separating from the first stream the syngas and the unused feed, in a first separator and recycling the unused feed to the reformer.
In another embodiment, the process comprises separating from the second stream, the DME and the first mixture of unconverted syngas and CO2 in a second separator, and separating the unconverted syngas and the CO2 in a third separator, and recycling the separated CO2 to the reformer, and the unconverted syngas to the first reactor.

In yet another embodiment, the process is carried out by heating the feed comprising CO2 and at least one alkane in a single reactor, at a first predetermined temperature and at a first predetermined pressure, in the presence of at least one tri-functional catalyst, to produce a third stream comprising H2O, unconverted syngas, unconverted CO2, unconverted alkane, olefins, and unconverted DME. Thereafter, H2O, unconverted syngas, unconverted CO2, unconverted alkane, and unconverted DME are separated from the third stream in the fractionation column to obtain olefins.

In accordance with one embodiment of the present disclosure, the olefin is at least one of ethylene and propylene.
In accordance with one embodiment of the present disclosure, the alkane is a C1 to C20 alkane.
The tri-functional catalyst includes, but is not limited to copper oxide, chromium oxide, zinc oxide, aluminium oxide, zeolites, aluminophosphate molecular sieve, and silicoaluminophosphate (SAPO).
The present disclosure also relates to an apparatus for producing olefins.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
A process for production of olefins will now be described with the help of the accompanying drawing, in which:
Figure 1 (prior art) depicts a flow-diagram, illustrating a conventional method for producing olefins from CO2 through methanol;
Figure 2 depicts a system (100) for producing olefins from CO2 through DME;
Figure 3 depicts a system for producing olefins from CO2 through DME without intermediate separation (S1);
Figure 4 depicts a system for producing olefins from CO2 through DME without any intermediate separation; and
Figure 5 depicts a system for producing olefins from CO2 in a single reactor.
The table below lists the numerals used in the drawing and their nomenclature.
Elements Reference number
CO2 1
Methane 2
Syngas with H2 : CO ratio of 1: 1 3
Water 4
H2 rich syngas after shift 5
Syngas with H2 : CO ratio of 2: 1 6
Intermediate stream – Methanol and unconverted syngas 7
Unconverted Syngas 8
Methanol 9
Intermediate stream – Olefins, unconverted DME, Methanol, lighter streams, C4+ water 10
Unconverted methanol and DME 11
Lighters - Methane, Ethane, propane 12
C4+ 13
Olefins 14
Description Unit
Water-gas shift 50
Reforming 100
Separation unit (1) 200
Methanol reactor 300
Separation (2) 400
Methanol To Olefin reactor 500
Separation unit (3) 600
Elements Reference letters
Feed (a)
Reformer (R)
Syngas (b)
First separator (S1)
First reactor (D)
Second stream (c)
Second Separator (S2)
Third Separator (S3)
Separated portion (g)
Separated CO2 (h)
Separated syngas (i)
Second reactor (O)
Separated DME (j)
Third stream (d)
Fractionation column or divided wall column (Dw)
Olefins (e)
Light Alkanes (f)
Heavies and unreacted DME (k)

DETAILED DESCRIPTION
In the process described in the background section, olefins can be produced from CO2, with methanol as an intermediate product, wherein syngas having H2: CO ratio of 1:1 is produced by reforming of CO2 and methane. Syngas having H2: CO ratio of 1:1 has to be converted to syngas with H2: CO ratio of 2:1 with an excess use of H2O, which is not desired.
Additionally, methanol section needs complete removal of CO2 in the feed. Complete separation of CO2 from syngas requires large and severe separation units, which leads to increase in the CAPEX and OPEX of the entire process. The final ratio of H2: CO varies according to the feed used and the process employed as summarized by the reactions below: Syngas mixture of CO and H2 can be produced from Natural Gas, Coal, Petcoke, Biomass or liquid fuel:
CH4 + H2O = CO + 3H2 (Steam reforming, H2: CO: 3: 1)
CH4 + CO2 = 2CO + 2H2 (Dry reforming, H2: CO: 1: 1)
2CH4 + O2= 2CO + 4H2 (Partial Oxidation, H2: CO: 2: 1)
3C + O2 + H2O = 3CO + H2 (Coal Gasification, H2: CO: 1: 3)
8C +3O2 + 2H2O +3H2 = 8CO + 5H2 (Petcoke Gasification, H2: CO: 1: 1.3)
However, there are many other reactions taking place simultaneously which are controlled by process parameters as per the process requirements:
CO + O2 = CO2
CO2 + 3H2 = CH4 + H2O
CO + H2O = H2 + CO2
It can be seen that the final H2: CO ratio is different for different feed and different process.
The optimum ratio of H2: CO can be produced by the following reactions:
CO + H2O = H2 + CO2 (Water-gas shift)
H2 + CO2 = CO + H2O (Reverse -water-gas shift)
The process leads to CO2 / H2O production, CO2 can be separated by sorbents / solvents, membrane or cryogenic distillation.
The present disclosure therefore envisages a process for producing olefins, with reduced CAPEX and OPEX, from CO2.
In an aspect of the present disclosure, there is provided a process for producing olefins. The process is described with reference to Figure 2, which depicts an apparatus for producing olefins, in accordance with one embodiment of the present disclosure. The apparatus of the present disclosure comprises a reformer (R), a first conduit (i), a first separator (S1), a second conduit (ii), a third conduit (iii), a first reactor (D), a fourth conduit (iv), a second separator (S2), a fifth conduit (v), a third separator (S3), a sixth conduit (vi), a seventh conduit (vii), an eighth conduit (viii), a second reactor (O), a ninth conduit (ix), a fractionation column (Dw), a tenth conduit (x), and an eleventh conduit (xi).
In accordance with one embodiment (Figure 2) of the present disclosure the process comprises heating a feed (a) at a first predetermined temperature in the range of 300 ºC to 1000 ºC and at a first predetermined pressure in the range of 1 kg/cm2 to 80 kg/cm2, in the presence of at least one first catalyst in a reformer (R), to produce a first stream comprising syngas (b) and unused feed.
The feed (a) comprises CO2 and at least one alkane. The alkane is at least one C1 to C20 alkane.
In accordance with the embodiments of the present disclosure, the ratio of the amount of CO2 to the amount the alkane is in the range of 1:1 to 4:1.
The first catalyst includes, but is not limited to, compounds of nickel, cerium and cobalt.
The so obtained syngas can have H2: CO ratio of 1:1. The H2: CO ratio of 1:1 facilitates the direct use of the so obtained syngas for DME production.
Further, since the ratio of H2 to CO is 1:1, it obviates the requirement of a separate reactor for shift reaction. One-step dimethyl ether (DME) process requires H2: CO ratio of 1:1, which leads to lower water consumption and CO2 generation. Since, the portion of CO2 in the syngas is relatively lower and the one-step DME process can accommodate some CO2 in feed, the separation of CO2 from syngas would be simpler. The one-step DME process can be carried out even in case where some CO2 is in the feed as compared to methanol process. Therefore, separation of CO2 from syngas in separate process equipment is less severe at this stage.
Next, the first stream comprising the syngas is separated from the unused feed in the first separator (S1) and then introduced into a first reactor (D), where the unused feed can be recycled to the reformer (R).
The first stream comprising syngas is contacted with at least one second catalyst, typically at a second predetermined temperature in the range of 100 ºC to 400 ºC and at a second predetermined pressure in the range of 1 kg/cm2 to 60 kg/cm2, to produce a second stream (c) comprising dimethyl ether (DME), and a first mixture of CO2, and unconverted syngas.
The first mixture of CO2, and syngas is separated from the second stream (c) in a second separator (S2) to obtain DME (j). Separation of CO2, and syngas is achieved with less energy requirement, as CO2 concentration is relatively higher and simpler separation process equipment can be used. The separated CO2, and syngas (g) are introduced into a third separator (S3) for separating CO2 (h), and syngas. The separated CO2 (h) can be recycled for producing syngas and the separated syngas can be recycled in to the first reactor (D).
The second catalyst includes, but is not limited to, copper oxide, chromium oxide, zinc oxide and, aluminum oxide.
The second stream comprising DME (j) is introduced into a second reactor (O) and contacted with at least one third catalyst, at a third predetermined temperature in the range of 200 ºC to 600 ºC and at a third predetermined pressure in the range of 0.5 kg/cm2 to 10 kg/cm2, to produce a third stream (d) comprising olefins, H2O, unreacted DME and a second mixture of alkanes comprising the alkane.
In accordance with the embodiments of the present disclosure, the third catalyst includes, but is not limited to, zeolites, aluminophosphate (ALPO) molecular sieves, silicoaluminophosphate (SAPO) molecular sieves and substituted forms thereof.
The third stream (d) is introduced into a fractionation column or a divided wall column (Dw) for separating, H2O, unreacted DME, light alkanes (f) and the heavies (k) from the second stream (d) to obtain olefins (e).
In accordance with the embodiments of the present disclosure, the unreacted DME and heavies can be recycled to the second reactor (O).
The separated CO2, and the mixture of alkanes can be recycled into the reformer (R) for producing syngas by dry reforming. The unconverted syngas can be recycled to the first reactor.
In accordance with one embodiment of the present disclosure, the olefin is at least one of ethylene and propylene.
In accordance with one embodiment of the present disclosure, the alkane is a C1 to C20 alkane.
In accordance with one embodiment of the present disclosure, the separated CO2 is recycled into the reformer (R) and a remaining portion of the separated CO2 can be vented out to the atmosphere.
As described herein above, syngas comprising 1:1 ratio of H2 to CO is utilized for producing olefins (e), the advantages of this process are:
• the amount of the feed required for producing olefins is reduced, because the separated CO2, light alkanes and heavies are utilized;
• One step DME process can accommodate some CO2 in the feed, which leads to simpler CO2 separation with minimum energy consumption;
• CO2, H2 and CO mixture can be easily separated from DME with minimum energy need and simpler separation equipment;
• Lower water required for shifts leads to lower volume occupancy in the reactor and lower energy loss;
• the intermediate step of water-gas shift and methanol production are obviated, thereby eliminating the use of a reactor for water-gas shift and producing methanol; and
• efficient separation of the streams by a divided wall column may lead to even more reduction in energy need for separation and thus saving the CAPEX of the entire process;
All these can lead to reduction of CAPEX significantly. Similarly OPEX can also be reduced up to 30% compared to the Methanol route.
One embodiment of the present disclosure provides a process for producing olefins as illustrated in Figure 3. Figure 3 depicts an apparatus for producing olefins without the intermediate separation S1. The process comprises heating the feed in the reformer (R) at a first predetermined temperature in the range of 300 ºC to 1000 ºC and at a first predetermined pressure in the range of 1 kg/cm2 to 80 kg/cm2, in the presence of the first catalyst, to produce a first stream (b) comprising syngas and unused feed.
The first stream is contacted with the second catalyst in the first reactor (D), at a second predetermined temperature in the range of 100 ºC to 400 ºC and at a second predetermined pressure in the range of 1 kg/cm2 to 60 kg/cm2, to produce a second stream comprising dimethyl ether (DME), and a first mixture comprising unconverted CO2, and syngas.
Dimethyl ether (DME) is separated from unconverted CO2, and syngas.
Next, DME is contacted with the third catalyst in the third reactor (O), at a third predetermined temperature in the range of 200 ºC to 600 ºC and at a third predetermined pressure in the range of 0.5 kg/cm2 to 10 kg/cm2, to produce a third stream comprising olefins, H2O, a second mixture of alkanes comprising the alkane.
Then, H2O, and the mixture of alkanes are separated from the third stream to obtain olefins.
The separated CO2 and the mixture of alkanes can be recycled to reformer (R) for producing syngas.
In yet another embodiment, the present disclosure provides a process for producing olefins as illustrated in Figure 4. Figure 4 depicts an apparatus for producing olefins without any intermediate separation steps. The process comprises heating the feed comprising CO2 and at least one alkane in the reformer (R) at a first predetermined temperature in the range of 300 ºC to 1000 ºC and at a first predetermined pressure in the range of 1 kg/cm2 to 80 kg/cm2, in the presence of the first catalyst, to produce a first stream (b) comprising syngas and unused feed.
The first stream comprising syngas and unused feed is directly contacted with the second catalyst in the first reactor (D), at a second predetermined temperature in the range of 100 ºC to 400 ºC and at a second predetermined pressure in the range of 1 kg/cm2 to 60 kg/cm2, to produce a second stream comprising dimethyl ether (DME), and a first mixture of unconverted CO2 and syngas.
Next, the second stream comprising DME is then directly contacted with the third catalyst, at a third predetermined temperature in the range of 200 ºC to 600 ºC and at a third predetermined pressure in the range of 0.5 kg/cm2 to 10 kg/cm2, to produce a third stream comprising olefins, H2O, unconverted DME, and a second mixture of alkanes.
Then, H2O, unconverted DME, unconverted CO2, Syngas, and the mixture of alkanes are separated from the third stream in a fractionation column to obtain olefins.
The separated CO2 and the mixture of alkanes can be recycled to the reformer for producing syngas.
In accordance with one embodiment, the present disclosure also provides a process for producing olefins as illustrated in Figure 5. Figure 5 depicts an apparatus for producing olefins in a single reactor.
The process comprises heating a feed comprising CO2 and an alkane in a reformer (R) at a first predetermined temperature in the range of 300 ºC to 1000 ºC and at a first predetermined pressure in the range of 1 kg/cm2 to 80 kg/cm2, in the presence of a tri-functional catalyst, to produce a third stream comprising olefins, H2O, unconverted DME, unconverted CO2, unconverted syngas and a second mixture of alkanes comprising at least one alkane.
Thereafter, H2O, unconverted syngas, unconverted CO2, unconverted alkane, and unconverted DME are separated from the third stream in the fractionation column to obtain olefins.
The separated CO2, syngas and the mixture of alkanes can be recycled to the single reactor with the tri-functional catalyst.
In accordance with one embodiment of the present disclosure, the olefin is at least one of ethylene and propylene.
In accordance with one embodiment of the present disclosure, the alkane is a C1 to C20 alkane.
In accordance with the present disclosure, the tri-functional catalyst includes, but is not limited to copper oxide, chromium oxide, zinc oxide, aluminium oxide, zeolites, aluminophosphate molecular sieve, and silicoaluminophosphate (SAPO).
The process of the present disclosure can lead to reduction of OPEX and CAPEX significantly.
TECHNICAL ADVANCES AND ECONOMICAL SIGNIFICANCE
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a process for producing olefins, where:
• CO2 is utilized in olefin production;
• Water required for the process is reduced leading to sparing the volumes in reactors and reducing the energy requirement to carry the water;
• energy required for separating products is reduced;
• energy required for separating CO2 and other streams is reduced; and
• CAPEX and OPEX for producing olefin are reduced.
The disclosure has been described with reference to the accompanying embodiments which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein.
The foregoing description of the specific embodiments so fully revealed the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.