Process and system for making cyclopentadiene and/or dicyclopentadiene
Processes and systems for making cyclopentadiene and/or dicyclopentadiene include converting acyclic C5 hydrocarbon(s) into CPD in a first reactor in the presence of a C1-C4 co-feedstock to obtain a product mixture, separating the product mixture in a separation sub-system such as compression train to obtain a C5-rich fraction comprising CPD and essentially depleted of hydrogen and C1-C4 hydrocarbons, dimerizing the C5-rich fraction in a dimerization reactor to obtain a product effluent comprising DCPD, followed by separating the product effluent to obtain a DCPD-rich fraction. Multiple-stage of dimerization and separation steps can be optionally used to obtain multiple DCPD-rich fractions of various degrees of purity and quantity. C5-rich fractions from various stages of the process may be recycled to the first reactor, or converted into mogas components after selective hydrogenation. C5-rich fractions and mogas components may be optionally separated to produce value-adding chemicals.
1. A process for making cyclopentadiene (CPD) and optionally dicyclopentadiene (DCPD), the process comprising:
(I) feeding a C5 feedstock comprising at least one acyclic C5 hydrocarbon and a light hydrocarbon co-feedstock comprising at least one C1-C4 hydrocarbon into a first reactor;
(II) contacting the at least one acyclic C5 hydrocarbon with a catalyst under conversion conditions to obtain a first reactor hydrocarbon effluent from an outlet on the first reactor comprising: C5 components including CPD and acyclic diolefins; light components including hydrogen and C1-C4 hydrocarbons; one-ring aromatics; and multiple-ring aromatics;
wherein sufficient light hydrocarbon co-feedstock is provided in step (I) such that:
the total absolute pressure of the first reactor hydrocarbon effluent at the outlet is P(fre);
the total partial pressure of C5 hydrocarbons in the first reactor hydrocarbon effluent at the outlet is P(C5);
the partial pressure of hydrogen in the first reactor hydrocarbon effluent at the outlet is P(H2);
[ P ( C 5)+ P ( H 2)]÷ P ( fre )≦0.90; and
P(fre) is greater than 100 kilopascal absolute.
2. The process of claim 1 , wherein:
the sum total of P(C5) and P(H2) is not higher than 95 kilopascal absolute; and
P(fre) is at least 110 kilopascal absolute.
3. The process of claim 1 , wherein:
the sum total of P(C5) and P(H2) is not higher than 50 kilopascal absolute; and
P(fre) is at least 110 kilopascal absolute.
4. The process of claim 1 , wherein at least a portion of the light hydrocarbon co-feedstock is recovered directly or indirectly from the first reactor hydrocarbon effluent.
5. The process of claim 1 , wherein hydrogen is also supplied to the first reactor in step (I).
6. The process of claim 5 , wherein at least a portion of the hydrogen is recovered directly or indirectly from the first reactor hydrocarbon effluent.
7. The process of claim 4 , wherein at least a portion of the hydrogen and light hydrocarbon co-feedstock are recovered from the first reactor hydrocarbon effluent as a mixture thereof, and then recycled to the first reactor as a mixture thereof.
8. The process of claim 1 , further comprising:
(III) separating the first reactor hydrocarbon effluent to produce (i) a light components-rich fraction and (ii) a first C5-rich fraction comprising CPD.
9. The process of claim 8 , further comprising:
(IV) separating at least a portion of the light components-rich fraction to obtain a hydrogen-rich fraction and at least one C1-C4-rich fraction.
10. The process of claim 9 , wherein:
in step (IV), a hydrogen-rich fraction, a methane-rich fraction, and a C2-C4 rich fraction are obtained.
11. The process of claim 10 , wherein:
a first portion of the hydrogen-rich fraction is supplied to the first reactor;
a second portion of the hydrogen-rich fraction is delivered to a disposition differing from the first reactor;
a first portion of the methane-rich fraction is supplied to the first reactor;
a second portion of the methane-rich fraction is delivered to a disposition differing from the first reactor; and
a portion of the C2-C4-rich fraction is delivered to a disposition differing from the first reactor.
12. The process of claim 11 , wherein:
the total molar amount of methane in (i) the second portion of the hydrogen-rich fraction; (ii) the second portion of the methane-rich fraction; and (iii) the first portion of the C2-C4-rich fraction is about the equal to the molar amount of methane produced in step (II).
13. The process of claim 1 , wherein:
the first reactor hydrocarbon effluent comprises CPD at a concentration of C(CPD)1 wt % and acyclic diolefins at a total concentration of C(ADO)1 wt %, both based on the total weight of C5 hydrocarbons in the first reactor hydrocarbon effluent; and
C ( CPD )1/ C ( ADO )1≧1.5.
14. The process of claim 1 , wherein the light hydrocarbon co-feedstock comprises methane, ethane, ethylene, and mixtures thereof.
15. The process of claim 1 , wherein:
in step (I), hydrogen is fed into the first reactor, and the molar ratio of the hydrogen to the C5 feedstock fed into the first reactor is in a range from 0.1 to 3.0.
16. The process of claim 1 , wherein the C5 feedstock comprises at least 50 wt % of saturated acyclic C5 hydrocarbon(s), based on the total weight of the C5 feed.
17. The process of claim 9 , wherein:
step (IV) comprises separating the light components-rich fraction by using one or more of a pressure swing adsorption process, a rapid cycle pressure swing adsorption process, a cryogenic process, a thermal swing adsorption process, and a membrane separation process.
18. The process of claim 8 , further comprising:
(V) supplying at least a portion of the first C5-rich fraction into a second reactor operating under a first set of dimerization conditions;
(VI) obtaining a second reactor effluent from the second reactor comprising CPD and dicyclopentadiene (DCPD); and
(VII) separating at least a portion of the second reactor effluent to obtain a first DCPD-rich fraction comprising DCPD and a second C5-rich fraction comprising CPD.
19. The process of claim 8 , wherein step (III) comprises at least one of the following:
(IIIa) cooling the first reactor hydrocarbon effluent;
(IIIb) increasing the total pressure of the first reaction effluent;
(IIIc) washing at least a portion of the first reactor hydrocarbon effluent with a wash oil;
(IIId) removing light components from the first reactor hydrocarbon effluent; and
(IIIe) removing C8+ components from the first reactor hydrocarbon effluent.
20. The process of claim 8 , wherein (III) comprises washing the first reactor hydrocarbon effluent with a wash oil comprising at least one of: cyclohexane; monoalkyl, dialkyl, and trialkyl cyclohexanes; benzene; monoalkyl, dialkyl, and trialkyl benzenes; monoalkyl, dialkyl, trialkyl, and tetraalkyl naphthalenes; other alkylated multiple-ring aromatics; and mixtures and combinations thereof.
21. The process of claim 8 , wherein step (III) comprises removing light components from the first reactor hydrocarbon effluent using a compression train with inter-stage cooling and vapor/liquid separation.
22. The process of claim 18 , further comprising:
(VIII) feeding at least a portion of the second C5-rich fraction into a third reactor operating under a second set of dimerization conditions;
(IX) obtaining a third reactor effluent from the third reactor comprising CPD and DCPD; and
(X) separating at least a portion of the third reactor effluent to obtain a second DCPD-rich fraction and a third C5-rich fraction comprising CPD.
23. The process of claim 22 , wherein the process further comprises:
(XI) feeding at least a portion of the third C5-rich fraction into a fourth reactor operating under a third set of dimerization conditions;
(XII) obtaining a fourth reactor effluent comprising CPD and DCPD; and
(XIII) separating at least a portion of the fourth reactor effluent to obtain a third DCPD-rich fraction and a fourth C5-rich fraction.
24. The process of claim 8 , further comprising:
(XIV) recycling, directly or indirectly, at least a portion of at least one of the first C5-rich fraction, the second C5-rich fraction, the third C5-rich fraction, and the fourth C5-rich fraction to the first reactor.
25. The process of claim 21 , comprising:
(XV) obtaining at least one of: (i) a cyclopentane-rich fraction; (ii) a cyclopentene-rich fraction; (iii) a 1,3-pentadiene-rich fraction; and (iv) a 2-methyl-1,3-butadiene fraction, from at least one of the first C5-rich fraction, the second C5-rich fraction, the third C5-rich fraction, and the fourth C5-rich fraction.