Systems and processes for polyacrylic acid production

1. An integrated system for producing polyacrylic acid (PAA) and superabsorbent polymer (SAP) from ethylene, comprising:

an oxidative reactor, comprising:

an inlet configured to receive ethylene,

an oxidative reaction zone configured to convert ethylene to ethylene oxide (EO), and

an outlet configured to provide an EO stream comprising the EO;

a central reactor, comprising:

an inlet configured to receive EO from the EO stream of the oxidative reactor, and carbon monoxide (CO) from a CO source,

a central reaction zone configured to convert EO to beta propiolactone (BPL) or polypropiolactone (PPL), or a combination thereof, and

an outlet configured to provide a carbonylation stream comprising the BPL, or a carbonylation stream comprising the PPL, or a combination thereof;

one or more of (i), (ii) and (iii):

(i) a first reactor, comprising:

an inlet configured to receive BPL from the carbonylation stream of the central reactor,

a first reaction zone configured to convert BPL to acrylic acid (AA), and

an outlet configured to provide an AA stream comprising the AA,

(ii) a second (a) reactor, comprising:

an inlet configured to receive BPL from the carbonylation stream of the central reactor,

a second (a) reaction zone configured to convert BPL to PPL, and

an outlet configured to provide a PPL stream comprising the PPL, and

a second (b) reactor, comprising:

an inlet configured to receive the PPL stream of the second (a) reactor,

a second (b) reaction zone configured to convert at least some of the PPL to AA, and

an outlet configured to provide an AA stream comprising the AA, and

(iii) a third reactor, comprising:

an inlet configured to receive PPL from the carbonylation stream of the central reactor,

a third reaction zone configured to convert PPL to AA, and

an outlet configured to provide an AA stream comprising the AA;

a fourth reactor, comprising:

an inlet configured to receive the AA stream of one or more of the first, second (b) and third reactor,

a fourth reaction zone configured to convert AA to polyacrylic acid (PAA), or a salt thereof, and

an outlet configured to provide a PAA stream comprising the PAA, or a salt thereof;

a fifth reactor, comprising:

an inlet configured to receive PAA, or a salt thereof, from the PAA stream of the fourth reactor,

a fifth reaction zone configured to directly convert the PAA, or a salt thereof, to superabsorbent polymer (SAP), and

an outlet configured to provide a SAP stream comprising the SAP; and

a controller to independently modulate production of the EO, BPL, PPL, AA, PAA and SAP.

2. The system of claim 1 , comprising two of (i), (ii) and (iii).

3. The system of claim 1 , comprising (i), (ii) and (iii).

4. The system of claim 1 , wherein the system produces AA at 200 kilotons to 800 kilotons per annum (kta).

5. The system of claim 1 , wherein the AA has less than 5% by weight of an aldehyde impurity or a compound that derives from the oxidation of propylene.

6. The system of claim 1 , wherein the inlet to the fourth reactor is configured to receive one or more reactant streams comprising sodium hydroxide, and the fourth reaction zone is configured to form a PAA sodium salt from the one or more reactant streams in the presence of a radical initiator.

7. The system of claim 1 , wherein the fourth reaction zone is configured to convert AA to polyacrylic acid (PAA), or a salt thereof, by gel polymerization, suspension polymerization, or solution polymerization.

8. The system of claim 1 , wherein the PAA, or a salt thereof, has less than 5% by weight of an aldehyde impurity or a compound that derives from the oxidation of propylene.

9. The system of claim 1 , wherein the inlet to the fourth reactor is configured to further receive one or more reactant streams each comprising a co-reactant to co-polymerize with AA, and the fourth reaction zone is configured to form one or more co-polymers of PAA selected from the group consisting of a polyacrylamide co-polymer, ethylene maleic anhydride co-polymer, cross-linked carboxymethylcellulose co-polymer, polyvinyl alcohol co-polymer, cross-linked polyethylene oxide co-polymer, and starch grafted polyacrylonitrile co-polymer of PAA.

10. The system of claim 1 , wherein the inlet to the fifth reactor is configured to further receive one or more reactant streams each comprising a cross-linking agent.

11. The system of claim 1 , wherein the SAP has less than 1000 parts per million residual monoethylenically unsaturated monomer, and has less than 5% by weight of an aldehyde impurity or a compound that derives from the oxidation of propylene.

12. The system of claim 1 , wherein the controller independently modulates production of the BPL by the central reactor.

13. The system of claim 1 , wherein the AA stream has:

less than 1000 parts per million residual monoethylenically unsaturated monomer,

(ii) less than 5% by weight or less than 10,000 ppm of an aldehyde impurity,

(iii) less than 5% by weight or less than 10,000 ppm of a compound that derives from the oxidation of propylene,

(iv) less than 5% by weight or less than 10,000 ppm of furfural,

(v) less than 5% by weight or less than 10,000 ppm of acetic acid,

(vi) less than 5% by weight or less than 10,000 ppm of stabilizers,

(vii) less than 5% by weight or less than 10,000 ppm of radical polymerization inhibitors,

(viii) less than 5% by weight or less than 10,000 ppm of anti-foam agents,

or any combination of (i)-(viii).