Solid acid catalyst and method for preparing and using the same

1. A process for preparing rubber antioxidant RD, comprising

feeding aniline or a derivative thereof into a tower from a top of the tower,

feeding gasified acetone or a derivative thereof into the tower from a bottom of the tower,

reacting the aniline or the derivative thereof and the acetone or the derivative thereof to form a reaction mixture comprising 2,2,4-trimethyl-1,2-dihydroquinoline monomers in presence of a solid acid catalyst under suitable conditions in the tower,

polymerizing the reaction mixture comprising 2,2,4-trimethyl-1,2-dihydroquinoline monomers to form a rubber antioxidant RD, and

recovering excess acetone or derivative thereof and water generated during the reaction by a distillation column connected to the tower,

wherein the solid acid catalyst is loaded on reaction beds in the tower, and the solid acid catalyst comprises a strong acid cation exchange resin having a cross-linking network and free aromatic sulfonic acids adsorbed in the cross-linking network structure.

2. The process according to claim 1 , wherein condensation of the aniline or derivative thereof and the acetone or the derivative thereof to generate 2,2,4-trimethyl-1,2-dihydroquinoline monomers and polymerization of the 2,2,4-trimethyl-1,2-dihydroquinoline monomers to yield the rubber antioxidant RD takes place simultaneously in the tower in presence of the solid acid catalyst-loaded reaction beds.

3. The process according to claim 1 , wherein the reaction beds are kept at about 100-135° C. during the reactions, and residence time of the aniline or derivative thereof and the acetone or derivative thereof in the tower is about 15-20 hours.

4. The process according to claim 1 , further comprising

recovering unreacted aniline and the 2,2,4-trimethyl-1,2-dihydroquinoline monomers from the reaction mixture under reduced pressure and at a temperature of about 220-230° C.

5. The process according to claim 1 , wherein condensation reaction of the aniline or the derivative thereof and the acetone or the derivative thereof to yield the 2,2,4-trimethyl-1,2-dihydroquinoline monomers proceeds in the tower under atmospheric pressure, the reaction bed are kept at about 100-135° C. during the condensation reaction, and residence time of the aniline or derivative thereof and the acetone or derivative thereof in the tower is about 2-7 hours, and polymerization of the 2,2,4-trimethyl-1,2-dihydroquinoline monomers occurs outside the tower.

6. The process according to claim 5 , wherein a feed ratio of the aniline or derivative thereof to the acetone or derivative thereof is about 1:(5-7) by weight.

7. The process according to claim 5 , further comprising

recovering unreacted aniline and monomers from the reaction mixture under reduced pressure at about 220-230° C.

8. The process according to claim 5 , further comprising

distilling out the 2,2,4-trimethyl-1,2-dihydroquinoline monomers from the reaction mixture, and

polymerizing the 2,2,4-trimethyl-1,2-dihydroquinoline monomers to dimers or multimers in high purity in a separate reaction vessel.

9. The process according to claim 1 , wherein the strong acid cation exchange resin is based on styrene, acrylic acid (ester), or both, and cross-linked by divinyl benzene, and bears sulfonic groups.

10. The process according to claim 1 , wherein the aromatic sulfonic acid is selected from the group consisting of benzene sulfonic acid, p-toluene sulfonic acid, o-toluene sulfonic acid, m-toluene sulfonic acid, p-ethyl benzene sulfonic acid, dimethyl benzene sulfonic acid, p-fluoro-benzene sulfonic acid, o-fluoro-benzene sulfonic acid, m-fluoro-benzene sulfonic acid, p-chloro-benzene sulfonic acid, o-chloro-benzene sulfonic acid, m-chloro-benzene sulfonic acid, p-benzene disulfonic acid, o-benzene disulfonic acid, m-benzene disulfonic acid, and a mixture thereof.

11. The process according to claim 1 , wherein the process is conducted as a continuous process and each step is conducted continuously.

12. The process according to claim 1 , wherein the strong acid cation exchange resin is based on styrene, is cross-linked by divinyl benzene, and bears sulfonic groups.

13. The process according to claim 1 , wherein the strong acid cation exchange resin is selected from the group consisting of Cation Exchange Resin 732, Cation Exchange Resin 734, Cation Exchange Resin DH, Cation Exchange Resin D001, Cation Exchange Resin D002, Cation Exchange Resin D061, Cation Exchange Resin D072, Cation Exchange Resin JK008, and a mixture thereof.

14. The process according to claim 1 , wherein the free aromatic sulfonic acids are about 0.01 to 3% by weight of total weight of the catalyst.

15. The process according to claim 1 , wherein the aromatic sulfonic acids are selected from the group consisting of benzene sulfonic acid, a monoalkyl benzene sulfonic acids, a dialkyl benzene sulfonic acids, a multi-alkyl benzene sulfonic acid, a halo-benzene sulfonic acid, an optionally substituted benzene disulfonic acid, an optionally substituted trisulfonic acid, and a mixture thereof.

16. The process according to claim 1 , wherein the aromatic sulfonic acid is selected from the group consisting of benzene sulfonic acid, p-toluene sulfonic acid, o-toluene sulfonic acid, m-toluene sulfonic acid, p-ethyl benzene sulfonic acid, dimethyl benzene sulfonic acid, p-fluoro-benzene sulfonic acid, o-fluoro-benzene sulfonic acid, m-fluoro-benzene sulfonic acid, p-chloro-benzene sulfonic acid, o-chloro-benzene sulfonic acid, m-chloro-benzene sulfonic acid, p-benzene disulfonic acid, o-benzene disulfonic acid, m-benzene disulfonic acid, and a mixture thereof.

17. The process according to claim 1 , wherein the solid acid catalyst is a compound of Cation Exchange Resin D002 and p-toluene sulfonic acid.

18. The process according to claim 17 , wherein weight ratio of Cation Exchange Resin D002 to p-toluene sulfonic acid is about 1:(0.001-0.5).

19. The process according to claim 18 , wherein weight ratio of Cation Exchange Resin D002 to p-toluene sulfonic acid is about 1:(0.01-0.2).

20. A method for using a solid acid catalyst according to claim 1 , comprising

applying the solid acid catalyst as described in claim 1 in the reaction for making rubber antioxidant RD.