Catalyst for producing N-substituted carbamates, and the preparation and application of the same
The present invention relates to a novel catalyst for producing N-substituted carbamates, the preparation of the catalyst and an improved method for producing N-substituted carbamates from these novel catalysts. The active component of the catalyst is a heteropoly acid and the catalyst support comprises a metal oxide or a metalloid oxide. The catalyst can be used to promote the reaction of carbamate and amine, thereby generating N-substituted carbamates with high yield. In the presence of the catalyst, the reaction conditions are relatively mild, the catalytic activity and selectivity of the reaction are high, and the reaction time is relatively short. Furthermore, the catalyst can be conveniently separated from the reaction system and recycled. therefore, the catalyst can be used to facilitate the further scale-up test and commercial application.
1. A method for preparing a N-substituted carbamate, comprising
(1) reacting
(a) one or more N-unsubstituted carbamates, with
(b) one or more amines selected from primary amines and secondary amines,
in the presence of
(c) a catalyst in which the active component comprises a heteropoly acid and the component of the catalyst support comprises a metal oxide or a metalloid oxide,
thereby forming the N-substituted carbamate wherein the catalyst support component comprising a metal oxide or a metalloid oxide is selected from the group consisting of zirconium oxide, titanium oxide, zinc oxide, silicon oxide, magnesium oxide, calcium oxide, tin oxide, barium oxide, cerium oxide, lanthanum oxide, vanadium pentoxide, aluminium oxide and mixtures thereof.
2. The method of claim 1 , wherein the heteropoly acid is a Keggin type heteropoly acid.
3. The method of claim 2 , wherein the heteropoly acid is selected from the group consisting of H 3 PW 12 O 40 .nH 2 O, H 3 PMo 12 O 40 .nH 2 O, H 4 SiW 12 O 40 .nH 2 O and H 4 SiMo 12 O 40 .nH 2 O.
4. The method of claim 3 , wherein the metal oxide is selected from the group consisting of a vanadium pentoxide, an aluminium oxide and mixtures thereof.
5. The method of claim 1 , wherein the load of the active component of the catalyst is from 0.1 to 20 wt. %, based on 100 wt. % of the catalyst support.
6. The method of claim 1 , wherein the amount of the catalyst is less than or equal to 20 parts by weight, based on 100 parts by weight of the amount of said amine component.
7. The method of claim 6 , wherein the amount of the catalyst is from 0.1 to 15 parts by weight, based on 100 parts by weight of the amount of said amine component.
8. The method of claim 7 , wherein the amount of the catalyst is from 3 to 8 parts by weight, based on 100 parts by weight of the amount of said amine component.
9. The method of claim 1 , wherein the mol ratio of the amino group of said amine component to said carbamate is from 1:1 to 1:30.
10. The method of claim 1 , wherein the reaction temperature of said reaction for preparing the N-substituted carbamate is greater than or equal to 100° C.
11. The method of claim 10 , wherein the reaction temperature of said reaction for preparing the N-substituted carbamate is from 140 to 200° C.