Processes for preparing C-4 sugars and ketose sugars
Various processes for preparing C 4 aldoses and/or ketones thereof are described. Various processes are described for preparing C 4 aldoses and/or ketones thereof from feed compositions comprising glycolaldehyde. Also, various processes for preparing useful downstream products and intermediates, such as erythritol and erythronic acid, from the C 4 aldoses and/or ketones thereof are described.
1 . A process for preparing a C4 aldose and/or ketone thereof, the process comprising:
contacting a feed composition comprising glycolaldehyde with a catalyst comprising an imidazolate framework in a reaction zone to condense at least a portion of the glycolaldehyde to the C 4 aldose and/or ketone thereof.
2 . A process for preparing a C4 aldose and/or ketone thereof, the process comprising:
feeding a feed composition comprising a carbohydrate having at least four carbon atoms to a pyrolysis reaction zone;
pyrolyzing the carbohydrate in the presence of water and a catalyst in the pyrolysis reaction zone to form a reaction product comprising glycolaldehyde, wherein the catalyst comprises a metal oxide on a catalyst support and at least one of the following conditions is satisfied:
(a) the pyrolysis reaction zone is heated to a temperature of 400° C. or greater;
(b) the catalyst support has a BET specific surface area that is 500 m 2 /g or less, 250 m 2 /g or less, 100 m 2 /g or less, 50 m 2 /g or less, 25 m 2 /g or less, 10 m 2 /g or less, 5 m 2 /g or less, or 1 m 2 /g or less;
(c) the catalyst support comprises a glass, ceramic, or refractory material;
(d) the pyrolysis reaction zone further comprises a reaction zone media that is different than the catalyst; and/or
(e) the yield of glycolaldehyde is 70% or greater, 75% or greater, or 80% or greater; and
contacting the reaction product comprising the glycolaldehyde with an imidazolate framework in a reaction zone to condense at least a portion of the glycolaldehyde to the C4 aldose and/or ketone thereof.
3 . The process of claim 1 , wherein the feed composition comprises a glycolaldehyde concentration of 1 wt. % or greater, 5 wt. % or greater, 10 wt. % or greater, 20 wt. % or greater, 30 wt. % or greater, 40 wt. % or greater, 50 wt. % or greater, 60 wt. % or greater, or 70 wt. % or greater.
4 . The process of claim 1 or 2 , wherein the feed composition further comprises at least one compound selected from the group consisting of pyruvaldehyde, formaldehyde, acetol, glyoxal, and combinations thereof.
5 . The process of claim 4 , wherein the feed composition further comprises water.
6 . The process of claim 1 or 2 , wherein the C4 aldose and/or ketone thereof comprises at least one compound selected from the group consisting of erythrose, threose, erythrulose, and combinations thereof.
7 . The process of claim 1 , wherein the imidazolate framework comprises one or more metal and/or metalloid.
8 . The process of claim 7 , wherein the imidazolate framework comprises one or more metal and/or metalloid selected from the group consisting of zinc, cobalt, copper, iron, lithium, boron, and combinations thereof.
9 . The process of claim 8 , wherein the imidazolate framework is selected from the group consisting of ZIF-4, ZIF-8, ZIF-14, BIF-2Li, BIF-2Cu, BIF-5, and combinations thereof.
10 . The process of claim 9 , wherein the imidazolate framework comprises a ZIF-4.
11 . The process of any one of claims 8-10 , wherein the imidazolate framework and/or the catalyst is free or essentially free of tin, zirconia, and/or silica.
12 . The process of claim 1 or 2 , wherein the condensing reaction is conducted at a temperature of 100° C. or less, 95° C. or less, 90° C. or less.
13 . The process of claim 1 or 2 , wherein the condensing reaction is conducted at a temperature of 0° C. or greater, 25° C. or greater, 50° C. or greater, or 80° C. or greater.
14 . The process of claim 1 or 2 , wherein the condensing reaction is conducted at a pH of 7 or less, 6 or less, or 5 or less.
15 . The process of claim 14 , wherein the condensing reaction is conducted free or essentially free of added base.
16 . The process of claim 1 or 2 , wherein the feed composition and/or reaction zone for the condensing reaction is free or essentially free of an alcohol solvent.
17 . The process of claim 1 or 2 , wherein the feed composition and/or reaction zone for the condensing reaction is free or essentially free of an organic solvent.