Processes for preparing C-4 sugars and ketose sugars

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 m2/g or less, 250 m2/g or less, 100 m2/g or less, 50 m2/g or less, 25 m2/g or less, 10 m2/g or less, 5 m2/g or less, or 1 m2/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.