PURPOSE: To prepare acrylic acid in high selectivity and yield, by catalytically reacting acetic acid or propionic acid with formaldehyde in the vapor phase in the presence of a solid acid catalyst having a moderately strong acid strength.
CONSTITUTION: Acetic acid or propionic acid in the vapor phase is brought into contact with formaldehyde in the presence of a solid catalyst to give acrylic acid or methacrylic acid. In the process, a solid catalyst having acid sites exhibiting ≤-3.0pKa, particularly within ≥-8.2pKa and ≤-3.0pKa range acid strength such as silica alumina is used as the catalyst exhibiting high activity, selectivity and conversion. The acid strength of acid sites even in an oxide or compound oxide having no acid site exhibiting within ≤-3.0pKa range can be increased, and such catalyst can be used.
ITOU TSUTOMU
MIKI TOSHIROU
KOJIMA SHIROU
AZUMA TAKASHIROU
KATOU HIROYUKI
MURAKAMI YUUICHI
Next Patent: PREPARATION OF PYROMELLITIC ACID OR ANHYDRIDE THEREOF