Nano-sized H-ZSM-5 zeolite catalyzes aldol condensation reaction to prepare methyl acrylate and acrylic acid

Abstract

The aldol condensation reaction of formaldehyde and methyl acetate is generally considered as a green, economical, non-petroleum route for one-step production of methyl acrylate (MA) and acrylic acid (AA). However, conventional aldol condensation catalysts are prone to rapid deactivation due to severe coking and quick loss of catalytic centers caused by acidic products and water. Here, we report an efficient and long-term stable nano-sized N-H-ZSM-5 zeolite catalyst for this condensation reaction. Its total lifetime reaches up to 226 h by three regeneration runs with the MA and AA formation rate being more than 0.9 mmol g⁻¹ h⁻¹ with the programmed temperature rising from 563 K to 663 K. After each regeneration, the aldol condensation activity and the single-pass lifetime of the N-H-ZSM-5 zeolite catalyst increased unexpectedly under the same reaction conditions. The results from a variety of characterization methods prove that the large capacity to hold big-sized polyaromatic coke, the good structural stability during the reaction and regeneration and the gradually improved diffusion performance after regeneration lead to the excellent performances of the nano-sized N-H-ZSM-5 catalyst during the aldol condensation reaction of formaldehyde and methyl acetate. This exhibits potential for development of a new route for MA and AA synthesis with non-petroleum resources.