(691h) Sustainable Pathways to Acrylic Acid – Conversion of Lactate Feeds over FAU-Based Zeolite Composite Catalysts

Acrylic acid and the four primary acrylate derivatives are the cornerstone of a $10B market with broad application across super-absorbent polymers, paints, coatings, and adhesives industries. Producing these chemicals necessary for modern life from sustainable pathways is of key interest. We focus on the use of feeds derived from lactic acid, a product sustainably fermented from a range of bio-derived sugar sources.

Utilizing an inert and site-selective chemical titrant to form an inorganic / organic composite can provide desirable selectivity tuning. Here, a selectivity enhancement from 60 to upwards of 96 C% was demonstrated for methyl lactate dehydration to methyl acrylate and acrylic acid over a composite Na-FAU based zeolite catalyst using amines as titrants to suppress side reactions on in situ-generated Brønsted acid sites (BASs).^1,2 We evaluate the effectiveness of BAS titration by considering basicity and steric properties of the titrant molecule to maximize selectivity enhancement. Several different amine titrants outperform the previously studied pyridine.³

1,2-bis(4-pyridyl)ethane (12BPE) and 4,4-trimethylenedipyridine (44TMDP), at a nominal loading of two molecules per Na-FAU supercage, afforded a dehydration selectivity of 96±3% over 2000 min time on stream, exceeding the commercial viability target for selectivity of 90%. Tuning the weight hourly space velocity (WHSV) from 0.9 to 0.2 h-1 afforded a yield as high as 92% at a selectivity of 96% with 44TMDP impregnated Na-FAU, resulting in the highest yield reported to date. Commercial production also requires scaled up catalyst and integrated reaction and separation processes; we conclude by presenting our latest results on scale-up.

1. Pang, Y.; Ardagh, M.A.; Shetty, M.; Chatzidimitriou, A.; Kumar, G.; Vlaisavljevich, B.; Dauenhauer, P.J. ACS Catal. 2021, 11, 5718−5735.
2. Pang, Y.; Lee, C.; Vlaisavljevich, B.; Nicholas, C.P.; Dauenhauer, P.J. JACS Au, 2023, 2, 368-377
3. Murphy, B. M.; Letterio, M. P.; Xu, B. ACS Catal. 2016, 6, 5117−5131.