Multifunctional Amine Modifiers for Selective Dehydration of Methyl Lactate to Acrylates

Abstract

Dehydration of methyl lactate to acrylic acid and methyl acrylate was experimentally evaluated over a Na-FAU zeolite catalyst impregnated with multifunctional diamines. 1,2-Bis(4-pyridyl)ethane (12BPE) and 4,4′-trimethylenedipyridine (44TMDP), at a nominal loading of 40 wt % or two molecules per Na-FAU supercage, afforded a dehydration selectivity of 96 ± 3% over 2000 min time on stream. Although 12BPE and 44TMDP have van der Waals diameters approximately 90% of the Na-FAU window opening diameter, both flexible diamines interact with internal active sites of Na-FAU as characterized by infrared spectroscopy. During continuous reaction at 300 °C, the amine loadings in Na-FAU remained constant for 12BPE but decreased as much as 83% for 44TMDP. Tuning the weighted 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.

Reaction Kinetics of the Autocatalytic Hydrolyses of Alkyl Lactates

“…[33][34][35] However, ester hydrolysis can be an autocatalytic system, as the lactic acid product can act to further accelerate the reaction. [36][37][38][39][40][41][42] While continuing our studies of the catalytic dehydration of alkyl lactates, 43,44 we observed that aqueous 6.9 mol% (30 wt%) solutions of methyl lactate slowly accumulated significant amounts of alcohol and lactic acid when kept at room temperature. The same was true with 6.2 mol% (30 wt%) solutions of ethyl lactate.…”

Lactic Acid Production by Enterococcus durans Is Improved by Cell Recycling and pH Control

“…Those polymers may have a shorter degradation rate than petrochemicals, and their monomer lactic acid can be obtained through the microbial fermentation of renewable resources. In addition, lactic acid can be used in acrylate production from dehydrating using zeolites and hydroxyapatite as catalysts, reducing the dependence on petrochemical sources to create acrylate-based monomers, which is another significant application of lactic acid [6][7][8].…”

Up Up Down Down Left Right Left Right B A Start for the Catalytic Hackers of Programmable Materials

“…[62] The strategy has for the most part adapted the catalysts developed for fossil fuel processing to new feedstocks derived from renewable resources such as carbohydrates, natural oils, or lignin. [63] This adaptability approach to sustainable catalysts has benefited a renewable chemicals industry developing pathways to many key chemicals such as drop-in renewable molecules including pxylene, [64] adipic acid, [65] acrylic acid, [66] and butadiene [67] while also inventing entirely new renewable molecules with improved characteristics such as γ-valerolactone, [68] methyl-caprolactone, [69] and oleofuran sulfonate (OFS) surfactants. [70] While catalysts for renewable chemicals have been remarkably effective, they have not fundamentally changed the practices and methods of heterogeneous catalysis; static catalytic surfaces are still designed to direct the flow of reactions down a fixed free energy gradient, with bias towards the downhill reaction pathways of interest.…”