Co-feeding an inert and site-selective chemical titrant provides desirable selectivity tuning when titrant adsorption is favored over side reaction pathways on a solid acid catalyst. Here, a selectivity enhancement from 61 to 84 C % was demonstrated for methyl lactate dehydration to methyl acrylate and acrylic acid over a NaY zeolite catalyst using amines as the co-fed titrants to suppress side reactions on in site-generated Bronsted acid sites (BASs). The effectiveness of BAS titration was evaluated by considering both the basicity and steric properties of the titrant molecule with the goal to maximize the selectivity enhancement. The presence of electron-donating alkyl functional groups not only enhances amine basicity but also introduces additional steric constraints to the molecule with respect to the pore dimensions of the NaY zeolite. While higher basicity of titrant amines favors stronger adsorption on BASs, steric limitations hinder site binding through contributions from internal diffusion limitations and local steric repulsion between the titrant and the zeolite wall around the BAS. Titrant bases with proton affinities above ~1040 kj/mol and sizes below 85% of the NaY supercage window or pore diameter are predicted to afford dehydration selectivities above 90 C % to acrylate products.
|Original language||English (US)|
|Title of host publication||2021 AIChE Annual Meeting|
|Publisher||American Institute of Chemical Engineers|
|Number of pages||18|
|State||Published - 2021|
|Event||2021 AIChE Annual Meeting - Boston, Virtual, United States|
Duration: Nov 15 2021 → Nov 19 2021
|Name||AIChE Annual Meeting, Conference Proceedings|
|Conference||2021 AIChE Annual Meeting|
|Period||11/15/21 → 11/19/21|
Bibliographical noteFunding Information:
We acknowledge financial support of the NSF Center for Sustainable Polymers, an NSF Center for Chemical Innovation at the University of Minnesota (CHE-1901635). The authors acknowledge the Minnesota Supercomputing Institute (MSI) at the University of Minnesota for providing resources that contributed to the research results reported within this paper. URL: http://www.msi.umn.edu/. The authors thank Prof. Omar Abdelrahman for valuable discussions, technical assistance, and guidance. The authors also thank Xinyu Li from University of Minnesota for providing the X-ray diffractograms for all zeolite samples and the argon physisorption isotherm for the HY sample.
© 2021 American Chemical Society.
- Acrylic acid
- Lactic acid