Investigating the impact of micropore volume of aminosilica functionalized SBA-15 on catalytic activity for amine-catalyzed reactions
Date
2022-09-24
Authors
Deshpande, Nitish
Chen, Jee-Yee
Kobayashi, Takeshi
Cho, Eun Hyun
Pineault, Hannah
Lin, Li-Chiang
Brunelli, Nicholas A.
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Iowa State University Digital Repository, Ames IA (United States)
Abstract
Mesoporous materials such as SBA-15 are used in many applications since the materials are robust and have tunable properties. Whereas these materials are thought to be ideal, the materials are complex with the common synthesis methods producing materials that contain micropores. This work will investigate the impact of micropores on catalytic activity of aminosilica materials. For comparison, materials are formed using a standard method that produces materials with micropores (REG-SBA-15) and using a modified method that produces materials with negligible micropore volume (NMP-SBA-15). After grafting the calcined support with an aminosilane (either (N-methyl amino propyl) trimethoxy silane (denoted as 2°Am) or (N,N-diethyl-3-amino propyl) trimethoxy silane (3°Am)), catalytic testing experiments reveal that NMP-SBA-15 functionalized materials are more active than REG-SBA-15 functionalized materials for a range of reactions. The reactions include (a) glucose isomerization where amines interacting with surface silanols limit catalytic activity and (b) aldol and Knoevenagel chemistry where amine-silanol interactions increase the reaction rate. For aldol chemistry, the observed difference in rate is further investigated using site quantification experiments. Interestingly, the results reveal that three types of sites exist for each material, including sites that are (1) highly active, (2) intermediate active, and (3) inactive. NMR experiments indicate that amines immobilized on REG-SBA-15 supports are less mobile than amines on NMP-SBA-15. For REG-SBA-15, the materials are found to have aminosilanes that have limited mobility and the largest fraction of inactive sites, which suggests that the inactive catalytic sites are in the micropores. Overall, the design of highly active catalytic materials can be achieved using materials that have limited micropore volumes.
Series Number
Journal Issue
Is Version Of
Versions
Series
IS-J 10938
Academic or Administrative Unit
Type
article
Comments
This is a manuscript of an article published as Deshpande, Nitish, Jee-Yee Chen, Takeshi Kobayashi, Eun Hyun Cho, Hannah Pineault, Li-Chiang Lin, and Nicholas A. Brunelli. "Investigating the impact of micropore volume of aminosilica functionalized SBA-15 on catalytic activity for amine-catalyzed reactions." Journal of Catalysis 414 (2022): 356-364.
DOI: 10.1016/j.jcat.2022.09.016.
Copyright 2022 Elsevier Inc.
Posted with permission.
DOE Contract Number(s): AC02-07CH11358; ACS-PRF 55946-DNI5; NSF 1653587; NSF 2015669; OSU IMR FG0211; EMR-G00018