Ionic liquids tailored and confined by one-step assembly with mesoporous silica for boosting the catalytic conversion of CO2 into cyclic carbonates

On the basis of economic and energy-saving criteria, the minimum effective dose of ionic liquids (ILs) for the catalytic conversion of CO2 into cyclic carbonates was first explored by confinement. With one-step assembly of mesoporous silica (mSiO2) by using a fixed amount of silicon source with vary...

Full description

Saved in:
Bibliographic Details
Published in:Green chemistry : an international journal and green chemistry resource : GC 2018, Vol.20 (14), p.3232-3241
Main Authors: Su, Qian, Yaqiong Qi, Yao, Xiaoqian, Cheng, Weiguo, Li, Dong, Chen, Songsong, Zhang, Suojiang
Format: Article
Language:English
Subjects:
Assembly
Bromides
Bromine
Carbon dioxide
Carbonates
Catalysts
Catalytic activity
Catalytic converters
Conversion
Density functional theory
Energy conservation
Green chemistry
Ionic liquids
Ions
Recyclability
Silica
Silicon dioxide
Synergistic effect
X ray photoelectron spectroscopy
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:On the basis of economic and energy-saving criteria, the minimum effective dose of ionic liquids (ILs) for the catalytic conversion of CO2 into cyclic carbonates was first explored by confinement. With one-step assembly of mesoporous silica (mSiO2) by using a fixed amount of silicon source with varying amounts of ILs as templates, certain amounts of 1-ethyl-3-methyl imidazolium bromides (EmimBr) were tailored and confined in mSiO2. The confined ILs (EmimBr@mSiO2) retained the advantages of homo- and heterogeneous catalysts, exhibiting higher performance than bulk EmimBr under identical reaction conditions. Amongst all the prepared materials, EmimBr@mSiO2 with the lowest amount of EmimBr (6.9 wt%) exhibited the biggest improvement in catalytic activity, achieving a TOF of 112.6 h−1 which is almost 1.7 times the bulk phase with good recyclability. The boosted catalytic activity could be attributed to the larger proportion of mesopores, the better dispersity of EmimBr (Si/Br = 25) and the synergistic effect from more exposed silanol groups (Si–OH/Br = 8) in the structure. The good recyclability was then explained by the XPS analysis and density functional theory (DFT) calculation, which confirmed that the compressing effect from Si–OH could enhance the cation and anion interaction to stabilize ILs in the space more firmly when less ILs were confined.
ISSN:1463-9262
1463-9270
DOI:10.1039/c8gc01038b