Nankai University

About: Nankai University is a education organization based out in Tianjin, China. It is known for research contribution in the topics: Catalysis & Enantioselective synthesis. The organization has 42964 authors who have published 51866 publications receiving 1127896 citations. The organization is also known as: Nánkāi Dàxué.

Metal–Organic Framework MIL-101 for High-Resolution Gas-Chromatographic Separation of Xylene Isomers and Ethylbenzene

Abstract: Metal–organic frameworks (MOFs) have received great attention because of their fascinating structures and intriguing applications in hydrogen storage, gas separation, catalysis, chiral separation, sensing, and imaging. Recently, MOFs such as MOF-508, MIL-47, and MIL53 have been shown to be promising as stationary phases for gas chromatography (GC) and liquid chromatography. 11] All these pioneering works on the utilization of MOFs as stationary phases in chromatography were performed on packed columns. However, packed columns usually result in low resolution as a result of peak broadening, which impairs the separation efficiency of MOFs. Moreover, gram-scale MOFs are needed for packed columns, leading to high-cost applications of MOFs as stationary phases in chromatographic separation. In contrast, capillary columns, either wall-coated open tubular (WCOT) columns or porous layer open tube (PLOT) columns, involve a thin film of MOFs coated on their inner walls, and thus improve the resolving power of MOFs and reduce the amount of MOFs required for GC applications. However, to the best of our knowledge, no work on the utilization of MOFs as stationary phases for high-resolution capillary GC separation has been reported so far. Herein we show the first fabrication of the MOF-coated capillary column for high-resolution GC separation. For a proof-of-concept demonstration, we choose MIL-101 as the stationary phase and xylene isomers and ethylbenzene (EB) as the targets for separation. Xylene isomers and EB are important raw chemicals in industry; in particular, p-xylene is used in the manufacture of terephthalic acid for the polyester industry. The separation and detection of individual xylene isomers and EB are also of environmental concern, and of great practical interest in air monitoring and blood analysis. For these reasons, numerous stationary phases have been developed for GC separation of xylene isomers and EB, for example, 7,8benzoquinoline, tetrachlorophthalate, 1,8-diaminonaphthalene, modified organo-clays Bentone-34, liquid-crystalline compounds, b-cyclodextrin derivatives, poly(ethylene glycol), and MIL-47. However, long analysis time (27–90 min) or temperature programming is often needed. MIL-101 is a chromium terephthalate MOF with coordinatively unsaturated sites (CUS). We utilized MIL-101 as the stationary phase because of its high surface area, large pores (2.9–3.4 nm), accessible CUS, and excellent chemical and thermal stability, which make it an attractive candidate for isomer separation. However, MIL-101 has never been explored as the stationary phase for chromatographic separation before, even though the tiny crystal size characteristic of MIL-101 is beneficial to the fabrication of MIL-101 coated capillary columns by a dynamic coating method. In this work, we prepared the MIL-101 coated capillary column and achieved a baseline separation of p-xylene, oxylene, m-xylene, and EB on the fabricated MOF coated capillary column by GC within 1.6 min without the need for temperature programming (Figure 1).

Exploring an Inverted U-Shape Relationship between Entrepreneurial Orientation and Performance in Chinese Ventures

Abstract: The critical role of entrepreneurial orientation (EO) in firm performance has been widely studied in the U.S. context. However, the examination of this key construct in emerging regions such as Chi...

Carbon dioxide utilization with C–N bond formation: carbon dioxide capture and subsequent conversion

Abstract: Carbon dioxide chemistry (in particular, capture and conversion) has attracted much attention from the scientific community due to global warming associated with positive carbon accumulation. The most widely used chemical absorption technique for carbon capture and storage/sequestration (CCS) would be essentially adopting amino-containing absorbents through formation of C–N bond in terms of mechanistic consideration. However, extensive energy input in desorption and compression process would be a crucial barrier to realize practical CCS. On the other hand, CO2 is very attractive as an environmentally friendly feedstock to replace the hazardous phosgene route for making commodity chemicals, fuels, and materials from a standpoint of green chemistry, whereas the reactions involving CO2 are commonly carried out at high pressure, which may not be economically suitable and also pose safety concerns. The challenge is to develop catalysts that are capable of activating CO2 under low pressure (preferably at 1 atm), and thus incorporating CO2 into organic molecules catalytically. We have proposed a carbon capture and utilization (CCU) strategy as an alternative approach to addressing the energy penalty problem in CCS. The essence of our strategy is to use captured CO2, also considered as the activated form of CO2, which could render this system suitable for accomplishing chemical transformation of CO2 under low pressure to avoid an additional desorption step. Indeed, CO2 could be activated through the formation of carbamate/alkyl carbonate with Lewis basic nitrogen species. In this review, we would like to discuss and update advances on CCU, particularly C–N bond formation with the production of oxazolidinones, quinazolines, carbamates, isocyanates and polyurethanes by using CO2 as C1 feedstock, and CO2 capture by amino-containing absorbents, including conventional aqueous solution of amine, chilled ammonia, amino-functionalized ionic liquids and solid absorbents such as amino-functionalized silica, carbon, polymers and resin, presumably leading to CO2's activation and thus subsequent conversion through C–N bond formation pathway.