Lu Yangfang,Wang Hui,Xue Yun,Gu Xue,Wang Yan,Yan Chao
Submicron, non-porous, chiral silica stationary phase has been prepared by the immobilization of functionalized β-CD derivatives to isocyanate-modified silica via chemical reaction and applied to the pressurized capillary electrochromatography (pCEC) enantio-separation of various chiral compounds. The submicron, non-porous, cyclodextrin-based chiral stationary phases (sub_μm-CSP2) exhibited excellent chiral recognition of a wide range of analytes including clenbuterol hydrochloride, mexiletine hydrochloride, chlorpheniramine maleate, esmolol hydrochloride, and metoprolol tartrate. The synthesized submicron particles were regularly spherical and uniformly non-porous with an average diameter of around 800 nm and a mean pore size of less than 2 nm. The synthesized chiral stationary phase was packed into 10 cm × 100 μm id capillary columns. The sub_μm-CSP2 column used in the pCEC system showed better separation of the racemates and at a higher rate compared to those used in the capillary liquid chromatography mode (cLC) system. The sub_μm-CSP2 possessed high mechanical strength, high stereoselectivity, and long lifespan, demonstrating rapid enantio-separation and good resolution of samples. The column provided an efficiency of up to 170 000 plates/m for n -propylbenzene.
Catalytic refining of lignin holds promise for producing sustainable platform chemicals. In this work, a gaseous hydrogen-free catalytic hydrodeoxygenation system is developed for upgrading lignin-derived phenols to alkane chemicals. Commercially available Raney Ni and HZSM-5 are used as a combinational catalyst, with isopropanol serving as the hydrogen-donating solvent. By modifying the temperature and the ratio of Raney Ni to HZSM-5, the reaction pathways for hydrogenation and deoxygenation can be tailored to specific requirements. As a result, a 97.1% yield of alkane fuels is achieved, with 64.4% propylcyclohexane and 32.7% propylbenzene obtained in one-pot reaction from the hydrodeoxygenation of 2-methoxy-4-propylphenol using a 3:1 mass ratio of Ni to HZSM-5, further increasing the ratio of HZSM-5 leads to a selectively production of propylbenzene in 62.0% yield. Through careful regulation of the catalytic system and the design of hydrogenation–deoxygenation pathways, excellent yields of 4-propylcyclohexanol (92.2%), propylcyclohexene (93.3%), and propylcyclohexane (93.2%) are directionally achieved. The catalyst maintained a conversion rate of over 99% after five cycles, demonstrating excellent robustness. This study offers a strategic system that expedites the selective upgrading of lignin-derived chemicals, heralding a pathway toward sustainable fuels and chemicals.
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