Abstract
Herein, we report the aerobic oxidation of several bio-oils (pyrolysis and microwave) derived from Kraft lignin using oxovanadium complex catalyst, (HQ)2Vv(O)(OiPr) (HQ=8-oxyquinoline) (2), ionic liquid (IL)-tagged oxovanadium complex, PF6-IL-salen-VIV(O) (3) (PF6=hexafluorophosphate) and copper catalyst CuX/TEMPO/2,6-lutidine (4) [X=OTf, trifluoro-methanesulfonate), Cl; TEMPO=2,2,6,6-tetramethylpiperidine-1-oxyl]. Cleavage of some lignin linkages and reduced phenolic content were observed by multinuclear NMR spectroscopy, FT-IR and 1D/2D GC/MS analysis. Catalyst 2 oxidized chloroform extracts of the microwave bio-oil more extensively than those from the pyrolysis bio-oil although reactivity trends were similar. With catalyst 3 in [MMIM][MeOSO3], the phenolic conversion was modest compared with the increase in carboxyl and decrease in aliphatic OH groups. IR spectra were consistent with phenol oxidation to quinone-type structures. In contrast, copper catalyst 4 showed formation of high molecular weight compounds after oxidation, likely resulting from radical recombination. Comparison of reactivity between the different types of lignin-derived bio-oils is also discussed.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
