161470-27-5Relevant articles and documents
One-Pot Conversion of Lignin into Naphthenes Catalyzed by a Heterogeneous Rhenium Oxide-Modified Iridium Compound
Li, Xinxin,Zhang, Bo,Pan, Xiaoli,Ji, Jianwei,Ren, Yujing,Wang, Hua,Ji, Na,Liu, Qiying,Li, Changzhi
, p. 4409 - 4419 (2020/03/04)
The direct transformation of lignin into fuels and chemicals remains a huge challenge because of the recalcitrant and complicated structure of lignin. In this study, rhenium oxide-modified iridium supported on SiO2 (Ir-ReOx/SiO2) is employed for the one-pot conversion of various lignin model compounds and lignin feedstocks into naphthenes. Up to 100 percent yield of cyclohexane from model compounds and 44.3 percent yield of naphthenes from lignin feedstocks are achieved. 2 D HSQC NMR spectroscopy before and after the reaction confirms the activity of Ir-ReOx/SiO2 in the cleavage of the C?O bonds and hydrodeoxygenation of the depolymerized products. H2 temperature-programmed reduction, temperature-programmed desorption of NH3, IR spectroscopy of pyridine adsorption, X-ray photoelectron spectroscopy, X-ray absorption fine structure analysis, and control experiments reveal that a synergistic effect between Ir and ReOx in Ir-ReOx/SiO2 plays a crucial role in the high performance; ReOx is mainly responsible for the cleavage of C?O bonds, whereas Ir is responsible for hydrodeoxygenation and saturation of the benzene rings. This methodology opens up an energy-efficient route for the direct conversion of lignin into valuable naphthenes.
Cleavage of lignin C-O bonds over a heterogeneous rhenium catalyst through hydrogen transfer reactions
Zhang, Bo,Qi, Zaojuan,Li, Xinxin,Ji, Jianwei,Zhang, Leilei,Wang, Hua,Liu, Xiaoyan,Li, Changzhi
supporting information, p. 5556 - 5564 (2019/10/28)
Hydrogenolysis is one of the most popular strategies applied in the depolymerization of lignin for the production of aromatic chemicals. Currently, this strategy is mainly conducted under high hydrogen pressure, which can pose safety risks and is not sustainable and economical. Herein, we reported that heterogeneous rhenium oxide supported on active carbon (ReOx/AC) exhibited excellent activity in the selective cleavage of lignin C-O bonds in isopropanol. High yields of monophenols (up to 99.0%) from various lignin model compounds and aromatic liquid oils (>50%) from lignin feedstock were obtained under mild conditions in the absence of H2. The characterization of the catalyst by X-ray absorption fine structure, X-ray photoelectron spectroscopy and H2-temperature-programed reduction suggested that the activity of ReOx/AC could be attributed to the presence of ReIV-VI. The interaction between the surface oxygen groups of the active carbon and rhenium oxide could also play an important role in the cleavage of the C-O bonds. Notably, an ReOx/AC-catalyzed C-O bond cleavage pathway beyond a typical deoxydehydration mechanism was disclosed. More importantly, 2D-HSQC-NMR and GPC characterizations showed that ReOx/AC exhibited high activity not only in β-O-4 cleavage, but also in the deconstruction of more resistant β-5 and β-β linkages in lignin without destroying the aromatic ring. This study paves the way for the development of rhenium-based catalysts for the controlled reductive valorization of realistic lignin materials through a hydrogen transfer pathway.
Unprecedented organocatalytic reduction of lignin model compounds to phenols and primary alcohols using hydrosilanes
Feghali, Elias,Cantat, Thibault
supporting information, p. 862 - 865 (2014/01/06)
The first metal-free reduction of lignin model compounds is described. Using inexpensive Et3SiH, PMHS and TMDS hydrosilanes as reductants, α-O-4 and β-O-4 linkages are reduced to primary alcohols and phenols under mild conditions using B(C6F5)3 as an efficient catalyst. The Royal Society of Chemistry.
