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The recalcitrance of lignin with non-hydrolyzable C–O–C bonds, as well as the tendency for its phenolic fragments to polymerize into more recalcitrant polymers, leads to low-efficiency lignin deconstruction processes, such as low lignin concentrations during treatment. Herein, we developed a tandem catalytic approach for the conversion of highly concentrated lignin to stable cyclic alkanes by introducing Pt/HAP into a Ni/ASA catalyst in dodecane media. The incorporated Pt/HAP changes the simultaneous hydrogenation and hydrogenolysis of lignin on Ni/ASA into tandem reactions on a physically mixed Pt/HAP and Ni/ASA catalyst, involving the initial selective lignin depolymerization over Pt/HAP and the following hydrodeoxygenation of phenols over Ni/ASA, as evidenced by kinetic studies. In this tandem approach, the preferred initial lignin depolymerization, instead of lignin hydrogenation, originates from the strong adsorption and high C–O cleavage selectivity of lignin on the introduced Pt/HAP, as confirmed by UV-Vis, gel permeation chromatography (GPC), 2D-heteronuclear single quantum coherence nuclear magnetic resonance (2D-HSQC NMR), and catalytic tests. The rates of lignin depolymerization and the hydrodeoxygenation of depolymerized phenols are matched when the mass ratio of Pt/HAP and Ni/ASA is set at 1 : 1, allowing this approach to proceed with the highest lignin concentrations (150 g L−1) so far reported, with conversion to cyclic alkanes with 42 wt% yield without coke formation in dodecane at 300 °C in the presence of 6 MPa H2. Promisingly, the developed approach may lay a solid foundation for future industrial applications relating to lignin valorization. [ABSTRACT FROM AUTHOR]

Correction for 'The conversion of a high concentration of lignin to cyclic alkanes by introducing Pt/HAP into a Ni/ASA catalyst' by Shufang Qin et al., Green Chem., 2020, 22, 2901–2908, DOI: 10.1039/D0GC00243G. [ABSTRACT FROM AUTHOR]

[Display omitted] • The multi-functional synergistic catalysis constructed an excellent and selective deoxygenation catalyst which could decarboxylate diverse fatty acids to alkanes under hydrogen-free conditions. • The Pt/HAP-IE has a much lower activation energy (127 kJ∙mol−1) and a fast rate (300 g∙g Pt −1∙h) for decarboxylation. • The unique adsorption mode activated carboxylates, which trended to be fast cleaved by the adjacent Pt nanoparticles anchored by OH groups to catalyze the target decarboxylation reaction. A highly effective and stable Pt/HAP catalyst was developed for the hydrogen-free deoxygenation of lipids to alkanes via specific stabilization and synergistic effect, which achieved ca. 90% yield at 320 °C at a high rate of 300 g∙g Pt −1∙h−1 with 50 wt% reactant concentration in dodecane. Such catalytic system was adapted to various triglyceride feedstock and even unprocessed waste oil, showing superior activities than other reported Pt catalysts. The Pt precursor was ion-exchanged with the OH surface groups of HAP, as confirmed by characterizations of CO 2 -TPD, NH 3 -TPD and IR, forming uniform and small Pt nanoparticles with an average size of 0.7 nm after reduction. Even after eight recycling runs, the particle sizes were slightly turned into 1.6 nm with high reactivity and stability. In situ IR spectra showed that carboxylic acid was physically adsorbed on Pt/SiO 2 and adsorbed as a bidentate on Pt/Al 2 O 3 , while adsorbed as a chelation on Pt/HAP-IE in comparison. Upon adsorption, protons of the carboxyl group were dissociated by phosphate, and the generated carboxylate anions were adsorbed on Ca2+ to form a chelated structure. Such adsorption mode activated carboxylates, which trended to be fast cleaved by the adjacent Pt nanoparticles anchored by OH groups to catalyze the target decarboxylation reaction, achieving the multi-functional synergistic catalysis. This Pt/HAP-IE catalyst can be applied to the hydrogen-free decarboxylation reactions, especially for the deoxygenation of compounds containing unsaturated C C, C O, C O, and O H bonds that are sensitive to hydrogen. [ABSTRACT FROM AUTHOR]