Ru nanoparticles anchored on porous N-doped carbon nanospheres for efficient catalytic hydrogenation of Levulinic acid to γ-valerolactone under solvent-free conditions.

The catalytic transformation of the biomass platform compound levulinic acid (LA) to γ-valerolactone (GVL) is a vital reaction to produce related renewable chemicals and fuels. Developing stable catalysts with highly dispersed and accessible ultrafine metal nanoparticle (NP) active sites for the hydrogenation of LA under solvent-free conditions is still a major challenge. Herein, a versatile nano-emulsion self-assembly method was employed to fabricate N-doped carbon nanospheres with a high specific surface area and hierarchically porous structure. Ultrafine Ru NPs were successfully anchored on the hierarchal porous N-doped carbon nanospheres (HPNC) with high dispersion. The obtained Ru/HPNC catalyst exhibited excellent catalytic performance for LA hydrogenation to GVL under solvent-free conditions with outstanding reusability. In contrast, Ru NPs embedded in other supports (including activated carbon and carbon nanotubes) were observed to be less effective under the same reaction conditions. The superior catalytic performance of the Ru/HPNC catalyst is due to the hierarchically porous catalyst structure, and accessible ultrafine Ru active sites which can promote the activation of CO bonds and H2 absorption during the catalytic process. The reaction pathway of LA hydrogenation to GVL is clearly researched by theoretical calculations. Thus, the current work provides a facile strategy for the synthesis of highly dispersed ultrafine metal NP-based catalysts for an important biomass transformation.

Facile preparation of ultrafine Pd nanoparticles anchored on covalent triazine frameworks catalysts for efficient N-alkylation.

The fabrication of stable and efficient catalysts for green and economic catalytic transformation is significant. Here, highly stable covalent triazine frameworks (CTF-1) were used as the supporting material for anchoring ultrafine Pd nanoparticles (NPs) via a facile impregnation process and a one-pot calcination-reduction strategy. The widespread dispersion of ultrafine Pd NPs was a result of the abundant high nitrogen-content triazine groups of CTF-1 that endowed the catalyst Pd@CTF-1 with high catalytic activity. The catalytic performance of Pd@CTF-1 was demonstrated by the one-pot N-alkylation of benzaldehyde with aniline (or nitrobenzene) under mild reaction conditions, and Pd@CTF-1 exhibited a wide range of general applicability for N-alkylation reactions. The reaction mechanism for the N-alkylation reaction was also studied in detail. In addition, the Pd@CTF-1 catalyst exhibited high thermal and chemical stability, maintaining good catalytic efficiency after multiple reaction cycles. This study provides new insights for the fabrication of organic supporting materials with highly dispersed active catalytic sites that can lead to excellent catalytic performance for efficient, economical, and green reactions.