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The selective conversion of levulinic acid (LA) obtained from lignocellulosic biomass represents a crucial pathway for producing the key value‐added chemical compound γ‐valerolactone (GVL). Herein, we constructed a series of Pt‐based titanium‐silicalite‐1 (TS‐1) bifunctional catalysts modified with rare earth metal Ce through a simple spin‐coating impregnation method, and the catalytic performance was significantly improved compared to the unmodified Pt1.2/TS‐1. Pt0.7‐Ce0.5/TS‐1 exhibited the best aqueous‐phase catalytic activity (with a GVL yield of 99.4%). The introduction of CeOx can reduce the particle size of Pt nanoparticles and promote the formation of electron‐rich Pt species while delivering abundant oxygen vacancies (OV) for the catalysts. The characterization and testing results highlight the synergistic effect of OV and electron‐rich Pt sites on the oriented adsorption and selective hydrogenation of LA, providing new insights into constructing more efficient noble metal‐based zeolite catalysts for biomass conversion. [ABSTRACT FROM AUTHOR]

Pt nanocatalysts have received enthusiastic attention in the field of clean energy technologies due to their high catalytic activity and selectivity. The growth size and dispersion of Pt particles play significant effects on the reaction activity, especially in high temperature catalytic reactions where catalysts are prone to deactivation due to agglomeration and sintering of Pt particles. Herein, the Pt nanoparticles were effectively stabilized on AIPO‐18 molecular sieve by a biomolecule‐mediated green synthesis method. Based on the biocompatibility and electrostatic synergy of carboxymethyl chitosan (CMC), a high degree of Pt nanoclusters dispersion in AIPO‐18 zeolites was achieved. The hydroconversion of levulinic acid (LA)was carried out at 160°C and 2 MPa hydrogen pressure, and the LA conversion of Pt/AIPO‐18 (5CMC) reached 95.2% and the selectivity of γ‐valerolactone (GVL) was 97.9% after 2 h. Pt/AIPO‐18 (5CMC) exhibited satisfactory results that superior to the initial reactivity of Pt/AIPO‐18 (0CMC) after five runs. [ABSTRACT FROM AUTHOR]

Novel SSZ-39 zeolite-based Ru catalysts were synthesized by impregnation on as-synthesized metallic and protonated SSZ-39 and a one-pot synthesis strategy. The study focused on the influence of the SSZ-39 zeolite characteristics and catalyst preparation method type toward levulinic acid (LA) selective conversion to γ-valerolactone (GVL) under relatively mild reaction conditions (150 °C, 4 h and 2 MPa of H 2 with H 2 O and THF as solvents). Catalysts exhibited excellent catalytic efficiency (100 % LA conversion and 98.3 % GVL selectivity) and remarkable hydrothermal stability. The results revealed a correlation between excellent catalytic activity and the structural features of the synthesized catalysts, predominantly dependent on their appropriate surface acidity (strong Lewis acid sites) and enhanced electronic interaction between Ru species and SSZ-39. The one-pot method promoted the formation of mesopores besides the zeolitic micropores present in SSZ-39; therefore, the catalyst prepared by the one-pot method (Ru/SSZ-39) showed purer SSZ-39 crystallites and a slightly larger catalytic surface area of 439 m2/g than the original zeolite surface area of 424 m2/g. In addition, the original zeolite crystals retained their morphology as spherical aggregates and remained unaffected by Ru impregnation on the metallic or protonated support during the synthesis of Ru/Na-SSZ-39 and Ru/H-SSZ-39 catalysts, respectively. Notably, it has been demonstrated that SSZ-39 zeolite effectively acts as a support for the preparation of Ru catalyst in biomass conversion reactions. Moreover, the reused catalyst exhibited consistent activity over six cycles, maintaining its structural framework without significant loss in activity. [Display omitted] • Ru/SSZ-39 zeolite catalysts were achieved using impregnation and one-pot method synthesis methods. • The one-pot synthesis yielded purer SSZ-39 crystallites and a larger catalytic surface area. • The addition of Ru generates intermediate acidic sites, enhancing catalytic performance toward hydrogenating LA to GVL. • SSZ-39 zeolite effectively acts as a Ru catalyst support in biomass conversion reactions. [ABSTRACT FROM AUTHOR]

Bifunctional Pt-Ru/zeolite Y catalysts were prepared by ethylene glycol reduction (EGR) method, with 3 wt% of Pt and various ratios of Ru. The performance of catalysts was investigated for hydrogenation of levulinic acid (LA) to produce gamma-valerolactone (GVL). Catalysts were thermally treated in presence of NaOH and re-evaluated. The results showed that the thermal treatment contributed to adjustment of bifunctional Pt-Rux/Y acidity and further improved hydrogenation activity conversion of LA up to 100% and yield of GVL up to 97.99%. It also preserved the crystal structure of zeolite and showed better thermal stability as compared to Pt/Y and Ru/Y catalysts. • Pt-Rux/zeolite Y catalyst was achieved using the ethylene glycol reduction method. • Subsequent alkaline treatment allowed activation of Pt sites and adjusted zeolite acidity. • Treated Pt-Ru/zeolite catalysts showed the highest product and selectivity to GVL. • The treated catalysts showed better thermal stability and preserved the structure of the zeolite. [ABSTRACT FROM AUTHOR]