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[Display omitted] • Single Cu atoms catalyst of Cu@UiO-66-(COOH) 2 was designed and synthesized. • High performance of LA hydrogenation to GVL was achieved via CTH route. • The defective sites in MOF facilitated the stabilization of Cu atoms. • The atomic dispersion of Cu and carboxyl group contributed to the high performance. Single-atom catalysts (SACs) have received great interests due to their high atomic utilization efficiency and unique electronic properties of active center atom. Here we reported a single-atom catalyst, Cu@UiO-66-(COOH) 2 , prepared by a simple, facile, and efficient solvothermal strategy, where Cu atoms were coordinated to the defect sites of secondary building units (SBUs) in a Zr-based metal–organic framework (MOF) UiO-66-(COOH) 2. The single-atom Cu@UiO-66-(COOH) 2 catalyst exhibited high activity for biomass derived platform chemical levulinic acid (LA) hydrogenation to γ-valerolactone (GVL) through catalytic transfer hydrogenation (CTH) process using isopropanol (IPA) as hydrogen donor under mild reaction conditions, where 96.7% GVL yield was achieved. The site isolation and uniform distribution of single Cu atoms combined with the aid of acid sites in MOF, attributing to the excellent catalytic performance for biomass upgrading. [ABSTRACT FROM AUTHOR]

[Display omitted] • One-step synthesis of gasoline fuels from γ-valerolactone was achieved. • Cu/HZSM-5 bifunctional catalyst with adjusting acidity and Cu loading content was designed. • The interfacial active sites composed of metallic Cu and proton acid of HZSM-5 determine the catalytic performance. • A spontaneous C O bond breaking path of γ-valerolactone was found. Direct synthesis of transportation liquid fuels from renewable biomass-based resources via γ-valerolactone (GVL) is a highly attractive but challenging target. The current conversion of biomass-derived GVL to liquid fuels suffers from low selectivity or multiple operation steps with high energy consumption. Herein, we reported a simple and efficient way for the high-selective conversion of GVL into gasoline fuels over designed Cu/HZSM-5 bifunctional catalyst in a single fixed-bed reactor. The excellent catalytic performance of 99.9 % conversion of GVL with 85.3 % selectivity to C 5+ hydrocarbons (mainly C 5 -C 12) and good stability were obtained. We demonstrated that the interfacial sites composed of metallic Cu and proton acid of HZSM-5 played a key role in determining the performance via providing a spontaneous C O bond breaking path of GVL, facilitating the formation of pentene intermediate that could be further converted to gasoline fuels through a series of aromatization, alkylation and oligomerization reactions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Oriented transformation of GVL into gasoline fuels was achieved. • Nano-HZSM-5 with adjusting acidity and pore structure was designed. • Small particle sizes facilitated fast diffusion of reactants and products in the pore channels. • Reducing acid sites on external surface promoted the formation of C5+ hydrocarbons. γ-Valerolactone (GVL) is one of a promising and versatile platform compounds, derived from renewable biomass, that could be widely used as key raw materials for the production of high value-added chemicals and energy fuels. Here, we report the oriented transformation of GVL into gasoline range hydrocarbons through an integrated two-stage fixed-bed catalytic system. The catalytic upgrading strategy involved the GVL feeds converting to butene isomers mixture and CO 2 by ring-opening and decarboxylation without use of external H 2 over SiO 2 -Al 2 O 3 catalyst, coupled with the oligomerization of butene isomers intermediates to gasoline fuels over the nano-HZSM-5 catalyst. This integrated two-stage processes could greatly simplify the products separation, avoid the incompatibility of their reaction conditions, and effectively improve the catalytic stability. The selectivity and yield for target C 5−12 gasoline range fuels was high as 82.2 % and 58.7 %, respectively, and no obvious deactivation was observed with time on stream of 50 h. [ABSTRACT FROM AUTHOR]

[Display omitted] • γ-Valerolactone converting to butene was achieved. • Amorphous SiO 2 -Al 2 O 3 catalyst with adjustable acidity was prepared. • Lower acid sites facilitated the decarboxylation of pentenoic acid. • A two-stage integration system was developed for converting GVL to gasoline. γ-Valerolactone (GVL) as a sustainable platform compound could be converted to renewable fuels and chemicals, whereas directly converting GVL to target products remains still the challenge. In this work, we report an amorphous SiO 2 -Al 2 O 3 catalyst with adjustable acidity, which presented an excellent selectivity of 97.5 % butene at GVL conversion of 99.5 %, and remained an outstanding stability for 50 h. Appropriate weak and strong acid sites were the key for the ring-opening of GVL. Lower acid sites facilitated the decarboxylation of pentenoic acid (PEA), while higher acid sites promoted the cracking of PEA. Besides, a two-stage integration system was developed for converting GVL to C 5 + hydrocarbons via butene intermediate, giving a good yield of 57.6 % C 5 + hydrocarbons via combining the SiO 2 -Al 2 O 3 catalyst with nano-HZSM-5 together. [ABSTRACT FROM AUTHOR]

• Highly dispersed and stable Cu nanoparticles was finely encapsulated in HZSM-5. • Selectivity of valeric biofuel from GVL upgrading was preciously controlled. • Synergetic effect of confined Cu centers and acidic zeolite was crucial for the catalytic performance. • C-O bond activation mode was determined by distinct electrons redistributions on GVL in different adsorbed environments. Achieving precise selectivity control by driving specific reaction paths involving selective C-O bond activation of multifunctional molecules in renewable biomass oriented-upgrading is highly attractive but challenging. Herein, a facile in-situ hydrothermal strategy was developed to obtain highly dispersed and stable Cu nanoparticles encapsulated in well-organized HZSM-5 zeolite, which exhibited extraordinary selectivity control in the lignocellulosic biomass-derived γ-valerolactone (GVL) upgrading toward valuable valeric biofuels with good stability. The as-synthesized Cu@HZSM-5 exhibited a framework Al-dependent Cu distribution characteristic in HZSM-5, while the Cu spatial confinement by zeolite framework together with the synergetic effect of confined Cu centers and acidic zeolite support endowed the optimized Cu@HZSM-5 catalysts exceedingly high hydro-conversion efficiency. Theoretical calculations demonstrated that the transferred electrons from Cu to GVL in different zeolite microenvironments (zeolite-encapsulated and -impregnated structure) showed the very distinct redistributions on the C atoms of GVL, which was crucial to tune the ring C-O bond activation mode in GVL ring-opening, consequently giving a well-controlled product selectivity. [ABSTRACT FROM AUTHOR]

Achieving precise selectivity control towards the sustainable production of biofuels and chemicals in biomass resources valorization via selective C-O bond activation is an important but challenging target. Herein, a selective conversion strategy of lignocellulosic-derived γ-valerolactone (GVL) using MFI-type HZSM-5 zeolite-mediated Co-based synergetic catalysts is reported. The as-synthesized Co@HZSM-5 catalyst with highly dispersed and stable Co nanoparticles inside microcrystal enables exceedingly high selectivity for the valeric biofuel production from GVL, whereas the zeolite-supported Co/HZSM-5 catalyst exhibits a selectivity switching towards pentane biofuel under otherwise identical conditions. This selectivity difference stems from the diverse synergetic catalysis between metallic Co and acidic HZSM-5 support of Co@HZSM-5 versus Co/HZSM-5 in GVL upgrading. Theoretical calculations further demonstrate the distinct ring C-O bond strength of GVL under these two Co chemical microenvironments, which is crucial to tune the C-O bond activation modes in GVL ring-opening, affording a flexible selectivity switching toward valeric- or pentane-oriented reaction channels. [Display omitted] • Highly dispersed and stable Co nanoparticles was finely encapsulated in HZSM-5. • Selectivity switching of valeric/pentane biofuels from GVL upgrading was achieved. • Diverse Co-acid synergetic effects under two Co chemical environments were found. • Well-controlled ring C-O bond activation mode in GVL ring-opening was achieved. [ABSTRACT FROM AUTHOR]