Search

Biodiesel is a type of widely recognized environmentally friendly and sustainable biofuel. The key point for the industrial manufacturing of biodiesel is its cost, especially the price of raw oil feedstocks. Oil feedstocks of low quality require highly effective catalysts with more active sites (e.g., acid, base, acid–base, and enzyme) for (trans)esterification. Metal–organic framework (MOF) is a kind of polyporous material that can control its pore size and topological structure to fit the requirements of the catalytic reactions or conversion routes. This review focuses on the application of MOF-based catalysts in the preparation of biodiesel. Two methods of linking the active sites with MOF are introduced including intermolecular forces and chemical bridging or bonding. Four kinds of MOF-based nanocatalysts (i.e., enzyme, base, acid, and bifunctional catalysts) are evaluated and compared with other heterogeneous catalysts. Besides, technologies such as ultrasound and microwave for MOF-based nanocatalyst applications to produce biodiesel through transesterification and esterification are described. Finally, a brief conclusion and perspective for MOF-based nanocatalyst that applies to biodiesel production are provided. The MOF-based functional catalytic materials show great potential in biodiesel production and other relevant biorefineries. [ABSTRACT FROM AUTHOR]

To efficiently capture the toxic uranyl ions (UO22+), a new hierarchical micro‐macroporous metal–organic framework was prepared under template‐free conditions, featuring interconnected multi‐nanocages bearing carbonyl groups derived from a semi‐rigid ligand. The material exhibits an unusually high UO22+ sorption capacity of 562 mg g−1, which occurs in an intriguing two‐steps process, on the macropore‐based crystal surface and in the inner nanocages. Notably, the latter is attributed to the cooperative interplay of the shrinkage of the host porous framework induced by uranyl accommodation and the free carbonyl coordination sites, as shown by both single‐crystal X‐ray diffraction and a red‐shift of the infrared [O=UVI=O]2+ antisymmetric vibration band. [ABSTRACT FROM AUTHOR]

Uniquely structured CoS/N‐doped carbon@MoS2 (denoted as CoS/NC@MoS2) hollow spheres were successfully synthesized by using a well‐designed N‐rich Co‐metal organic framework (ZIF‐67) precursor and template. Owing to the good mechanical stability and conductivity of carbon hollow spheres, N‐doped carbon, and Co−Mo bonds, the as‐prepared CoS/NC@MoS2 composites exhibit outstanding electrochemical performance both in electrocatalytic and energy storage applications. An overpotential of 77 mV at 10 mA cm−2, and a Tafel slope of 67 mV dec−1 could be obtained in acid environment for the hydrogen evolution reaction. As an anode material for lithium‐ion batteries, the as‐prepared composites exhibit good cycling stability with a high reversible specific capacity of 802.4 mA h g−1 at a current density of 1 A g−1 after 400 cycles and good rate capability. Time to evolve: CoS/NC@MoS2 hollow spheres show outstanding electrocatalytic hydrogen evolution properties and good cycling stability as the anode for lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

Co9S8 is considered a promising candidate as the anode material in lithium-ion batteries (LIBs) because of its remarkable electrical conductivity, high theoretical capacity, and low cost. However, the practical application of Co9S8 is greatly restricted because of its poor cycling stability and rate performance, which result mainly from the large volume expansion and dissolution of the polysulfide intermediates during the charge/discharge process. In this report, Co9S8 embedded in N-rich carbon hollow spheres are successfully designed and synthesized through an in situ pyrolysis and sulfurization process, employing the well-known ZIF-67 as the precursor and ethanethiol as the sulfur source. Co9S8 nanoparticles embedded in the N-rich hollow carbon shell exhibit excellent lithium storage properties at a high charge/discharge rate. A discharge capacity of 784 mAh g−1 is obtained upon battery testing at a current density of 1 C (544 mA g−1). Even upon cycling at a current density of 4 C, the as-prepared Co9S8/N-C can still deliver a discharge capacity of 518 mAh g−1. The excellent battery performance can be attributed to the hollow structure as well as the N-rich carbon encapsulation. Moreover, this metal-organic framework sulfurization route also shows good generality for the synthesis of other metal sulfide-carbon composites such as ZnS/N-C and Cu2S/C. [ABSTRACT FROM AUTHOR]

Magnetic self-assembly metal-organic frameworks (MOFs) were constructed for the co-production of biodiesel and hydrogen from waste oils. The highly active MOF nanoparticles were synthesized and catalyzed crude glycerol with 126.8% hydrogen yield in subcritical water (350 °C, 5 min). By coupling alkali with MOF-derived carriers, continuous process of fast production of biodiesel (with microwave heating at 90 °C in 15 min, 15:1 methanol/oil molar ratio and 9 wt.% catalyst dosage) and hydrogen (350 °C, 5 min) were achieved with yield of 95.3% biodiesel from waste oil (AV of 3.95 mg KOH) and 102.6% H 2 from crude glycerol by-product, respectively. The nanoparticles were magnetically separated for 5 cycles with 95% biodiesel yield. Subsequently, the deactivated catalyst was used for hydrothermal gasification with 50% increasing in hydrogen yield. Characterization techniques showed active sites of MOF-derived nanoparticles were well dispersed with surface area increased by 3.9 times for highly efficient production of biodiesel and hydrogen. It revealed that MOF materials can be designed to make active catalysts and carriers for loading catalytic sites for biomass conversions to targeted biofuels. [Display omitted] • Ni-MOF-derived catalysts were synthesized for hydrothermal H 2 (126.8% yield). • Ni-MOF as magnetic carrier for its large surface area to load base for biodiesel. • Biodiesel from soybean oil reached 98.4% yield with 6 cycles (94.5%). • Biodiesel yield realized 95.3% from waste oil with 5 cycles (95.0%). • H 2 yield achieved 102.6% from crude glycerol with deactivated catalyst in 5 min. [ABSTRACT FROM AUTHOR]

Design an effective absorbent that has high surface area, and perfect recyclable is imperative for pollution elimination. Herein, we report a facile two-step strategy to fabricate magnetically separable 3-dimensional (3D) hierarchical carbon-coated nickel (Ni@C) nanocomposites by calcinating nickel based metal organic framework (Ni 3 (OH) 2 (C 8 H 4 O 4 ) 2 (H 2 O) 4 ). SEM and TEM images illuminate that the nanocomposites were constructed by 8 nm nickel nanoparticle encapsulated in 3D flake like carbon. The specific surface area of the obtained nanocomposites is up to 120.38 m 2 g −1 . Room temperature magnetic measurement indicates the nanocomposites show soft magnetism property, which endows the nanocomposites with an ideal fast magnetic separable property. The maximum adsorption capacity of the nanocomposites for rhodamine B is 84.5 mg g −1 . Furthermore, the nanocomposites also exhibit a high adsorption capacity for heavy metal ions. The adsorbent can be very easily separated from the solution by using a common magnet without exterior energy. The as-prepared Ni@C nanocomposites can apply in waste water treatment on a large-scale as a new adsorbent with high efficiency and excellent recyclability. [ABSTRACT FROM AUTHOR]