Zeolite Y supported nickel phosphide catalysts for the hydrodenitrogenation of quinoline as a proxy for crude bio-oils from hydrothermal liquefaction of microalgae

This work demonstrates the potential of zeolite Y supported nickel phosphide materials as highly active catalysts for the upgrading of bio-oil as improved alternative to noble metal and transition metal sulphide systems. Our systematic work studied the effect of using different counterions (NH4 + , H+ , K+ and Na+ ) and Si/Al ratios (2.56 and 15) of the zeolite Y. It demonstrates that whilst the zeolite counterion itself has little impact on the catalytic activity of the bare Y-zeolite, it has a strong influence on the activity of the resulting nickel phosphide catalysts. This effect is related to the nature of the nickel phases formed during the synthesis process Zeolites containing K+ and Na+ favour the formation of a mixed Ni12P5/Ni2P phase, H+ Y produces both Ni2P and metallic Ni, whereas NH4 + Y produces pure Ni2P, which can be attributed to the strength of the phosphorus-aluminium interaction and the metal reduction temperature. Using quinoline as a model for the nitrogen-containing compounds in bio-oils, it is shown that the hydrodenitrogenation activity increases in the order Ni2P > Ni0 > Ni12P5. While significant research has been dedicated to the development of bio-oils produced by thermal liquefaction of biomass, surprisingly little work has been conducted on the subsequent catalytic upgrading of these oils to reduce their heteroatom content and enable processing in conventional petrochemical refineries. This work provides important insights for the design and deployment of novel active transition metal catalysts to enable the incorporation of bio-oils into refineries

Secretion and Reversible Assembly of Extracellular-like Matrix by Enzyme-Active Colloidosome-Based Protocells

The secretion and reversible assembly of an extracellular-like matrix by enzyme-active inorganic protocells (colloidosomes) is described. Addition of N-fluorenyl-methoxycarbonyl-tyrosine-(O)-phosphate to an aqueous suspension of alkaline phosphatase-containing colloidosomes results in molecular uptake and dephosphorylation to produce a time-dependent sequence of supramolecular hydrogel motifs (outer membrane wall, cytoskeletal-like interior and extra-protocellular matrix) that are integrated and remodelled within the microcapsule architecture and surrounding environment. Heat-induced disassembly of the extra-protocellular matrix followed by cooling produces colloidosomes with a densely packed hydrogel interior. These procedures are exploited for the fabrication of nested colloidosomes with spatially delineated regions of hydrogelation

Hierarchical Assembly of Zeolite Nanoparticles into Ordered Macroporous Monoliths Using Core−Shell Building Blocks

Hierarchical Assembly of Zeolite Nanoparticles into Ordered Macroporous Monoliths Using Core−Shell Building Block

Bioactive Hybrid Organogels Based on Miniemulsion Synthesis of Morphologically Complex Polymer/Surfactant/Calcium Phosphate Nanostructures

Morphologically complex amorphous calcium phosphate nanostructures are synthesized within supersaturated water-in-oil miniemulsions stabilized by a mixture of a calcium bis­(2-ethylhexyl)­phosphate (Ca­(DEHP)₂) surfactant and poly­(ethylene oxide)₁₉-poly­(propylene oxide)₆₉-poly­(ethylene oxide)₁₉ (P123) triblock copolymer. Solvent evaporation at room temperature results in self-supporting viscous organogels comprising an interconnected network of calcium phosphate nanofilaments embedded within a continuous polymer/surfactant matrix. The P123/DEHP/calcium phosphate organogels are employed as a bioactive filler for the occlusion of exposed dentine tubules using a standard bovine tooth model

Nanoparticle-Based Membrane Assembly and Silicification in Coacervate Microdroplets as a Route to Complex Colloidosomes

The chemical construction of complex colloidosomes consisting of a molecularly crowded polyelectrolyte-enriched interior surrounded by a continuous shell of closely packed silica nanoparticles is studied using optical and fluorescence microscopy, high-resolution X-ray microcomputed tomography, and synchrotron radiation X-ray tomographic microscopy. The colloidosomes are prepared by addition of partially hydrophobic silica nanoparticles to dodecane dispersions of positively or negatively charged coacervate microdroplets consisting of aqueous mixtures of poly­(diallyldimethylammonium chloride) (PDDA) and adenosine 5′-triphosphate (ATP) or PDDA and poly­(acrylic acid) (PAA), respectively. Interfacial assembly of the nanoparticles produces a polydisperse population of well-defined PDDA/PAA droplets with diameters ranging from 50 to 950 μm. In contrast, reconstruction of the PDDA/ATP coacervate interior occurs on addition of the silica nanoparticles to produce a nanoparticle-stabilized oil-in-coacervate-in-oil multiphase emulsion. Transfer of the coacervate-containing colloidosomes into water and replication of their internal structure are achieved by addition of tetramethoxysilane, which serves as both a cross-linking and silicification agent to produce mineralized PDDA/PAA or PDDA/ATP microstructures with a uniform solidified texture or multichambered interior, respectively. The integration of colloidosome and coacervate technologies offers a route to a new type of multifunctional microcompartmentalized system based on the membrane-mediated incarceration of molecularly crowded chemical environments

Nanoparticulate Palladium Supported by Covalently Modified Silicas: Synthesis, Characterization, and Application as Catalysts for the Suzuki Coupling of Aryl Halides

We present a study of the use of amine-functionalized, mesoporous silicas as supports for nanoparticulate palladium, and the use of the composite materials as heterogeneous catalysts for the Suzuki coupling of aryl bromides. Upon modification of the silica, via attachment of N-functionalized aminopropylsilyl ethers to surface silanol groups, only a small reduction in surface area and average pore diameter is observed. The mesoporosity and high surface area are also maintained after introduction of nanoparticulate palladium, as evidenced by the measurement of BET nitrogen sorption isotherms. Electron microscopy shows that the palladium particles are well-dispersed and of typical diameter 3−6 nm. Catalysis was initially tested using the coupling of phenylboronic acid with 4-bromoanisole in the presence of K2CO3 and with toluene as solvent. This revealed that the choice of organic modification has a crucial role in determining the activity and recyclability of the catalyst:  optimum behavior was found for diamine- and triamine-containing systems, while quaternary alkylammonium salts showed poor activities. The optimized catalysts are also active in the coupling of a range of aryl bromides and phenylboronic acids, and after three catalytic runs they show virtually no drop in activity. Upon further cycling, however, and after six catalytic runs, we do observe a drop in activity, and this is accompanied by some leaching of palladium and pore-blocking by reaction products and byproducts

Zeolite Y supported nickel phosphide catalysts for the hydrodenitrogenation of quinoline as a proxy for crude bio-oils from hydrothermal liquefaction of microalgae

This work demonstrates the potential of zeolite Y supported nickel phosphide materials as highly active catalysts for the upgrading of bio-oil as improved alternative to noble metal and transition metal sulphide systems. Our systematic work studied the effect of using different counterions (NH4 + , H+ , K+ and Na+ ) and Si/Al ratios (2.56 and 15) of the zeolite Y. It demonstrates that whilst the zeolite counterion itself has little impact on the catalytic activity of the bare Y-zeolite, it has a strong influence on the activity of the resulting nickel phosphide catalysts. This effect is related to the nature of the nickel phases formed during the synthesis process Zeolites containing K+ and Na+ favour the formation of a mixed Ni12P5/Ni2P phase, H+ Y produces both Ni2P and metallic Ni, whereas NH4 + Y produces pure Ni2P, which can be attributed to the strength of the phosphorus-aluminium interaction and the metal reduction temperature. Using quinoline as a model for the nitrogen-containing compounds in bio-oils, it is shown that the hydrodenitrogenation activity increases in the order Ni2P > Ni0 > Ni12P5. While significant research has been dedicated to the development of bio-oils produced by thermal liquefaction of biomass, surprisingly little work has been conducted on the subsequent catalytic upgrading of these oils to reduce their heteroatom content and enable processing in conventional petrochemical refineries. This work provides important insights for the design and deployment of novel active transition metal catalysts to enable the incorporation of bio-oils into refineries

Sustained Frictional Instabilities on Nanodomed Surfaces: Stick–Slip Amplitude Coefficient

Understanding the frictional properties of nanostructured surfaces is important because of their increasing application in modern miniaturized devices. In this work, lateral force microscopy was used to study the frictional properties between an AFM nanotip and surfaces bearing well-defined nanodomes comprising densely packed prolate spheroids, of diameters ranging from tens to hundreds of nanometers. Our results show that the average lateral force varied linearly with applied load, as described by Amontons’ first law of friction, although no direct correlation between the sample topographic properties and their measured friction coefficients was identified. Furthermore, all the nanodomed textures exhibited pronounced oscillations in the shear traces, similar to the classic stick–slip behavior, under all the shear velocities and load regimes studied. That is, the nanotextured topography led to sustained frictional instabilities, effectively with no contact frictional sliding. The amplitude of the stick–slip oscillations, σ_<i>f</i>, was found to correlate with the topographic properties of the surfaces and scale linearly with the applied load. In line with the friction coefficient, we define the slope of this linear plot as the stick–slip amplitude coefficient (SSAC). We suggest that such stick–slip behaviors are characteristics of surfaces with nanotextures and that such local frictional instabilities have important implications to surface damage and wear. We thus propose that the shear characteristics of the nanodomed surfaces cannot be fully described by the framework of Amontons’ laws of friction and that additional parameters (<i>e.g.</i>, σ_<i>f</i> and SSAC) are required, when their friction, lubrication, and wear properties are important considerations in related nanodevices