Structure-activity relations in Cs-doped heteropolyacid catalysts for biodiesel production

A series of insoluble heteropolytungstate (H3PW12O40 HPW) salts, CsxH3−xPW12O40 (x=0.9–3x=0.9–3), were synthesized and characterized using a range of bulk and surface sensitive probes including N2 porosimetry, powder XRD, FTIR, XPS, 31P MAS NMR, and NH3 calorimetry. Materials with Cs content in the range x=2.0–2.7x=2.0–2.7 were composed of dispersed crystallites with surface areas ∼100 m2 g−1 and high Brönsted acid strengths [ΔH0ads(NH3)=−150 kJmol−1], similar to the parent heteropolyacid. The number of accessible surface acid sites probed by α -pinene isomerization correlated well with those determined by NH3 adsorption calorimetry and surface area measurements. CsxH3−xPW12O40 were active toward the esterification of palmitic acid and transesterification of tributyrin, important steps in fatty acid and ester processing for biodiesel synthesis. Optimum performance occurs for Cs loadings of x=2.0–2.3x=2.0–2.3, correlating with the accessible surface acid site density. These catalysts were recoverable with no leaching of soluble HPW.

Promoter effects in the polymerisation of a mixed hydrocarbon feed with silica-supported BF3

The activity of a silica-supported BF3–methanol solid acid catalyst in the cationic polymerisation of an industrial aromatic C9 feedstock has been investigated. Reuse has been achieved under continuous conditions. Titration of the catalyst acid sites with triethylphosphine oxide (TEPO) in conjunction with 31P MAS NMR shows the catalyst to have two types of acid sites. Further analysis with 2,6 di-tert-butyl-4-methylpyridine (DBMP) has revealed the majority of these acid sites to be Brønsted in nature. The role of α-methylstyrene in promoting resin polymerisation via chain transfer is proposed.

Synthesis and characterization of silica-supported L-Lysine-based dendritic branches

Two series of novel modified silicas have been prepared in which individual dendritic branches have been attached to aminopropylsilica using standard peptide coupling methodology. The dendritic branches are composed of enantiomerically pure l-lysine building blocks, and hence, the modified silicas have the potential to act as chiral stationary phases in chromatography. In one series of modified silicas, the surface of the dendritic branch consists of Boc carbamate groups, whereas the other has benzoyl amide surface groups. Different coupling reagents have been investigated in order to maximize the loading onto the solid phase. The new supported dendritic materials have been fully characterized with properties of the bulk material determined by elemental analysis, 13C NMR, and IR spectroscopy, whereas XPS provides important information about the surface of the modified silica exposed to the incident X-rays, the key region in which potential chromatographic performance of these materials will take place. Although the bulk analyses indicate that loading of the dendritic branch onto silica decreases with increasing dendritic generation (and consequently steric bulk), XPS indicates that the optimum surface coverage is actually obtained at the second generation of dendritic growth.

Highly selective hydrogenation of furfural over supported Pt nanoparticles under mild conditions

The selective liquid phase hydrogenation of furfural to furfuryl alcohol over Pt nanoparticles supported on SiO2, ZnO, γ-Al2O3, CeO2 is reported under extremely mild conditions. Ambient hydrogen pressure, and temperatures as low as 50 °C are shown sufficient to drive furfural hydrogenation with high conversion and >99% selectivity to furfuryl alcohol. Strong support and solvent dependencies are observed, with methanol and n-butanol proving excellent solvents for promoting high furfuryl alcohol yields over uniformly dispersed 4 nm Pt nanoparticles over MgO, CeO2 and γ-Al2O3. In contrast, non-polar solvents conferred poor furfural conversion, while ethanol favored acetal by-product formation. Furfural selective hydrogenation can be tuned through controlling the oxide support, reaction solvent and temperature.

Catalytic supercritical water gasification of plastics with supported RuO2:a potential solution to hydrocarbons-water pollution problem

Here we report on a potential catalytic process for efficient clean-up of plastic pollution in waters, such as the Great Pacific Garbage Patch (CPGP). Detailed catalytic mechanisms of RuO2 during supercritical water gasification of common polyolefin plastics including low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP) and polystyrene (PP), have been investigated in a batch reactor at 450 °C, 60 min. All four plastics gave very high carbon gasification efficiencies (CGE) and hydrogen gasification efficiencies (HGE). Methane was the highest gas component, with a yield of up to 37 mol kg−1LDPE using the 20 wt% RuO2 catalyst. Evaluation of the gas yields, CGE and HGE revealed that the conversion of PS involved thermal degradation, steam reforming and methanation; whereas hydrogenolysis was a possible additional mechanism during the conversion of aliphatic plastics. The process has the benefits of producing a clean-pressurized methane-rich fuel gas as well as cleaning up hydrocarbons-polluted waters.

Effect of Cu and Sn promotion on the catalytic deoxygenation of model and algal lipids to fuel-like hydrocarbons over supported Ni catalysts

The ability of Cu and Sn to promote the performance of a 20% Ni/Al2O3 catalyst in the deoxygenation of lipids to fuel-like hydrocarbons was investigated using model triglyceride and fatty acid feeds, as well as algal lipids. In the semi-batch deoxygenation of tristearin at 260 °C a pronounced promotional effect was observed, a 20% Ni-5% Cu/Al2O3 catalyst affording both higher conversion (97%) and selectivity to C10-C17 alkanes (99%) in comparison with unpromoted 20% Ni/Al2O3 (27% conversion and 87% selectivity to C10-C17). In the same reaction at 350 °C, a 20% Ni-1% Sn/Al2O3 catalyst afforded the best results, giving yields of C10-C17 and C17 of 97% and 55%, respectively, which contrasts with the corresponding values of 87 and 21% obtained over 20% Ni/Al2O3. Equally encouraging results were obtained in the semi-batch deoxygenation of stearic acid at 300 °C, in which the 20% Ni-5% Cu/Al2O3 catalyst afforded the highest yields of C10-C17 and C17. Experiments were also conducted at 260 °C in a fixed bed reactor using triolein − a model unsaturated triglyceride − as the feed. While both 20% Ni/Al2O3 and 20% Ni-5% Cu/Al2O3 achieved quantitative yields of diesel-like hydrocarbons at all reaction times sampled, the Cu-promoted catalyst exhibited higher selectivity to longer chain hydrocarbons, a phenomenon which was also observed in experiments involving algal lipids as the feed. Characterization of fresh and spent catalysts indicates that Cu enhances the reducibility of Ni and suppresses both cracking reactions and coke-induced deactivation.

Base-free, one-pot chemocatalytic conversion of glycerol to methyl lactate using supported gold catalysts

We report an efficient one-pot conversion of glycerol (GLY) to methyl lactate (MLACT) in methanol in good yields (73 % at 95 % GLY conversion) by using Au nanoparticles on commercially available ultra-stable zeolite-Y (USY) as the catalyst (160 °C, air, 47 bar pressure, 0.25 M GLY, GLY-to-Au mol ratio of 1407, 10 h). The best results were obtained with zeolite USY-600, a catalyst that has both Lewis and Brønsted sites. This methodology provides a direct chemo-catalytic route for the synthesis of MLACT from GLY. MLACT is stable under the reaction conditions, and the Au/USY catalyst was recycled without a decrease in the activity and selectivity. From glycerol to green building blocks and solvents! An efficient, base-free conversion of glycerol to methyl lactate in methanol is reported, achieving good yields (73 % at 95 % glycerol conversion) using Au/ultra-stable zeolite-Y (USY) as the catalyst and environmentally benign oxygen as the oxidant by combining two separate reaction steps efficiently in a one pot procedure. The Au/USY catalyst can be recycled without a decrease in the activity and selectivity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Strongly localized moving discrete dissipative breather-solitons in Kerr nonlinear media supported by intrinsic gain

We investigate the mobility of nonlinear localized modes in a generalized discrete Ginzburg-Landau-type model, describing a one-dimensional waveguide array in an active Kerr medium with intrinsic, saturable gain and damping. It is shown that exponentially localized, traveling discrete dissipative breather-solitons may exist as stable attractors supported only by intrinsic properties of the medium, i.e., in the absence of any external field or symmetry-breaking perturbations. Through an interplay by the gain and damping effects, the moving soliton may overcome the Peierls-Nabarro barrier, present in the corresponding conservative system, by self-induced time-periodic oscillations of its power (norm) and energy (Hamiltonian), yielding exponential decays to zero with different rates in the forward and backward directions. In certain parameter windows, bistability appears between fast modes with small oscillations and slower, large-oscillation modes. The velocities and the oscillation periods are typically related by lattice commensurability and exhibit period-doubling bifurcations to chaotically "walking" modes under parameter variations. If the model is augmented by intersite Kerr nonlinearity, thereby reducing the Peierls-Nabarro barrier of the conservative system, the existence regime for moving solitons increases considerably, and a richer scenario appears including Hopf bifurcations to incommensurately moving solutions and phase-locking intervals. Stable moving breathers also survive in the presence of weak disorder. © 2014 American Physical Society.

The contradictions and complementarities of combining ERP systems with enterprise 2.0 supported informal systems

The chapter discusses both the complementary factors and contradictions of adopting ERP based systems with enterprise 2.0. ERP is characterized as achieving efficient business performance by enabling a standardized business process design, but at a cost of flexibility in operations. It is claimed that enterprise 2.0 can support flexible business process management and so incorporate informal and less structured interactions. A traditional view however is that efficiency and flexibility objectives are incompatible as they are different business objectives which are pursued separately in different organizational environments. Thus an ERP system with a primary objective of improving efficiency and an enterprise 2.0 system with a primary aim of improving flexibility may represent a contradiction and lead to a high risk of failure if adopted simultaneously. This chapter will use case study analysis to investigate the use of a combination of ERP and enterprise 2.0 in a single enterprise with the aim of improving both efficiency and flexibility in operations. The chapter provides an in-depth analysis of the combination of ERP with enterprise 2.0 based on social-technical information systems management theory. The chapter also provides a summary of the benefits of the combination of ERP systems and enterprise 2.0 and how they could contribute to the development of a new generation of business management that combines both formal and informal mechanisms. For example, the multiple-sites or informal communities of an enterprise could collaborate efficiently with a common platform with a certain level of standardization but also have the flexibility in order to provide an agile reaction to internal and external events.