Blaž Likozar

Simultaneous Liquefaction and Hydrodeoxygenation of Lignocellulosic Biomass over NiMo/Al2O3, Pd/Al2O3, and Zeolite Y Catalysts in Hydrogen Donor Solvents

The one‐step solvolysis and hydro‐treatment of oak, fir and beech sawdust was studied in a slurry reactor using tetralin, phenol and glycerol as solvents and representative heterogeneous catalysts used in the petrochemical industry for hydrogenolysis (the sulfide form of NiMo/Al2O3), hydrogenation (Pd/Al2O3) or fluid catalytic cracking (zeolite Y). Deoxyliquefaction products of cellulose, hemicellulose and lignin were characterised in terms of solvent fractionation, FTIR and diffuse reflectance infrared Fourier transform spectroscopy, elemental analysis and an innovative method for particle size distribution and mean grain size determination by SEM image processing. A new lumped kinetic model was developed according to the reaction mechanisms, which contain wood de‐polymerisation, decarbonylation, decarboxylation and demethanation, tar phase hydrodeoxygenation by molecular and in situ generated hydrogen, as well as charring inhibition by free‐radical stabilisation hydrogen transfer.

The effect of ionic liquid type on the properties of hydrogenated nitrile elastomer/hydroxy-functionalized multi-walled carbon nanotube/ionic liquid composites

In order to achieve good morphological, mechanical, structural, and thermal properties of a polymer electrolyte, ionic-liquid-in-polymer electrolytes have been explored. It was found that 1-ethyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, and 1-butyl-1-methylpyrrolidinium tetrafluoroborate (EMImBF4, BMImBF4, and BMPyBF4), hexafluorophosphate (EMImPF6, BMImPF6, and BMPyPF6), and bis(trifluoromethylsulfonyl)imide (EMImTFSI, BMImTFSI, and BMPyTFSI) in hydroxy-functionalized multi-walled carbon nanotubes (MWCNT–OH) reinforced hydrogenated poly(acrylonitrile-co-1,3-butadiene) (HNBR) produce homogeneous solids. HNBR/MWCNT–OH/ionic liquid solid electrolytes were prepared by melt compounding of the nanotubes in the elastomer, mixing with curing system, curing, and immersion in the ionic liquid. Cross-linked with 12.9 wt% of the curing system (per total composite weight prior to ionic liquid sorption), these HNBR-based electrolytes displayed elastomeric properties and high tensile strength (up to 24 MPa). HNBR/MWCNT–OH/ionic liquid composites had the elongation at break up to 378% (BMPyTFSI) at the room temperature and ionic liquid concentrations up to 18 wt% (BMImTFSI). Thermal analysis showed that the Tg of HNBR/MWCNT–OH/ionic liquid systems decreased as a function of increasing ionic liquid content at the constant polymer content in a composite.

In situ Generation of Ni Nanoparticles from Metal–Organic Framework Precursors and Their Use for Biomass Hydrodeoxygenation

So far, in situ-generated Ni nanoparticles have been reported to be efficient catalysts for tar cracking during wood liquefaction by pyrolysis. Herein, their performance in further bio-oil conversion steps is evaluated. Nanoparticles were generated for the first time from a Ni-containing metal-organic framework, MIL-77, during the hydrotreatment of glycerol-solvolyzed lignocellulosic (LC) biomass. Reactions were conducted at 300 °C and the H2 pressure was 8 MPa in a slurry reactor. The catalytic activity and selectivity of the deoxygenation and hydrocracking reactions for real biomass-derived feedstock using in situ-generated nanoparticles was compared with Ni nanoparticles dispersed on a silica-alumina support (commercial Ni/SiO2 -Al2 O3 catalyst). The mass activity of the in situ-generated nanoparticles for hydrogenolysis was more than ten times higher in comparison to their commercial analogues, and their potential for the use in LC biorefinery is discussed.

Optimization of Ligninolytic Enzyme Activity and Production Rate with Ceriporiopsis subvermispora for Application in Bioremediation by Varying Submerged Media Composition and Growth Immobilization Support

Response surface methodology (central composite design of experiments) was employed to simultaneously optimize enzyme production and productivities of two ligninolytic enzymes produced by Ceriporiopsis subvermispora. Concentrations of glucose, ammonium tartrate and Polysorbate 80 were varied to establish the optimal composition of liquid media (OLM), where the highest experimentally obtained activities and productivities were 41 U L−1 and 16 U L−1 day−1 for laccase (Lac), and 193 U L−1 and 80 U L−1 day−1 for manganese peroxidase (MnP). Considering culture growth in OLM on various types of immobilization support, the best results were obtained with 1 cm beech wood cubes (BWCM). Enzyme activities in culture filtrate were 152 U L−1 for Lac and 58 U L−1 for MnP, since the chemical composition of this immobilization material induced higher Lac activity. Lower enzyme activities were obtained with polyurethane foam. Culture filtrates of OLM and BWCM were applied for dye decolorization. Remazol Brilliant Blue R (RBBR) was decolorized faster and more efficiently than Copper(II)phthalocyanine (CuP) with BWCM (80% and 60%), since Lac played a crucial role. Decolorization of CuP was initially faster than that of RBBR, due to higher MnP activities in OLM. The extent of decolorization after 14 h was 60% for both dyes.

Temperature Dependent Dynamic Mechanical Properties of Hydrogenated Nitrile Butadiene Rubber and the Effect of Peroxide Cross-linkers

Abstract The viscoelastic behavior of hydrogenated nitrile butadiene rubber (HNBR) was studied over a range of temperatures and shear frequencies. Dynamic mechanical properties were studied and modelled using the generalized Maxwell model and the Williams-Landel-Ferry equation. A fitting algorithm was developed to provide the best agreement between the experimental data and the model results. In addition to dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) was applied. The HNBR structure was characterized by X-ray diffraction (XRD). The developed model exhibited an excellent agreement with either isothermal or dynamic experiment data, yet only up to the rubbery plateau, after which a structure ordering occurred. This was explained by the cyano group secondary bonding and consequentially the cross-linking between HNBR chains. A molecular modeling simulation was made to confirm the cross-linking. The effect of peroxide cross-linking agents in a compound resembled the one usually observed in the filler formulated compounds.

Effect of O2, CO2 and N2O on Ni–Mo/Al2O3 catalyst oxygen mobility in n-butane activation and conversion to 1,3-butadiene

A commercial heterogeneous Ni–Mo/Al2O3 catalyst was tested for the oxidative dehydrogenation (ODH) reaction of n-butane with different oxidant species: O2, CO2 and N2O. The effect of the lattice oxygen mobility and storage in Ni–Mo/Al2O3 on catalytic conversion performance was investigated. Experiments indicated that a high O2-storage/release is beneficial for activity, however at the expense of selectivity. A significant amount of butadiene with no oxygenated compound products was formed upon using carbon dioxide and nitrous oxide, while O2 favoured the formation of cracked hydrocarbon chains and COx. The highest turnover yield to 1,3-butadiene was achieved at an oxidant-to-butane molar ratio of 2 : 1 at temperatures of 350 °C and 450 °C. With CO2, significant amounts of hydrogen and carbon monoxide have evolved due to a parallel reforming pathway. Partial nickel/molybdenum oxidation was also observed under CO2 and N2O atmospheres. TPR revealed the transformation of the high valence oxides into structurally distinct metal sub-oxides. In TPRO, three distinct peaks were visible and ascribed to surface oxygen sites and two framework positions. With N2O, these peaks shifted towards a lower temperature region, indicating better diffusional accessibility and easier bulk-to-surface migration. XRD revealed the presence of an α-NiMoO4 active phase, which was used in DFT modelling as a (110) plane. Theoretical ab initio calculations elucidated fundamentally different reactive chemical intermediates when using CO2/N2O or O2 as the oxidant. The former molecules promote Mo atom oxygen termination, while in an O2 environment, Ni is also oxygenated. Consequently, CO2 and N2O selectively dehydrogenate C4H10 through serial hydrogen abstraction: butane → butyl → 1-butene → 1-butene-3-nyl → butadiene. With O2, butane is firstly transformed into butanol and then to butanal, which are prone to subsequent C–C bond cleavage. The latter is mirrored in different mechanisms and rate-determining steps, which are essential for efficient butadiene monomer process productivity and the optimisation thereof.

Biofuel from Lignocellulosic Biomass Liquefaction in Waste Glycerol and Its Catalytic Upgrade

Liquid biofuel was obtained by solvolytic liquefaction of lignocellulosic (LC) biomass in glycerol. Different types of wood, reaction temperatures and homogeneous catalysts were tested to obtain solvolytic oil with suitable fuel properties. Liquefaction conditions have little effect on fuel properties, so the upgrade step had to be introduced. Feasibility of hydrodeoxygenation (HDO) upgrading method using commercially available Ni, NiMo and Pd catalysts was investigated under elevated pressure and temperatures between 200 and 325 °C.

Experimental Dimensional Accuracy Analysis of Reformer Prototype Model Produced by FDM and SLA 3D Printing Technology

The subject of this paper is the evaluation of the dimensional accuracy of FDM and SLA 3D printing technologies in comparison with developed reformer polymer electrolyte membrane (PEM) fuel cell CAD model. 3D printing technologies allow a bottom-up approach to manufacturing, by depositing material in layers to final shape. Dimensional inaccuracy is still a problem in 3D printing technologies due to material shrinking and residual stress. Materials used in this research are PLA (Polylactic Acid) for FDM technology and the standard white resin material for SLA technology. Both materials are commonly used for 3D printing. PLA material is printed in three different height resolutions: 0.3 mm, 0.2 mm and 0.1 mm. White resin is printed in 0.1 mm height resolution. The aim of this paper is to show how layer height affects the dimensional accuracy of FDM models and to compare the dimensional accuracy of FDM and SLA printed reformer models with the same height resolution.

Influence of geometry on pressure and velocity distribution in packed-bed methanol steam reforming reactor

The main tasks of this research is to propose several changes in the packed bed micro methanol steam reformer geometry in order to ensure its performance. The reformer is an integral part of the existing indirect internal reforming high temperature PEMFC and most of its geometry is already defined. The space for remodeling is very limited.

Comparison of conventional and controlled bulk polymerization of styrene by N-methyl-2-pyrrolidone and 1-dodecanethiol

Abstract Controlled radical polymerization of styrene was initiated using Nmethyl- 2-pyrrolidone (NM2P) and 1-dodecanethiol (1DT). This polymerization system exhibited “living” characteristics, namely the molecular weight averages of resulting polymers increased linearly with conversion, which has been determined by gel permeation chromatography (GPC) analysis. The polymer was additionally characterized with Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H NMR) spectroscopy. Kinetics of controlled radical polymerization has been studied and the temperature dependency of overall polymerization rate constant has been determined. A comparison of conventional bulk radical and controlled bulk radical polymerization of styrene has been explored. Conventional radical polymerization was initiated with 2,2’-azobis(2- methylpropionitrile) (AIBN), whereas 1-dodecanethiol was applied as a chain transfer agent. The reaction rate of controlled radical polymerization was slower than the reaction rate of conventional radical polymerization initiated with AIBN. Consequentially, the activation energy and the pre-exponential factor were lower in the case of controlled polymerization in comparison to the ones observed in the conventional - AIBN initiated - system. Furthermore, by comparing the controlled to the conventional radical polymerization lower polydispersities were observed. Macromolecular structure analysis suggested a more linear chain structure in the controlled radical polymerization system. The thermal properties of polymer products have also been studied and the corresponding glass transition temperatures were higher upon comparison of the conventional and the AIBN initiated system, respectively