Liquid Feedstock Research Articles

Chemical upcycling of polyolefins into liquid refinery feedstock from the circularity and chemical engineering aspects

Three quarters of all plastics produced each year are discarded to landfill after a single use without proper waste management practices, causing a global environmental crisis: waste plastics suffocating our world at enormously large volumes. Discarding plastics into landfill, inefficiently processing them to lower value materials, or incinerating them cause an irreversible loss of the stored energy in plastics. These plastics, however, represent a tremendous resource for the production of chemicals and can be upcycled into high-quality value-added refinery feedstock that could be used to produce virgin polyolefins. In this article, we review pyrolysis and hydrogenolysis based chemical transformations to convert waste polyolefins into liquid hydrocarbons with a special emphasis on life cycle assessment (LCA), reactor technologies, and integration to existing refineries. Several patented technologies are described in detail to shed a light on engineering aspects of the chemical recycling. Liquid products obtained from chemical recycling are examined from the circularity point of view. Feedstock and stream locations in existing refineries and around steam crackers are recommended to feed and/or blend the products obtained from chemical recycling of polyolefins. Challenges, perspectives, and emerging areas of research and engineering are mentioned.

High-pressure gallium seeder for atomic fluorescence measurements

This work presents the design and testing of a seeder based on laser ablation capable of introducing gallium particles into a gaseous flow at elevated pressures typical of that found in practical combustion devices. The ability to seed such a flow with gallium particles is required to apply Ga-TLAF, a spatially and temporally resolved thermometry imaging technique well suited to harsh combustion environments. The design criteria for this gallium particle seeder are first listed and all the necessary details required to understand and replicate it are then provided. Next, the efficiency of gallium ablation is verified as a function of the ablation laser's fluence and repetition rate and of the pressure using gallium laser induced fluorescence and laser scattering measurements at ∼403 nm. For the conventional 355-nm nanosecond, Nd:YAG laser used for ablation in this study, data show that the quantity of gallium seeded into the flow can be conveniently modulated by varying the fluence of the ablation laser and/or its repetition rate. Data also show that the efficiency of ablation is marginally better for solid gallium than for liquid gallium, but that ablation of liquid gallium should be preferred to avoid a loss of ablation efficiency after some time. The temperature of the liquid gallium feedstock is found to be unimportant. SEM, EDX, and SPMS analyses show that laser ablation yields pure gallium particles with a characteristic size ranging at least from 50 nm to 10 μm and that the size distribution is insensitive to the pressure and to the ablation laser's fluence. Also important for future applications of Ga-TLAF in high-pressure flames, data show that the gallium LIF intensity recorded at room temperature or in the hot products of a flame is not significantly affected by pressure.

Reactive Carbon Capture Enables CO2 Electrolysis with Liquid Feedstocks.

ConspectusThe electrochemical reduction of carbon dioxide (CO2RR) is a promising strategy for mitigating global CO2 emissions while simultaneously yielding valuable chemicals and fuels, such as CO, HCOO-, and C2H4. This approach becomes especially appealing when integrated with surplus renewable electricity, as the ensuing production of fuels could facilitate the closure of the carbon cycle. Despite these advantages, the realization of industrial-scale electrolyzers fed with CO2 will be challenged by the substantial energy inputs required to isolate, pressurize, and purify CO2 prior to electrolysis.To address these challenges, we devised an electrolyzer capable of directly converting reactive carbon solutions (e.g., a bicarbonate-rich eluent that exits a carbon capture unit) into higher value products. This "reactive carbon electrolyzer" operates by reacting (bi)carbonate with acid generated within the electrolyzer to produce CO2 in situ, thereby facilitating CO2RR at the cathode. This approach eliminates the need for expensive CO2 recovery and compression steps, as the electrolyzer can then then coupled directly to the CO2 capture unit.This Account outlines our endeavors in developing this type of electrolyzer, focusing on the design and implementation of materials for electrocatalytic (bi)carbonate conversion. We highlight the necessity for a permeable cathode that allows the efficient transport of (bi)carbonate ions while maintaining a sufficiently high catalytic surface area. We address the importance of the supporting electrolyte, detailing how (bi)carbonate concentration, counter cations, and ionic impurities impact selectivity for products formed in the electrolyzer. We also catalog state-of-the-art performance metrics for reactive carbon electrolyzers (i.e., Faradaic efficiency, full cell voltage, CO2 utilization efficiency) and outline strategies to bridge the gap between these values and those required for commercial operation Collectively, these findings contribute to the ongoing efforts to realize industrial-scale electrochemical reactors for CO2 conversion, bringing us closer to a sustainable and closed-loop carbon cycle.

Laser Processing of Liquid Feedstock Plasma-Sprayed Lithium Titanium Oxide Solid-State-Battery Electrode

The astonishing safety and capacity characteristics of solid-state-batteries are encouraging researchers and companies to work on the manufacturing, development, and characterization of battery materials. In the present work, the effects of laser beam interaction with a liquid feedstock plasma-sprayed ceramic solid-state-battery (SSB) material coating were studied. Lithium Titanium Oxide (LTO) in the form of an aqueous suspension consisting of submicron powder particles was plasma-sprayed for the first time using a high-power axial III plasma torch on an aluminum substrate. The plasma-sprayed LTO coating suspension was subsequently post-processed using a fiber laser. The energy input of the laser beam on the surface of the deposited layer was the main variable. By varying the laser power and laser processing speed, the energy input values were varied, with values of 3.8 J/mm2, 9.6 J/mm2, 765.9 J/mm2, and 1914.6 J/mm2, and their effects on some key characteristics such as laser-processed zone dimensions and chemical composition were investigated. The results indicated that changing the laser beam parameter values has appreciable effects on the geometry, surface morphology, and elemental distribution of laser-processed zones; for instance, the highest energy inputs were 33% and 152%, respectively, higher than the lowest energy input.

Heterogeneous liquid discharge cracking of n-hexadecane as a heavy oil model compound: A way to generate plasma in liquid hydrocarbons at low voltage

Plasma is an excellent way of coupling renewable power resources and poor-quality heavy oil resources into high value petrochemicals. In order to achieve discharge in liquid hydrocarbons under low-voltage operating conditions, it was proposed a new liquid-phase discharge mode - heterogeneous liquid discharge. The aqueous-phase feedstock was injected into n-hexadecane as a heavy oil model compound through a pin electrode, and plasma was generated directly in the liquid feedstocks at room temperature, atmospheric pressure, and low voltage to achieve the in-situ reforming of n-hexadecane and the generation of syngas, C2 hydrocarbons, and other high value-added chemicals. The effects of injection of water and ethanol solution on the gaseous and liquid products, and feedstocks conversion were discussed, and the distribution of various products was explored in detail. Gas production increased with the concentration of injected ethanol up to a maximum of 110.8 mL/min. A n-hexadecane conversion of 2.0% was obtained on injection of 50% ethanol, 4.56 kV, and discharge for 2 min. Varying the ethanol concentration can regulate the composition of the product. The auxiliary effects of water and ethanol on n-hexadecane cracking and the origin of the main gaseous products were examined in the mechanistic analysis section.

Liquid plasma spraying of NiO-YSZ anode layers applicable for SOFC

Plasma spraying (PS) from liquid feedstocks is a promising alternative for fabricating the NiO-YSZ anodes for Solid Oxide Fuel Cell (SOFC). However, despite the inherent advantages of the PS process, the plasma sprayed anodes are still inferior to the conventional ones prepared by wet-ceramic techniques due to the difficulty of achieving the optimal porosity level. This study shows that due to recent development, the NiO-YSZ anode layers with desirable porosity and microstructure can now be effectively fabricated in a one-step process using PS equipment with a water-argon stabilized plasma torch. As a liquid feedstock, we utilized Ni nitrate (hexahydrate) solutions and YSZ suspensions with different ratios, using ethanol or water as solvents. We show that the ethanol-based feedstock provides a favorable microstructure and porosity of the resulted layers over the water-based one. In addition, apart from NiO and YSZ phases, the layers deposited with ethanol solvent contained even metallic Ni. Different ratios of Ni nitrate to YSZ in ethanol-based feedstocks greatly affected the layer’s characteristics; when the content of Ni nitrate was high, the resulting layers had a non-uniform morphology with a very porous microstructure. On the contrary, the equal contents of Ni nitrate and YSZ in the feedstock resulted in the most optimal layer's microstructure, chemical composition, and thus sufficient electrical resistance, making such material potentially useful as anode for SOFC.

Oxygen-Resistant CO2 Reduction Enabled by Electrolysis of Liquid Feedstocks.

Electrolytic CO2 reduction fails in the presence of O2. This failure occurs because the reduction of O2 is thermodynamically favored over the reduction of CO2. Consequently, O2 must be removed from the CO2 feed prior to entering an electrolyzer, which is expensive. Here, we show that the use of liquid bicarbonate feedstocks (e.g., aqueous 3.0 M KHCO3), rather than gaseous CO2 feedstocks, enables efficient and selective CO2 reduction without additional procedures for removing O2. This effect is made possible because liquid bicarbonate solutions, which serve as a liquid CO2 carrier, deliver high concentrations of captured CO2 to the cathode, while the low solubility of O2 in aqueous media maintains a low O2 concentration at the same cathode surface. Consequently, electrolyzers fed with liquid bicarbonate feedstocks create an environment at the cathode that favors the reduction of CO2 over O2. We validate this claim by electrochemically converting CO2 into CO with reaction selectivities of 65% at 100 mA cm-2 using a 3.0 M KHCO3 solution bubbled with 100% CO2 or 100% O2. Similar experiments performed with a gaseous CO2 feedstock showed that merely 0.5% of O2 in the feedstock reduced CO selectivity by >90% after 1 h of electrolysis. Our findings demonstrate that a liquid bicarbonate feedstock enables efficient CO2 reduction without the need for expensive O2 removal steps.

Hybrid photothermal–photocatalyst sheets for solar-driven overall water splitting coupled to water purification

Photocatalytic water splitting converts sunlight directly into storable hydrogen, but commonly involves the use of pure water and land for plant installation while generating unusable waste heat. Here we report a hybrid device consisting of a photocatalyst (PC) and a solar vapour generator (SVG) for simultaneous overall water splitting and water purification from open water sources. Specifically, an ultraviolet light-absorbing RhCrOx–Al:SrTiO3 PC is deposited on top of a floating, visible and infrared light-absorbing porous carbon SVG, which produces green fuel with a solar-to-hydrogen efficiency of 0.13 ± 0.03% and 0.95 kg m−2 h−1 of water vapour as the feed for the PC and collectable purified water. This integrated system maintains operational stability in seawater and other aqueous waste streams for over 154 h due to the isolation of the PC from contaminants in the liquid feedstock. This work provides a new concept for developing an off-grid energy production/storage solution and is a first step towards alleviating both energy and water supply challenges.

Masked stereolithography of wollastonite-diopside glass-ceramics from novel silicone-based liquid feedstock

Silicate bioceramics, including systems based on the simultaneous presence of wollastonite (CaSiO3) and diopside (CaMgSi2O6), are of great interest in bone tissue engineering applications, especially in form of variously shaped three-dimensional scaffolds, as determined by application of several additive manufacturing technologies. In this framework, silicone resins, properly modified with CaO- and MgO-based fillers and blended with photocurable acrylates, are attractive both as precursors and as feedstock for additive manufacturing technologies, including stereolithography. The use of powder fillers, however, may lead to issues with homogeneity or with printing resolution (owing to light scattering). The present paper aims at presenting the first results from a new concept of incorporation of CaO and MgO, relying on salts dispersed in emulsion within a photocurable silicone/acrylate blend. Direct firing at 1100 °C of printed scaffolds successfully produced wollastonite-diopside glass-ceramic scaffolds, with a very fine crystal distribution. The strength-to-density was tuned by operating either on the topology of scaffolds or on the firing atmosphere (passing from air to N2).

A large-eddy simulation study of the transcritical mixing process in coaxial jet flow under supercritical condition

Supercritical water gasification (SCWG) is a promising clean energy technology for utilizing fossil fuels or organic solid waste with the challenge of delivering and dispersing liquid feedstock into the reactor. This paper investigates the transcritical mixing process in coaxial injections using large-eddy simulation. The results reveal that large temperature and density gradients exist between the inner injected water and the ambient fluid in the near field of transcritical water injection. Structure comparison demonstrates that the cross-section of the inner potential core shrinks more quickly in the non-premixing coaxial injection than the single injection, which can facilitate the dispersion and dilution of injected water during the heating process due to the shear mixing with the coaxial high-velocity outer injection. In addition, in the premixing coaxial injections, the substantial radial velocity fluctuation induced by the contracting cross-section leads to a much shorter inner potential core and more intensive heat and mass transfer. Swirling inlets can significantly strengthen the radial velocity fluctuation, thereby accelerating the temperature increase and species blending. Coaxial injections can effectively be used for dispersing feedstock in the SCWG process, particularly for high-viscosity materials.

Drying behaviour and visualization of surfactants after co-spray drying of surfactant-stabilized aqueous suspensions

Surfactants are widely used in many industries as dispersants or flocculants for suspensions. As the addition of low concentrations of surfactant is sufficient to execute their effect, they barely alter the formulation composition. In this research it was examined whether surfactants, in particular polysorbate 80 (PS80), were suitable as suspension stabilizers for co-spray drying of drug-filler combinations. Therefore, their drying behaviour at different process and formulation settings was studied and mapped by means of fluorescently labelled PS80. Co-spray drying of 10% w/w aqueous suspensions stabilized with 0.1% w/w PS80 resulted in excessive loss of sticky powder in the conical lower part of the drying chamber and the powder conveyor ducts. Up to 16% of powder was lost in the first transporter (i.e. the first part of the conveyor ducts). The amount of powder deposited in the first transporter, and by extension the stickiness of the recovered powder, was correlated with the presence of PS80 on the surface of the spray dried particles. Redistribution of free surfactant molecules during droplet drying depended on the process and formulation parameters. Enrichment of PS80 at the particle surface was most pronounced after co-spray drying of liquid feedstocks with low suspended fraction at process conditions favouring rapid droplet drying.

Efficiency improvement of biomass gasifier using porous media heat recuperator

Nowadays, energy crisis and environmental problems become the important issues affect all lives on the earth. All fossil-based energy will be depleted within the next few-ten years, if it is used at this current rate. Utilizations of renewable energy via efficient system poses an opportunity to address both fossil fuel depletion and environmental issues simultaneously. Among all renewable energies, biomass is one of the best forms of energy, in term of it can be actually managed by the curtain plan, e.g.: energy crop strategy. Gasification is one of the best thermal processes that converts liquid and solid hydrocarbon feedstocks into gas fuel, called syngas or producer gas (mainly comprises CO and H2). This research aims to improve the efficiency of the gasification reactor using Porous Media Heat Recuperator (PMHR). With the expectation that using this heat exchanger not only improve the gasification processes, but the producer gas temperature can be also reduced as the requirement for running the internal combustion engine (ICE). Charcoal, the carbonized product of wood or biomass, was selected as feedstock for this proposed system as it would produce a producer gas suitable for the ICE with low or free of tars uniform properties and low moisture content. The gasifier system was tested in a forced draught method using air as the gasifying agent. The experimental results shown that the efficiency of the proposed system with PMHR can be increased about 77% and the temperature of output producer gas can be increased for approximately 58%, compared with the conventional system.

Gasification of Waste Machine Oil by the Ultra-Superheated Mixture of Steam and Carbon Dioxide

Reported in the article is further progress in the development of the novel pulsed detonation gun (PDG) technology for the conversion of organic wastes into syngas in a two-component gasifying agent (GA) containing ultra-superheated steam and carbon dioxide obtained by pulsed detonations of a natural gas–oxygen mixture at a frequency of 1 Hz. Experimental studies were carried out on a waste converter with a 40 dm3 flow reactor and two PDGs with a total volume of 2.4 or 3.2 dm3, which is approximately a factor of 6 and 4.5 less than in previous studies, respectively. The objective of the research was to find the design and operation parameters of the waste converter that provide a minimum amount of CO2 in the gasification products. Waste machine oil was used as a feedstock. It is shown that, compared with the earlier experiments with a higher average temperature of the reactor wall and with a PDG of a much larger volume, the contents of H2, CO, CH4, and CO2 in the syngas remained virtually unchanged, whereas the efficiency of the gasification process increased significantly: the use of 1 g of natural gas made it possible to gasify up to 4 g of the feedstock. It is also shown that the determining role in the gasification process of liquid feedstock is played by the feedstock residence time in the PDG rather than in the reactor. The minimum ratio between the flow rates of the GA and liquid feedstock, the minimum ratio between the flow rates of combustible gas and liquid feedstock, as well as the actual GA consumption in the gasification process are determined experimentally.

What is the long-term demand for liquid hydrocarbon fuels and feedstocks?

Liquid hydrocarbons made from crude oil serve many functions: (1) a dense, easy-to-store, easy-to-transport energy source, (2) a method for daily-to-seasonal energy storage, (3) a chemical feedstock, (4) a chemical reducing agent and (5) a method to enhance high-temperature heat transfer in many furnaces and industrial processes. Liquid hydrocarbons can be produced and used without increasing atmospheric carbon dioxide levels if made from non-fossil feedstocks such as carbon dioxide or biomass. Understanding future liquid hydrocarbon demand is the starting point in assessing the viability of such options. Our assessment is that U.S. demand for liquid hydrocarbons is unlikely to go below the equivalent of 10 million barrels per day of crude oil but could be as high as 20 million barrels per day. The costs to replace liquid hydrocarbons increases rapidly at lower liquid hydrocarbon consumption rates. Hydrocarbon biofuels from cellulosic feedstocks can meet such demands if produced with large external inputs of heat and hydrogen. Options based on more limited feedstocks (starches, plant oils, sugars, etc.) can’t meet such demands.

Transport limitations in polyolefin cracking at the single catalyst particle level.

Catalytic cracking is a promising approach to chemically recycle polyolefins by converting them into smaller hydrocarbons like naphtha, and important precursors of various platform chemicals, such as aromatics. Cracking catalysts, commonly used in the modern refinery and petrochemical industry, are tailored to process gaseous or liquid feedstock. Polyolefins, however, are very large macromolecules that form highly viscous melts at the temperatures required to break their backbone C-C bonds. Therefore, mass transport is expected to limit the performance of traditional cracking catalysts when applied to the conversion of polymers. In this work, we study these effects during the cracking of polypropylene (PP) over catalysts utilized in the fluid catalytic cracking (FCC) process. Thermogravimetric experiments using PP of varying molecular weight (Mw) and catalysts of varying accessibility showed that low Mw model polymers can be cracked below 275 °C, while PP of higher Mw required a 150 °C higher temperature. We propose that this difference is linked to different degrees of mass transport limitations and investigated this at length scales ranging from milli- to nanometers, utilizing in situ optical microscopy and electron microscopy to inspect cut open catalyst-polymer composites. We identified the main cause of transport limitations as the significantly higher melt viscosity of high Mw polymers, which prohibits efficient catalyst-polymer contact. Additionally, the high Mw polymer does not enter the inner pore system of the catalyst particles, severely limiting utilization of the active sites located there. Our results demonstrate that utilizing low Mw polymers can lead to a significant overestimation of catalyst activity, and suggest that polyolefins might need to undergo a viscosity reducing pre-treatment in order to be cracked efficiently.

Combination of different preservation techniques as low-cost strategies inhibiting sugar degradation in liquid feedstock used for bioethanol fermentation

Just like for the food supply chain, sugar-based feedstock used in the bioethanol industry might be affected by biological contamination, resulting in important economic losses. Therefore, it is necessary to develop cost-effective storage techniques capable of preserving feedstock over several months. In this study, three different techniques (ozonation, acidification, and addition of a corn oil layer) were investigated individually as well as combined for the long-term storage of sugars dedicated to fermentation. After 300 days of storage, up to 100% of the initial fermentable sugars were preserved with acidification (pH 2.0), independently or in conjunction with other conservation techniques. However, in terms of fermentation potential, the groups treated with acid had a lower ethanol yield than the groups maintained at pH 6.0. When the solution was treated with ozone combined with acidification, it yielded 55.71% of bioethanol efficiency, whereas when treated only with ozonation at pH 6.0, fermentation reached a 67.20% yield. Ozonation was found to be efficient to preserve fermentable sugars, either with the use of an oil layer (80% conservation) or at lower pH (100% ethanol efficiency). Finally, the combination of ozonation and an oil layer presented the highest total ethanol production, reaching 101g L−1 after 96h of incubation using Saccharomyces cerevisiae. Thus, the combined use of ozonation and an oil layer has the potential to be used in the bioethanol sector as a system to preserve liquid feedstock without the use of evaporation to increase sugar concentration.

Design optimization of integrated cooling inserts in modular Fischer-Tropsch reactors

Sustainable production of liquid fuels and feedstocks from atmospheric CO2 through carbon recycling technologies is necessary to broaden decarbonization efforts and further reduce global emissions. Fischer–Tropsch (FT) reactors can address this challenge by providing storable, high-value liquid hydrocarbon fuels and feedstocks from syngas generated through reductive CO2 utilization. FT technology, however, is most cost effective at large-scale, fixed-site plants and does not effectively address the smaller, globally distributed CO2 point sources. Alternatively, smaller, modular reactors can be composed together to the specific scale of the emission source, yielding a flexible solution that enables more widespread deployment. In these modular reactors, thermal management using a finned cooling insert embedded within the catalyst matrix is critical to maintaining the performance and viability. Thus, in this work, topology optimization is used to determine the cooling insert geometry that maximizes reactor productivity while preventing auto-thermal runaway. Optimal designs are generated for varying number of constituent fins and over a range of maximum operating temperatures. Constraints including minimum feature length-scales and prescribed cooling insert material are imposed on the designs to enhance manufacturability. The impact of design features such as insert tapering and increased length scale hierarchy is automatically revealed by the systematic design framework employed. This approach thus generates novel optimal geometries while automating, accelerating, and enhancing the design process compared to traditional heuristic approaches for cooling insert design in modular FT reactors.

Nepenthes mirabilis Fractionated Pitcher Fluid Use for Mixed Agro-Waste Pretreatment: Advocacy for Non-Chemical Use in Biorefineries

This study determined whether it is feasible to pretreat mixed agro-waste of different particle sizes using the pitcher fluid of Nepenthes mirabilis (N. mirabilis), which is known to digest leaf litter due to the enzyme cocktail contained in the fluid. This is due to the need for the holocellulolysis (a source of fermentable sugars) of mixed agro-waste to produce fermentable hydrolysates. The pitcher fluid was fractionated (<3 kDa, >3 kDa, <10 kDa, >10 kDa) and slurrified with the mixed agro-waste, i.e., 25% (w/w) for each waste—orange peels, apple peels, maize cobs, grape pomace, and oak plant leaf litter of various particle sizes, i.e., >75 µm x < 106 µm and >106 µm. The process of producing a high concentration of total reducible sugars (TRSs) with the lowest production of total phenolic compounds (TPCs) was determined to be a particle size of >106 µm, pretreatment for 72 h, and an enzyme fraction of <10 kDa, whereby 97 g/L of TRSs were produced with a significantly lower TPCs load (1 g/L). Furthermore, the <10 kDa showed preferable physico-chemical properties, with the highest reduction-oxidation potential including acidity. Several enzymes, i.e., β-1,3-Glucanase, Putative peroxidase 27, Thaumatin-like protein, among others, were identified in the <10 kDa fraction, i.e., enzymes known to perform various functions in plant-based waste. Therefore, there is a need for the renewable energy industry to consider solely using pitcher fluids to pretreat mixed agro-waste for fermentable hydrolysates’ production, which can be used as liquid feedstock for the bioenergy and/or biorefinery industries for environmental pollution reduction.

FAST PYROLYSIS OF SULFUR-FREE LIGNIN FROM ALKALINE PULPING WITH A HOT-WATER PRETREATMENT STAGE

"The pyrolytical conversion of birch (Betula pendula/pubescens) lignin fractions separated from hot-water pretreatment/sulfur-free delignification black liquors was investigated by pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS). Based on pyrolytical data, the main condensable compounds were organized into respective component groups, and the relative mass portions of the pyrolysis products (mainly monomer-related fragmented products) formed during pyrolysis of various feedstocks were determined. It could be concluded that relatively pure aromatic fractions, mainly of guaiacol and syringol origin, without carbohydrate impurities, could be produced by this integrated biorefinery approach, in which all biomass fractions can be utilized for manufacturing biobased chemicals and chemical precursors. It could be determined that the formation of the individual pyrolytical components was characteristically dependent on the utilized production conditions (i.e., alkali charge, temperature, pretreatment), creating the possibility for adjustment of the process parameters for pronounced production of desired product fractions. Hence, it could be concluded that this sulfur-free concept facilitated the environmentally friendly production of aromatics, without the need for removing sulfur or carbohydrates-derived impurities from the liquid feedstocks. The practical importance of the approach presented in this manuscript lies in the development of rapid and reliable characterization tools for various lignocellulosics-originated feedstocks possessing potential for thermochemical conversion and for creating novel biorefinery concept alternatives for producing aromatics and chemical precursors from currently underutilized feedstock, lignin."

Challenging zircon coatings by suspension plasma spraying

Zircon is a ceramic material that decomposes at high temperature, limiting its use by conventional thermal spraying. In this work, it is intended to use thermal spraying from concentrated aqueous suspensions to evaluate the possibility of obtaining coatings in which a significant proportion of zircon could be preserved. For this purpose, stable concentrated suspensions of zircon have been prepared, which have been subsequently sprayed at two different spraying distances. The coatings were characterised in terms of microstructural features and the amount of zircon present in the coatings was quantified. All the coatings obtained display the typical microstructure derived from the deposition of liquid feedstocks by plasma spraying. In all cases, the XRD analysis demonstrates the partial decomposition of zircon into zirconia and residual silica, but also that a significant percentage (about 20%) is preserved without decomposing, which marks a strong difference with respect to reported data for atmospheric plasma spraying.