Effects of microwave-enhanced pretreatment on oil shale milling performance

Oil shale, as an unconventional fossil fuel, exhibits unique properties compared with coal and other petroleum. Due to the nature of sedimentary rock, large amounts of inorganic mineral impurities in rock matrix reduce the grade of oil shale, whilst increase the grinding resistance. This investigation presents the effects of microwave-enhanced pretreatment on the nature of oil shale and compared with conventional preheating process. Two Chinese oil shale from Fushun and Xingsheng Deposits were grounded and sieved into a size fraction (1-1.18mm) and were cut into eighteen cube-shaped specimens respectively. The prepared samples were processed accordingly to investigate how the grindability changed, in comparison to that of raw samples, and how the fundamental chemical properties of oil shale were altered after pretreatment. Quantitive data were used to assess the effects of different pretreatment methods on oil shale milling performance in a lab-scale pulverizer along with the impacts on moisture content, chemical properties. The uniaxial compressive strength (σmax) of Fushun oil shale was reduced 63.1% and the breakage rate increased 44.9% by short exposure to microwave irradiation. In conclusion, microwave-enhanced pretreatment presents significant improvement in oil shale milling performance compared to conventional preheating process in terms of breakage rate (Si) and uniaxial compressive strength (σmax) which showed negligible alterations. © 2019 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the scientific committee of ICAE2018 - The 10th International Conference on Applied Energy

Investigation on Co–Modified NixMgyO solid solutions for hydrogen production from steam reforming of acetic acid and a model blend

This paper is focused on the Co-modified NixMgyO solid solutions (10wt% Ni, 2-6wt% Co) for the steam reforming of acetic acid and a model blend. The pristine rocksalt structured NixMgyO solid solution and the modified NixMgyO-Co catalysts were synthesized via hydrothermal method and co-impregnation. The activity of the catalysts was evaluated in the temperature range of 500-800 °C with a steam/carbon molar ratio of 3 and a gas hourly space velocity (GHSV) of 57,000 h-1. Low cobalt content (Co loading = 2wt%) catalysts exhibited significant promotion of H2 yield via enhancement of both water-gas shift (WGS) reaction and methane decomposition. A 30-hour test at 700 °C achieved excellent acetic acid conversion rate and H2 yield of 99.1% and 86.9%, respectively. However, the catalysts with higher cobalt loading (Co loading ≥ 4wt%) suffered a much quicker deactivation mainly due to carbon deposition. In addition, the catalysts were also tested on a model blend combined acids, alcohols and aromatic species and exhibited outstanding performance with carbon conversion above 90% and H2 yield above 70% for 100 h

Effect of the addition of different waste carbonaceous materials on coal gasification in CO2 atmosphere

YesIn order to evaluate the feasibility of using CO2 as a gasifying agent in the conversion of carbonaceous materials to syngas, gasification characteristics of coal, a suite of waste carbonaceous materials, and their blends were studied by using a thermogravimetric analyser (TGA). The results showed that CO2 gasification of polystyrene completed at 470 °C, which was lower than those of other carbonaceous materials. This behaviour was attributed to the high volatile content coupled with its unique thermal degradation properties. It was found that the initial decomposition temperature of blends decreased with the increasing amount of waste carbonaceous materials in the blends. In this study, results demonstrated that CO2 co-gasification process was enhanced as a direct consequence of interactions between coal and carbonaceous materials in the blends. The intensity and temperature of occurrence of these interactions were influenced by the chemical properties and composition of the carbonaceous materials in the blends. The strongest interactions were observed in coal/polystyrene blend at the devolatilisation stage as indicated by the highest value of Root Mean Square Interaction Index (RMSII), which was due to the highly reactive nature of polystyrene. On the other hand, coal/oat straw blend showed the highest interactions at char gasification stage. The catalytic effect of alkali metals and other minerals in oat straw, such as CaO, K2O, and Fe2O3, contributed to these strong interactions. The overall CO2 gasification of coal was enhanced via the addition of polystyrene and oat straw

Synthesis of Sodium Alginate-Silver Nanocomposites Using Plasma Activated Water and Cold Atmospheric Plasma Treatment

In this study, sodium alginate (SA)-based, eco-friendly nanocomposites films were synthesized for potential food packaging applications using silver nitrate (AgNO(3)) as the metal precursor, reactive nitrogen and oxygen species (RNOS) created within plasma activated water (PAW), or through cold plasma treatment (CP) as reducing agent and SA as stabilizing agent. The formation of silver nanoparticles (AgNPs) was confirmed via the absorption peaks observed between 440 and 450 nm in UV-vis spectroscopy. The tensile strength (TS) and tensile modulus (TM) of the nanocomposite films were significantly higher than those of the SA films. An increase in the TS was also observed as the AgNP concentration was increased from 1 to 5 mM. The storage modulus (G’) of the nanocomposite solution was higher than that of the SA solution. The synthesis of AgNPs resulted both in a higher solution viscosity and a more marked shear-thinning effect. The synthesized AgNPs showed antimicrobial activity against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The AgNPs were spherical in shape with an average size of 22 nm

Application of supercritical fluid in the synthesis of graphene materials: a review

The studies on the utilisation of supercritical fluids (SCFs) in processing chemicals and materials have garnered significant attention in the past two decades. SCFs possess both gas- and liquid-like properties that are tunable, rendering them as superior solvents for reactions and processes, for example in the delamination of graphite. SCF technologies are deemed to be potential alternatives to existing technologies for graphene production that are yet to be industrially scalable. This review features recent works on the production of graphene facilitated by SCFs, with emphasis on the conversion of graphite to graphene through exfoliation and reduction. The exfoliation processes report the yield of 6 to 27% of monolayer graphene and 3 to 25% of ≤ 5 layers of graphene, whilst the carbon-to-oxygen (C/O) ratio of graphene produced via different reduction processes ranges from 0.37 to 28.2 with interlayer spacing of 0.35 to 0.38 nm. Recent applications of gas-expanded solvents for the synthesis of graphene and the fabrication of functionalised graphene materials via SCF-aided processes are also described. In addition, a summary of the properties of common SCFs as well as the characterisation of graphene materials, such as the number of layers, C/O ratio, interlayer spacing, pore size and surface area, is included to provide insights on the process efficiency

Application of supercritical fluid in the synthesis of graphene materials: a review

The studies on the utilisation of supercritical fluids (SCFs) in processing chemicals and materials have garnered significant attention in the past two decades. SCFs possess both gas- and liquid-like properties that are tunable, rendering them as superior solvents for reactions and processes, for example in the delamination of graphite. SCF technologies are deemed to be potential alternatives to existing technologies for graphene production that are yet to be industrially scalable. This review features recent works on the production of graphene facilitated by SCFs, with emphasis on the conversion of graphite to graphene through exfoliation and reduction. The exfoliation processes report the yield of 6 to 27% of monolayer graphene and 3 to 25% of ≤ 5 layers of graphene, whilst the carbon-to-oxygen (C/O) ratio of graphene produced via different reduction processes ranges from 0.37 to 28.2 with interlayer spacing of 0.35 to 0.38 nm. Recent applications of gas-expanded solvents for the synthesis of graphene and the fabrication of functionalised graphene materials via SCF-aided processes are also described. In addition, a summary of the properties of common SCFs as well as the characterisation of graphene materials, such as the number of layers, C/O ratio, interlayer spacing, pore size and surface area, is included to provide insights on the process efficiency.publishedVersio