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Renewable source-derived carbon is found to be a green alternative catalyst to zeolite for the pyrolysis of plastics. However, only polyethylene (PE) catalytic pyrolysis over biomass-derived carbon has been extensively studied. In this work, carbon was produced from industrial organic solid waste using different activation agents, and their catalytic performance on the thermal degradation of typical polymers, namely PE, polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET) were investigated. The degradation mechanisms and the roles of different active sites of the carbons are discussed. Steam failed to activate the carbon, which has a low specific surface area (6.7 m2/g). Chemical activation using H3PO4 and ZnCl2 produces carbons with higher specific surface area and more porosity. The pyrolysis characteristics of LDPE, PP, PS, and PET catalyzed by the carbons were studied using TGA and a fixed-bed reactor. The thermogravimetric results indicate that all three carbons reduce the pyrolysis temperature. The analysis of the products shows that the P- and Zn-involved acid sites on the AC-HP and AC-ZN change the reaction pathway of plastics and promote: (1) C-C cracking and aromatization of polyolefins; (2) the protonation of phenyl carbon of PS to yield higher benzene, toluene, and ethylbenzene; and (3) the decarboxylation of the terephthalic acid intermediate of PET, resulting in higher CO2 and benzene. In addition, the high-value chemicals, long-chain alkylbenzenes, were found in the liquids of AC-ZN and AC-HP. The long-chain alkylbenzenes are probably formed by acid-catalyzed alkylation of aromatic hydrocarbons. This study provides basic data for the development of a cheap catalyst for plastic pyrolysis.

The RE (rare earth) Ba2Cu3Ox (REBCO)-coated conductor has shown its high potential in various applications. However, the quench problem under overcurrent conditions, as well as some other problems, is still hindering its practical use. In this research, we have developed a versatile 3D electromagnetic and thermal field coupled FEM analysis tool for REBCO coils, and verified its capability in studying the transient electromagnetic and thermal behaviors, such as current density, Joule heating, temperature distribution, etc., with two case studies. In the first case study, the transient electromagnetic and thermal behaviors of SFCL REBCO coils under overcurrent are studied in the cases of uniform JC distribution and local JC degradation. The influence of current leads and local JC degradation on the quench is investigated. In the second case study, the influence of external energy input, input area, and different time constants of current decrease on the quench of magnet REBCO coils is studied. Moreover, the limitation and improvement of the quench detection scheme based on voltage detection are discussed. The influence of external energy input on the current density distribution is also investigated.

The effective disposal of municipal solid wastes (MSW) and its incineration-derived fly ash (IFA), which contains large amounts of heavy metals (HMs) and chlorine (Cl), is an urgent task. In this study, IFA was used to reform MSW pyrolysis volatiles within 500-800 °C. The changes of reformed pyrolysis products, the migration characteristics of HMs and Cl between IFA and pyrolysis products were investigated. The results indicated that the O- and Cl-containing compounds in pyrolysis oil tended to decrease, light hydrocarbons and its calorific value increased accordingly after reforming; more CH

Hydrogen-rich gas production from catalytic steam gasification of coal was investigated in the presence of iron ore in a vertical fixed bed reactor. The addition of iron ore significantly promoted the H2 yields. The effects of operation parameters (upper zone temperature, lower zone temperature, steam concentration, and iron to coal ratio) on the yield of selected gaseous products (H2 and CO) during catalytic steam gasification, were studied using Taguchi method. The results of signal-to-noise ratio indicated that steam concentration and iron to coal ratio were the most important parameters in determining the yield of H2 and CO, respectively. Semi-quantification X-ray diffraction analysis of iron ores indicated that increase in steam concentration intensified the oxidization of low valence iron compounds to Fe3O4. In addition, formation of Fe3O4 was also favored with increasing reaction temperatures (600 °C–900 °C). However, the formation of Fe3O4 was inhibited at higher reaction temperature (1000 °C) due to the destruction of porous structures of the iron ore.

The economic feasibility of a facility producing jet fuel range cycloalkanes, hydrogen and biochar via microwave-assisted catalytic pyrolysis integrated with mild hydrogenation was evaluated by modeling a 1000 metric dry tonne feedstock/day using ASPEN PLUS®. The effects of hydrogenation solvent, heat integration, and coproducing H2 or syngas were investigated in different analysis scenarios. The results indicated that the production of jet fuel could reach 47882.74 Gallon/day, with 9.58 Metric tonne/day biochar and 28200 kg/day H2 as coproducts. The lowest minimum selling price of 3.78 $/Gallon was obtained when using n-hexane as the hydrogenation solvent and coproducing H2 with heat integration. The sale of H2 offset the high production cost, resulting in a significant decrease in the minimum selling price. Sensitivity analysis indicated that the production process was greatly sensitive to total capital investment, internal rate of return, market prices of feedstock and H2.

The catalytic conversion of Douglas fir sawdust into bio-phenols on activated carbons (AC) obtained by chemical activation of corn stover with H3PO4 was investigated. Taguchi experimental design was used to optimize the preparation of AC using microwave assisted pyrolysis. Based on an overall consideration of AC yield, bio-oil yield, and phenols content, the optimized conditions were phosphoric acid to biomass ratio of 0.8, microwave power of 600 W and reaction time of 20 min. The bio-oils were rich in phenolic compounds (up to 90 area %) that mainly comprised phenol, methyl and ethyl phenol. During the catalytic pyrolysis of biomass with AC, phenolic compounds could either be derived from decomposition of lignin, followed by deoxygenation, or derived from furfurals, which were degradation products of carbohydrates. The catalytic activities of ACs were mainly owing to the well-developed porosity and abundant acidic surface functional groups. The porous structures of ACs were characterized by N2 isotherms, showing a strong dependence on the acid impregnation ratio and microwave irradiation power. The presence of acidic phosphoric-containing surface functional groups was confirmed by SEM/EDX, FTIR and NH3-TPD.

The activated carbons (ACs) enriched in P-containing functional groups were obtained through one-pot microwave-induced pyrolysis from corn stover activated with phosphoric acid and were further tested as the catalyst for selective monophenol production from cellulose pyrolysis for the first time. Maximum AC yield (44.3 wt %) was obtained with an acid to biomass ratio of 0.85. Increasing phosphoric acid to corn stover ratios could enhance the porosity and peak intensities of P-containing functional groups in obtained ACs. Attained ACs had an excellent catalytic performance in phenol production with the highest selectivity of phenol (99.02 % based on peak area) in the obtained organic compounds at the catalytic temperature of 450 °C. The catalytic performance of ACs remained highly selective for phenol after using two times. The experimental results indicated that P-containing groups such as −O–P, O═P, and −O–P–O– were the active reaction sites and more mespores promoted phenol production. The phenol can be...

In situ and ex situ catalytic upgrading of pyrolysis vapors from Douglas fir pellets in the presence of activated carbon (AC) prepared by chemical activation was studied in a microwave pyrolyzer. The in situ catalytic upgrading configuration gave lower bio-oil yields (10.25–25.5 wt%) than ex situ catalytic upgrading configuration (20.03–32 wt%). The bio-oil yield from the in situ upgrading process was significantly affected by both catalytic reaction temperature and catalyst to biomass ratio. However, the bio-oil yield from ex situ upgrading process was only significantly affected by catalyst to biomass ratio. Bio-oils compositional analysis indicated that the ex situ upgrading process generated higher phenols concentration (4.14–19.76 mg ml−1) than in situ upgrading (4.14–9.90 mg ml−1). However, the selectivity of phenols from in situ upgrading process reflected by the peak area percentages was higher than that from ex situ upgrading. The catalyst recycling tests showed that the prepared AC catalyst can be reused for three times in phenol-rich bio-oil production via catalytic microwave pyrolysis.

Weight loss and gas release behavior of mengdong coal (MD) during pyrolysis was investigated using thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TGA-FTIR), and char evolution of coal chars derived at different pyrolysis temperature were analyzed with two dimensional perturbation correlation infrared spectroscopy (2D-PCIS) method to reveal the mechanism of mengdong coal pyrolysis. The MD coal showed a significant weight loss at 300– 600 °C during pyrolysis. Free OH groups reacted before OH-πand self-associated n-mers hydrogen bond. The demethylenation reaction sequence was aliphatic R3-CH groups and asymmetric aliphatic R-CH3 > symmetric aliphatic R2-CH2 > asymmetric aliphatic R2-CH2. CO2 releasing mainly resulted from the crack of C O in aryl ethers groups, C O in alcohols in coal molecular. The effect of K2CO3 on char structure was also studied. The results showed that, inherent mineral of coal presented stronger catalytic effects towards pyrolysis. K2CO3 addition influenced the reaction sequences of R3-CH, symmetric R2-CH2 and asymmetric R2-CH2 insignificantly, but could significantly change the correlation of C O, C O, CH CH3, and aromatic C C bond.

The gas and oil product derived from municipal solid waste (MSW) pyrolysis was upgraded by utilizing the interaction between the volatile compounds and the char and the mechanism involved is explored. The influences of operation parameters, including interaction temperature, char/volatiles mass ratio (C/V) and gas hourly space velocity (GHSV) of the volatiles on the distribution and property of the upgraded products were investigated. The results showed that the higher interaction temperature, higher C/V and lower GHSV favored the conversion of condensable volatiles into gas products, thus increasing the gas yield in the outlet stream. The highest gas yield (44.14 wt%) was obtained at 700 °C with the natural C/V ratio (0.8) and GHSV, which was twice of the gas yield in the volatiles. The chemical energy portion of gas increased to 8065 kJ/kgMSW from 3209 kJ/kgMSW at this condition. Syngas with H2/CO molar ratio of around 2 can be obtained at 700 °C with C/V ratio of 0.8 or at 600 °C with higher C/V ratios (C/V = 1.5–2.2). Oxygenates and acidity of the reformed oil products decreased; but monoaromatics and light polyaromatics concentration increased greatly. Heavy polycyclic aromatic hydrocarbons (PAHs) in the liquid products were degraded after volatiles/hot char interaction. Suitable conditions can be varied and recommended for obtaining different desired high-quality products based on this process.

Chars from wastes/biomass pyrolysis are widely used as catalysts. But their catalytic mechanism is not clear enough. To explore the role of inorganics in char-based catalysts, in this research, chars from municipal solid wastes (MSW) and wheat straw (WS) were compared for their catalytic performances and structure changes in reforming volatiles from MSW and WS pyrolysis. Results showed that MSW char (ash: 43 wt%) was more active than WS char (ash: 16 wt%) in reforming both volatiles within 500–700 °C, which facilitated higher syngas yield. 74% of the metals existed as non-evaporable acid-soluble inorganics in MSW char, which favored the transformation of microcrystalline carbon into amorphous carbon by carbon gasification yet increased aromaticity of its carbon matrix; while 27% of metals in WS char were organically bound alkali and alkaline-earth metals (AAEMs), and aromaticity of its carbon lattice increased from 0.39 to 0.67 with increase in reforming temperature. Additionally, WS char was characterized with larger aromatic ring size after reforming temperatures. Rich acid-soluble inorganics in MSW char were found to be favorable to its high activity; while migration of AAEMs caused the lower activity of WS char. These findings will help to improve catalytic activity of char-based catalysts.

The purpose of this study was to utilize gasification derived char as a catalyst support for tar removal. Red cedar char collected from downdraft bed gasification was chemically activated into activated carbon and impregnated with nickel acetate and nickel nitrate. The effects of nickel salts precursor, nitric acid treatment of support and reduction of nickel in hydrazine medium on catalyst performance were studied. It was found nickel nitrate was a better nickel precursor than nickel acetate for preparation of char supported nickel catalyst. The catalyst impregnated with nickel nitrate was found more active in steam reforming of toluene than the catalyst impregnated with nickel acetate. TEM results indicated that nickel particle size of the catalyst impregnated with nickel nitrate was much smaller than that of the catalyst impregnated with nickel acetate. Toluene showed higher removal efficiency than naphthalene. The presence of naphthalene decreased the toluene removal.

Tar removal is one of the major challenges in implementation of biomass gasification technology. Syngas tars causes formation of aerosols and soots, which plug filters, reactors and fuel lines. In this study, a char-derived catalyst was tested in removal of tar produced from pyrolysis of kraft lignin in a pyroprobe reactor. The effects of reaction temperature (700, 800 and 900 °C), water amount (5–10 μl), pressure (0.1–2.2 MPa) and atmosphere (inert and hydrogen) on catalytic conditioning of tar components were assessed. The tar components were analyzed by GC/MS. Catechols were the most abundant tar components followed with phenols and guaiacols during non-catalytic kraft lignin pyrolysis. Results indicated that the char-based catalyst effectively decreased the contents of lignin tar. Reaction temperature, water loading and reaction pressure significantly affected the tar removal. An increase in reaction temperature led to an increase in removal efficiency of most tar components except naphthalene. Excessive water loading (10 μl) decreased the tar removal efficiency of char-based catalyst. High pressure promoted the catalytic conversion of lignin tar. Tar contents decreased significantly when hydrogen was used as a reaction medium and thus promoted the conversion of lignin into non-condensable gas.

Downdraft gasification of forage sorghum and red cedar wood was studied with the aim of determining the characteristics of produced char for its further application, such as soil amendment, sorbent and solid fuel. Ultimate, proximate, XRD and NMR were used to investigate physical and chemical properties of char and thermo-analytic methods were used to determine kinetics of char gasification. The NMR results showed that red cedar and sorghum chars both contain aromatic carbon, but aliphatic carbon and o-alkyl carbon are more evident in the red cedar char than in the sorghum char. Char derived from downdraft gasification had higher heating values and lower ash contents than char derived from fluidized bed gasification, indicating char derived from downdraft gasification is more suitable for applications, such as soil amendment, than char from fluidized bed gasification. Micropores and mesopores were found in both red cedar and sorghum chars. The gasification reactivity of red cedar char was higher than that of sorghum char. Activation energies were found to be 163 and 167 kJ/mol based on shrinking core model and 147 and143 kJ/mol based on random pore model for sorghum char and red cedar char, respectively.

Superconducting cables have shown the advantages in large power transmission with higher efficiency and lower loss. In particular, the application to DC electric system is now attracting increasing attention. However, after introduction of superconducting cables, the increased fault current may be a threat to the safety and stability. To cope with this issue, the resistive SFCL offers one of the most ideal solutions due to its operating principle and limiting performance. This paper discusses the influence of three main design parameters of resistive type SFCL with a model DC system using superconducting cables, and proposes the design method and criterion. Then, the electromagnetic and thermal design of the SFCL is discussed for two model systems: low voltage HTS DC distribution system and high voltage HTS DC transmission system. Furthermore, it is shown that how the differences in system characteristics influence the design of SFCL.

In thermochemical utilization of biomass, ash fusion temperature is an important parameter for the efficient and continuous operation of boilers/gasifiers and high value-added utilization of the ash. Fusion characteristics and transformation properties of the inorganic components in biomass ash are investigated using X-ray fluorescence (XRF), thermal gravimetric analyzer (TGA), X-ray diffraction (XRD), ash melting point test system and phase diagrams. XRF and TGA results show the changes of ash content, elemental composition and performance with the variation of temperature. Two main weight loss routes of biomass ash, decomposition and volatilization, are identified. XRD results show the transformation behavior of crystalline structure of different biomass ash. Intense internal reactions that occur in biomass ash at higher temperature generate a large amount of eutectic compounds, which lowered the melting point significantly. The contribution of different ash compositions to fusion can be assessed by binary diagrams while the fusion properties of silica-rich biomass ashes obtained by phase diagrams could be appropriate for industrial running.

Biomass as a feedstock for activated carbon (AC) production is attractive because they are available and renewable. Greatest challenge, as in any biomass conversion technologies, is the technological and economic efficiency. In context of controlling process parameters to obtain a desired textural quality of AC, chemical activation is favored over physical activation because process variables such temperature and oxidizing agent of the physical activation process show minimal influence on the final AC textural quality. Recent studies suggest use of microwave in activated carbon production emphasizing efficient use of energy in the process. Specifically as mode of heating in carbonization step, it can promote significantly reduced heating time compared to conventional furnaces. Main goal of the study is to find the optimum phosphoric acid concentration for chemical activation of biomass in obtaining desirable AC yield and characteristics while elucidating the microwave heating mechanism on the carbonization step of the AC production. It was found that residual H3PO4 has negative effect of slowing down pyrolysis as it decreases microwave absorption capacity of the biomass-phosphoric acid complex. In addition, residual H3PO4 undergoing conversion to its anhydride, P2O5, requires additional energy and conversion time extending the overall carbonization time. Chemical activation by 60% phosphoric acid is practically rational as carbonization time is just about half of that of 85% while having similar textural characteristics and slightly higher yield compared to other concentrations used. Textural characterization of AC derived from 60% phosphoric acid activated Douglas fir show SBET of 1285 m2/g and mesoporous nature.

A resistive type superconducting fault current limiter (SFCL) using REBCO tapes has shown its advantages in power applications. However, the hotspot problem, which can be caused by the uniformity of critical current density JC over long-length of REBCO tapes, is still a threat to the SFCL safety. In this paper, we have studied the limiting performance and transient temperature rise distribution of a nonintersecting type non-inductive solenoidal SFCL REBCO coil using three-dimensional electromagnetic and thermal coupled FEM analysis. Firstly, we modelled a local degradation of JC and studied its influence on the transient temperature rise distribution during the over current. The results indicated that a narrow and severe JC degradation leads to the concentration of current and heat generation in the normal JC area, which is opposite to the case of a relatively wider and slighter JC degradation area. Furthermore, REBCO tapes with different thickness of substrate and Ag over-layer were analysed to study the influence on limiting performance and temperature rise. A thicker substrate leaded to a slower temperature rise because of its higher heat capacity, and the Ag over-layer of 4 μm showed better limiting performance and thermal stability because of its better thermal conductivity as well as uniform temperature rise and SN transition.