Publications
131 results found
Tang W, Chen Z, Millan M, et al., 2023, Facile fabrication of porous carbon nanofibers encapsulated with nanoscale exposed Ni for producing high-purity hydrogen from cheap glycerol, International Journal of Hydrogen Energy, Vol: 48, Pages: 38172-38187, ISSN: 0360-3199
Transition metal nanoparticles supported on porous carbon materials as hydrothermal stable and highly effective catalysts are increasingly attracting worldwide attention. Herein, a controllable electrospinning technique was employed to prepare the promising catalysts to produce hydrogen. Different proportions of polymethyl methacrylate and nickel nitrate were introduced into polyacrylonitrile spinning solution to prepare nanoscale Ni encapsulated in porous carbon nanofiber (Ni@PCNF) through an in-situ pore-making strategy. The results show that the prepared 10 wt% Ni@PCNF catalyst possesses an enhanced specific surface area, hierarchical porous structure, and uniformly-dispersed Ni nanoparticles (∼17 nm). This porous and fibrous catalyst presents relatively high performance of producing high-purity H2 by aqueous phase reforming of glycerol compared with several reference catalysts on different supports (e.g., activated carbon fibers and γ-Al2O3) under similar reaction conditions. The selectivity and purity of H2 produced by 10 wt% Ni@PCNF catalyst at 260 °C for 1 h are nearly 100% and 93%, respectively. This is related to the moderate catalytic activity of active Ni nanoparticles encapsulated in PCNFs. By contrast, those Ni nanoparticles supported on the reference supports show a high catalytic activity and thus produce low-purity H2 due to the considerable byproducts of CH4, CO and CO2. Moreover, Ni@PCNF catalyst exhibits a good structure stability and reuse effect in comparison with reference catalysts. This work provides a roadmap for preparing effective and stable Ni-based catalysts to produce high-purity H2 from cheap glycerol through a low-temperature thermocatalysis.
Wang P, Yu J, Liu X, et al., 2023, On the effect of pellet density on biomass pyrolysis in a pressurized fixed bed reactor, FUEL, Vol: 354, ISSN: 0016-2361
Zhao Z, Long X, Millan M, et al., 2023, The influence of carbon supports and their surface modification on aqueous phase highly selective hydrogenation of phenol to cyclohexanol over different Ni/carbon catalysts, Carbon, Vol: 213, ISSN: 0008-6223
Cyclohexanol is an important feedstock in the chemical industry. Highly selective hydrogenation of phenols to cyclohexanol over non-noble metal catalysts remains a challenge. Herein, four distinctive carbon materials, carbon black (CB), activated carbon (AC), activated carbon fiber (ACF) and carbon nanotube (CNT) were selected as catalyst supports to load Ni nanoparticles for effective phenol hydrogenation. The results show that the phenol conversion and cyclohexanol selectivity in aqueous phase hydrogenation reaction at 180 °C for 2 h over 10 wt% Ni/AC catalyst could reach 99.7% and 94.8%, respectively. These values are better than those obtained over 10 wt% Ni/ACF, Ni/CNT and Ni/Al2O3. After surface modification of carbon supports, the catalytic activity and reuse effect of modified catalysts are significantly enhanced and the optimal temperature decreases to 150 °C. This is because that modified carbon supports have abundant surface functional groups so as to provide a high dispersion and stable anchor of ultrafine active Ni nanoparticles (∼12 nm). Phenol hydrogenation catalyzed by different Ni/carbon catalysts conforms to a first-order reaction, and their apparent activation energies are in a range of 49∼68 kJ mol−1 (49 corresponds to the modified catalyst Ni/MAC), which are markedly lower than that of Ni/Al2O3 (∼96 kJ mol−1). The potential mechanism of highly selective hydrogenation of phenol to cyclohexanol in this work is mainly controlled by the reaction kinetics, which is closely related to the different desorption abilities of cyclohexanone and cyclohexanol from the catalysts.
Wang P, Qiao L, Wang W, et al., 2023, The behavior of heteroatom compounds during the pyrolysis of waste composite plastics, JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS, Vol: 173, ISSN: 0165-2370
Yu J, Liu X, Millan M, 2023, A study on pyrolysis of wood of different sizes at various temperatures and pressures, FUEL, Vol: 342, ISSN: 0016-2361
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Bikane K, Yu J, Shah SM, et al., 2023, High pressure CO<sub>2</sub> gasification of Morupule coal: Kinetics and morphological development of chars, CHEMICAL ENGINEERING JOURNAL, Vol: 462, ISSN: 1385-8947
Wu Y, Chang W, Millan M, et al., 2023, Synergetic removal characteristics of mercury for ultra-low emission coal-fired power plant, Fuel, Vol: 332, ISSN: 0016-2361
The synergetic mercury removal by flue gas treatment process in coal-fired power plants is widely accepted, but there is a lack of a corresponding model to describe mercury transformations. In this work, a model for mercury transformations is established in a flue gas treatment process model using Aspen Plus. The concentrations, mass flow rates, and normalized emission factors of mercury, NOX, particulate matters (PM), and SO2 are investigated in a 660 MW coal-fired power plant. The mercury oxidation efficiency of the selective catalytic reduction (SCR) unit is 56.9 %. The mercury removal efficiency of the electrostatic precipitator (ESP) and wet flue gas desulphurization (WFGD) units are 53.5 % and 34.4 %, respectively. The ultra-low emission system achieves 63.3 % removal of mercury. Approximately 53.5 % of mercury is retained in the fly ash. The emission factor of mercury is 0.0131 mg/kWh and increases to 0.0265 mg/kWh when the load decreases from 100 % to 50 %. The emission factors of PM, SO2 and NOX are 7.1, 97.1, and 142.9 mg/kWh at full load, and 10.9, 97.4, 150.0 mg/kWh at 50 % load, respectively. The proposed flue gas treatment process model is considered a feasible approach for quantitative evaluation of multi-pollutants emissions at plant level.
Zhu HL, Chen Z, Pastor-Perez L, et al., 2023, How syngas composition affects catalytic steam reforming of tars: An analysis using toluene as model compound, International Journal of Hydrogen Energy, Vol: 48, Pages: 1290-1303, ISSN: 0360-3199
Tar removal by catalytic steam reforming has an important role to play in gasification hot gas treatment. Despite the importance of understanding the influence gas atmosphere has on this reaction, the effect of a full syngas mixture has not been comprehensively investigated. This study aims to bridge that gap by analyzing the effect of each component as well as their combinations on steam reforming of toluene as biomass gasification tar model over a Ni/Al2O3 catalyst. It has been found that H2, CO and CO2 have minor inhibitory effects, slightly decreasing the initial toluene conversion. On the other hand, while CO and CO2 do not lead to catalyst deactivation, H2 and CH4 deactivate Ni/Al2O3 by promoting coke deposition. Only 3 vol.% of CH4 can significantly increase deactivation, despite being insignificant with toluene or CH4 separately. The joint presence of CH4 and H2 causes further drops in conversion with time on stream.
Yan F, Long X, Cui Z, et al., 2022, Stretching modification on mesophase-pitch-based fibers during carbonization process: From laboratory batch experiments to pilot continuous production, CARBON, Vol: 197, Pages: 52-64, ISSN: 0008-6223
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- Citations: 2
Long X, Boldrin P, Zhang Y, et al., 2022, Towards integrated gasification and fuel cell operation with carbon capture: Impact of fuel gas on anode materials, Fuel, Vol: 318, ISSN: 0016-2361
Integrated gasification fuel cell technology is a promising option for processing solid fuels, which would enable high efficiencies to be reached in small-scale power generation. Among the different fuel cell types, solid oxide fuel cells present a good temperature match with fluidised bed gasification as well as greater versatility in terms of the fuel gas composition they can handle. However, their resistance to impurities in the gas needs to be addressed. The main objective of this work is to assess the impact on typical materials used in fuel cell anodes of the gases produced from a gasifier operating with a N2-free gasification agent, which would make the system carbon-capture ready. A laboratory scale continuous pressurised fluidised bed reactor has been modified to study CO2 and steam (concentration up to 40 mol%.) gasification of lignite at 850 °C. A second stage fixed bed reactor has been specially designed and constructed to study degradation of two SOFC anode materials (nickel/yttrium–stabilised zirconium oxide (Ni/YSZ) and nickel/gadolinium-doped ceria (Ni/CGO)) after exposure to real fuel gas at 765 °C. Under these conditions, which did not involve any gas cleaning/conditioning between stages, carbon deposition on the surface of anode materials was much smaller than in previous studies that used model tar compounds as feeds. Fuel gas from CO2/H2O gasification tended to deposit less carbon and sulphur on tested anode materials, particularly on Ni/CGO, than that from CO2 gasification. The anode materials converted a significant fraction of the fed tar to gas.
Ayala-Cortés A, Arcelus-Arrillaga P, Millan M, et al., 2022, Solar hydrothermal processing of agave bagasse: Insights on the effect of operational parameters, Renewable Energy, Vol: 192, Pages: 14-23, ISSN: 0960-1481
Hydrothermal processing of agave was performed using a batch solar reactor designed to operate with a coupling method where a concentrated solar system provides heat. This work analyzes the performance of a reactor and the main characteristics of the products at different operational parameters: temperature, biomass concentration and holding time under subcritical conditions. Experimental findings demonstrate that the solar heated reactor prototype allows reaching maximum reaction temperatures of 300 °C with stable pressures. Low heating rates reduced the propensity of the system to leak, which prevented variations in pressure throughout experiments. The most favorable conditions to improve the yields (up to 28%) and properties of the oil produced were 300 °C and no holding time at peak temperature (τ = 0 min), and an average constant direct normal irradiation of 745 ± 47 W/m2.
Yu J, Reina TR, Paterson N, et al., 2022, On the primary pyrolysis products of torrefied oak at extremely high heating rates in a wire mesh reactor, APPLICATIONS IN ENERGY AND COMBUSTION SCIENCE, Vol: 9, ISSN: 2666-352X
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- Citations: 5
Jin Z, Cui Z, Long X, et al., 2021, Understanding the correlation between microstructure and electrochemical performance of hybridized pitch cokes for lithium-ion battery through tailoring their evolutional structures from ordered soft carbon to disordered hard carbon, Journal of Alloys and Compounds, Vol: 887, ISSN: 0925-8388
Pitch-derived cokes (PCs) with different optical textures and microstructures were produced by thermo-polymerization and subsequent heat treatment of a mixture of graphitizable and non-graphitizable precursors (i.e., naphthalene pitch and C9 resin). The effects of weight fractions of C9 resin and heat-treating temperatures on the evolutional microstructure and electrochemical performance of different hybridized PCs used as an anode material for lithium-ion batteries were investigated. The results show that the macro-texture, microstructure and structural evolution of PCs could be controlled by facilely tailoring the synthetic precursors through pitch-resin co-polymerizing reaction. The versatile and tunable structure of PCs closely dominates the inserting and extracting capability of lithium ions in the resultant PCs. With the introduction of C9 resin in the pitches from 0 to 100 wt%, the microstructure of resulting PCs changes from a highly oriented lamellar texture to a fine-grained mosaic texture (i.e., from anisotropic soft carbon to isotropic hard carbon). In addition, the electrochemical performance (e.g., in the range of 200–370 mA h g−1 for the specific capacity) of the PCs varies according to the textural orientation, microcrystallite sizes and graphitization degrees. The relationship between preliminary microstructure and electrochemical performance of PCs with controllable microstructure and crystalline orientation has been studied to understand the importance of structure control. Furthermore, this work provides a new strategy to adjust the electrochemical performance of hybridized PCs through tailoring the liquid crystal development of texture-tunable pitch precursor synthesis.
Spiegl N, Long X, Berrueco C, et al., 2021, Oxy-fuel co-gasification of coal and biomass for negative CO2 emissions, Fuel, Vol: 306, Pages: 1-8, ISSN: 0016-2361
A novel process has been investigated to enable CO2 to be isolated as a concentrated stream from the exhaust of a power station, without the use of separate, downstream capture technology. In this concept, a fluidised bed gasifier is operated with pure O2 and CO2, recycled from the combusted fuel gas stream, combining the advantages of gasification, fluidised bed operation and use of oxygen. With the combination of CO2 capture and biomass as the feedstock, net negative emissions can be achieved. This is the fifth in a series of papers which investigate the underlying science of the concept. It studies the influence of the use of different coals and mixtures containing coal/biomass on the process performance. A continuously fed, laboratory scale spouted bed reactor has been used for this study, and Daw Mill coal (DM), German lignite (GL), Polish coal (PC) and Olive bagasse (OB) were used as fuels. Carbon conversions for DM and PC were around 20–30% and dominated by release by pyrolysis. High conversions (60–80%) were observed for GL and the char showed an appreciable gasification reactivity. Co-processing of OB with GL proved to be a good way to further improve the overall process performance and complete conversion was achieved under some conditions. Processing biomass with lignite, with CO2 capture, is a technically viable way of producing energy from a waste material with a negative process carbon footprint.
Bikane K, Yu J, Shankar R, et al., 2021, Early-stage kinetics and char structural evolution during CO<sub>2</sub> gasification of Morupule coal in a wire-mesh reactor, CHEMICAL ENGINEERING JOURNAL, Vol: 421, ISSN: 1385-8947
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- Citations: 18
Cardoso A, Pastor-Perez L, Reina TR, et al., 2021, Lignin to Monoaromatics with a Carbon-Nanofiber-Supported Ni-CeO<sub>2-<i>x</i></sub> Catalyst Synthesized in a One-Pot Hydrothermal Process, ACS SUSTAINABLE CHEMISTRY & ENGINEERING, Vol: 9, Pages: 12800-12812, ISSN: 2168-0485
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- Citations: 5
Long X, Spiegl N, Berrueco C, et al., 2021, Emission of species of environmental and process concern during simulated oxy-fuel gasification, Fuel, Vol: 299, ISSN: 0016-2361
The release of species of environmental concern during simulated oxy-fuel gasification in a laboratory scale fluidised bed have been investigated. Fluidising gases containing a high partial pressure of CO2 and in some tests, steam, were used. The species considered are tars, H2S and NH3 and the aim has been to gain an understanding of the impact of the gasifer operating conditions on their release. This is part of a programme of work on the potential of oxy-fuel gasification as a means of enabling the use of coal to continue as a source of energy, whilst capturing the CO2 for sequestration to minimise the impact on climate change. It has been shown that the tars released during pyrolysis are efficiently destroyed during their passage through the hot, char containing bed. The measured emission of tar was very low, particularly when compared to a conventional fixed bed gasifier. The extent of S release as H2S depends on the fuel-S and ash-Ca contents, and on the operating conditions. Increasing the partial pressure of CO2, steam and raising the temperature increased the proportion of S released. Adding dolomite, to retain S, decreased the emission level at atmospheric pressure, provided the temperature was above 950 °C. The use of this method to reduce S emissions at elevated pressure would require careful consideration, as the high partial pressure of CO2 in the fluidising gas can prevent the calcination of the dolomite and therefore reduce its effectiveness. Steam was found to increase the proportion of fuel-N converted to NH3 and the concentration also depended on the bed temperature. A peak in the concentration was noted at 850 °C, due to the opposing impacts on increased release as the temperature was raised and increasing equilibration of NH3 to N2 and H2.
Ayala-Cortés A, Arcelus-Arrillaga P, Millan M, et al., 2021, Solar integrated hydrothermal processes: A review, Renewable and Sustainable Energy Reviews, Vol: 139, ISSN: 1364-0321
Hydrothermal processes are attractive options for the transformation of mixtures of biomass with large amounts of water, i.e. above 20wt%. At hydrothermal conditions, the special properties of water makes it an attractive reaction medium to obtain several bio-based platform chemicals or fuel gases, such as hydroxymethilfurfural or fufurals, syngas, hydrogen, methane, etc. However, one of the main challenges is that a large amount of energy is required to heat reactants (mixture of water and biomass), which is usually achieved by combustion of a fraction of the bio-oil product. Therefore, to reduce this consumption, their integration with an external renewable energy source, such as concentrated solar radiation has been proposed. This approach has been recently analyzed by several research groups as an option to have sustainable and economically attractive processes. This work provides an overview of the different experimental and theoretical strategies to incorporate concentrated solar technologies into hydrothermal processing of biomass, including the main challenges of such integration for process technical feasibility.
Daud ARM, Berrueco C, Hellgardt K, et al., 2021, Oxidative cracking of three to five-member ring polycyclic aromatic hydrocarbons in subcritical and supercritical water, The Journal of Supercritical Fluids, Vol: 167, Pages: 105050-105050, ISSN: 0896-8446
Polycyclic aromatic hydrocarbons (PAH) are refractory structures common in heavy hydrocarbons. Thermal cracking in supercritical water (SCW) is limited but PAH can be completely oxidised if an oxidant is added. By restricting oxidant supply to substoichiometric amounts, this study aims to achieve partial oxidation as a route to useful chemicals, such as mono- and bi-aromatics. Oxidative cracking reactions of anthracene, pyrene and benzo[a]pyrene in subcritical and SCW were studied. PAH conversions well above 90 % were achieved along a fast heating ramp in a batch reactor. This quick initial oxidation took place predominantly in inner rings, weakening the aromatic structure and increasing cracking reactivity. This oxidation-cracking pathway became dominant in the SCW region, producing mostly oxygenated compounds with fewer aromatic rings. On the other hand, competing reactions leading to polymerization were favoured in the subcritical water region. PAH reactivity was found to follow the order anthracene > benzo[a]pyrene > pyrene.
Bikane K, Yu J, Long X, et al., 2020, Linking char reactivity to structural and morphological evolution during high pressure pyrolysis of Morupule coal, Chemical Engineering Science: X, Vol: 8
Understanding the influence of pressure on char physicochemical properties and reactivity during pyrolysis is principal for the design and optimisation of coal gasification technologies. This work investigated the pyrolysis behaviour of Morupule coal at various pressures and temperatures in a high-pressure wire-mesh reactor (HPWMR). The effect of pressure was pronounced at 600 and 800 °C, resulting in lower total volatile yields at higher pressures due to the repolymerisation of volatiles. Although graphitisation was limited during the heating period, an increase in the concentration of ordered structures was observed during holding at 1000 °C. Marked blowholes on the char surface suggested an explosive bubble transport phenomenon during pyrolysis. Chars produced during the ramping period under high pressure showed higher combustion reactivities than their low-pressure counterparts. However, prolonged holding at peak temperature produced chars of similar reactivity, with their CO2 gasification reactivity found to be independent of pyrolysis pressure.
Long X, Spiegl N, Berrueco C, et al., 2020, Fluidised bed oxy-fuel gasification of coal: Interactions between volatiles and char at varying pressures and fuel feed rates, Chemical Engineering Science: X, Vol: 8, Pages: 1-11, ISSN: 2590-1400
Fluidised bed gasification is a versatile technology in terms of load flexibility and ability to process various fuels. However, fluidised bed gasification processes are usually air-blown, making integration with CO2 capture difficult and expensive. Operation of a fluidised bed gasifier with O2/recycled CO2 mixtures has been proposed as a route to overcome this drawback. In this work, the effect of pressure and fuel feed rate on the extent of gasification of German lignite in a CO2 rich atmosphere has been examined in a fluidised bed reactor (FBR). A 19% decrease in carbon conversion with increasing pressure from 5 to 20 bara was observed. The higher fuel feeding rates needed to maintain the gasification agent to coal ratio in the FBR at high pressures produces a larger concentration of tars in the reactor, which seems to cause deposition, by intra and inter particle reaction, on the char and reduces its reactivity.
Chen Z, Kukushkin R, Yeletsky P, et al., 2020, Coupling hydrogenation of guaiacol with in-situ hydrogen production by glycerol aqueous reforming over Ni/Al2O3 and Ni-X/Al2O3 (X = Cu, Mo, P) catalysts, Nanomaterials, Vol: 10, ISSN: 2079-4991
Biomass-derived liquids, such as bio-oil obtained by fast pyrolysis, can be a valuable source of fuels and chemicals. However, these liquids have high oxygen and water content, needing further upgrading typically involving hydrotreating using H2 at high pressure and temperature. The harsh reaction conditions and use of expensive H2 have hindered the progress of this technology and led to the search for alternative processes. In this work, hydrogenation in aqueous phase is investigated using in-situ produced hydrogen from reforming of glycerol, a low-value by-product from biodiesel production, over Ni-based catalysts. Guaiacol was selected as a bio-oil model compound and high conversion (95%) to phenol and aromatic ring hydrogenation products was obtained over Ni/γ-Al2O3 at 250 °C and 2-h reaction time. Seventy percent selectivity to cyclohexanol and cyclohexanone was achieved at this condition. Hydrogenation capacity of P and Mo modified Ni/γ-Al2O3 was inhibited because more hydrogen undergoes methanation, while Cu showed a good performance in suppressing methane formation. These results demonstrate the feasibility of coupling aqueous phase reforming of glycerol with bio-oil hydrogenation, enabling the reaction to be carried out at lower temperatures and pressures and without the need for molecular H2.
Puron H, Pinilla JL, Saraev AA, et al., 2020, Hydroprocessing of Maya vacuum residue using a NiMo catalyst supported on Cr-doped alumina, Fuel, Vol: 263, ISSN: 0016-2361
Mesoporous alumina was doped with Cr using a co-precipitation method to prepare a support for hydrocracking catalysts. Ni and Mo were then impregnated on Cr-doped mesoporous alumina (NiMo/Al2O3-Cr). Catalytic activity was tested in hydrodeasphaltenisation (HDA), hydrodesulfurisation (HDS) and hydrodemetallisation (HDM) of Maya vacuum residue in a batch reactor and compared with NiMo supported on mesoporous alumina not doped with Cr (NiMo/Al2O3). Following activation and initial carbon deposition, experiments involving contact of the catalysts with fresh feed were performed. Greater HDA extent and maltene to asphaltene ratios were obtained with NiMo/Al2O3-Cr than NiMo/Al2O3 despite a larger amount of coke deposits. Significant activity of both NiMo/Al2O3-Cr and NiMo/Al2O3 towards HDS and HDM were also observed. Alumina textural properties remained relatively unaffected by the co-precipitation of Cr. X-ray photoelectron spectroscopy (XPS) showed that the catalysts contained Cr3+ and after reduction all Ni was present in metallic state at least in the near-surface region, while Mo6+ was reduced to Mo4+ and Moδ+ (0 ≤ δ ≤ 3) to a larger extent in NiMo/Al2O3-Cr. Lower reduction temperatures in the presence of Cr were determined, suggesting a larger number of metal sites available in reduced form at operating conditions. It was found that Cr aided metal dispersion in catalyst synthesis and coke dispersion during reaction. Spent catalysts showed reductions in surface area and pore volume. However, while spent NiMo/Al2O3 catalysts had a decrease in average pore diameter (APD), NiMo/Al2O3-Cr maintained the fresh material APD, which may explain the sustained catalytic activity.
Arcelus-Arrillaga P, Pinilla JL, Millan M, 2020, CHAPTER 3: Catalytic Conversion of Fossil and Renewable Fuel Resources: Approaches Using Sub and Supercritical Water as a Reaction Medium, RSC Energy and Environment Series, Pages: 46-79
Access to energy is one of the main challenges society will face in the decades to come. Liquid fuels are expected to remain one of the main sources of energy, despite the depletion of conventional fossil fuel reserves. The development of cleaner technologies to transform unconventional energy resources such as heavy oil, biomass and organic residues into fuels is crucial to meeting the world's future energy demand. Water in hydrothermal conditions near or above the critical point can provide an efficient route to obtain fuels from unconventional sources in a clean and efficient way. For instance, due to its particular physicochemical properties, near-critical water and supercritical water are considered excellent solvents for catalytic organic chemical reactions. In hydrothermal processes, the addition of a catalyst has the purpose of increasing rates of reaction and product yields, suppressing the formation of solids, reducing re-polymerization of intermediate species and promoting cracking reactions. Successful implementation of catalytic processes in hydrothermal conditions requires the development of highly active catalysts that are stable under these conditions without deactivation. In this work, a thorough review of the literature on the application of catalytic hydrothermal processes for the conversion and upgrading of fossil and renewable unconventional fuel resources is presented.
Spiegl N, Berrueco C, Long X, et al., 2020, Production of a fuel gas by fluidised bed coal gasification compatible with CO<inf>2</inf> capture, Fuel, Vol: 259, ISSN: 0016-2361
A continuously fed, laboratory scale spouted bed gasifier has been used to study oxy-fuel gasification of German lignite. In this paper, the influence of different gasification agents and bed temperature on the process performance, during tests at atmospheric and elevated pressure are studied. Two gasification agents have been used, CO2 (with different CO2/C ratios) and mixtures of CO2/steam. The results show that despite the relatively slow CO2-char reaction, good gasification performance could be achieved with German lignite by adjusting the operating conditions at atmospheric pressure: complete carbon conversion, high energy conversion and a medium heating value fuel gas (8–10 MJ m−3). The CO2/C ratio was found to have a large effect on the gasification performance. Increasing the ratio increased the carbon conversion, but the CO2 conversion decreased. At 950 °C, maximum carbon conversion was already achieved with pure CO2, therefore using steam at this temperature could not increase the conversion, but did increase the H2/CO ratio in the fuel gas. At 850 °C, replacing 25% of CO2 with steam increased the carbon conversion to the level achieved at 950 °C without steam. Replacing more than 25% of CO2 with steam increased the H2/CO ratio further. Therefore, with the addition of steam, the operating temperature could be reduced from 950 °C to 850 °C while maintaining the gasification performance. The changes of gasification performance with steam addition at pressures up to 10 bara followed the same trends achieved at atmospheric pressure.
Zhu HL, Pastor-Pérez L, Millan M, 2020, Catalytic steam reforming of toluene: Understanding the influence of the main reaction parameters over a reference catalyst, Energies, Vol: 13
Identifying the suitable reaction conditions is key to achieve high performance and economic efficiency in any catalytic process. In this study, the catalytic performance of a Ni/Al2O3 catalyst, a benchmark system-was investigated in steam reforming of toluene as a biomass gasification tar model compound to explore the effect of reforming temperature, steam to carbon (S/C) ratio and residence time on toluene conversion and gas products. An S/C molar ratio range from one to three and temperature range from 700 to 900 °C was selected according to thermodynamic equilibrium calculations, and gas hourly space velocity (GHSV) was varied from 30,600 to 122,400 h-1 based on previous work. The results suggest that 800 °C, GHSV 61,200 h-1 and S/C ratio 3 provide favourable operating conditions for steam reforming of toluene in order to get high toluene conversion and hydrogen productivity, achieving a toluene to gas conversion of 94% and H2 production of 13 mol/mol toluene.
Durkin A, Millan-Agorio M, Guo M, 2020, Process Systems Design Framework for Resource Recovery from Wastewater, Editors: Pierucci, Manenti, Bozzano, Manca, Publisher: ELSEVIER SCIENCE BV, Pages: 1039-1044
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Volpe R, Menendez JMB, Reina TR, et al., 2019, Free radicals formation on thermally decomposed biomass, FUEL, Vol: 255, ISSN: 0016-2361
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Yu J, Paterson N, Millan M, 2019, The primary products of cellulose pyrolysis in the absence of extraparticle reactions, FUEL, Vol: 237, Pages: 911-915, ISSN: 0016-2361
Almeida RSR, Taccini MM, 2019, Effect of Storage Time on the Chemical Characterization of Pyroligneous Liquor From Eucalyptus Wood, Waste and Biomass Valorization, Pages: 1-7, ISSN: 1877-2641
© 2017 Springer Science+Business Media B.V. Abstract: This research focused on the effect of storage time on the chemical composition of the pyroligneous liquor (PL) produced during the pyrolysis of eucalyptus wood in a laboratory furnace at a relatively low heating rate (1 °C min−1) and a maximum temperature of 400 °C. The chemical compounds present in PL were identified through gas chromatography-mass spectrometry. This analysis was repeated over 19 months to observe changes in PL composition. Compounds such as 1,2-butanediol, 2-methoxytetrahydrofuran, 1,2-cyclopentanedione were only detected in the fresh PL and not after 11 or 19 months of storage. On the other hand, in PL stored for 11 and 19 months, new compounds were found, such as propanoic acid, butanediol, 5,9-dodecadien-2-one,6-10-dimethyl cyclopentanone, which were not observed in fresh PL. This suggests that PL from eucalyptus wood pyrolysis contains reactive compounds, mainly oxygenated, that interact during storage. Regarding the moment of stabilization of the qualitative composition of the PL, this research suggests that it is only reached after 11 months of storage. Phenol and furan derivatives were found to be stable, only reacting in their side chains without affecting the central ring. On the other hand, derivatives of tetrahydrofuran showed significant reactivity and tended to disappear with storage time. Graphical Abstract: [Figure not available: see fulltext.]
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