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A kinetic study of steam gasification of char derived from solid recovered fuel (SRF) was performed. The char was prepared by using pyrolysis and using a nitrogen atmosphere at a temperature of 900 °C for 1 h. Gasification in a steam atmosphere was conducted for the char product using isothermal thermogravimetry analysis (TGA). The gasification was carried out at three different temperatures: 800, 850, and 900 °C for at least 1 h. The calculation of the kinetic parameters were done by considering the volumetric model, shrinking core model, and random pore model. The results show that the increase of the gasification temperature was linearly correlated to the rise of the reaction rate of the carbon conversion. Moreover, the activation energy of the char reaction is known to range between 58-83 kJ/mol. The kinetic parameters of char gasification were affected by their corresponding SRF component and the char particle size. Also, there were no significant different in the kinetic parameters calculated using the three different models as the difference between the results was less than 3.5 %. [ABSTRACT FROM AUTHOR]

• Different fractions of excavated landfill waste were pyrolyzed to produce chars. • The characteristics of the pyrolysis products (gas, oil, and char) were reported. • The chars were tested by using thermogravimetry under a steam atmosphere. • The reactivity and the kinetics parameters of char-steam reaction were determined. The focus of this study is the pyrolysis and gasification of Refuse Derived Fuel (RDF) and fine fractions recovered from the excavation of landfill waste, with an emphasize on the characterization of the reactivity and kinetics of the char-steam gasification. The results from the pyrolysis tests demonstrated that CO and CO 2 are the main produced gases during the pyrolysis of the finer fraction of landfill waste. This might be caused by the accumulation of degraded organic materials. The oil products from the pyrolysis of landfill waste were dominated by the derivative products of plastics such as styrene, toluene, and ethylbenzene. The chars obtained from the pyrolysis process were gasified under steam and steam/air atmospheres at temperatures between 800 and 900 °C by using thermogravimetry. The results from the gasification tests demonstrated that the char reactivity was mainly affected by the amount ratio between catalytic elements (K, Ca, Na, Mg, and Fe) over the inhibitor elements (Si, Al, and Cl), as well as the ash amount in the char. The results showed that char from the fine fraction of landfill waste has a higher reactivity than the RDF fraction, due to the high content of catalytic metal elements. These results suggest the use of a smaller sieve opening size for landfill waste separation processes may produce waste fuels with a high reactivity during gasification. Further, based on the thermogravimetric data, the kinetic parameters of landfill waste char gasification were calculated to have activation energies ranging from 54 to 128 kJ/mol. [ABSTRACT FROM AUTHOR]

• Different integration scenarios are proposed for DRI production using biosyngas. • Mature fluidised bed gasifiers (TRLs 9) are considered for producing biosyngas. • The novel biosyngas DRI route can compete with other existing and emerging routes. • Carbon negative is possible as up to 1.13 t CO 2 per t DRI can be captured and stored. Bioenergy with carbon capture and storage (CCS) in iron and steel production offers significant potential for CO 2 emission reduction and may even result in carbon-negative steel. With a strong ambition to reach net-zero emissions, some countries, such as Sweden, have recently proposed measures to incentivise bioenergy with CCS (BECCS), which opens a window of opportunities to enable the production of carbon-negative steel. One of the main potential applications of this route is to decarbonise the iron reduction processes that account for 85 % of the total CO 2 emission in the iron and steel plants. In this study, gasification is proposed to convert biomass into biosyngas to reduce iron ore directly. Different cases of integrating the biomass gasifier, Direct Reduced Iron (DRI) shaft furnace, and CCS are evaluated through process simulation work. Based on the result of the work, the proposed biosyngas DRI route has comparable energy demand compared to other DRI routes, such as the well-established coal gasification and natural gas DRI route. The proposed process can also capture 0.65–1.13 t of CO 2 per t DRI depending on the integration scenarios, which indicates a promising route to achieving carbon-negative steel production. [ABSTRACT FROM AUTHOR]

The promising properties of torrefied biomass provide a valid co-firing option for large percentage biomass utilization in existing coal-fired boilers. Torrefied biomass is expected to have a better combustion stability than raw biomass and similar to that of coal. The present work will characterizes the oxidation properties of torrefied biomass char and compare with that of raw biomass char. The studied two chars are produced from raw and torrefied biomass in an Isothermal Plug Flow Reactor (IPFR) at high temperature and high heating rate, a sufficient residence time is applied for the completion of the high temperature devolatilization. Char oxidation tests are carried out in the IPFR by varying temperature, oxygen concentration and residence time. The reactivity of two studied chars are analyzed and compared with referenced biomass char and coal char, and the impact of torrefaction on char reactivity is also discussed in this paper. Finally, the char oxidation kinetic parameters are determined using a parameter optimization method, and the obtained kinetics are examined by comparing the experimental and predicted mass conversions. [ABSTRACT FROM AUTHOR]

Highlights: [•] CaO shows a good capacity of CO2 adsorption at devolatilization stage of MSW. [•] CaO acted as a catalyst both in MSW devolatilization and char steam gasification. [•] Good dispersion and mobility of calcium in char were observed. [•] Catalytic mechanism during devolatilization and char gasification were discussed. [ABSTRACT FROM AUTHOR]

In this study, a sustainable in situ catalytic fast pyrolysis (CFP) of lignin was developed by using biochar and activated carbon (AC) as catalysts, which is derived from the same CFP of lignin process. The results showed that using biochar as the catalyst mainly promoted the production of non-condensable gas, water, and guaiacol-rich oil regardless of the biochar-to-lignin ratio. The catalytic effect of the biochar was mainly attributed to the surface sodium and alkali metals. Using AC 44.7% and AC 48.6% as the catalyst resulted in a high yield of guaiacol-rich oil, whereas using AC 64.3% induced a great decrease of the tarry oil yield and a significant increase of the phenol concentration in bio-oil. The diffusion efficiency of the reactive intermediates inside the catalysts determined by the pore size was believed to be the greatest determinant of the catalytic performance of the ACs. The mesopores were large enough to allow most of the reactive intermediates to diffuse quickly and react. Moreover, by using the same catalyst, char agglomeration was almost completely suppressed after in situ CFP. Two major problems, tar production and char agglomeration, which limit the large-scale application of fast lignin pyrolysis are believed to be solved. • CFP of lignin with biochar and ACs from the same pyrolysis process were studied. • Char agglomeration can be avoided by mixing lignin with char or ACs. • AC with more mesopores in structure induces the extremely low tarry oil yield. • The diffusion efficiency of the intermediates determines the performance of ACs. [ABSTRACT FROM AUTHOR]

Abstract: Experiments on gasification of chars obtained from original and pulverised wood pellets were conducted in atmosphere of water steam and nitrogen under temperatures of 800, 900 and 950°C. Molar flow rates of carbon containing product gases were measured and approximated using different models with respect to extents of carbon conversion in char of the pellets. Comparison of the random pore, grain and volumetric models revealed the best applicability for approximations of the random pore model. Apparent activation energies obtained as a result of application of the models to the data from experiments with char of original pellets were higher in comparison to those of pulverised pellets, except for a grain model. Approximations under 800°C showed relatively big deviations from experimental data on the beginning of char gasification. This is attributed to catalytic effects from alkali metals in the pellets. [Copyright &y& Elsevier]

• The synergistic effect between digestate and salix during pyrolysis is investigated. • A maximum of 36.4% of the energy of the feedstock is distributed in the liquid organic fraction. • Short-chain and long-chain acids compete to react with amines. • The recalcitrant-to-labile carbon ratio in biochar is enhanced by copyrolysis. Anaerobic digestion is a practical process for recovering energy and materials from sewage sludge. However, land disposal of the derived digestate results in environmental problems, such as eutrophication and salinization. Copyrolysis of sewage sludge digestate and lignocellulosic biomass produces a high-quality oil, a diluted hazardous component of biochar. This study investigates the copyrolysis behavior of lignocellulosic biomass and sludge digestate with different blending ratios using bench-scale experiments. Compared to individual feedstock pyrolysis, copyrolysis shows a higher energy distribution in the liquid product and a lower energy distribution in the char and gas product. The highest energy yield with respect to the organic fraction of liquid product is observed in the copyrolysis case, corresponding to 36.4% of the total energy in the feedstock. The interaction between the sludge digestate and lignocellulosic biomass is studied through product characterizations, mechanistic investigations and char stability assessments. The liquid products in the copyrolysis cases show a relatively high abundance of esters, aliphatic hydrocarbons, pyridines and pyrroles. The reaction pathways of proteins, lipids and carbohydrates are investigated. Two synergistic reaction pathways are proposed. The char stability and nitrogen distribution are investigated. According to the results, the synergistic interaction between feedstocks enhances the quality and energy yield of the liquid biofuel. The char product from copyrolysis has higher potential for use as a carbon sink and fertilizer. [ABSTRACT FROM AUTHOR]