Hydrothermal carbonization of fructose—effect of salts and reactor stirring on the growth and formation of carbon spheres

Hydrothermal carbonization (HTC) has become a promising technology for the production of hydrochar and carbon spheres. Several studies indicate a strong dependency of the reaction conditions on the sphere diameter. The usage of additives, such as salts, is one possibility to increase the size of the spheres. However, the growth mechanism which leads to larger particles is not fully understood. In this work, kinetic studies of HTC with fructose were performed with different salts as additives. The growth of the particles (the increase in size) has been compared to the formation rates (increase in yield) of hydrochar by using the reaction rate constants from the kinetic model. The results indicate that the acceleration of the growth rate is independent of the formation rate. It is therefore assumed that coagulation, as a growth mechanism, took place. With longer reaction times, the particles reached a stable particle size, independently from the added salts; therefore, it was assumed that the particles underwent some sort of solidification. The state of matter can therefore be described as an intermediate state between liquid and solid, similar to mesophase pitch. Experiments with a stirrer resulted in squashed particles, which supports the model, that the particles exhibit emulsion-like behavior

Enhanced hydrogen production using a tandem biomass pyrolysis and plasma reforming process

Converting biomass into energy and fuels is considered a promising strategy for replacing the exhaustible fossil fuels. In this study, we report on a tandem process that combines cellulose pyrolysis and plasma-assisted reforming for H-2 production. The hybrid pyrolysis/plasma reforming process was carried out in a two-stage reaction system incorporating a coaxial dielectric barrier discharge (DBD) plasma reactor. The effects of discharge power, steam, reforming temperature, and catalyst on the reaction performance were investigated. The results show that low temperatures are preferred in the non-catalytic plasma reforming process, whereas high temperatures are desired to achieve a high H-2 yield and a high H-2 selectivity in the plasma-catalytic reforming system. The synergistic effect of plasma catalysis was dominant in the plasma-catalytic reforming process at 250 degrees C. In contrast, the catalyst, rather than the plasma, played a dominant role in the plasma-catalytic reforming at higher temperatures (550 degrees C). Using Ni-Co/Al(2)O3 at a reforming temperature of 550 degrees C, a high H-2 yield of 26.6 mmol/g was attainted, which was more than 8 times and about 100% greater than that obtained using plasma alone and catalyst alone, respectively. This work highlights the potential of non-thermal plasmas in lowtemperature biomass conversion.European Union [823745]; Science and Technology Ex-change Project of the Chinese Ministry of Science and Technology [2021-12-2]; Education Cooperation Project between China and Central Eastern European Countries [2021086]; British Council Newton Fund Institutional Links Grant [623389161]; Scientific and Technological Research Council of Turkey (TUBITAK) [219M123]; Chinese Scholarship Council; University of LiverpoolThis project has received the funding from the European Union's Horizon 2020 Research and Innovation Programme under the Marie Sklodowska Curie Grant Agreement (No. 823745) . C. Quan and N. Gao gratefully acknowledge funding from the Science and Technology Ex-change Project of the Chinese Ministry of Science and Technology (No. 2021-12-2) and the Education Cooperation Project between China and Central Eastern European Countries (No. 2021086) . X. Tu gratefully acknowledges the British Council Newton Fund Institutional Links Grant (No. 623389161) . J. Yanik gratefully acknowledges funding from the Scientific and Technological Research Council of Turkey (TUBITAK Project Contract no. 219M123) . W. Wang thanks the University of Liverpool and the Chinese Scholarship Council for funding this PhD

Two-step steam pyrolysis of biomass for hydrogen production

WOS: 000406725500009In this study, different char based catalysts were evaluated in order to increase hydrogen production from the steam pyrolysis of olive pomace in two stage fixed bed reactor system. Biomass char, nickel loaded biomass char, coal char and nickel or iron loaded coal chars were used as catalyst. Acid washed biomass char was also tested to investigate the effect of inorganics in char on catalytic activity for hydrogen production. Catalysts were characterized by using Brunauer Emmet Teller (BET) method, X-ray diffraction (XRD) analyzer, X-ray fluorescence (XRF) and thermogravimetric analyzer (TGA). The results showed that the steam in absence of catalyst had no influence on hydrogen production. Increase in catalytic bed temperature (from 500 degrees C to 700 degrees C) enhanced hydrogen production in presence of Ni-impregnated and non -impregnated biomass char. Inherent inorganic content of char had great effect on hydrogen production. Ni based biomass char exhibited the highest catalytic activity in terms of hydrogen production. Besides, Ni and Fe based coal char had catalytic activity on H-2 production. On the other hand, the results showed that biomass char was not thermally stable under steam pyrolysis conditions. Weight loss of catalyst during steam pyrolysis could be attributed to steam gasification of biomass char itself. In contrast, properties of coal char based catalysts after steam pyrolysis process remained nearly unchanged, leading to better thermal stability than biomass char. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Ege UniversityEge University [2012-FEN-041]The financial support from Ege University under contract 2012-FEN-041 is highly appreciated. The authors wish to thank Chiara Lorenzetti for GC/MS analysis of bio-oil and Prof. Dr. Daniele Fabbri for interpretation of GC/MS results

Production of biochars from textile fibres through torrefaction and their characterisation

WOS: 000455694300055In this study, the utilization of textile fibres as energy feedstock in the form of biochar was investigated depending on the fibre type. The biochars were produced from waste natural and synthetic fibres and its blends. For this purpose, different types of textile fibres (cotton, viscose, polyester, acrylic) and their blends (cotton/polyester, acrylic/wool, acrylic/polyester, acrylic/viscose) were torrefied at temperatures between 300 and 400 degrees C. The effects of torrefaction temperature and fibre type on biochar yield and biochar properties (fuel properties, morphological and structural properties and combustion characteristics) were investigated. The results showed that the temperature had a significant effect on biochar yield whereas the fibre type was the only significant factor on energy densification ratio and biochar properties. The torrefaction of tested fibres and blends resulted in an energy-intensive solid fuel, having a negligible amount of ash and sulphur. Although torrefied acrylic based textile fibres had similar H/C and O/C ratios to bituminous coal, it was concluded that high nitrogen contents will limit their usage as fuel. Overally, this study showed that torrefaction of cotton and cotton/polyester textile wastes is a promising process for the production of a solid fuel, which can be used as a substitute fuel in coal/waste co-firing systems. (C) 2018 Elsevier Ltd. All rights reserved.Scientific and Technical Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [216M406]; Ege University Scientific Research Projects Coordination Unit, Turkey [16-TKUAM-002, 18-BIL-007, 17-FEN-063]The authors would like to gratefully acknowledge the financial support for this research received through the project (No: 216M406) of The Scientific and Technical Research Council of Turkey (TUBITAK); and the projects (No: 16-TKUAM-002, 18-BIL-007 and 17-FEN-063) of Ege University Scientific Research Projects Coordination Unit, Turkey

The effect of char properties on gasification reactivity

WOS: 000329384200011In this study, CO2 gasification of raw and acid-washed chars obtained from various types of lignocellulosic biomasses (woody and agricultural waste biomasses) was studied under isothermal conditions (850 degrees C) using thermal gravimetric analysis. The effect of surface area and alkali/earth alkali metals on the reactivity of the chars was investigated. The different kinetic models were used to fit with the reactivity data by using least square. method. The gasification of chars with higher surface area was found to be faster than that of chars having lower surface area. The acid treatment decreased the overall gasification rate for each raw chars. However, although the AI (alkali index) values of chars obtained from agricultural biomasses had equal or higher than that of woody biomass chars, their initial rates were considerably lower. It was concluded that indigenous alkali metals of chars have a remarkable influence of gasification reactivity but an adequate surface area should be provided to react with CO2. (C) 2013 Elsevier B.V. All rights reserved.European CommissionEuropean Commission Joint Research Centre [IRSES 247550]The research is funded by the European Commission in the framework of 7th Programme, Project No: IRSES 247550. We also thank to Prof. Dr. Yoshiei Kato for his collaboration and invitation to Environmental Analytical Chemistry Laboratory, Okayama University

Influences of feedstock type and process variables on hydrochar properties

WOS: 000430740000042PubMed ID: 29182991In this study, the effect of process variables, such as temperature, biomass: water ratio and reaction time, in hydrothermal carbonization (HTC) has been studied for different type biomasses. Response surface methodology was used to study the influence of each factors as well as their combined interactive effect on the mass yield and energy density of hydrochars. The results showed that the temperature and time were significant factors effecting the mass yield and energy densification ratio in HTC of the sunflower stalk and algae, whereas temperature was only significant factor in HTC of poultry litter. The biomass: water ratio was found insignificant for all tested biomasses. In addition, the fuel properties of hydrochars were compared with the properties of biochar derived from torrefaction at 300 degrees C. The results showed that for all tested biomass, the biochars had lower volatile matter and fixed carbon than hydrochars.TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [114 M001, 2014/FEN/055]The financial supports from TUBITAK under contract 114 M001 and 2014/FEN/055 are gratefully acknowledged. The authors would like to acknowledge the contribution of the COST Action TD1107 (Biochar as option for sustainable resource management)