| 1. |
- Chen, Xu, et al.
(författare)
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Catalytic fast pyrolysis of biomass to produce furfural using heterogeneous catalysts
- 2017
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Ingår i: Journal of Analytical and Applied Pyrolysis. - : Elsevier BV. - 0165-2370 .- 1873-250X. ; 127, s. 292-298
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Tidskriftsartikel (refereegranskat)abstract
- Furfural is a valuable chemical, the production of furfural from renewable biomass resources becomes more attractive in recent years. In this study, biomass fast pyrolysis with heterogeneous catalysts (titanium compounds (TiN, TiO2 and TiOSO4) and metal nitrides (MoN, GaN and VN)) for furfural production was investigated experimentally by means of pyrolysis-gas chromatography/mass-spectrometry (Py-GC/MS). The measurement results indicated that TiN and GaN promoted the furfural compounds production notably mainly through direct decomposition of oligosaccharides. The formation of furfural was promoted when the amount of TiN was increased, and the yield of furfural formed was about 5.5 times the size of that from non-catalytic pyrolysis when TiN/cellulose mass ratio was 4. The furfural yield decreased when the pyrolysis residence time increased from 10 to 30 s, which suggests competitive reactions (formation of 1, 6-anhydro-beta.-D-glucopyranose) against the formation of furfural. TiN, as a catalyst for fast pyrolysis towards furfural production, can be well applied to agriculture biomass residues. Comparing three biomass residues: corncob, wheat straw and cotton stalk, corncob showed higher furfural yield due to the higher holocellulose content, while wheat straw showed higher furfural selectivity.
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| 2. |
- Hu, Junhao, et al.
(författare)
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Co-gasification of coal and biomass : Synergy, characterization and reactivity of the residual char
- 2017
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 244, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- The synergy effect between coal and biomass in their co-gasification was studied in a vertical fixed bed reactor, and the physic-chemical structural characteristics and gasification reactivity of the residual char obtained from co-gasification were also investigated. The results shows that, conversion of the residual char and tar into gas is enhanced due to the synergy effect between coal and biomass. The physical structure of residual char shows more pore on coal char when more biomass is added in the co-gasification. The migration of inorganic elements between coal and biomass was found, the formation and competitive role of K2SiO3, KAlSiO4, and Ca3Al2(SiO4)(3) is a mechanism behind the synergy. The graphization degree is enhanced but size of graphite crystallite in the residual char decreases with biomass blending ratio increasing. TGA results strongly suggest the big difference in the reactivity of chars derived from coal and biomass in spite of influence from co-gasification.
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| 3. |
- Liu, Huihui, et al.
(författare)
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Conversion of high-ash microalgae through hydrothermal liquefaction
- 2020
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Ingår i: Sustainable Energy & Fuels. - : Royal Society of Chemistry (RSC). - 2398-4902. ; 4:6, s. 2782-2791
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Tidskriftsartikel (refereegranskat)abstract
- Natural microalgae (NM,Scenedesmus) cultivated by utilization of exhaust gas from a municipal solid waste combustion power plant were used for the biofuel production through hydrothermal liquefaction (HTL). The high-ash NM underwent acid-washing to obtain deashing microalgae (DA). HTL experiments were carried out at different temperatures from 260 °C to 340 °C with NM and DA. Products derived from NM and DA were examined by various techniques in order to identify the influence of the ash on the hydrothermal decomposition behavior. The results show that the ash inhibits the transformation of microalgae. The bio-oil yield including heavy oil and light oil is in the range of 17.59-22.09% for NM and 24.30-31.14% for DA, respectively. Calcium carbonate in the ash promotes deamination, resulting in an increase in the relative content of ketones in the NM-derived light oil. The concentration of NH4+in the aqueous phase derived from NM is in the range of 1373-1860 mg L−1, and PO43−is undetected due to the precipitation reaction between phosphorus and calcium ions. The HHV values of NM-derived hydrochars are low, ranging from 8.83 MJ kg−1to 9.88 MJ kg−1, compared with those of DA-derived hydrochars,. For natural microalgae, the deashing pretreatment before HTL is of great significance for improving the biocrude yield and quality, as well as the biomass conversion efficiency, nitrogen utilization and the hydrochar quality.
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| 4. |
- Liu, Huihui, et al.
(författare)
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Hydrothermal carbonization of natural microalgae containing a high ash content
- 2019
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 249, s. 441-448
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Tidskriftsartikel (refereegranskat)abstract
- The potential to convert natural microalgae (Scenedesmus) into solid fuels by hydrothermal carbonization (HTC) was evaluated. The deashing microalgae (DA) were obtained by acid-washing natural microalgae (NM) with HCl. The deashing efficiency was high from 44.66% for NM to 14.45% for DA. HTC carried out at temperature in the range from 180 to 260 degrees C with this two types feedstock (i.e. NM and DA). The results showed that DA-derived hydrochars had good physicochemical and fuel properties compared with that of NM-derived hydrochars. HTC process of DA was mainly based on polymerization, and the hydrolysis process was short. The hydrochars obtained from DA at 220 degrees C (HC-D220) had the highest value of 51.86% with a carbon content and fixed carbon content 1.15 and 1.33 times, respectively, greater than that of DA. The high heating value (HHV) of HC-D220 reached 26.64 MJ/kg which is equivalent to medium-high calorific coal. The thermogravimetric analysis (TG) demonstrated that the hydrochars derived from DA have good combustion properties with stable at high temperature zones. They can easily mix with coal or replace coal in combustion application. The results of this study revealed that natural microalgae can be utilized by hydrothermal carbonization to generate renewable fuel resources.
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| 5. |
- Liu, Huihui, et al.
(författare)
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Hydrothermal Treatment of High Ash Microalgae : Focusing on the Physicochemical and Combustion Properties of Hydrochars
- 2020
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 34:2, s. 1929-1939
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Tidskriftsartikel (refereegranskat)abstract
- Natural microalgae with high ash content are common in water environment. Converting them into biofuels not only meets the energy demands but also improves the aquatic environment. This study aims to explore the physicochemical properties and molecular structural features of hydrochars derived from hydrothermal treatment of natural microalgae. Meanwhile, the combustion behavior and kinetics analysis of hydrochars were also evaluated. The hydrothermal treatment was performed with natural microalgae and its acid-washing microalgae under different temperatures from 260 to 340 °C to reveal the effect of ash on hydrochars properties. The results indicate that the ash significantly influences the functional groups composition and physicochemical property of hydrochars. The yields of hydrochars derived from deashing microalgae are lower than those of hydrochars derived from natural microalgae. However, the relative content of the C-C/C-H/C=C groups representing hydrocarbon carbon in hydrochars derived from deashing microalgae is higher than that of hydrochars derived from natural microalgae. Both natural microalgae and deashing microalgae contain the protein-N and pyrrole-N, and natural microalgae also contain a small amount of inorganic-N. The Brunauer-Emmett-Teller (BET) surface areas of hydrochars derived from natural microalgae and deashing microalgae are in the range of 5.97-10.29 and 21.34-34.74 m2 g-1, respectively. The thermogravimetric analysis results show that hydrochars derived from deashing microalgae have better fuel quality in view of the comprehensive combustibility indexes compared with hydrochars derived from natural microalgae, which is conducive to their application to solid fuels. The acid-washing pretreatment can effectively improve the utilization of natural microalgae.
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| 6. |
- Zhu, Youjian, et al.
(författare)
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Reduction of fine particulate matter emissions from cornstalk combustion by calcium phosphates additives
- 2021
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 283
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Tidskriftsartikel (refereegranskat)abstract
- The emission of fine particulate matters with an aerodynamic diameter of less than 1 µm (PM1) is usually high from straw biomass combustion, resulting in great danger to atmospheric environment and public health. In this work, the effect of three calcium phosphate additives on PM1 emission from cornstalk combustion was investigated using a lab-scale reactor. The addition of Ca(H2PO4)2, CaHPO4 and Ca3(PO4)2 reduced PM1 emission by 1.5–50.6%, 22–55.6% and 23–53.7%, respectively. For Ca(H2PO4)2, PM1 reduction rate reached its maximum values of 50.6% at P/K molar ratio equal to 1 and then decreased significantly with further increasing of P/K molar ratio. For both CaHPO4 and Ca3(PO4)2, PM1 reduction rate increased approximately linearly with increasing the amount of additives under the current operating conditions. Analyses of the collected particulate matters and residual ashes indicated that phosphorus was mainly transformed into PM1-10 and residual ash in the form of K-Ca/Mg phosphates and Ca/Mg phosphates, respectively. The PM1 reduction mechanism was proposed based on the characterization results. Finally, economic analysis showed that the addition of Ca3(PO4)2 is a potentially promising method to reduce PM1 emissions during straw biomass combustion.
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| 7. |
- Yang, Haiping, et al.
(författare)
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Effects of potassium salts loading on calcium oxide on the hydrogen production from pyrolysis-gasification of biomass
- 2018
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 249, s. 744-750
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Tidskriftsartikel (refereegranskat)abstract
- The effects of potassium (K) salts loading on CaO on the H2 production from pyrolysis-gasification of wheat straw were investigated. The loading of 0.25 wt% KCl could significantly enhance the CO2 absorption capability of CaO. The CO2 concentration in the product gas decreased sharply from 20.83 to 11.70 vol%, and the H2 concentration increased from 48.2 to 55.5 vol%. While the loading of 0.25 wt% K2CO3/K2SO4 inhibited the enhancing effect of CaO. Further increasing the loading of KCl on CaO, the CO2 absorption of CaO declined, but the catalytic effect of KCl on the gasification process was promoted. The loading of 0.25 wt% KCl on CaO significantly improved the cyclic performance of CaO during the pyrolysis-gasification process. Higher H2 concentration and more CO2 absorbed by CaO were obtained with the loading of 0.25 wt% KCl even after 5 cycles compared with those of pure CaO in the first cycle.
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| 8. |
- Zhu, Youjian, et al.
(författare)
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Ash Fusion Characteristics and Transformation Behaviors during Bamboo Combustion in Comparison with Straw and Poplar
- 2018
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 32:4, s. 5244-5251
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the bamboo ash fusion and sintering characteristics were studied to evaluate its potential application in combustion for the production of heat and power. Poplar and wheat straw were used in the experimental test as the reference fuels for comparison. Standard ash fusion tests and ash sintering tests were carried out at elevated temperatures. The results indicate that bamboo has a low ash melting temperature of 862 °C, much lower than that of poplar. In spite of the high K content in bamboo ash, no severe melting and sintering was observed under the temperature lower than 1000 °C. The ashes after the tests were analyzed using SEM/EDX, XRF, and XRD techniques to illustrate the ash transformation behavior. Standard ash fusion tests indicated that the melting temperatures of bamboo, wheat straw, and poplar ashes are 862 °C, 770 °C, and 1088 °C, respectively. No severe sintering can be observed for poplar due to the large existence of refractory compounds. Ash sintering occurred when the temperature is higher than 800 °C, for wheat straw, due to the formation of the low melting temperature K-rich silicate. Additionally, bamboo ash has a relatively high P content compared to that of wheat straw, which facilitates the formation of high melting temperature compounds of K-Ca/Mg phosphates. Moreover, the ash content in bamboo is low. As a conclusion, bamboo is a good quality biofuel which can be fired in biomass combustion plants without severe sintering at a temperature lower than 1000 °C.
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| 9. |
- Zhu, Youjian, et al.
(författare)
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Characterization of Hydrochar Pellets from Hydrothermal Carbonization of Agricultural Residues
- 2018
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 32:11, s. 11538-11546
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the effects of operating conditions of hydrothermal carbonization on the hydrochar pelletization and combustion characteristics were investigated. Corn stalk was carbonized under different conditions and then pelletized to obtain the hydrochar pellets. It was found that hydrothermal temperature and residence time greatly affect the pellet quality. When the temperature was raised up to 240 °C with the residence time longer than 60 min, the heating values of hydrochar were close to or even higher than those of lignite. After hydrothermal treatment, 73.71-94.71% K and 91.81-94.32% Cl contained in the feedstock were removed, indicating a low fouling and slagging tendency when the pellets are used in combustion. The compressive strength and durability increased first with increasing temperature and then decreased with further increasing the temperature from 240 to 300 °C. The influence of residence time showed a similar trend, and the compressive strength and durability reached its maximum value at the temperature of 240 °C and residence time of 60 min. The hydrophobicity of the hydrochar pellets increased with increasing the temperature and residence time. Hydrochar pellets obtained at the temperature of 240 °C with residence time of 60 min gives the best performance, which can meet the requirement of industrial fuel pellets. Finally, the combustion characteristics were investigated by thermogravimetric analysis, and the results indicated that hydrochar pellets were combusted in a comparatively mild way with a high thermal efficiency. As a general conclusion, the hydrochar pellets have much better qualities than the raw corn stalk, facilitating the transportation, long-term storage, and combustion application.
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| 10. |
- Zhu, Youjian, et al.
(författare)
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Effect of sodium carboxymethyl cellulose addition on particulate matter emissions during biomass pellet combustion
- 2018
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 230, s. 925-934
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Tidskriftsartikel (refereegranskat)abstract
- Sodium carboxymethyl cellulose (CMC) can be used as a cost-effective and environmentally friendly binder in the pelletizing process for production of biomass pellets with good quality. However, the effect of its addition on the emission of particulate matters (PM) during the combustion process, are still not clear. In this study, four typical biomass fuels, cotton stalk, cornstalk, camphorwood and rice husk, were used to investigate the effect of the addition of 5 wt% CMC in the biomass pellets on PM emissions during the combustion process. In the case of pure CMC combustion, a large amount of PM mainly with PM2.5 were generated, which was associated to the evaporation and condensation of NaOH and Na2CO3. The PM10 emission from the combustion of the four biomass fuels varied from 9.72 mg/Nm3 to 23.12 mg/Nm3 with mainly PM1. The addition of 5 wt% CMC in cotton stalk, corn stalk and camphorwood significantly increased the PM emissions due to the evaporation and subsequent condensation of Na-containing species, e.g. NaCl, Na2SO4, NaOH and Na2CO3. For rice husk, the addition of CMC hardly affected PM1 emission due to the dominated SiO2 component in rice husk ash, which reacted with the Na-containing species from the combustion of CMC and facilitated the formation of coarse ash particles and the reduction of PM1 emission. Although the addition of CMC in biomass fuels can greatly enhance the pellets qualities, its addition increases the PM emissions to varying degree. Therefore, in the industrial application of CMC to biomass densification, countermeasures such as mixing of high Si-containing rice husk or SiO2-rich minerals with biomass fuels should be taken to alleviate the PM issues resulting from the introduction of CMC.
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