| 1. |
- Chen, Yifeng, et al.
(författare)
-
Developing aqueous porous carbons for biogas upgrading
- 2024
-
Ingår i: Separation and Purification Technology. - : Elsevier B.V.. - 1383-5866 .- 1873-3794. ; 329
-
Tidskriftsartikel (refereegranskat)abstract
- Developing novel sorbents is essential for biogas upgrading. In this study, mixed sorbents of aqueous porous carbons were developed to separate CO2 from the biogas, where the porous carbon with the developed micropore structure was identified as the most desirable constituent. Both thermodynamics and kinetics were studied experimentally, and Henry’s constant (KH) and the liquid-side mass-transfer coefficient (kL) of CO2 in the mixed sorbent as well as the selectivity of CO2/CH4 were obtained accordingly. Furthermore, the CO2 separation performance was evaluated with a proposed index, and the cost of biogas upgrading using the mixed sorbent was estimated and compared. The results showed that the porous carbon with the developed micropore structure led to better performance on KH and kL of CO2 in the mixed sorbent, and the mixed sorbent with 3.03 wt% porous carbon exhibited the best CO2 separation performance, reducing 36.2 % in cost compared to the current technologies.
|
|
| 2. |
- Chen, Yifeng, et al.
(författare)
-
Kinetics study and performance evaluation of a hybrid choline-glycine/polyethylene glycol/water absorbent for CO2 separation
- 2023
-
Ingår i: Separation and Purification Technology. - : Elsevier B.V.. - 1383-5866 .- 1873-3794. ; 304
-
Tidskriftsartikel (refereegranskat)abstract
- Thermodynamic and kinetic properties of absorbents are beneficial in evaluating their CO2 separation performance. In this study, the kinetic properties of CO2 in a hybrid choline-glycine/polyethylene glycol/water absorbent, including the liquid-side mass-transfer coefficient, enhancement factor, and reaction rate constant, were systematically determined through experimental measurements and data processing. Furthermore, an index referred to as “absorbility” was proposed to combine the kinetic properties determined in this study with the thermodynamic properties obtained in our previous study to evaluate the CO2 separation performance. Additionally, the regeneration performance of the hybrid absorbent was also conducted. The results show that the performance of the hybrid absorbent (30 wt% [Cho][Gly] + 10 wt% PEG200 + 60 wt% H2O) is comparable to that of aqueous monoethanolamine, and is thus promising for CO2 separation, considering its low regeneration temperature and low environmental impact.
|
|
| 3. |
- Jin, Yanghao, et al.
(författare)
-
A novel three-stage ex-situ catalytic pyrolysis process for improved bio-oil yield and quality from lignocellulosic biomass
- 2024
-
Ingår i: Energy. - : Elsevier Ltd. - 0360-5442 .- 1873-6785. ; 295
-
Tidskriftsartikel (refereegranskat)abstract
- This study aims to improve the quality and yield of bio-oil produced from ex-situ catalytic pyrolysis of lignocellulosic biomass (sawdust) using a combination of stage catalysts with Al-MCM-41, HZSM-5, and ZrO2. The research employed various methods, including thermogravimetric analysis (TGA), differential scanning calorimetry, bench-scale experiments, and process simulations to analyze the kinetics, thermodynamics, products, and energy flows of the catalytic upgrading process. The introduction of ZrO2 enhances the yield of monoaromatic hydrocarbons (MAHs) in heavy organics. Compared with the dual-catalyst case, the MAHs yield escalates by approximately 344% at a catalyst ratio of 1:3:0.25. Additionally, GC-MS data indicate that the incorporation of ZrO2 promotes the deoxygenation reaction of the guaiacol compound and the oligomerization reactions of PAHs. The integration of ZrO2 as the third catalyst enhances the yield of heavy organics significantly, achieving 16.85% at a catalyst ratio of 1:3:1, which increases by nearly 35.6% compared to the dual-catalyst case. Also, the addition of ZrO2 as the third catalyst enhanced the energy distribution in heavy organics. These findings suggest that the combination of these catalysts improves the fuel properties and yields of the bio-oil.
|
|
| 4. |
- Lu, Xincheng, et al.
(författare)
-
Comprehensive insights into the influences of acid-base properties of chemical pretreatment reagents on biomass pyrolysis behavior and wood vinegar properties
- 2020
-
Ingår i: Journal of Analytical and Applied Pyrolysis. - : Elsevier BV. - 0165-2370 .- 1873-250X. ; 151
-
Tidskriftsartikel (refereegranskat)abstract
- Pyrolysis of biomass is an effective approach to produce high-value added solid, liquid and gaseous products. Wood vinegar (WV) is obtained as one of the main liquid products of biomass pyrolysis and has been used as the sustainable chemicals in agriculture. In this study, the effects of acid-base properties of chemical reagents on the biomass pyrolysis behavior and WV properties were investigated, and the mechanism was further discussed. The results indicated that acid-base properties of chemical reagents exhibited the significant effects on pyrolysis behavior and WV properties. Alkaline compounds showed the more obviously effects on changes in biomass chemical structure rather than acids, while acids removed the metallic species more efficiently than alkaline compounds. All chemical pretreatments increased the cellulose crystallinity, and the alkaline compounds were more favorable than the acidic compounds for increasing the crystallinity. Meanwhile, chemical pretreatments changed the chemical structure of biomass and promoted the pyrolysis process. All chemical pretreatments increased the organic content of WV. The relative content of phenols increased after all pretreatments, which increased more obviously by the acids pretreatments. Whereas, the relative content of acids decreased after pretreated by inorganic acids, and increased after pretreated by organic acids and alkaline compounds.
|
|
| 5. |
- Lu, Xincheng, et al.
(författare)
-
Enhanced antioxidant activity of aqueous phase bio-oil by hydrothermal pretreatment and its structure-activity relationship
- 2021
-
Ingår i: Journal of Analytical and Applied Pyrolysis. - : Elsevier BV. - 0165-2370 .- 1873-250X. ; 153
-
Tidskriftsartikel (refereegranskat)abstract
- The antioxidant activity and the structure-activity relationship of aqueous phase bio-oil (APBO), obtained from hydrothermal treatment (HTT) combined with pyrolysis of biomass, have been investigated in this study. HTT increased the relative content of phenolic compounds and reduced the relative content of acids. Phenolic compounds possessed as the dominant chemical components in APBO, representing up to 61.68 %. 2-methoxyphenol (guaiacol) and its derivatives were the major components of phenolic compounds. HTT promoted the antioxidant activity of APBOs and APBO-180 showed higher antioxidant activity than that of commercial chemical antioxidant (butylated hydroxyl toluene) with IC50 values of 0.402 mg/mL of reducing power, 0.132 mg/mL of DPPH free radical scavenging capacity and 0.405 mg/mL of hydroxyl free radical scavenging capability. The antioxidant activity of APBO was affected by its chemical composition. Phenols exhibited a promotion effect on antioxidant activity, while acids showed an inhibition effect. In addition, the substituent structure of phenols played a key role in antioxidant activity. Phenols with the shorter carbon side chain showed higher antioxidant activity (e.g. 2-methylphenol>2-methoxyphenol, 4-methyl-2-methoxyphenol>4-ethyl-2methoxyphenol). This study suggested that APBO could be developed as the natural feed additives or alternative antioxidant, providing a new strategy for efficient utilization of APBO.
|
|
| 6. |
- Sun, Yunjuan, et al.
(författare)
-
Development of a bimetallic dolomite based tar cracking catalyst
- 2012
-
Ingår i: Catalysis communications. - : Elsevier BV. - 1566-7367 .- 1873-3905. ; 20, s. 36-40
-
Tidskriftsartikel (refereegranskat)abstract
- In this study a bimetallic dolomite based tar cracking catalyst was developed and tested. It was enriched in Ni and Fe with BET surface area of 12.31 m(2)/g. The catalytic characterizations were tested with tar simulated by naphthalene, and with tar produced by biomass and coal co-pyrolysis. 93% naphthalene was decomposed at 950 degrees C. A first order apparent kinetic model was developed. Activation energy of 63.96 kJ/mol and pre-exponential factor of 396.2/s were calculated. Furthermore, reduction in char yield by 7%, when the catalyst was used in the biomass-coal co-pyrolysis, was observed.
|
|
| 7. |
- Wang, Shule, 1994-, et al.
(författare)
-
A machine learning model to predict the pyrolytic kinetics of different types of feedstocks
- 2022
-
Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904 .- 1879-2227. ; 260, s. 115613-
-
Tidskriftsartikel (refereegranskat)abstract
- An in-depth knowledge of pyrolytic kinetics is vital for understanding the thermal decomposition process. Numerous experimental studies have investigated the kinetic performance of the pyrolysis of different raw materials. An accurate prediction of pyrolysis kinetics could substantially reduce the efforts of researchers and decrease the cost of experiments. In this work, a model to predict the mean values of model-free activation energies of pyrolysis for five types of feedstocks was successfully constructed using the random forest machine learning method. The coefficient of determination of the fitting result reached a value as high as 0.9964, which indicates significant potential for making a quick initial pyrolytic kinetic estimation using machine learning methods. Specifically, from the results of a partial dependence analysis of the lignocellulose-type feedstock, the atomic ratios of H/C and O/C were found to have negative correlations with the pyrolytic activation energies. However, the effect of the ash content on the activation energy strongly depended on the organic component species present in the lignocellulose feedstocks. This work confirms the possibility of predicting model-free pyrolytic activation energies by utilizing machine learning methods, which can improve the efficiency and understanding of the kinetic analysis of pyrolysis for biomass and fossil investigations.
|
|
| 8. |
- Wang, Shule, 1994-, et al.
(författare)
-
Renewable hydrogen production from the organic fraction of municipal solid waste through a novel carbon-negative process concept
- 2022
-
Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 252
-
Tidskriftsartikel (refereegranskat)abstract
- Bioenergy with carbon capture and storage (BECCS) is one of the prevailing negative carbon emission technologies. Ensuring a hydrogen economy is essential to achieving the carbon-neutral goal. In this regard, the present study contributed by proposing a carbon negative process for producing high purity hydrogen from the organic fraction of municipal solid waste (OFMSW). This integrated process comprises anaerobic digestion, pyrolysis, catalytic reforming, water-gas shift, and pressure swing adsorption technologies. By focusing on Sweden, the proposed process was developed and evaluated through sensitivity analysis, mass and energy balance calculations, techno-economic assessment, and practical feasibility analysis. By employing the optimum operating conditions from the sensitivity analysis, 72.2 kg H2 and 701.47 kg negative CO2 equivalent emissions were obtained by treating 1 ton of dry OFMSW. To achieve these results, 6621.4 MJ electricity and 325 kg of steam were utilized during this process. Based on this techno-economic assessment of implementing the proposed process in Stockholm, when the negative CO2 equivalent emissions are recognized as income, the internal rate of return and the discounted payback period can be obtained as 26% and 4.3 years, respectively. Otherwise, these values will be 13% and 7.2 years.
|
|
| 9. |
- Wang, Shule, et al.
(författare)
-
Van Krevelen diagrams based on machine learning visualize feedstock-product relationships in thermal conversion processes
- 2023
-
Ingår i: Communications Chemistry. - : Springer Nature. - 2399-3669. ; 6:1
-
Tidskriftsartikel (refereegranskat)abstract
- Feedstock properties play a crucial role in thermal conversion processes, where understanding the influence of these properties on treatment performance is essential for optimizing both feedstock selection and the overall process. In this study, a series of van Krevelen diagrams were generated to illustrate the impact of H/C and O/C ratios of feedstock on the products obtained from six commonly used thermal conversion techniques: torrefaction, hydrothermal carbonization, hydrothermal liquefaction, hydrothermal gasification, pyrolysis, and gasification. Machine learning methods were employed, utilizing data, methods, and results from corresponding studies in this field. Furthermore, the reliability of the constructed van Krevelen diagrams was analyzed to assess their dependability. The van Krevelen diagrams developed in this work systematically provide visual representations of the relationships between feedstock and products in thermal conversion processes, thereby aiding in optimizing the selection of feedstock and the choice of thermal conversion technique.
|
|
| 10. |
- Yang, Hanmin, et al.
(författare)
-
In situ catalytic fast pyrolysis of lignin over biochar and activated carbon derived from the identical process
- 2022
-
Ingår i: Fuel processing technology. - : Elsevier B.V.. - 0378-3820 .- 1873-7188. ; 227
-
Tidskriftsartikel (refereegranskat)abstract
- 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 AC44.7% and AC48.6% as the catalyst resulted in a high yield of guaiacol-rich oil, whereas using AC64.3% 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. © 2021 The Authors
|
|
