| 1. |
- Cheah, You Wayne, 1993, et al.
(författare)
-
Thermal annealing effects on hydrothermally synthesized unsupported MoS2 for enhanced deoxygenation of propylguaiacol and kraft lignin
- 2021
-
Ingår i: Sustainable Energy and Fuels. - 2398-4902. ; 5:20, s. 5270-5286
-
Tidskriftsartikel (refereegranskat)abstract
- Catalytic hydrodeoxygenation (HDO) is an important hydrotreating process that is used to improve the quality of bio-oils to produce biomass-derived fuel components and chemicals. Molybdenum disulfide (MoS2) has been widely used as a catalyst in hydrodesulfurization (HDS) applications for several decades, which can be further improved for effective unsupported catalyst synthesis. Herein, we studied a universally applicable post-annealing treatment to a hydrothermally synthesized MoS2 catalyst towards developing efficient unsupported catalysts for deoxygenation. The effect of the annealing treatment on the catalyst was studied and evaluated for HDO of 4-propylguaiacol (PG) at 300 °C with 50 bar H2 pressure. The annealing of the as-synthesized catalyst under nitrogen flow at 400 °C for 2 h was found to enhance the HDO activity. This enhancement is largely induced by the changes in the microstructure of MoS2 after the annealing in terms of slab length, stacking degree, defect-rich sites and the MoS2 edge-to-corner site ratio. Besides, the effect of hydrothermal synthesis time and acid addition combined with the annealing treatment on the MoS2 catalytic activity was also studied for the same model reaction. The annealed MoS2 with a synthesis time of 12 h under an acidic environment was found to have improved crystallinity and exhibit the highest deoxygenation degree among all the studied catalysts. An acidic environment during the synthesis was found to be crucial in facilitating the growth of MoS2 micelles, resulting in smaller particles that affected the HDO activity. The annealed unsupported MoS2 with the best performance for PG hydrodeoxygenation was further evaluated for the hydrotreatment of kraft lignin and demonstrated a high deoxygenation ability. The results also indicate a catalyst with high activity for deoxygenation and hydrogenation reactions can suppress char formation and favor a high lignin bio-oil yield. This research uncovers the importance of a facile pretreatment on unsupported MoS2 for achieving highly active HDO catalysts.
|
|
| 2. |
- Cheah, You Wayne, 1993, et al.
(författare)
-
Upgrading of triglycerides, pyrolysis oil, and lignin over metal sulfide catalysts: A review on the reaction mechanism, kinetics, and catalyst deactivation
- 2023
-
Ingår i: Journal of Environmental Chemical Engineering. - : Elsevier BV. - 2213-3437 .- 2213-2929. ; 11:3
-
Forskningsöversikt (refereegranskat)abstract
- Human activities such as burning fossil fuels for energy production have contributed to the rising global atmospheric CO2 concentration. The search for alternative renewable and sustainable energy sources to replace fossil fuels is crucial to meet the global energy demand. Bio-feedstocks are abundant, carbon-rich, and renewable bioresources that can be transformed into value-added chemicals, biofuels, and biomaterials. The conversion of solid biomass into liquid fuel and their further hydroprocessing over solid catalysts has gained vast interest in industry and academic research in the last few decades. Metal sulfide catalysts, a common type of catalyst being used in the hydroprocessing of fossil feedstocks, have gained great interest due to their low cost, industrial relevance, and easy implementation into the current refining infrastructures. In this review, we aim to provide a comprehensive overview that covers the hydrotreating of various bio-feedstocks like fatty acids, phenolic compounds, pyrolysis oil, and lignin feed using sulfided catalysts. The main objectives are to highlight the reaction mechanism/networks, types of sulfided catalysts, catalyst deactivation, and reaction kinetics involved in the hydrotreating of various viable renewable feedstocks to biofuels. The computational approaches to understand the application of metal sulfides in deoxygenation are also presented. The challenges and needs for future research related to the valorization of different bio-feedstocks into liquid fuels, employing sulfided catalysts, are also discussed in the current work.
|
|
| 3. |
- Di, Wei, 1986, et al.
(författare)
-
Modulating the Formation of Coke to Improve the Production of Light Olefins from CO2 Hydrogenation over In2O3 and SSZ-13 Catalysts
- 2023
-
Ingår i: Energy & Fuels. - 1520-5029 .- 0887-0624. ; 37:22, s. 17382-17398
-
Tidskriftsartikel (refereegranskat)abstract
- Moderately acidic aluminophosphates (SAPOs) are often integrated with methanol synthesis catalysts for the hydrogenation of CO2 to olefins, but they suffer from hydrothermal decomposition. Here, an alternative SSZ-13 zeolite with high hydrothermal stability is synthesized and coupled with an In2O3 catalyst in a hybrid system. Its performance regarding selectivity for olefins and coke formation was investigated for CO2 hydrogenation under varying temperatures and pressures. Various reactions occur, producing mainly CO and different hydrocarbons. The results indicate that the hydrogenation of hydrocarbons are dominant at high temperatures (around 400 °C) over SSZ-13 zeolite with a high acid density and that the coke deposition rate is slow. Polymethylbenzenes are the main coke species, but the selectivity for light olefins is low among hydrocarbons at high temperatures. However, at low temperatures (around 325 °C), and especially under high pressure (40 bar), methanol disproportionation becomes significant. This results in an increased selectivity for light olefins; however, it also leads to a rapid coke deposition, which gives inactive adamantanes as the main coke species that block the pores and cause rapid deactivation. However, after coking at 325 °C and regeneration at 400 °C under the reaction atmosphere, the accumulated adamantanes can be decomposed into smaller coke species, which reopens the channel structure and generates modulated active sites within the zeolite, resulting in a higher yield of olefins without deactivation. The performances of acidic SSZ-13 zeolites, with varying ratios of Si/Al in transient experiments, further verified that a dynamic balance exists between the formation and degradation of coke within the SSZ-13 zeolite during a long-term CO2 hydrogenation reaction. This balance can be achieved by optimizing the reaction conditions to match the acid density of the catalyst. Using the conditions of 20 bar and 375 °C, with a H2 to CO2 mole ratio of 3, the results obtained for the precoked hybrid catalysts of In2O3 and SSZ-13 (Si/Al = 25) exhibited very stable activity, with the selectivity for light olefins (based on hydrocarbons formed) of max. 70% after 100 h time-on-stream. This work provides new insights into the design of stable hybrid catalysts, especially the influence of a precoking process for SSZ-13 zeolite in the production of light olefins.
|
|
| 4. |
- Fagerström, Anton, et al.
(författare)
-
Large scale bio electro jet fuel production integration at CHP-plant in Östersund, Sweden
- 2021. - B 2407
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This document reports the findings of the project “Large scale bio electro jet fuel production integration at CHP-plant in Östersund, Sweden”. BEJF is an electrofuel produced in a synthesis process where biogenic carbon dioxide (CO2) is the main carbon source and hydrogen from electrolysis of water using renewable electricity is the main energy source. The project is a feasibility study for a factory for such fuel located at Jämtkraft's facility for CHP in Östersund. Thus, the aim of the project is to assess the feasibility for producing renewable aviation fuel at a specific location considering and evaluating e.g., different processes, operations and integrations, costs, environmental impact, business models and actors.IVL The Swedish Environmental Research Institute, Jämtkraft (JK), Chalmers University (CU), Lund University (LU), Nordic Initiative for Sustainable Aviation (NISA), and Fly Green Fund (FGF) have been the primary implementers in this project. Other project stakeholders (AFAB, and The Power Region), have provided relevant data to the various working groups. The project has included experimental work, modelling and calculations, as well as literature-based studies but not the construction of any facilities.
|
|
| 5. |
- Ghosh, Sreetama, 1990, et al.
(författare)
-
Experimental and kinetic modeling studies of methanol synthesis from CO 2 hydrogenation using In 2 O 3 catalyst
- 2021
-
Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947. ; 416
-
Tidskriftsartikel (refereegranskat)abstract
- Catalytic hydrogenation of CO2 to methanol has gained considerable interest for its significant role in CO2 utilization using heterogeneous catalysts. This study is the first to propose a kinetic model based on Langmuir-Hinshelwood-Hougen-Watson (LHHW) mechanism for CO2 hydrogenation to methanol over a highly effective indium oxide (In2O3) catalyst. The work focuses on different reaction conditions mainly revolving around the variation of operating temperature, total reactor pressure, H2/CO2 molar feed ratio and weight hourly space velocity (WHSV) of the system. The experimental data were modeled using a competitive single-site kinetic model based on LHHW rate equations. A parameter optimization procedure was undertaken to determine the kinetic parameters of the developed rate equations. The model predicts that when the methanol synthesis reaction becomes equilibrium limited, the progress of the RWGS reaction forces the methanol yield to decrease due to the reversal of the methanol synthesis reaction. A mixture of CO2 and H2 has been used as the reactor feed in all the cases. Significantly w.r.t. the CO2 partial pressure, the reaction rate for methanol synthesis initially increased and then slightly decreased indicating a varying order. The single-site model accurately predicted the trends in the experimental data which would enable the development of reliable reactor and process designs.
|
|
| 6. |
- Ghosh, Sreetama, 1990, et al.
(författare)
-
Methanol mediated direct CO 2 hydrogenation to hydrocarbons: Experimental and kinetic modeling study
- 2022
-
Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947. ; 435
-
Tidskriftsartikel (refereegranskat)abstract
- Carbon dioxide can be utilized as a feedstock to produce chemicals and renewable fuels sustainably. CO2 hydrogenation to hydrocarbons through a methanol mediated pathway requires a more detailed study, examining interactions between reaction processes leading to different product selectivities. In this particular work, we propose a kinetic model for the direct CO2 hydrogenation to different hydrocarbon products over an In2O3/HZSM-5 bifunctional catalytic bed. The model includes a CO2 hydrogenation to methanol model based on a Langmuir Hinshelwood Hougen Watson (LHHW) reaction mechanism over In2O3 catalyst combined with a lump-type methanol to hydrocarbon (MTH) model over the HZSM-5 zeolite. Interestingly, the combined model could largely predict the suppression of the reverse water gas shift (RWGS) reaction and an increase in the yield of hydrocarbons compared to the formation of methanol in case of the same reaction conditions carried out with only the methanol synthesis catalyst (In2O3). Further, by varying the mass ratio of the individual components of the bifunctional catalytic bed, it was demonstrated that a higher outlet concentration of methanol achieved with a higher mass ratio of the methanol synthesis catalyst caused less suppression of the RWGS reaction and shifted the hydrocarbon product distribution to a slightly larger share of higher hydrocarbons. These changes in product selectivity caused by variation of the catalyst mass ratio were both also successfully reproduced by the model. Therefore, a comparison between the experimental results and the model predictions shows that this model, including equilibrium effects for the reactions, can accurately predict the trends of the experimental findings for direct CO2 hydrogenation to hydrocarbons over the In2O3/HZSM-5 catalyst.
|
|
| 7. |
- Ho, Hoang Phuoc, 1983, et al.
(författare)
-
Effect of the Preparation Methods on the Physicochemical Properties of Indium-Based Catalysts and Their Catalytic Performance for CO 2 Hydrogenation to Methanol
- 2024
-
Ingår i: Energy & Fuels. - 1520-5029 .- 0887-0624. ; 38:6, s. 5407-5420
-
Tidskriftsartikel (refereegranskat)abstract
- Indium oxides (In2O3) and indium oxides supported zirconia (ZrO2) have been known possible alternatives for conventional copper-based catalysts in the CO2-hydrogenation to methanol. This study aims to investigate the effect of preparation techniques on the physicochemical properties of indium-based materials and their catalytic performance for the hydrogenation of CO2 to methanol. Two series of both single oxide In2O3 and binary In2O3-ZrO2 have been synthesized by combustion, urea hydrolysis, and precipitation with different precipitating agents (sodium carbonate and ammonia/ethanol solution). Physicochemical properties of materials are characterized by elemental analysis, XRD, N2 physisorption, SEM/EDX, micro-Raman, XPS, H2-TPR, and CO2-TPD. Cubic In2O3 was the common phase generated by all four synthesis methods, except for urea hydrolysis, where rhombohedral In2O3 was additionally present. The combustion method produced the materials with the lowest specific surface areas while the precipitation using ammonia/ethanol aided in creating more oxygen defects. The synthesis methods strongly influenced the degree of interaction between the oxides and resulted in improvements in properties that boosted the catalytic performance of the binary oxides compared to their single-oxide counterparts.
|
|
| 8. |
- Sharma, Poonam, 1990, et al.
(författare)
-
Recent advances in hydrogenation of CO2 into hydrocarbons via methanol intermediate over heterogeneous catalysts
- 2021
-
Ingår i: Catalysis Science and Technology. - : Royal Society of Chemistry (RSC). - 2044-4753 .- 2044-4761. ; 11:5, s. 1665-1697
-
Forskningsöversikt (refereegranskat)abstract
- The efficient conversion of CO2 to hydrocarbons offers a way to replace the dependency on fossil fuels and mitigate the accumulation of surplus CO2 in the atmosphere that causes global warming. Therefore, various efforts have been made in recent years to convert CO2 to fuels and value-added chemicals. In this review, the direct and indirect hydrogenation of CO2 to hydrocarbons via methanol as an intermediate is spotlighted. We discuss the most recent approaches in the direct hydrogenation of CO2 into hydrocarbons via the methanol route wherein catalyst design, catalyst performance, and the reaction mechanism of CO2 hydrogenation are discussed in detail. As a comparison, various studies related to CO2 to methanol on transition metals and metal oxide-based catalysts and methanol to hydrocarbons are also provided, and the performance of various zeolite catalysts in H-2, CO2, and H2O rich environments is discussed during the conversion of methanol to hydrocarbons. In addition, a detailed analysis of the performance and mechanisms of the CO2 hydrogenation reactions is summarized based on different kinetic modeling studies. The challenges remaining in this field are analyzed and future directions associated with direct synthesis of hydrocarbons from CO2 are outlined.
|
|
