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https://odr.chalmers.se/handle/20.500.12380/41

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Carbon and climate efficient use of biogenic carbons in solid waste for circular chemicals through gasification
(2024) Mola Mendoza, Marina; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Chalmers University of Technology / Department of Chemistry and Chemical Engineering; Leion, Henrik; Dattarao Surywanshi, Gajanan
Municipal Solid Waste (MSW) generation is a growing global concern, aggravated by rapid urbanization, population growth, and industrialization. Annually, approximately 2.1 billion metric tons of MSW are generated, with the trend expected to rise. To address this urgent challenge, solutions must include both capacity increase and MSW treatment sustainability, like converting the non-recyclable waste into chemicals like methanol via gasification. This can potentially reduce the dependence on fossil-based raw materials in the chemical industry, increasing the circularity of the carbon in waste streams. This study explores the feasibility of using gasification for chemical synthesis from MSW, focusing on the Bubbling Fluidized Bed (BFB) gasifier. Moreover, it includes the development of a comprehensive Aspen Plus model to simulate the MSW-to-methanol process for a feedstock input of 100 MWth. It includes drying, gasification, syngas cleaning, syngas conditioning, methanol synthesis loop, and methanol purification stages. The auto-thermal gasification system is modelled using steam as gasifying agent, with a steam-to-feedstock (S/F) ratio of 0.8, and oxygen from an Air Separation Unit (ASU) to combust the volatile matter in the feedstock. In this model, the MSW input is converted into 16.31 tonnes/h of syngas in the gasifier operating at 920 °C, requiring an oxygen flow of 2.12 kg/s from the ASU for the volatiles combustion to sustain the autothermal operation. After the cleaning stage, the syngas has an energy content of 15.31 MJ/kg on a LHV basis. Then, the ratio of H2/CO in the syngas is adjusted to 2.5 via a Water Gas Shift reactor before entering the chemical synthesis loop. In the medium pressure vapor phase reactor, operating at 220 °C with a Cu/Zn/Al/Zr catalyst bed, the syngas is converted into methanol. After distillation, 9500 kg/h of methanol is produced with a molar purity of 99.3%. The overall process energy efficiency is 0.45 and the carbon conversion efficiency is 0.41, meaning that 41% of the biogenic carbon in the MSW is converted into the carbon contained in the methanol product. The techno-economic analysis reveals promising financial indicators, including a payback period of 5 years, a high NPV (276.28 M€), and a competitive levelized cost of methanol of 414.92 €/tonne, suggesting that the proposed process can be economically viable and competitive with current methanol production methods.
Oxyfuel combustion and carbon capture of a cogeneration plant for synthetic fuel production
(2024) Simmank, Patrick; Srinivas Donni, Jatin; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Chalmers University of Technology / Department of Chemistry and Chemical Engineering; Creaser, Derek; Creaser, Derek
Purification of conjugated polymers. Better polymers through HPLC purification and Soxhlet extraction
(2024) Öhberg, Jessika; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Chalmers University of Technology / Department of Chemistry and Chemical Engineering; Giovannitti, Alexander; Westwood, Megan
Abstract The purification of conjugated polymers, specifically the polymer D18, was investigated using the purification methods of Soxhlet extraction and High-Performance Liquid Chromatography (HPLC). The objective was to purify D18 from residual Pd impurities remaining from synthesis and fractionate the molecular weight for lower dispersity and higher molecular weights. This is crucial for conjugated polymers like D18, as with robust and effective purification methods, they have a prominent future as materials extensively used in organic electronic devices such as solar cells. The purification process has a significant impact on the polymer’s properties, influencing its electronic and optical performance which highlights the importance of standardized purification and reproducible results. The study demonstrates that while Soxhlet extraction was effective in removing low molecular weight fractions, HPLC proves to be superior in narrowing down the dispersity and reducing palladium (Pd) content for the polymer D18. The work also investigates the use of TOF-SIMS for measuring Pd content before and after purification by developing a calibration curve. Two palladium complexes, Pd(PPh3)4 and Pd2(dba)3 chloroform adduct, were along with the polymer P3HT used to create calibration curves, with Pd2(dba)3 showing better performance due to its solubility and stability. Challenges included potential contamination, suggesting the need for stricter environment protocols for sample handling. Calculating the Pd content from the calibration curves underscored the importance of a robust normalization technique to obtain absolute quantification. This research provides insights into purification methods that can enhance the performance of conjugated polymers in organic electronic applications and demonstrates the use of TOF-SIMS as an evaluation method of metal impurities. Keywords: Conjugated polymers, Purification, Soxhlet extraction, HPLC, TOFSIMS.
Local structure and dynamics of two novel metal-organic framework materials investigated with Raman spectroscopy and neutron scattering techniques
(2024) Reinsfelt, David; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Chalmers University of Technology / Department of Chemistry and Chemical Engineering; Weber, Daniel; Karlsson, Maths
Metal-Organic Frameworks (MOFs) show a wide variety of new applications in areas such as energy storage, catalysis, sensor technology and drug delivery, due to their inherent porous structures and facile tunability. Some MOFs also show structural flexibility upon temperature variation, which opens up even more possibilities for applications. However, the local structure and dynamics, underpinning this flexibility, are often unclear. This thesis deals with a study of the local structure and dynamics of two newly discovered MOFs, namely La2(CPB) and Ce2(CPB), where CPB refers to the hexagon shaped hexatopic linker 1,2,3,4,5,6-hexakis(4- carboxyphenyl) benzene. La2(CPB), also called CTH-17, has previously proven to show gate opening effects under CO2 gas sorption measurements by drastically increase the adsorption after certain pressure values. Changes in the crystal structure in the form of twisted phenyl rings and stretching in the rod direction of the rod-shaped CTH-17 have also been observed when measured with SCXRD in 90 K, 300 K and 500 K. This study seeks to confirm these observed structure changes by studying local atomic vibrations, using Raman spectroscopy and inelastic neutron scattering (INS). The goal is not only to observe the static material structures before and after undergone the mentioned changes observed with SCXRD measurements, but also to observe the structural dynamics upon temperature variation. The samples were synthesized with a solvothermal synthesis method which yielded La2(CPB) and Ce2(CPB) as the majority phase with variable amounts of La or Ceformate as side phases. Both Raman and INS spectra of La2(CPB) and Ce2(CPB) show negligible differences, indicating that their local structure and dynamics are very similar. Room temperature Raman spectroscopy measurements of activated La2(CPB) and Ce2(CPB) samples show photoluminescence. The variable temperature Raman spectroscopy results show indications of DMF leaving the porous structures around 200-300 ◦C. Linearly shifting frequency trends with increased temperature is observed for several bands indicating thermal expansion, and a big irreversible shift at 300 ◦C is observed indicating a new structural phase. Indications of luminescence in combination with DMF leaving the structure is also observed. The similarities between La2(CPB) and Ce2(CPB) suggests that changing the metal ion nodes in this type of hexagonal shaped MOF from La to a similar metal such as Ce, does not alter the local structure and dynamics. The supposed observed thermal expansion and structural phase shift for both La2(CPB) and Ce2(CPB) could explain the gate opening effect during CO2 gas sorption measurements by showing that the porous structure changes upon increased temperature which can create more space for molecules to enter the pores.
Local structure and dynamics of two novel metal-organic framework materials investigated with Raman spectroscopy and neutron scattering techniques
(2024) Reinsfelt, David; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Chalmers University of Technology / Department of Chemistry and Chemical Engineering; Weber, Daniel; Karlsson, Maths
Metal-Organic Frameworks (MOFs) show a wide variety of new applications in areas such as energy storage, catalysis, sensor technology and drug delivery, due to their inherent porous structures and facile tunability. Some MOFs also show structural flexibility upon temperature variation, which opens up even more possibilities for applications. However, the local structure and dynamics, underpinning this flexibility, are often unclear. This thesis deals with a study of the local structure and dynamics of two newly discovered MOFs, namely La2(CPB) and Ce2(CPB), where CPB refers to the hexagon shaped hexatopic linker 1,2,3,4,5,6-hexakis(4- carboxyphenyl) benzene. La2(CPB), also called CTH-17, has previously proven to show gate opening effects under CO2 gas sorption measurements by drastically increase the adsorption after certain pressure values. Changes in the crystal structure in the form of twisted phenyl rings and stretching in the rod direction of the rod-shaped CTH-17 have also been observed when measured with SCXRD in 90 K, 300 K and 500 K. This study seeks to confirm these observed structure changes by studying local atomic vibrations, using Raman spectroscopy and inelastic neutron scattering (INS). The goal is not only to observe the static material structures before and after undergone the mentioned changes observed with SCXRD measurements, but also to observe the structural dynamics upon temperature variation. The samples were synthesized with a solvothermal synthesis method which yielded La2(CPB) and Ce2(CPB) as the majority phase with variable amounts of La or Ceformate as side phases. Both Raman and INS spectra of La2(CPB) and Ce2(CPB) show negligible differences, indicating that their local structure and dynamics are very similar. Room temperature Raman spectroscopy measurements of activated La2(CPB) and Ce2(CPB) samples show photoluminescence. The variable temperature Raman spectroscopy results show indications of DMF leaving the porous structures around 200-300 ◦C. Linearly shifting frequency trends with increased temperature is observed for several bands indicating thermal expansion, and a big irreversible shift at 300 ◦C is observed indicating a new structural phase. Indications of luminescence in combination with DMF leaving the structure is also observed. The similarities between La2(CPB) and Ce2(CPB) suggests that changing the metal ion nodes in this type of hexagonal shaped MOF from La to a similar metal such as Ce, does not alter the local structure and dynamics. The supposed observed thermal expansion and structural phase shift for both La2(CPB) and Ce2(CPB) could explain the gate opening effect during CO2 gas sorption measurements by showing that the porous structure changes upon increased temperature which can create more space for molecules to enter the pores.

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