Matching Items (6)
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- All Subjects: Biofuels
- All Subjects: Hydrogen Production
- Creators: Deng, Shuguang
Description
Hydrothermal Liquefaction of Algae represents one of many pathways for the sustainable replacement of fossil fuels in transportation. When processing and researching algal biofuel, determination of the higher heating value (HHV) is paramount. Bomb calorimetry represents to current method for direct determination of HHV. When determining HHV’s indirectly, the industry standard is using one of many linear correlations relating elemental composition to HHV. Most of these correlations were developed from coal industry data, meaning that they do not necessarily fit algal product data well. In this study bomb calorimetry data and CHNS/O elemental composition data were collected for Chlorella, Micract, GS 5587.1, Kirchnella, and Gal 87.1 MM8 algae species. This data was added to CHNS/O and HHV values for other algal products in literature, and utilized to test the accuracy of the Dulong, Gumz, Vandralek and Boie correlations for algae products. Several preliminary algae specific correlations were proposed through a linear regression model of the data. Of the 5 samples tested, Kirchnella exhibited the highest HHV (23.2405 ± 0.0216 MJ/kg) and Chlorella exhibited the lowest (20.2055 ± 0.0484 MJ/kg). For both the experimental, and literature CHNS/O vs HHV data, the Vandralek and Boie correlations provided the best approximations in this study. For the totality of the data collected and researched in this study, 6 of 8 proposed correlations outperformed the Vandralek equation for HHV approximation. The most promising proposed correlations incorporated multiple linear regressions for elemental fractions of CHS, CHSO and CHNSO. Being that only 20 distinct algal product samples were regressed to create the proposed correlations, more data should be incorporated before publication of a final correlation. This study should serve as a starting point for the compilation of an exhaustive database for algal product assay and HHV data.
ContributorsCopp, Connor Joseph (Author) / Deng, Shuguang (Thesis director) / Muppaneni, Tapaswy (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
This honors thesis is focused on two separate catalysis projects conducted under the mentorship of Dr. Javier Pérez-Ramírez at ETH Zürich. The first project explored ethylene oxychlorination over supported europium oxychloride catalysts. The second project investigated alkyne semihydrogenation over nickel phosphide catalysts. This work is the subject of a publication of which I am a co-author, as cited below.
Project 1 Abstract: Ethylene Oxychlorination
The current two-step process for the industrial process of vinyl chloride production involves CuCl2 catalyzed ethylene oxychlorination to ethylene dichloride followed by thermal cracking of the latter to vinyl chloride. To date, no industrial application of a one-step process is available. To close this gap, this work evaluates a wide range of self-prepared supported CeO2 and EuOCl catalysts for one-step production of vinyl chloride from ethylene in a fixed-bed reactor at 623 773 K and 1 bar using feed ratios of C2H4:HCl:O2:Ar:He = 3:3 6:1.5 6:3:82 89.5. Among all studied systems, CeO2/ZrO2 and CeO2/Zeolite MS show the highest activity but suffer from severe combustion of ethylene, forming COx, while 20 wt.% EuOCl/γ-Al2O3 leads to the best vinyl chloride selectivity of 87% at 15.6% C2H4 conversion with complete suppression of CO2 formation and only 4% selectivity to CO conversion for over 100 h on stream. Characterization by XRD and EDX mapping reveals that much of the Eu is present in non-active phases such as Al2Eu or EuAl4, indicating that alternative synthesis methods could be employed to better utilize the metal. A linear relationship between conversion and metal loading is found for this catalyst, indicating that always part of the used Eu is available as EuOCl, while the rest forms inactive europium aluminate species. Zeolite-supported EuOCl slightly outperforms EuOCl/γ Al2O3 in terms of total yield, but is prone to significant coking and is unstable. Even though a lot of Eu seems locked in inactive species on EuOCl/γ Al2O3, these results indicate possible savings of nearly 16,000 USD per kg of catalyst compared to a bulk EuOCl catalyst. These very promising findings constitute a crucial step for process intensification of polyvinyl chloride production and exploring the potential of supported EuOCl catalysts in industrially-relevant reactions.
Project 2 Abstract: Alkyne Semihydrogenation
Despite strongly suffering from poor noble metal utilization and a highly toxic selectivity modifier (Pb), the archetypal catalyst applied for the three-phase alkyne semihydrogenation, the Pb-doped Pd/CaCO3 (Lindlar catalyst), is still being utilized at industrial level. Inspired by the very recent strategies involving the modification of Pd with p-block elements (i.e., S), this work extrapolates the concept by preparing crystalline metal phosphides with controlled stoichiometry. To develop an affordable and environmentally-friendly alternative to traditional hydrogenation catalysts, nickel, a metal belonging to the same group as Pd and capable of splitting molecular hydrogen has been selected. Herein, a simple two-step synthesis procedure involving nontoxic precursors was used to synthesize bulk nickel phosphides with different stoichiometries (Ni2P, Ni5P4, and Ni12P5) by controlling the P:Ni ratios. To uncover structural and surface features, this catalyst family is characterized with an array of methods including X-ray diffraction (XRD), 31P magic-angle nuclear magnetic resonance (MAS-NMR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Bulk-sensitive techniques prove the successful preparation of pure phases while XPS analysis unravels the facile passivation occurring at the NixPy surface that persists even after reductive treatment. To assess the characteristic surface fingerprints of these materials, Ar sputtering was carried out at different penetration depths, reveling the presence of Ni+ and P-species. Continuous-flow three-phase hydrogenations of short-chain acetylenic compounds display that the oxidized layer covering the surface is reduced under reaction conditions, as evidenced by the induction period before reaching the steady state performance. To assess the impact of the phosphidation treatment on catalytic performance, the catalysts were benchmarked against a commercial Ni/SiO2-Al2O3 sample. While Ni/SiO2-Al2O3 presents very low selectivity to the alkene (the selectivity is about 10% at full conversion) attributed to the well-known tendency of naked nickel nanoparticles to form hydrides, the performance of nickel phosphides is highly selective and independent of P:Ni ratio. In line with previous findings on PdxS, kinetic tests indicate the occurrence of a dual-site mechanism where the alkyne and hydrogen do not compete for the same site.
This work is the subject of a publication of which I am a co-author, as cited below.
D. Albani; K. Karajovic; B. Tata; Q. Li; S. Mitchell; N. López; J. Pérez-Ramírez. Ensemble Design in Nickel Phosphide Catalysts for Alkyne Semi-Hydrogenation. ChemCatChem 2019. doi.org/10.1002/cctc.201801430
Project 1 Abstract: Ethylene Oxychlorination
The current two-step process for the industrial process of vinyl chloride production involves CuCl2 catalyzed ethylene oxychlorination to ethylene dichloride followed by thermal cracking of the latter to vinyl chloride. To date, no industrial application of a one-step process is available. To close this gap, this work evaluates a wide range of self-prepared supported CeO2 and EuOCl catalysts for one-step production of vinyl chloride from ethylene in a fixed-bed reactor at 623 773 K and 1 bar using feed ratios of C2H4:HCl:O2:Ar:He = 3:3 6:1.5 6:3:82 89.5. Among all studied systems, CeO2/ZrO2 and CeO2/Zeolite MS show the highest activity but suffer from severe combustion of ethylene, forming COx, while 20 wt.% EuOCl/γ-Al2O3 leads to the best vinyl chloride selectivity of 87% at 15.6% C2H4 conversion with complete suppression of CO2 formation and only 4% selectivity to CO conversion for over 100 h on stream. Characterization by XRD and EDX mapping reveals that much of the Eu is present in non-active phases such as Al2Eu or EuAl4, indicating that alternative synthesis methods could be employed to better utilize the metal. A linear relationship between conversion and metal loading is found for this catalyst, indicating that always part of the used Eu is available as EuOCl, while the rest forms inactive europium aluminate species. Zeolite-supported EuOCl slightly outperforms EuOCl/γ Al2O3 in terms of total yield, but is prone to significant coking and is unstable. Even though a lot of Eu seems locked in inactive species on EuOCl/γ Al2O3, these results indicate possible savings of nearly 16,000 USD per kg of catalyst compared to a bulk EuOCl catalyst. These very promising findings constitute a crucial step for process intensification of polyvinyl chloride production and exploring the potential of supported EuOCl catalysts in industrially-relevant reactions.
Project 2 Abstract: Alkyne Semihydrogenation
Despite strongly suffering from poor noble metal utilization and a highly toxic selectivity modifier (Pb), the archetypal catalyst applied for the three-phase alkyne semihydrogenation, the Pb-doped Pd/CaCO3 (Lindlar catalyst), is still being utilized at industrial level. Inspired by the very recent strategies involving the modification of Pd with p-block elements (i.e., S), this work extrapolates the concept by preparing crystalline metal phosphides with controlled stoichiometry. To develop an affordable and environmentally-friendly alternative to traditional hydrogenation catalysts, nickel, a metal belonging to the same group as Pd and capable of splitting molecular hydrogen has been selected. Herein, a simple two-step synthesis procedure involving nontoxic precursors was used to synthesize bulk nickel phosphides with different stoichiometries (Ni2P, Ni5P4, and Ni12P5) by controlling the P:Ni ratios. To uncover structural and surface features, this catalyst family is characterized with an array of methods including X-ray diffraction (XRD), 31P magic-angle nuclear magnetic resonance (MAS-NMR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Bulk-sensitive techniques prove the successful preparation of pure phases while XPS analysis unravels the facile passivation occurring at the NixPy surface that persists even after reductive treatment. To assess the characteristic surface fingerprints of these materials, Ar sputtering was carried out at different penetration depths, reveling the presence of Ni+ and P-species. Continuous-flow three-phase hydrogenations of short-chain acetylenic compounds display that the oxidized layer covering the surface is reduced under reaction conditions, as evidenced by the induction period before reaching the steady state performance. To assess the impact of the phosphidation treatment on catalytic performance, the catalysts were benchmarked against a commercial Ni/SiO2-Al2O3 sample. While Ni/SiO2-Al2O3 presents very low selectivity to the alkene (the selectivity is about 10% at full conversion) attributed to the well-known tendency of naked nickel nanoparticles to form hydrides, the performance of nickel phosphides is highly selective and independent of P:Ni ratio. In line with previous findings on PdxS, kinetic tests indicate the occurrence of a dual-site mechanism where the alkyne and hydrogen do not compete for the same site.
This work is the subject of a publication of which I am a co-author, as cited below.
D. Albani; K. Karajovic; B. Tata; Q. Li; S. Mitchell; N. López; J. Pérez-Ramírez. Ensemble Design in Nickel Phosphide Catalysts for Alkyne Semi-Hydrogenation. ChemCatChem 2019. doi.org/10.1002/cctc.201801430
ContributorsTata, Bharath (Author) / Deng, Shuguang (Thesis director) / Muhich, Christopher (Committee member) / Chemical Engineering Program (Contributor, Contributor) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Mixed-ionic electronic conducting (MIEC) oxides have drawn much attention from researchers because of their potential in high temperature separation processes. Among many materials available, perovskite type and fluorite type oxides are the most studied for their excellent oxygen ion transport property. These oxides not only can be oxygen adsorbent or O2-permeable membranes themselves, but also can be incorporated with molten carbonate to form dual-phase membranes for CO2 separation.
Oxygen sorption/desorption properties of perovskite oxides with and without oxygen vacancy were investigated first by thermogravimetric analysis (TGA) and fixed-bed experiments. The oxide with unique disorder-order phase transition during desorption exhibited an enhanced oxygen desorption rate during the TGA measurement but not in fixed-bed demonstrations. The difference in oxygen desorption rate is due to much higher oxygen partial pressure surrounding the sorbent during the fixed-bed oxygen desorption process, as revealed by X-ray diffraction (XRD) patterns of rapidly quenched samples.
Research on using perovskite oxides as CO2-permeable dual-phase membranes was subsequently conducted. Two CO2-resistant MIEC perovskite ceramics, Pr0.6Sr0.4Co0.2Fe0.8 O3-δ (PSCF) and SrFe0.9Ta0.1O3-δ (SFT) were chosen as support materials for membrane synthesis. PSCF-molten carbonate (MC) and SFT-MC membranes were prepared for CO2-O2 counter-permeation. The geometric factors for the carbonate phase and ceramic phase were used to calculate the effective carbonate and oxygen ionic conductivity in the carbonate and ceramic phase. When tested in CO2-O2 counter-permeation set-up, CO2 flux showed negligible change, but O2 flux decreased by 10-32% compared with single-component permeation. With CO2 counter-permeation, the total oxygen permeation flux is higher than that without counter-permeation.
A new concept of CO2-permselective membrane reactor for hydrogen production via steam reforming of methane (SRM) was demonstrated. The results of SRM in the membrane reactor confirm that in-situ CO2 removal effectively promotes water-gas shift conversion and thus enhances hydrogen yield. A modeling study was also conducted to assess the performance of the membrane reactor in high-pressure feed/vacuum sweep conditions, which were not carried out due to limitations in current membrane testing set-up. When 5 atm feed pressure and 10-3 atm sweep pressure were applied, the membrane reactor can produce over 99% hydrogen stream in simulation.
Oxygen sorption/desorption properties of perovskite oxides with and without oxygen vacancy were investigated first by thermogravimetric analysis (TGA) and fixed-bed experiments. The oxide with unique disorder-order phase transition during desorption exhibited an enhanced oxygen desorption rate during the TGA measurement but not in fixed-bed demonstrations. The difference in oxygen desorption rate is due to much higher oxygen partial pressure surrounding the sorbent during the fixed-bed oxygen desorption process, as revealed by X-ray diffraction (XRD) patterns of rapidly quenched samples.
Research on using perovskite oxides as CO2-permeable dual-phase membranes was subsequently conducted. Two CO2-resistant MIEC perovskite ceramics, Pr0.6Sr0.4Co0.2Fe0.8 O3-δ (PSCF) and SrFe0.9Ta0.1O3-δ (SFT) were chosen as support materials for membrane synthesis. PSCF-molten carbonate (MC) and SFT-MC membranes were prepared for CO2-O2 counter-permeation. The geometric factors for the carbonate phase and ceramic phase were used to calculate the effective carbonate and oxygen ionic conductivity in the carbonate and ceramic phase. When tested in CO2-O2 counter-permeation set-up, CO2 flux showed negligible change, but O2 flux decreased by 10-32% compared with single-component permeation. With CO2 counter-permeation, the total oxygen permeation flux is higher than that without counter-permeation.
A new concept of CO2-permselective membrane reactor for hydrogen production via steam reforming of methane (SRM) was demonstrated. The results of SRM in the membrane reactor confirm that in-situ CO2 removal effectively promotes water-gas shift conversion and thus enhances hydrogen yield. A modeling study was also conducted to assess the performance of the membrane reactor in high-pressure feed/vacuum sweep conditions, which were not carried out due to limitations in current membrane testing set-up. When 5 atm feed pressure and 10-3 atm sweep pressure were applied, the membrane reactor can produce over 99% hydrogen stream in simulation.
ContributorsWu, Han-Chun (Author) / Lin, Jerry Y.S. (Thesis advisor) / Deng, Shuguang (Committee member) / Jiao, Yang (Committee member) / Emady, Heather (Committee member) / Muhich, Christopherq (Committee member) / Arizona State University (Publisher)
Created2020
Description
Fossil fuels have been the primary source of energy in the world for many decades. However, they are among the top contributors of the greenhouse gas emissions in the atmosphere. The objective of this research was to produce a more environmentally friendly biofuel from Algae-Helix and Salicornia biomasses. Experiments were conducted using a hydrothermal liquefaction (HTL) technique in the HTL reactor to produce biofuel that can potentially replace fossil fuel usage. Hydrothermal Liquefaction is a method used to convert the biomass into the biofuels. HTL experiments on Algae-Helix and Salicornia at 200°C-350°C and 430psi were performed to investigate the effect of temperature on the biocrude yield of the respective biomass used. The effect of the biomass mixture (co-liquefaction) of Salicornia and algae on the amount of biocrude produced was also explored. The biocrude and biochar (by-product) obtained from the hydrothermal liquefaction process were also analyzed using thermogravimetric analyzer (TGA). The maximum biocrude yield for the algae-helix biomass and for the Salicornia biomass were both obtained at 300°C which were 34.63% and 7.65% respectively. The co-liquefaction of the two biomasses by 50:50 provided a maximum yield of 17.26% at 250°C. The co-liquefaction of different ratios explored at 250°C and 300°C concluded that Salicornia to algae-helix ratio of 20:80 produced the highest yields of 22.70% and 31.97%. These results showed that co-liquefaction of biomass if paired well with the optimizing temperature can produce a high biocrude yield. The TGA profiles investigated have shown that salicornia has higher levels of ash content in comparison with the algae-helix. It was then recommended that for a mixture of algae and Salicornia, large-scale biofuel production should be conducted at 250℃ in a 20:80 salicornia to algae biocrude ratio, since it lowers energy needs. The high biochar content left can be recycled to optimize biomass, and prevent wastage.
ContributorsLaideson, Maymary Everrest (Co-author) / Luboowa, Kato (Co-author) / Deng, Shuguang (Thesis director) / Nielsen, David (Committee member) / Chemical Engineering Program (Contributor) / Economics Program in CLAS (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Fossil fuels have been the primary source of energy in the world for many decades. However, they are among the top contributors of the greenhouse gas emissions in the atmosphere. The objective of this research was to produce a more environmentally friendly biofuel from Algae-Helix and Salicornia biomasses. Experiments were conducted using a hydrothermal liquefaction (HTL) technique in the HTL reactor to produce biofuel that can potentially replace fossil fuel usage. Hydrothermal Liquefaction is a method used to convert the biomass into the biofuels. HTL experiments on Algae-Helix and Salicornia at 200°C-350°C and 430psi were performed to investigate the effect of temperature on the biocrude yield of the respective biomass used. The effect of the biomass mixture (co-liquefaction) of Salicornia and algae on the amount of biocrude produced was also explored. The biocrude and biochar (by-product) obtained from the hydrothermal liquefaction process were also analyzed using thermogravimetric analyzer (TGA). The maximum biocrude yield for the algae-helix biomass and for the Salicornia biomass were both obtained at 300°C which were 34.63% and 7.65% respectively. The co-liquefaction of the two biomasses by 50:50 provided a maximum yield of 17.26% at 250°C. The co-liquefaction of different ratios explored at 250°C and 300°C concluded that Salicornia to algae-helix ratio of 20:80 produced the highest yields of 22.70% and 31.97%. These results showed that co-liquefaction of biomass if paired well with the optimizing temperature can produce a high biocrude yield. The TGA profiles investigated have shown that salicornia has higher levels of ash content in comparison with the algae-helix. It was then recommended that for a mixture of algae and Salicornia, large-scale biofuel production should be conducted at 250℃ in a 20:80 salicornia to algae biocrude ratio, since it lowers energy needs. The high biochar content left can be recycled to optimize biomass, and prevent wastage.
ContributorsLuboowa, Kato Muhammed (Co-author) / Laideson, Maymary (Co-author) / Deng, Shuguang (Thesis director) / Nielsen, David (Committee member) / Chemical Engineering Program (Contributor) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
A Study of the gasification of municipal solid waste (MSW) for hydrogen production was completed through research and statistical design of experiment. The study was done for general syngas production with conditions of high temperature and pressure. Waste samples from kitchen waste including rice, avocado, and egg shells were used. Dry orange blossom tree leaves were included and a very minimal fraction of used paper and Styrofoam. One of the components of the syngas predicted was hydrogen, but this study does not discuss techniques for the separation of the hydrogen from the syngas. A few suggestions, however, such as the use of gas chromatography and membranes are made for the study of the syngas and separation of the hydrogen from the syngas. A three level, three factors-half factorial design was used to analyze the impact of pressure, residence time and temperature on the gasification of MSW through a hydrothermal gasification approach. A series 4590 micro stirred reactor of 100mL was used to gasify MSW, but first, it was established through a TGA approach that the waste was about 5% moisture content and 55% organic content (OC). The TGA device used was the TG 209 F1 Libra. Results of the gasification indicated that the most important factor in the gasification of MSW is temperature, followed by residence time and that the syngas yield increases with a decreasing pressure of the system. A thermodynamic model relating the three factors and the syngas yield was developed.
ContributorsBuyinza, Allan Smith (Author) / Deng, Shuguang (Thesis director) / Nannenga, Brent (Committee member) / Chemical Engineering Program (Contributor) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05