Thesis (M.S.)--Ohio University, August, 1984. / Title from PDF t.p.

Thesis (M. Sc.)(Chemisty) -- University of Pretoria, 2009. / Summary in English.

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains x, 106 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 101-102).

Hydrothermal carbonization is a process by which biomass in water is thermochemically converted to a brown activated carbon known as hydrothermal char. As a biomass upgrading process hydrothermal carbonization has several advantages, the process is conducted in liquid water meaning pretreatment in the form of drying is not required. The process is normally conducted in batch reactors at temperatures ranging from 180 to 350°C and reactions of 0.5 to 24 hours. These mild conditions are not energy intensive and allow for the technique to deployed cheaply. The process involves no dangerous solvents or chemicals, and the liquid product has potential applications as a liquid fuel. Hydrothermal carbonization is a cost-effective technology that provides a solution to the growing waste and biomass production of the United States. However, there is a growing interest in the processes potential to produce a material that can be utilized for advanced materials. Hydrothermal chars have been shown to be highly susceptible to post-treatment by acid, temperature and mechanical methods. With a wide variety of potential feedstocks, treatment and post-treatment conditions a deeper understanding of the structure of material and how this structure is impacted by these conditions is needed to allow for its optimal use. Vibrational spectroscopy is a powerful tool for elucidating the structure of materials. Specifically, Raman spectroscopy is largely untapped method for the characterization of Hydrothermal chars. Raman spectroscopy is a scattering method that like IR spectroscopy utilizes an incident laser to produce vibrational responses in the molecule being studied. Raman spectroscopy can potentially be used to observe the carbon structure of a molecule. Typically, observations of this structure are conducted using Nuclear Magnetic Resonance, which is a relatively slow an expensive technique. Previous use of Raman spectroscopy in the field of hydrothermal carbonization has either underutilized the technique making observations of the presence of carbon or has been mischaracterized incorrectly stating the structure. In this work we have used Density Functional Theory to elucidate the Raman patterns of polycyclic aromatic hydrocarbons such as the ones that are the building blocks of hydrothermal chars. As a result of this work we have established a fitting method that explains the origins of Raman bands that are consistent with the structural motifs observed by more expensive techniques. The theoretical method is next deployed to the Raman spectrum of hydrothermal char derived from the treatment of glucose, a common model biomass. It is shown that common Raman spectroscopy methods when applied to hydrothermal char severely change the surface of material. How Raman spectroscopy impacts the surface of hydrothermal chars was studied and methods of mitigating these changes were developed. With a full compliment of theoretical and practical tools at our disposal we then apply these methods in attempt to understand the changes that occur to the structure of glucose based hydrothermal chars as a function of temperature and time.

Hydrothermal carbonization is a process by which biomass in water is thermochemically converted to a brown activated carbon known as hydrothermal char. As a biomass upgrading process hydrothermal carbonization has several advantages, the process is conducted in liquid water meaning pretreatment in the form of drying is not required. The process is normally conducted in batch reactors at temperatures ranging from 180 to 350°C and reactions of 0.5 to 24 hours. These mild conditions are not energy intensive and allow for the technique to deployed cheaply. The process involves no dangerous solvents or chemicals, and the liquid product has potential applications as a liquid fuel. Hydrothermal carbonization is a cost-effective technology that provides a solution to the growing waste and biomass production of the United States. However, there is a growing interest in the processes potential to produce a material that can be utilized for advanced materials. Hydrothermal chars have been shown to be highly susceptible to post-treatment by acid, temperature and mechanical methods. With a wide variety of potential feedstocks, treatment and post-treatment conditions a deeper understanding of the structure of material and how this structure is impacted by these conditions is needed to allow for its optimal use. Vibrational spectroscopy is a powerful tool for elucidating the structure of materials. Specifically, Raman spectroscopy is largely untapped method for the characterization of Hydrothermal chars. Raman spectroscopy is a scattering method that like IR spectroscopy utilizes an incident laser to produce vibrational responses in the molecule being studied. Raman spectroscopy can potentially be used to observe the carbon structure of a molecule. Typically, observations of this structure are conducted using Nuclear Magnetic Resonance, which is a relatively slow an expensive technique. Previous use of Raman spectroscopy in the field of hydrothermal carbonization has either underutilized the technique making observations of the presence of carbon or has been mischaracterized incorrectly stating the structure. In this work we have used Density Functional Theory to elucidate the Raman patterns of polycyclic aromatic hydrocarbons such as the ones that are the building blocks of hydrothermal chars. As a result of this work we have established a fitting method that explains the origins of Raman bands that are consistent with the structural motifs observed by more expensive techniques. The theoretical method is next deployed to the Raman spectrum of hydrothermal char derived from the treatment of glucose, a common model biomass. It is shown that common Raman spectroscopy methods when applied to hydrothermal char severely change the surface of material. How Raman spectroscopy impacts the surface of hydrothermal chars was studied and methods of mitigating these changes were developed. With a full compliment of theoretical and practical tools at our disposal we then apply these methods in attempt to understand the changes that occur to the structure of glucose based hydrothermal chars as a function of temperature and time.

Thesis (MSc.(Chemistry)) - University of Pretoria, 2008. / Summary in English.

Thesis (M.C.E.)--University of Delaware, 2007. / Principal faculty advisor: Richard P. Wool, Dept. of Chemical Engineering. Includes bibliographical references.

The influence of aggregate and binder phase characteristics on formcoke products has been studied. This involved investigating the compaction kinetics of the system and determining the mechanical strength of the briquettes produced. The char phase was characterized in terms of density, hardness, porosity and residual volatile matter content and the rheological properties of the binder phases used were established elsewhere. The strength and wetting behaviour of the aggregate-binder interface were studied using model materials (an SRC pitch binder and a graphite rod aggregate) as well as those produced in this work. Analysis of compaction curves was carried out using the CCWL Hot Compaction Model for Char-Binder Coal systems which was found to adequately describe the observed compaction behaviour. Briquette strength was characterized by ultimate compressive strength and comparisons were made for a constant briquette bulk porosity of 35% (by volume). Results indicate that binder phase fluidity affects compaction viscosity during the particle flow stage of compaction and that char porosity influences final briquette bulk density by affecting the amount of total compaction required to obtain a given bulk density. In general, increased total compaction was shown to result in higher product bulk density and high bulk density was found to yield higher gross composite strength. The latter relationship was seen to be approximately linear over the range of bulk porosity encountered in this study. A higher briquette strength was found for systems with aggregates carbonized at lower temperatures. This was attributed to a combination of higher porosity and stronger char-binder interfacial strength, although the former effect was considered to predominate in the systems considered here. Binder phase fluidity was also seen to affect briquette strength, higher fluidity resulting in higher strength. It was concluded that this was due to increased binder penetration of the aggregate phase. With no significant pore structure in the aggregate, as found with high temperature char, briquette strength was seen to become approximately constant for the three binder coals used. It was concluded that a good formcoke product was aided by a highly fluid binder and a char pore structure accessible to the binder phase. / Applied Science, Faculty of / Materials Engineering, Department of / Unknown

This thesis reports a study on the effects of size distribution, moisture content and oil addition on bulk density and angle of repose of coal. The experimental work includes four stages. The first stage is to develop reliable experimental techniques. The results confirm that ASTM cubic foot test is reliable for measurement of bulk density and angle of repose if properly operated, although the latter is better measured in a piling process. Stages 2 and 3 are to investigate the effects of size distribution by using -3.55mm% for stage 2 and mean size do.s for stage 3, water content and oil addition on bulk density and angle of repose of coal. For each of them, empirical equations are formulated to predict bulk density and angle of repose. The results indicate that the fraction -3.55mm cutting size in stage 2 does not affect bulk density significantly, while the increase of do.s decreases bulk density to a minimum and then increases. Particle size distribution does not affect angle of repose much. The increase of moisture content decreases bulk density and increases angle of repose significantly. The increase of oil addition increases bulk density while decreases angle of repose significantly. The correlation between bulk density and angle of repose can also be observed: the higher bulk density, the lower angle of repose. There are other variables affecting bulk density and angle of repose. They include oil type, absorption time discharging height and external loading. Their effects on bulk density and angle of repose are quantified in stage 4. The results suggest that, a higher discharging position or larger external loading increase bulk density significantly. Angle of repose decreases when increase the height of discharging position. Diesel oil performed better than waste oil addition in terms of bulk density enhancement. For most of the cases examined, bulk density and angle of repose become stable after ~24 hours oil absorption time.

No description available.