Wax crystal formation in diesel and related hydrocarbon fuels during cold weather is a long standing problem. Current polymeric additives to diesel fuel modify the crystal habit of the wax, in a variety of ways, to improve its performance at low temperature. These wax crystal modifiers (WCM) have to operate at low concentrations (0.01-0.1%) to make their use economical, so it is critical that their structures are optimised for the application. The objectives of this work was to synthesise, characterise and test some new polymeric additives which are anticipated to effect the crystallisation of the wax from the fuel and to prepare a model ethylene vinyl acetate (EVA) polymer to gain insights into the mode of action of the EVA co-polymers which are currently in use as WCM. Ring opening metathesis polymerisation was chosen as the method of preparation for these new polymeric additives. An introduction to wax crystallisation in diesel fuel and some proposals for the preparation of these new polymeric additives are given in Chapter 1. Chapter 2 discusses olefin metathesis and ring opening metathesis polymerisation reactions. The synthesis and characterisation of monomers and polymers are given in Chapters 3 and 4 respectively. Results from fuel tests are described in Chapter 5.

Biodiesel is rapidly growing as a fuel of interest due to the various advantages it has over conventional diesel fuel. While the pros – non-toxic, biodegradable, low green house gas emissions seem advantageous, the major issue that plagues the use of biodiesel is its cold weather operability. Biodiesel can present challenges in cold-weather operation, because certain of its constituent compounds can form precipitates in the fuel. These precipitates can cause undesired effects like plugging of fuel filters and deposits. This issue has been attributed to the presence of impurities (mostly saturated monoglycerides, di-glycerides, soap etc) in biodiesel and has been discussed in the literature. There is a move by users and standards associations to implement more stringent norms and quality control to avoid problems in the widespread use of biodiesel. This study involves ways to reduce MG’s in biodiesel by mitigating to a greater extent the possibility of side reactions (formation of soap). The effect of selective transesterification of oil as a function of alcohol, temperature and catalyst concentration was also studied. Although saturated MG’s with high melting points are a greater source of deposits, it can be hypothesized that the polymorphic nature of unsaturated Monoglycerides could also be contributing to cold flow issues. It is hence vital to make sure the biodiesel is free from all forms of monoglycerides. It was also seen that there is very little specificity of selection of fatty acid types in the transesterification reaction and that the amount and type of MGs present in the biodiesel is reflected by the relative amount of fatty acids types present in the oil. In biodiesel derived from Canola oil, a preponderance of monoolein was found for all runs. The initial runs carried out as a two stage process using the membrane followed by batch reactor gave very low MG concentrations, well below ASTM standards.

Biodiesel is a re-emerging biofuel as an alternative to the traditional petroleum derived diesel. There are however, several factors that currently hinder the widespread uptake. Majority of the biodiesel are currently produced from edible oils thereby sparking the food versus fuel debate, the cost of feedstock is significantly high, there are problems experienced in the traditional production process and the resulting fuel is of inadequate quality. This work focused on addressing the issue of poor cold flow properties to improve the overall quality of biodiesel. The skeletal isomerisation of linear fatty acid methyl esters (FAMEs) into branched chain isomers, using solid acid catalysts, appears to be the most comprehensive solution in enhancing the cold flow properties of biodiesel. However, obtaining high branched chain yields, mitigation of undesired side reactions, achieving shorter reaction times, using fewer processing steps and lower operating conditions have still not been achieved to a large extent. Moreover, no studies were found to date investigating isomerisation of FAMEs as a continuous process. A trickle bed reactor (TBR) system has been identified to be an effective continuous reactor. Its key features of being a three phase system and allowing a high degree of contact between the reactant and the catalyst offering a high conversion per unit volume provides an encouraging opportunity to lower reaction times, reaction steps and conditions whilst increasing branched chain yields. This thesis explores the use of the TBR system, for the first time, to enhance the cold flow properties of biodiesel through molecular modification using zeolite beta catalyst with Si/Al ratios of 180 and 12.5. A range of reactions have been investigated including isomerisation, dewaxing (hydroisomerisation and hydrocracking) and decarboxylation on biodiesels derived from camelina, palm and coconut oils. Significant progress has been made in this research area with a 7 °C drop in MP being achieved upon the dewaxing of the coconut biodiesel at 250 °C, 1.01 bar pressure, 0.2 ml/min LF and 37.5 ml/min GF. To achieve greater drops in melting points it has been suggested to investigate mesoporous catalysts as they will ensure greater facilitated molecular access to the active sites, resulting in a higher conversion by preventing pore blockages. All in all, a series of key findings and serendipitous discoveries have brought to surface an array of new challenges as well as paving the way for a host of exciting opportunities for future research. The ability to continuously produce high quality renewable fuel offers a fascinating prospective for various industrial associates such as Argent Energy, Olleco, Neste Oil and ConocoPhillips.

Biodiesel is rapidly growing as a fuel of interest due to the various advantages it has over conventional diesel fuel. While the pros – non-toxic, biodegradable, low green house gas emissions seem advantageous, the major issue that plagues the use of biodiesel is its cold weather operability. Biodiesel can present challenges in cold-weather operation, because certain of its constituent compounds can form precipitates in the fuel. These precipitates can cause undesired effects like plugging of fuel filters and deposits. This issue has been attributed to the presence of impurities (mostly saturated monoglycerides, di-glycerides, soap etc) in biodiesel and has been discussed in the literature. There is a move by users and standards associations to implement more stringent norms and quality control to avoid problems in the widespread use of biodiesel. This study involves ways to reduce MG’s in biodiesel by mitigating to a greater extent the possibility of side reactions (formation of soap). The effect of selective transesterification of oil as a function of alcohol, temperature and catalyst concentration was also studied. Although saturated MG’s with high melting points are a greater source of deposits, it can be hypothesized that the polymorphic nature of unsaturated Monoglycerides could also be contributing to cold flow issues. It is hence vital to make sure the biodiesel is free from all forms of monoglycerides. It was also seen that there is very little specificity of selection of fatty acid types in the transesterification reaction and that the amount and type of MGs present in the biodiesel is reflected by the relative amount of fatty acids types present in the oil. In biodiesel derived from Canola oil, a preponderance of monoolein was found for all runs. The initial runs carried out as a two stage process using the membrane followed by batch reactor gave very low MG concentrations, well below ASTM standards.

Improvement of biodiesel’s cold flow properties still remains one of the major challenges for using it as an alternative fuel in diesel engines. Therefore, the main objective of the present research was to use newly developed liquid biofuels, 3-hydroxyl fatty acid esters and ethers, as an additive for improving biodiesel cold weather properties. Test results revealed that blending with 10% 3-hydroxyl fatty acid esters (C4, C6, C8 and C12) improved biodiesel volatility, cloud point, flash point and kinematic viscosity without a significant loss in LHV. However, blending biodiesel with 3-hydroxyl fatty acid esters negatively affected the oxidation stability which was then found to improve by blending with 3-hydroxyl fatty acid ethers (1,3-DMO and 1,3-DMD). The latter novel fuel substance (1,3-DMO and 1,3-DMD) exhibited much higher evaporation rate compared to biodiesel and only slightly lower than that of decane, gasoline or ethanol. Moreover, the LHV of 1,3-DMO and 1,3-DMD was found to be almost equal to that of canola biodiesel, and higher than that of methanol and ethanol. These findings suggest that 1,3-DMO and 1,3-DMD have the potential to be used as additive to improve biodiesel cold weather combustion performance or as standalone fuels. / February 2016

Biodiesel is rapidly growing as a fuel of interest due to the various advantages it has over conventional diesel fuel. While the pros – non-toxic, biodegradable, low green house gas emissions seem advantageous, the major issue that plagues the use of biodiesel is its cold weather operability. Biodiesel can present challenges in cold-weather operation, because certain of its constituent compounds can form precipitates in the fuel. These precipitates can cause undesired effects like plugging of fuel filters and deposits. This issue has been attributed to the presence of impurities (mostly saturated monoglycerides, di-glycerides, soap etc) in biodiesel and has been discussed in the literature. There is a move by users and standards associations to implement more stringent norms and quality control to avoid problems in the widespread use of biodiesel. This study involves ways to reduce MG’s in biodiesel by mitigating to a greater extent the possibility of side reactions (formation of soap). The effect of selective transesterification of oil as a function of alcohol, temperature and catalyst concentration was also studied. Although saturated MG’s with high melting points are a greater source of deposits, it can be hypothesized that the polymorphic nature of unsaturated Monoglycerides could also be contributing to cold flow issues. It is hence vital to make sure the biodiesel is free from all forms of monoglycerides. It was also seen that there is very little specificity of selection of fatty acid types in the transesterification reaction and that the amount and type of MGs present in the biodiesel is reflected by the relative amount of fatty acids types present in the oil. In biodiesel derived from Canola oil, a preponderance of monoolein was found for all runs. The initial runs carried out as a two stage process using the membrane followed by batch reactor gave very low MG concentrations, well below ASTM standards.

A cold flow model circulating fluidized bed reactor was designed and built to determine any correlation that may exist between the percentage of fine bed material in the overall reactor inventory, and both the solids circulation rate as well as the riser axial particle distribution. It was determined that for Geldart group B particles (sand), there may be a direct relationship between an increase in the percentage of fine particles and an increase in the solids circulation rate for a given riser superficial velocity. There may also be a direct relationship between the percentage of fine particles and an increase in the overall solids concentration in the upper zones of the riser for a given riser superficial velocity. It is theorized that these effects are due to a reduction in the overall mean particle size of any particle clusters formed due to the increase of the percentage of fines.

An understanding of the mechanism for hydrate formation from water-in-oil emulsions is integral for progressing from preventing hydrate formation through expensive thermodynamic means to hydrate blockage prevention. This work presents hydrate formation and agglomeration in a stirred system studied using two complementary particle size analysis techniques, a Particle Video Microscope (PVM) and a Focused Beam Reflectance Measurement (FBRM). The PVM provides qualitative visual information through digital images in the black oil illuminated by a series of lasers. The FBRM provides a quantitative chord length distribution of the particles/droplets in the system. Three sets of experiments were performed using two different Crude oils, Conroe with a very small asphaltene content and poor emulsion stability, and Caratinga with a much higher asphaltene content and emulsion stability. The first experiments looked at ice as an analogy to hydrates, studying the morphology with both the PVM and FBRM. The second experiments looked at the effect of droplet size on hydrate formation and agglomeration, and the third set of experiments studied the dissociation process using a combination of the PVM and in situ conductivity measurements to determine the continuous phase. For hydrate formation, droplet size was found to have a major effect on whether or not agglomeration will occur. During dissociation agglomeration is extremely dramatic due to the creation of surface water on the particles. The dissociation of these agglomerates results in a significant destabilization of the suspension into a water/hydrate phase at the bottom of the cell until dissociation is complete. The dissociation conceptual picture presented illustrates an important implication when operating a flow line with hydrates present; dissociation within the pipeline should be prevented until the hydrates are out of the flow line.

Nonadhesive hydrate slurries have been shown to exhibit low viscosities in a field-scale flow loop when formed under appropriate conditions. The factors that favor formation of low-viscosity hydrate slurries include high Reynolds Number and Capillary Number, and high mass transfer and heat transfer rates. High liquid loading and high superficial fluid velocities are found to be conducive to the formation of low viscosity hydrate slurries. Dispersed bubble flow has been observed to facilitate flowable hydrate slurry production. Alternatively, the formation of nonadhesive hydrates at moderate superficial velocity is possible when a static mixer is used upstream of the hydrate formation location. For certain fields, low-viscosity hydrate slurry technology could eliminate the need for insulation and hydrate inhibitor chemicals (revised version of ICGH 2008 paper 5818) .

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第20478号 / エネ博第347号 / 新制||エネ||69(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー社会・環境科学専攻 / (主査)教授 坂 志朗, 教授 塩路 昌宏, 准教授 河本 晴雄 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DGAM