Catalytic naphthalene hydrogenation to tetralin in water/hydrocarbon emulsions with simultaneous water gas shift as the hydrogen source was performed in a 300 ml batch autoclave as a model for aromatic hydrogenation in water/bitumen emulsions. The catalyst utilized was an unsupported and dispersed type based on molybdenum sulfide (MoS2). Distinguishing the fate of hydrogen from water as opposed to molecular hydrogen in hydrogenation and water gas shift was accomplished by utilizing deuterium oxide (D2O) with NMR spectroscopy. The use of D2O allowed determination of isotope effects when compared with H2O. Diffuse Reflectance Infrared Fourier Transform Spectroscopy was performed to observe CO adsorption on the MoS2 sulfide surface. Ruthenium was tested as a potential candidate to enhance the activity of the Mo catalyst. Iron, nickel and vanadium were utilized in combination with molybdenum to test promotional/inhibitive activity during naphthalene hydrogenation and water gas shift since Ni and V are found in significant quantities in real bitumen feed. Finally, a multifactorial experiment was performed to test the hydrogenation and water gas shift activity of a binary VNiMo-sulfide catalyst towards H2S partial pressure, temperature and H2 versus CO atmospheres. Deuterium from D2O was incorporated into both saturated and aromatic hydrogen positions in tetralin products. Calculation of a Hydrogenation Index and Exchange Index indicated the extent of H-exchange is greater than hydrogenation. Exchange between D2O and organic products was enhanced with the MoS2 catalyst under H2 or CO compared to N2. A kinetically measured isotope effect of 1.58 was in agreement with a quasi-equilibrium thermodynamic isotope effect for O-H dissociations measured in the literature. A true kinetic isotope effect may be masked by transient surface concentrations occurring under batch conditions. Two strong vibrational bands associated with adsorbed CO were observed over MoS2 above 160 °C. Activation of the MoS2 surface with CO produces COS, suggesting an analgous mechanism to the production of H2S during reduction in H2. In the presence of H2S, Ru displayed low catalytic activity for both water gas shift and naphthalene hydrogenation, attributed to incomplete sulfidation to active RuS2. FeMo and VMo exhibited lower hydrogenation activity than Mo, but the water gas shift activity of VMo was high. A ternary VNiMo displayed lower hydrogenation activity than NiMo and Mo but was higher than VMo, implying Ni could offset the inhibition caused by V. Recycle of V and Ni rich asphaltene residues in catalytic slurry upgrading may therefore be feasible. An analysis of the effect of H2S pressure, temperature and type of reduction gas (CO vs. H¬2) concluded that temperature had the greatest positive effect on rate, followed by a small interaction effect of temperature/gas type and PH2S/gas type. The proximity to equilibrium conversions in WGS limited the analysis, while equilibrium limited the conversion of naphthalene at 380 °C in the batch reactor.

Catalytic naphthalene hydrogenation to tetralin in water/hydrocarbon emulsions with simultaneous water gas shift as the hydrogen source was performed in a 300 ml batch autoclave as a model for aromatic hydrogenation in water/bitumen emulsions. The catalyst utilized was an unsupported and dispersed type based on molybdenum sulfide (MoS2). Distinguishing the fate of hydrogen from water as opposed to molecular hydrogen in hydrogenation and water gas shift was accomplished by utilizing deuterium oxide (D2O) with NMR spectroscopy. The use of D2O allowed determination of isotope effects when compared with H2O. Diffuse Reflectance Infrared Fourier Transform Spectroscopy was performed to observe CO adsorption on the MoS2 sulfide surface. Ruthenium was tested as a potential candidate to enhance the activity of the Mo catalyst. Iron, nickel and vanadium were utilized in combination with molybdenum to test promotional/inhibitive activity during naphthalene hydrogenation and water gas shift since Ni and V are found in significant quantities in real bitumen feed. Finally, a multifactorial experiment was performed to test the hydrogenation and water gas shift activity of a binary VNiMo-sulfide catalyst towards H2S partial pressure, temperature and H2 versus CO atmospheres. Deuterium from D2O was incorporated into both saturated and aromatic hydrogen positions in tetralin products. Calculation of a Hydrogenation Index and Exchange Index indicated the extent of H-exchange is greater than hydrogenation. Exchange between D2O and organic products was enhanced with the MoS2 catalyst under H2 or CO compared to N2. A kinetically measured isotope effect of 1.58 was in agreement with a quasi-equilibrium thermodynamic isotope effect for O-H dissociations measured in the literature. A true kinetic isotope effect may be masked by transient surface concentrations occurring under batch conditions. Two strong vibrational bands associated with adsorbed CO were observed over MoS2 above 160 °C. Activation of the MoS2 surface with CO produces COS, suggesting an analgous mechanism to the production of H2S during reduction in H2. In the presence of H2S, Ru displayed low catalytic activity for both water gas shift and naphthalene hydrogenation, attributed to incomplete sulfidation to active RuS2. FeMo and VMo exhibited lower hydrogenation activity than Mo, but the water gas shift activity of VMo was high. A ternary VNiMo displayed lower hydrogenation activity than NiMo and Mo but was higher than VMo, implying Ni could offset the inhibition caused by V. Recycle of V and Ni rich asphaltene residues in catalytic slurry upgrading may therefore be feasible. An analysis of the effect of H2S pressure, temperature and type of reduction gas (CO vs. H¬2) concluded that temperature had the greatest positive effect on rate, followed by a small interaction effect of temperature/gas type and PH2S/gas type. The proximity to equilibrium conversions in WGS limited the analysis, while equilibrium limited the conversion of naphthalene at 380 °C in the batch reactor.

Dans un contexte politique où les enjeux énergétiques et environnementaux sont de plus en plus importants, il faut favoriser les techniques économes en énergie et plus respectueuse de l'environnement. Parmi ces pratiques, l'utilisation d’enrobés à l’émulsion de bitume s'est révélée être prometteuse. La fabrication et la conception d’une chaussée comprenant une couche d’enrobé à l’émulsion sont très empiriques et reposent sur des compétences locales qui tendent à en limiter le développement. La première étape pour concevoir une chaussée consiste à connaître le comportement mécanique réversible engendrées par de lourd trafic de chaque matériau qui la compose. Lors d'une deuxième étape, ces valeurs doivent être comparées aux critères de durabilité mécanique des matériaux. Dans le cas de l'enrobé à l’émulsion, aucune loi de comportement mécanique n'a été établie pour tenir compte à la fois de son états frais et durcis. Ce travail de thèse vise donc à pallier à ce manque et à améliorer les connaissances acquises sur ce matériau. Pour cela, un modèle évolutif pour l’enrobé à l’émulsion intégrant l'évolution du matériau de son état frais à l'état durci a été développé. De plus, un nouvel essai de caractérisation a été développé et mis en place pour permettre de suivre l’évolution des performances mécaniques réversibles du matériau. Les résultats obtenus à partir des différentes campagnes d’essais ont permis de caler le modèle et de montrer la pertinence du modèle. / Given a political context in which energy and environmental stakes have become increasingly dominant, road engineering practices have favoured saving energy and protecting the environment. Among these practices, the use of cold mixes treated with bitumen emulsion has proven to be a suitable technique. Cold mix design however, as well as the design of pavements including cold mix asphalt layers, is highly empirical and based on local skills. From prior experience, the transposition of established local rules from one site to another and their application to medium or heavy traffic pavements are not simple steps and tend to limit the development of this environmentally-friendly pavement technique. The first step in designing a pavement consists of knowing the stress-strain relationship of its constitutive materials in order to determine the stresses and strains generated by heavy lorry traffic. During a second step, these values must be compared with the mechanical durability of materials by reliance on damage tests comprising large numbers of load cycles. In the case of CMA, no mechanical behaviour law has been established to take into account both the fresh and cured states. This work aims to improve the knowledge acquired on this material. For this, an evolutiv model for the cold mix asphalt with bitumen emulsion incorporating the evolution of the material from its fresh state to its cured state has been developed. In addition, a new characterization test was developed and put in place to monitor the evolution of the reversible mechanical performance of the material. The results obtained from the test campaigns helped to calibrate the model and show the relevance of the model.

Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Surface seals are widely used in South Africa. There are a number of reasons which include affordability, versatility and durability. There are, however, in some cases problems with stone loss that can lead to a shortened lifespan of the pavement. The loss of aggregate chippings in surface seals poses a major problem in the seal pavement industry. This study aims to identify the influencing factors that lead to these adhesive failures as well as to find optimum combinations of binders and aggregates at various conditions. Various binders commonly used in South African surface seal construction will be tested using the Bitumen Bond Strength (BBS) test method. The binders used in the study include 80/100 penetration grade bitumen, elastomer modified bitumen, bitumen rubber, elastomer modified emulsion and cationic rapid setting emulsion. Aggregates used in the study include dolerite, granite and quartzite. The test samples were cured and tested at two temperatures, 15 °C and 35 °C. The samples were also cured for 2, 6 and 24 hours respectively. The study tackles a wide range of variables in order to obtain a good understanding of adhesion properties of surface seals used in South Africa. Tests were repeated at least once to ensure repeatability and in some cases up to four repeats were performed. The loading rate at which the tests were performed had a significant influence on the BBS results. This rate varied which complicated the process of comparing the results. It was therefore decided to unify the loading rates. The BBS results exposed the difference between hot applied binders and emulsions. The former having significant stronger adhesion properties. It was also confirmed by the results that temperature plays a key role in the BBS results due to the visco-elastic properties of bitumen. These influences will be discussed along with others such as aggregate types and curing times. The type of failure is also discussed. Failure can either be adhesive or cohesive, the former being a failure between the aggregate and the binder while the later refers to a failure in the binder itself. The results of other students will also be discussed and compared to the results of this study. These include results of predecessors that tested emulsions as well as results from tests done on fractured aggregate surfaces and precoated aggregates. This study showed very similar results as these from other students, except for tests done with emulsions. It was discovered that the method of curing of the emulsions must be adapted to ensure proper curing of the emulsions. It was found that aggregates did not influence the BBS properties to the same extent as temperature and binder application type. The BBS results of hot applied binders also did not significantly increase as the curing time increased, but the results of emulsions showed some increase. However, the emulsions needed more time to cure properly. / AFRIKAANSE OPSOMMING: Oppervlak seëls word algemeen gebruik in Suid-Afrika. Daar is verskeie redes hiervoor waaronder bekostigbaarheid,veelsydigheid en duursaamheid. Daar is egter in sommige gevalle probleme met klipverlies wat kan lei tot n verkorte leeftyd. Hierdie klipverlies ontstaan as gevolg van verskeie redes of kombinasies daarvan. Die studie beoog om hierdie faktore wat die adhesie eienskappe beïnvloed te identifiseer sowel as om optimum kobinasies van bindmiddels en klipsoorte te bewerkstellig by verkeie kondisies. ‘n Verskeidenheid van bindmiddels wat algemeen in Suid-Afrika gebruik word, word in die studie getoets met die Bitumen Bond Sterkte (BBS) toets metode. Die bindmiddels wat in die studie gebruik word sluit 80/100 penetrasie graad bitumen, elastomeer gemodifiseerde bitumen, bitumen rubber, elastomeer gemodifiseerde emulsie en kationiese snel settende emulsie. Die klipsoorte wat vir die studie gebruikword is doleriet, graniet en kwartsiet. Hierdie gesteentes word algemeen in die praktyk gebruik. Die toets monsters word ook by twee temperature gekuur en getoets. Hierdie temperature is 15 °C en 35 °C. Die toets monsters word ook onderskeidelik vir 2, 6 en 24 uur gekuur. Die studie ondersoek 'n wye verskeidenheid van veranderlikes om sodoende 'n goeie begrip van adhesie eienskappe van die oppervlak seëls wat in Suid-Afrika gebruik word te verkry. Elke toets was ten minste een maal herhaal om herhaalbaarheid te verseker. Sommige toetse was tot 4 keer herhaal. Die belasting tempo van die toetse het ‘n beduidende uitwerking op die BBS resultate as gevolg van die visko-elastiese eienskappe van bitumen. Hierdie tempo het gewissel en dit moeilik gemaak om die resultate te vergelyk. Daarom was daar besluit om die tempo van die toetse te verander na ‘n gelykvormige tempo. Daar was ‘n duidelike verskil in BBS resultate van die warm toegepaste bindmiddels en die emulsies. Die warm bindmiddels het baie hoër BBS resultate gelwer. Dit was ook bevestig in die resultate dat temperatuur ‘n beduidende rol speel in die BBS. Hierdie invloede sal bespreek word tesame met ander, soos klipsoorte en kuring tye. Die tipe versaking word ook bespreek. Versaking kan plaasvind as gevolg van adhesie of cohesie, waar adhesie versaking 'n versaking is tussen die klip en die bindmiddel terwyl cohesie versaking verwys na 'n versaking in die bindmiddel self. Die uitslae van die ander studente sal ook bespreek word en vergelyking word met die resultate van hierdie studie. Dit sluit die resultate van voorgangers in wat emulsies getoets het sowel as die resultate van toetse wat gedoen is op gebreekte klipoppervlaktes en bitumen behandelde klippe. Hierdie studie het baie soortgelyke resultate getoon as dié van ander studente, behalwe vir die toetse wat gedoen was met emulsies. Daar is vasgestel dat die metode van kuring van die emulsies moet aangepas word om behoorlike kuring van die emulsies te verseker. Daar is ook gevind dat klipsoorte nie die BBS eienskappe in dieselfde mate as temperatuur en bindmiddel toepassingstipe beïnvloed het nie. Die BBS resultate van warm aangewende bindmiddels het ook nie aansienlik verhoog soos die kuringstyd toegeneem het nie, maar die resultate van emulsies het wel 'n toename getoon. Die emulsies het wel meer tyd nodig gehad om behoorlik te kuur.

Approximately 75 percent (300 000 km) of the total Swedish road network and 20 percent(20 000 km) of the national road network consists of gravel roads. One of the most significantproblems associated with gravel roads is traffic-generated dust emission, which contributes tothe deterioration of the road surface and acts as a major source of particulate matter releasedinto the atmosphere, thereby involving public economics, road safety, human health, andenvironmental quality. In order to bind the fine granular material, which is prone to rise into theair, dust suppressants are applied on roads on a yearly basis. Methods for evaluating the efficiency of dust suppressants will facilitate in the selection of themost appropriate product and its optimal application rate. For example, methods forsupervision of residual dust suppressant concentration are valuable tools for estimatinglongevity and optimal application rates, and, consequently, effectiveness of different products. Application of the proper dust suppressant to a gravel road ensures road safety and ridingcomfort as well as creating a cleaner and healthier environment for residents in buildingsadjacent to the road. It also reduces the need and cost for vehicle repair, road maintenanceactivities, and aggregate supplementation. Both field-based and laboratory research were performed to evaluate the efficiency of varioussuppressants and the influence such factors as product concentration, leaching, and fine materialcontent have on the efficiency of different products. Within the field-based research, a newlydeveloped mobile methodology was used to measure dust emission on numerous test sectionstreated with various dust suppressants. In general, all dust suppressants tested, except apolysaccharide (sugar) and products, which form a brittle surface crust, i.e. lignosulphonate andbitumen emulsion, showed acceptable dust reduction. Test sections treated with a magnesium- or calcium chloride solution were the most effectivelydust suppressed. The application of solutions instead of a solid salts achieves a more uniformproduct distribution and, therefore, probably a more efficient performance. By applying acalcium- or magnesium chloride solution instead of traditionally used solids, the cost for annualdust control, as well as the environmental impact from the release of these chemicals in theenvironment, can be reduced by 50 percent. A significant problem when using dust suppressants is their tendency to leach during rainfalldue to their soluble properties. Residual chloride could be detected in the gravel wearing courseover a longer period of time than lignosulphonate and, therefore, showed more effective longtermperformance. Optimal percentages of fine material for minimal lignosulphonate andchloride leaching were found to be 15 percent by weight and 10-16 percent by weight,respectively. Ions of calcium chloride seemed to initiate flocculation of clay particles, therebypreventing them from leaching. Still, the fine material in gravel wearing courses has to be replenished regularly as indicated by studies of the longevity of fine material. Loss up to80 percent was found after two years. Toxicity tests show that dust suppressant application for dust control purposes, at traditionallyused application rates, does not constitute a threat to sensitive aquatic life. Tests on subsoilwater samples indicated elevated chloride levels, which possibly could cause corrosion to pipes,but not high enough to flavour drinking water. / QC20100616