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A membrane-covered polarographic sensor is commonly used to measure dissolved oxygen activities in test fluids. However, it is incapable of determining the oxygen concentration or solubility in fluids directly. To convert the activity to its corresponding concentration, the oxygen solubility data are needed. For complex samples such as refinery hydrocarbon streams, a complementary technique for oxygen solubility measurement is often employed to aid the polarographic determination of the dissolved oxygen concentration. In this work, an indirect polarographic method has been developed to determine the oxygen solubility in a refinery hydrocarbon, thus eliminating the need of any complementary techniques. The method involves mixing an air-saturated hydrocarbon sample with an oxygen-free reference solvent such as toluene at various blending ratios. The oxygen solubility in the sample can be obtained by regression of the measured activities versus the volume fractions of the sample. The determined oxygen solubi...

Carbothermal reduction is a reducing reaction involving carbonaceous materials at high temperatures. Oil sand fluid coke is a high-carbon byproduct of the thermal cracking of oil sand bitumen via a process called fluid coking. To lay a foundation for the development of a process that removes and converts sulfur dioxide into elemental sulfur, the kinetics of the carbothermal reduction of SO2 by coke at 700−950 °C was investigated using a packed-bed reactor. Analysis using the shrinking core model revealed that the overall process is controlled jointly by surface chemical reaction and diffusion in a product ash layer. The existence of the layer was confirmed by SEM examination of a cross section of spent coke particles. The activation energy of the overall reaction was found to be 154 kJ/mol, which is in a good agreement with literature values. The sulfur balance was analyzed with data obtained using a total sulfur analyzer and a gas chromatograph. SEM-EDS analysis indicated that the ash layer was low in su...

Accumulation of fine particles by packed-bed catalytic reactors causes increased pressure drop, sometimes causing premature shut down. Deposition in a reactor, i.e., filtration, is enhanced when the particle suspension is unstable. A model system of 0.68 μm of kaolin in light gas oil was selected to study deposition at hydrotreating conditions. The surface of the kaolin was modified by adsorbing polymeric asphaltene molecules. Particle suspensions were circulated through a packed bed of either glass beads or catalyst in a batch reactor at 375 °C. The filtration mechanism switched from cake filtration to deep-bed filtration when kaolin was pretreated with asphaltene. Deposition of kaolin particles in the bed decreased with increasing asphaltene concentration. These results are consistent with steric stabilization of colloids by adsorbed polymers. Hydrotreating of the liquid phase enhanced desorption of the asphaltene polymer from particle surfaces and increased particle flocculation and deposition along th...