Hindered amine light stabilizers (HALS) possess many functions unlike other additives and are frequently used to extend the service life of polymeric materials, but show particular compatibility with certain other additives. However, combination does not always show synergistic actions, but sometimes has antagonistic effects. Most previous research into the interaction of HALS with other additives has focused on qualitative high synergism to high antagonism, and no common understanding has been reached. HALS and homologs have many derivatives which are classified here as "good" HALS and "bad" HALS, including a new HALS derivative, HALS nitrosonium. The investigation of the antagonism of HALS with other additives has been based on only "good" HALS. The present study discusses the chaotic interactions of HALS with other additives kinetically and thermodynamically by separately considering the synergism of "good" HALS and the antagonism of "bad" HALS. This approach has lead to a new technique for unified evaluation of the interaction semi-quantitatively. The results summarized here clarify the complex and diverse characteristics of HALS and present the possibility that the action mechanism of HALS alone and together with other additives can be discussed based on a unified mechanism. Such united ideas can determine additive formulation much more easily and facilitate the development of new additives, resulting in more stable and functional polymeric materials.
Two new methods for the catalytic synthesis of propene using solid acid catalysts are presented. The first approach is a new method for the activation of methane, involving conversion of methane to propene over silver-exchanged zeolite in the presence of ethene. In the second method, ethene conversion proceeds directly and selectively over proton-exchanged zeolite under the control of a molecular sieving effect. The heterolytic dissociation of methane over silver cationic clusters (Agn+) in Ag+-exchanged zeolites, leading to the formation of silver hydride (Agn-H) and CH3δ+ species, which reacts with ethene to form propene around 673 K. Using 13C-labeled methane as a reactant, propene is shown to be a primary product from methane and ethene. Thus, a significant proportion of propene was singly 13C-labeled (13CC2H6). Under these reaction conditions, H+-exchanged zeolites, such as H-ZSM-5 do not catalyze the methane conversion, only ethene being converted into higher hydrocarbons, such as propene. Ethene is selectively converted to propene over SAPO-34 at 723 K with a yield of 52.2% and selectivity of 73.3% at ethene conversion of 71.2%. The high and selective propene yields achieved over SAPO-34 can be attributed to a shape selectivity effect of the small-pore SAPO-34.
Asphaltene precipitation is frequently the cause of increased cost of oil production in the petroleum industry. To avoid or minimize problems due to asphaltene precipitation, a model to predict the amount of asphaltene precipitation under the petroleum reservoir conditions is required. In this study, the Flory-Huggins solution theory with a correctly tuned equation of state for calculation of the solubility parameter of liquid oil and a second order polynomial equation for variations of asphaltene solubility with pressure were applied to model asphaltene precipitation. The advantage of this model is that expensive and time consuming experiments are not required to obtain the asphaltene and liquid oil solubility parameters. Routine pressure/volume/temperature (PVT) tests and the amount of asphaltene precipitated at the bubble point pressure are sufficient. Data generated by the model were compared to the experimental asphaltene precipitation data on two live oils under reservoir conditions, showing that the model could accurately represent the behavior of asphaltene precipitation in the reservoir.
Sulfur-containing compounds in straight-run naphtha and catalytic-cracked gasoline were analyzed quantitatively using gas chromatography with a sulfur chemiluminescence detector. Pretreatment of the samples by open column chromatography and silver nitrate treatment were introduced to assign sulfur species. Commercial reagents, prepared standard samples and a commercial mass spectrum library were also utilized to assign the sulfur species. The sulfur content of naphtha was 242 ppm and 83 compounds were identified. Sulfur species consisted of 34 wt% of thiacycloalkanes, 38 wt% of thiols and sulfides, 12 wt% of thiophenes, 11 wt% of disulfides, and 5 wt% of unknown compounds. The sulfur content of gasoline was 154 ppm and 41 compounds were assigned. Sulfur species consisted of 46 wt% of thiophenes, 32 wt% of benzothiophenes, 14 wt% of thiols and sulfides, 4 wt% of thiacycloalkanes, 0.6 wt% of disulfides, 0.3 wt% of hydrogen sulfide and 3 wt% of unknown compounds. The combination of two types of pretreatment methods was effective for quantitative analysis of sulfur compounds contained in the distillate. The results of hydrodesulfurization of light distillate suggested that difficulty of hydrodesulfurization could be predicted from the composition of sulfur compounds in the distillates.
Various H-ZSM-5 catalysts were assessed for ethanol conversion into lower olefins. Ethanol was converted to lower olefins over H-ZSM-5 catalyst without modification. The selectivities for ethylene and propylene were much lower than those for aromatics such as benzene, toluene, and xylene (BTX), and C1-C4 saturated hydrocarbons. Addition of W and La was found to reduce aromatization and olefin hydrogenation, and, under ethanol conversion of almost 100%, the selectivity for propylene and ethylene was improved, whereas the selectivity for BTX was decreased. The amount of carbon deposit was almost the same as that without modification. The selectivity for propylene formation may be associated with the percentage of Brønsted acid sites on the catalyst surface.
Inspection for flaws is very important in offshore oil pipelines for avoiding disasters. An ultrasonic inspection device for offshore oil pipelines was developed. High speed data acquisition and storage systems were developed to process the high frequency ultrasonic signals. The main function of the inspection system is ultrasonic signal pre-processing, data acquisition, de-noising and data compression in real time. The system includes a micro-computer, transducers, pre-processing circuit, digital signal processor (DSP), Field Programmable Gate Array (FPGA), storage device, USB interface and other components. Experimental testing demonstrated the usefulness and effectiveness of the present data acquisition and storage system for ultrasonic pipeline inspection.
A practical solubilization plant (3 m3) for activated sludge was constructed beside the wastewater treatment plant (600 m3 activated sludge vessel) of a petroleum refinery to solubilize activated sludge with a combination of alkaline treatment and high speed mixer. In the preliminary experiments, optimum alkaline concentration and rotation speed were determined as 0.025 mol/l and 2500 rpm, which gave 40-50% solubilization. Extended operation under these optimum conditions achieved continuous solubilization and return of alkaline solubilized broth into the activated sludge vessel for 64 days. Excess sludge of 144 kg-dry weight/day produced normally in this wastewater plant without solubilization was solubilized and returned by this new plant. The COD of treatment water was 12-27 mg/l and COD removal was 87%. Final average reduction of excess sludge was up to 47% during the 64 days. This new solubilization and sludge reduction plant is stable during extended operation for the reduction of activated sludge without damage to activated sludge.
Ru/Al2O3 catalyst was investigated by using Mn addition for Fischer-Tropsch synthesis under pressurized conditions. On the basis of catalyst activity, selectivity and deactivation, small amount of Mn addition such as Mn/Al=1/19 molar ratio on Ru/Mn/Al2O3 was effective for improving the catalytic performance, where Ru/Al2O3 was deactivated in the slurry phase reaction. Under high pressure of 6 MPa, equilibrium CO conversion was estimated to be about 96%.