Several heterogeneous catalysts were prepared starting from Mg-Al and Zn-Al hydrotalcites (HTs) and evaluated for oxidation, ozonation, dehydrogenation and reforming of hydrocarbons, and the CO shift reaction. All catalysts exhibited unique and excellent activities in these reactions. Fe/Mg/Al oxide catalysts prepared from Mg-Al(Fe) HT exhibited high activity for Baeyer-Villiger oxidation of various ketones and dehydrogenation of ethylbenzene. Ozonation activity of Cu/Mg/Al oxide catalysts similarly prepared from Mg(Cu)-Al HT was enhanced by the 'memory effect,' as reconstituted HT on the catalyst surface adsorbed oxalic acid and assisted in complete oxidation. Ni/Mg(Al)O catalysts prepared from Mg(Ni)-Al HT exhibited high and stable activity in steam reforming and oxidative reforming of methane and propane. Moreover, the activity of the Ni catalysts was improved by doping a trace amounts of noble metals by adopting the 'memory effect.' Use of these catalysts in the production of hydrogen for the PEFCs under daily start-up and shut-down operation showed that the catalysts were self-activated and the active Ni metal particles were self-regenerated during the reaction, resulting in high and sustainable activity. CO shift activity of Cu/Zn(Al)O catalysts was also improved by doping a trace Pt or Mg by adopting the memory effect of Zn(Cu)-Al HT in the precursor, resulting in the high sustainability.
Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has high resolution, so provides a viable method to characterize extremely complex mixtures. The molecular formulas of individual components are determined simply by accurate mass measurement. Here, recent advances in FT-ICR MS application to petroleum derived heavy materials are reviewed after a brief introduction of the features and history of FT-ICR MS. Advantages and limitations of ionization techniques, such as electron ionization (EI), electrospray ionization (ESI), field desorption (FD), and liquid secondary ionization (LSI), connected to FT-ICR MS are evaluated by application to petroleum derived materials. Our improved ionization techniques are also explained to adapt very complex petroleum derived samples, ex., to suppress fragmentation and to accelerate vaporization in EI, and to detect specific compounds selectively in ESI. Characterization procedures to estimate the structural features of components can be based on heteroatom composition, carbon number and Z-value (hydrogen deficiency index, as a measure of degree of aromatic ring condensation), through spectral analysis using the Kendrick mass. Such characterization can be applied to estimate structural changes of components during hydroprocessing.
Our recently developed potential characterization method for studying the zeolite acidity is reviewed. In this method, ammonia TPD is a principle technique and first the principle of the method was explained. In order to overcome the drawback existed in the usual TPD, IRMS-TPD method was developed, in which IR and MS were measured simultaneously to monitor the thermal behavior of ammonia molecules on the surface and in the gas phase. The developed method made it possible not only to measure the Brønsted and Lewis acid sites individually but also to clarify the distribution of Brønsted acid sites. In addition, DFT calculations were carried out to confirm the obtained information of the Brønsted acidity. Based on these studies, a new technique was developed by combining the IRMS-TPD experiment and DFT calculation to precisely characterize the zeolite acidity. Using the developed method, the modified Y zeolites active for the cracking of hydrocarbons were studied.
Aromatics extraction was investigated using aqueous solution of sulfolane as the solvent phase and model gasoline, consisting of a benzene, toluene, xylene and hexane mixture, and reformate gasoline as the feed phase. Firstly, the liquid-liquid equilibrium was measured to examine the distribution coefficient and the separation selectivity of aromatics relative to hexane. The distribution coefficients and selectivities of benzene were the highest, followed by those of toluene and xylene. Increased water content of the solvent phase reduced the distribution coefficients and increased the selectivities. The measured equilibria were compared with the results estimated by the UNIFAC method. Countercurrent extraction was conducted, using a packed column with glass Rashig rings as the contactor. The solvent and feed phases were contacted as the continuous and dispersed phases, respectively, and the flow rates of both phases and the water content in the solvent phase were selected as experimental parameters to examine the yield, separation selectivity and volumetric overall mass transfer coefficient. The selectivities for benzene were the highest, followed by toluene and xylene. In the case of extraction from the reformate gasoline with 9 wt% water content in the solvent phase, the selectivity for benzene was approximately equal to 20, showing higher selectivities for aromatic components. The volumetric overall mass transfer coefficients were mainly affected by the flow rate of the continuous phase and the mass transfer resistance in the continuous phase was the controlling factor in the overall mass transfer resistance.
Injection of polymer solutions has been recognized as an effective means to improve oil recovery. To provide a comparative evaluation of the influence of water-soluble polymer on the flow behavior and oil recovery, numerical simulations were performed on layered reservoirs with adsorption and crossflow. A three-dimensional numerical model for fluid flow and mass transport is used to analyze the performance of the reservoir in a five-spot pattern operating under polymer flood followed by waterflood. Results are examined for different scenarios in the degree of crossflow, reservoir adsorption parameters, and permeability reduction. For different parameters of the system, the performances of polymer flooding were compared in terms of cumulative recovery and water-oil ratio (WOR) at the production well and pressure drop at the injection well. Properties of polymer and reservoir rock such as adsorption parameter, vertical permeability heterogeneity, and permeability reduction are shown to impact the predicted recovery. With increase of polymer loss due to large value of adsorption parameter, decrease in oil recovery and increase in water-oil ratio are obtained by unfavorable mobility ratio and low the sweep efficiency. Polymer flood in reservoirs with a severe permeability contrast between horizontal strata leads to lower volumetric sweep efficiency and displacement efficiency. An increase in the degree of crossflow induced by sufficient vertical permeability is responsible for the enhanced sweep of the low permeability layers, which results in increased oil recovery and decreased WOR. The permeability reduction by polymer has a limited effect on oil recovery and WOR, particularly in reservoirs with high crossflow, but considerably on injectivity impairment. In considering the application of polymer floods, a through understanding of permeability heterogeneity of layered reservoirs, retention properties of polymer solution, and accompanying changes in reservoir properties is crucial.
Petroleum pollution is a major and global disaster. Phytoremediation of petroleum polluted soils was based on degradation of oil using plants and its dependent fungi. A field study was conducted in a petroleum contaminated site at Arak refinery (Iran) to find the petroleum-resistant plant species and the rhizospheral fungi for being used in phytoremediation. Results showed that eight plant species were growing on the contaminated sites: Polygonum aviculare, Centureae virgata, Carthamus onyacantha, Alhaji cameleron, Glycyrrhiza glabra, Poa sp., Lactuca serula and Hordeum bulbosum. The germination assay showed that all studied plants are capable to survive in oil contaminated soils but they have different germination ability under petroleum pollution. 22 fungal species were found in the rhizosphere of the plants growing in the polluted areas; four of these species were common in all the plants and the others have species-specific distribution within the plants. The variation of fungi in petroleum-polluted areas was more than non-polluted zones. Culture of fungi in oil-contaminated media showed that although all the studied fungi were resistant to low petroleum pollution (1%) but a few species, especially Fusarium species, are resistant to higher petroleum pollution (10%).
For the purpose of heightening hydrocarbon desorption temperature for hydrocarbon adsorption-combustion catalyst, we researched about some kinds of zeolites and of hydrocarbon adsorption elements. The hydrocarbon desorption temperature for 5 type of zeolites were measured by temperature programmed desorption (TPD) with model gas which simulated engine start exhaust one. The TPD measurement showed that the beta zeolite had that the highest hydrocarbon desorption temperature and its amounts was largest among all zeolites evaluated in this study. Ag, Mg, Ni, Co, Cu, Ce and Sr addition to beta zeolite increased the toluene desorption temperature as much as 170-320°C. On the other hand, among these added elements, only Ag increased the pentane desorption temperature by 90°C. The chemical states of Ag was measured with an ultra violet visible spectrophotometer (UV-vis). UV-vis suggested that Ag+ and Ag0 (metal) increased the desorption temperature of paraffin and aromatics, respectively. After the endurance test by being exposed to an air excessive gas and a fuel excessive gas alternately at 800°C or 850°C for the catalysts, the desorption temperature of the hydrocarbon, especially of paraffin lowered. These phenomena were thought to be caused by the change of chemical state for Ag+ which existed besides the ion exchange site to Agxn+ (cluster) or Ag0 and by the sintering of Ag. The hydrocarbon desorption temperature obtained in the vehicle test was the same as the temperature predicted from the chemical state of Ag and the composition of the exhaust gas.
Aggregation of the active metal components as NiMoO4 during oxidative regeneration of residue hydrodesulfurization catalyst was studied by conventional and micro X-ray diffraction (XRD). The formation of NiMoO4 was observed only on catalyst regenerated above 723 K by conventional XRD. Distribution of NiMoO4 formation through the section of a catalyst particle was investigated by micro-XRD. The center of the catalyst particle showed higher aggregation of NiMoO4 compared to the outside of the catalyst. These results indicate that NiMoO4 formation is mainly caused by temperature increase inside the catalyst due to the heat accumulation from coke burning. Since the distribution of NiMoO4 was not associated with that of vanadium, which was mainly present on the outside of the catalyst particle, vanadium did not chemically affect the active metal states.
One zeolite capsule catalyst with core(Co/Al2O3)/shell(H-beta membrane) structure was prepared and used for isoparaffin direct synthesis via FTS reaction. Based on this core/shell zeolite capsule catalyst, a novel palladium painted zeolite capsule catalyst with three-component core (Co/Al2O3)/shell (H-beta membrane)/paint (Pd) structure was designed. In the isoparaffin synthesis on this three-component zeolite capsule catalyst, the olefins effused from the zeolite capsule catalyst were in-situ hydrogenated effectively, mostly converted to isoparaffin.