Partial oxidation of hydrocarbons including heavy oil in supercritical water forms CO and CO2, which undergoes the water-gas shift reaction to form active hydrogen and then hydrogenation of heavy oil proceeds. In the case of partial oxidation of hydrocarbons and bitumen in supercritical water, the selectivity for partial oxidative products such as CO increased with increasing water density. In the case of hydrogenation of heavy oil in supercritical water through the water-gas shift reaction, reverse water-gas shift reaction and decomposition of formic acid that is a reaction intermediate of the water-gas shift reaction, coke formation was suppressed compared to that in only supercritical water. The main factors for suppressing coke formation were as follows: high water density improving the reactivity of hydrogen source in the oil-rich phase that enhanced hydrogenation of asphaltene core, direct injection of hydrogen source into the oil-rich phase increasing the concentration of active hydrogen in that phase, and coexisting gases with supercritical water facilitating the extraction of coke precursor from the oil-rich phase. The upgrading of heavy oil through a series of partial oxidation and hydrogenation reactions in supercritical water proceeded in the presence of catalyst and possible optimum conditions were proposed.
The advantage of using supercritical water (SCW) as a reaction medium for bitumen upgrading was investigated through comprehensive analyses and comparisons of the products obtained using SCW or high-pressure nitrogen. SCW showed almost no chemical effect, but it showed a dispersion effect that led to intramolecular dehydrogenation of the heavier component and prevented recombination reactions. The optimal condition for maximizing this dispersion effect was estimated using the dielectric constant and Hansen solubility parameter (HSP). The necessary condition of SCW to show good miscibility with heavy oil was when the dielectric constant was >2.2 and the HSP hydrogen bonding component was <10 MPa0.5. The optimal conditions were confirmed by the highest extraction yield of asphaltene and the greatest yield of upgraded oil.
Heavy oils require substantial cracking in order to be economically refined to produce usable products. One major problem affecting the economics of refining heavy oils is the metal compounds contained in many of these oils which poison the catalyst used to crack the oil. Demetallization methods include physical, chemical, electrochemical, catalytic and supercritical water (SCW) techniques. Few of these methods are viable and/or efficient for the demetallization of heavy oil. This paper discusses the SCW based demetallization process by reviewing the open literature. The potential benefits of SCW based demetallization of heavy oils are also explored. Water partial pressure (WPP) has a moderate effect on the reaction of metalloporphyrins (MPs) in SCW; but temperature has a remarkably high effect. Metal removal is sensitive to the conversion of MP and increases exponentially with higher conversion. The kinetics are consistent with first-order dependency on MP disappearance. The reaction mechanism can be explained in terms of the free radical mechanism, but additional experiments and analysis are required to understand the fate of the metal after reaction. This non-catalytic SCW based upgrading process has the potential to allow production of refined fuel from heavy oils.
Various types of zeolites were evaluated for the adsorptive separation of ethanol and gasoline in ethanol blended gasoline. Mixed solution of ethanol and n-heptane was used as a model fuel. Adsorption selectivities of zeolites for ethanol and n-heptane were measured by a pulse testing method at 80 °C. These properties were dependent on the framework structures, exchangeable cations and Si/Al atomic ratios of zeolites. The adsorption capacities of zeolites for ethanol and n-heptane were evaluated by a continuous flow adsorption testing method at 80 °C. Zeolites with the FAU type structure (Na-Y and H-Y) showed higher adsorption capacities compared to the other types of zeolites. Adsorption strength of ethanol on zeolites was evaluated by a temperature programmed desorption method. Ethanol molecules adsorbed on Na-Y and H-Y were desorbed by heat treatment at around 300 °C, but ethanol adsorbed on H-Y was partially dehydrated because of zeolite acidity.
Hierarchical Y zeolite-containing mesoporous silica–aluminas were prepared by the one pot sol-gel method using malic acid. Properties for the catalytic cracking of vacuum gas oil (VGO) were estimated using a Curie point pyrolyzer, to establish a novel and very simple estimation method for the catalytic cracking of VGO. Prepared catalysts showed higher conversions and selectivities for gasoline than zeolite single, indicating that yields of gasoline for zeolite-containing catalysts increased compared with that of zeolite single. Higher content of aluminum species in the catalysts resulted in decreased olefin/paraffin ratios and increased iso-/n-ratios (ratio of branched products to straight-chained ones), indicating that hydrogen transfer and isomerization were promoted by the addition of acid sites into the matrix. Catalysts with mesopores tended to form larger amounts of multi-branched products, which are very important in modern petroleum refining. When the yields of gasoline, single-branched products and multi-branched products were plotted against the conversion of VGO, the linear relationships were observed and the effect of kinds of zeolite was rather small, indicating that the activity and the selectivity were largely affected by the presence of matrices. Comparison of the yields of gasoline, single-branched products and multi-branched products at the same conversions showed that Y zeolite-containing catalysts always showed the highest yields and ZSM-5-containing catalysts showed the lowest yields although the differences were small. Pore size of the zeolite probably also affected the yields in the treatment of large molecules such as VGO. The present findings suggest that the appropriate combination of zeolite and matrix is the most important factor to obtain high catalytic activity and high yields of gasoline and branched products.
Traditional approaches to the problem of oil field life cycle partitioning onto the successive stages is mainly based on heuristic evaluations with no well-defined criteria. To solve this problem, we proposed a stage wise structuring based on the identification of the current oil production distribution in the individual stages and isolation of adjacent stages’ boundary points defining the duration of each stage. Using statistical analysis of experimental data on development of a large number (more than twenty) of specific fields reduced into one "generalized deposit" followed The Savitzky-Golay smoothing filter shows that the life cycle of the field can be divided into four successive stages which are definitely described as logarithmically normal, exponential, Pareto and Weibull distributions. Using non-linear logistic model for the cumulative oil production in the last fourth stage of the life cycle a computational procedure has been developed for assessing the initial recoverable reserves, as well as the method for estimating the maximum level of oil production has been proposed. The method is based on finding inflection point of the curve describing the dynamics of cumulative oil production, by examining second order differences. Based on the values of cumulative oil production in the later points of the final development stages oil production was predicted and the design parameters for the current development system were evaluated using adaptive Kalman filter in discrete time.
Metal-organic framework compound consisting of terephthalic acid and chromium cation (TPA–Cr) was prepared by the hydrothermal method and characterized by XRD, N2 adsorption-desoprtion isotherm, TGA-DTA and TEM. The prepared TPA–Cr was crystalline and phase-pure. Noble metal was supported on TPA–Cr by the conventional impregnation method. The specific Pd salt and solvent for impregnation significantly influenced the location of Pd. With [Pd(NH3)4](NO3)2 dissolved in water, Pd was located in the micropores of TPA–Cr, whereas with PdCl2 dissolved in water or methanol, Pd was located on the external surface of TPA–Cr. Hydrogenation of cinnamaldehyde and crotonaldehyde, and cross-coupling between aryl bromides and phenylboronic acid were studied using Pd/TPA–Cr and Ru/TPA–Cr prepared as above. Hydrogenation of the two model aldehydes occurred in the micro- and meso-pores of TPA–Cr whereas cross-coupling reaction of bulkier compounds occurred mostly on the external surface of TPA–Cr.