An overview of several refinery process options that convert high boiling point fractions of crude oil into more valuable distillates is presented. The combination of Residuum Desulfurization (RDS) with Residuum Fluid Catalyst Cracking (RFCC) produces high yields of transportation fuels and chemicals feedstock with minimal fuel oil by-product. This process scheme can present formidable technical challenges for the catalysts of each process to handle the increased levels of contaminants such as Microcarbon Residue (MCR), nickel and vanadium present in heavy oil. This paper presents the results of hydrotreating heavier Atmospheric Residuums (AR) in RDS pilot plants with Ni-Mo supported catalysts. RDS pilot plant life tests are conducted and middle of run products are collected and distilled for analysis and further RFCC testing. Process condition variation and new catalyst development has been applied to improve RDS capability to handle heavier, more contaminated residuum. The RDS products are tested for RFCC reactivity using Advanced Cracking Evaluation (ACE) tests. The development of improved RFCC catalyst is applied to boost cracking catalyst tolerance of residuum metal contaminants. Judicious selection of newly developed RDS and RFCC catalysts enable production of higher yields of gasoline from heavier AR's. The coordinated application of new RDS and RFCC catalysts enables the conversion of dirtier residuum feedstock to produce greater yields of distillates.
Ru/Mn/Al2O3 and Ru/Al2O3 catalysts, which prepared with various ruthenium precursors into impregnation method, were investigated for Fischer-Tropsch (FT) synthesis in a continuous stirred tank reactor; and the catalysts were characterized by H2-chemisorption, TPR, XRD, TEM and XPS. On the basis of Ru/Mn/Al2O3 catalysts, Ru(Cl)/Mn/Al2O3 prepared with ruthenium chloride exhibited much higher catalytic activity and stability than those on Ru(A)/Mn/Al2O3 and Ru(N)/Mn/Al2O3, which were prepared with ruthenium acetylacetonate and ruthenium nitrosyl nitrate precursors. The order of the CO conversion was Ru(Cl)/Mn/Al2O3>>Ru(A)/Mn/Al2O3 > Ru(N)/Mn/Al2O3. This order was also agreed with the order of CO conversion on Ru/Al2O3 in various ruthenium precursors. One explanation is in characterization results that the particle size of Ru and the pore diameter of the support such as 8 nm can be performed to influence high FT activity. On the other hand, over Ru(Cl)/Mn/Al2O3 and Ru(Cl)/Al2O3 catalysts, lower activity and higher deactivation rate with reaction time on Ru(Cl)/Al2O3 were clearly observed, where Ru(Cl)/Mn/Al2O3 showed high resistance to catalyst deactivation. In this observation, manganese chloride can be formed by removing chlorine atoms from ruthenium chloride, thus increasing the concentration of metallic Ru active species on the catalyst surface and with inhibiting catalyst deactivation.
Adsorptive removal of t-butanethiol (TBT), an odorant additive, from city gas was carried out using metal ion-exchange Y type zeolites at ambient temperature and pressure. The adsorption capacity of TBT on Na-Y under the wet gas condition was extremely low, although that under the dry gas condition was certainly higher. The adsorption capacity of TBT on silver ion-exchange Y type zeolites (Ag(Na)–Y) increased with higher silver ion-exchange ratio in Ag(Na)–Y under wet gas condition. In contrast, the adsorption capacity of TBT on Ag(Na)–Y under the dry gas condition decreased with higher silver ion-exchange ratio in Ag(Na)–Y. Formation of silver sulfide clusters in Ag(Na)–Y causes the decrease in sulfur adsorption capacity of it under the dry gas condition. The adsorption capacity of TBT on copper ion-exchange Y type zeolites (Cu(Na)–Y) increased with higher copper ion-exchange ratio in Cu(Na)–Y under the wet gas condition. In the case of Cu(Na)–Y, the decrease of TBT adsorption capacity under the dry gas condition did not occur with higher copper ion-exchange ratio in Cu(Na)–Y. The both spent samples of Ag(Na)–Y and Cu(Na)–Y were regenerated by heat treatment in air. The decrease in adsorption capacity of TBT on Cu(Na)–Y was slightly lower than that on Ag(Na)–Y.
Dehydrogenation of ethylbenzene was evaluated with Fe–K and Fe–Ce–K mixed oxide catalysts to examine the addition effect of Ce. Fe–Ce mixed oxide was prepared by co-precipitation of Fe and Ce nitrate solutions. K2CO3 was added to Fe oxide or Fe–Ce mixed oxide. Only a small amount of Ce addition, Ce/Fe = 3.0 × 10−5 (atomic ratio), was effective to improve the dehydrogenation activity, but excess Ce addition, above Ce/Fe = 2.0 × 10−3, did not further improve the activity. BET surface area measurement, SEM observation and XRD were performed before and after the dehydrogenation reaction. BET surface area was increased significantly by addition of Ce. However, the yield of styrene per unit surface area remained constant independent of the amount of Ce addition. SEM observation revealed that the particle size of Fe–Ce–K was smaller than that of Fe–K both before and after the reaction. We concluded that the addition of Ce retarded crystal growth of the mixed oxide, and improved the styrene yield by enlarging the surface area.
For photocatalytic water splitting rate enhancement, it is said efficient to add oxidizing sacrifice agents to water, which can consume produced O2, in order to repress the reverse reaction, i.e. re-coupling of produced H2 and O2. From the viewpoint of carbon-neutral taking photosynthesis in nature into account, saccharides of foodstuffs are selected as experiementing oxidizing sacrifice agents. Additionally, a pyroligneous acid is also adopted as one of candidates of nonfood oxidizing sacrifice agents together with an acetic acid of its main component as a reference chemical. Since the most promising photocatalyst for water splitting is TiO2, that is clear from its electronic band structure, three commercial TiO2 are utilized after loading Pt. A simple batch vessel is employed as an apparatus since the purposes of this study are to clarify the fundamental characteristics of photocatalytic H2 production and to optimize the operating conditions. As the results, 0.10 wt%-Pt loaded P25 is realized to provide the highest H2 producing rate of 2.60 l/(m2 · h) from 50 g/l glucose aqueous solution. Though slightly higher efficiency can be obtained by regulating pH value, above-mentioned operating conditions with free pH are concluded superior from the viewpoint of consuming chemical for intending pH to efficiency increment. On the contrary to similar high photocatalytic H2 producing rates from solutions of monosaccharide (glucose and fructose) and disaccharide (sucrose), solution of polysaccharide (starch) shows remarkably slow H2 producing rate down to one-eighth of prescribed ones from monosaccharide and disaccharide, resulting in necessity of pretreating such macromolecules to unimolecules and/or micromolecules, controlling their adsorption to photocatalyst in order to adopt them as oxidizing sacrifice agents. A remarkably low H2 producing rate is recognized from a solution of nonfood pyroligneous acid. Therefore, searches for other natural oxidizing sacrifice agents remain as an indispensable future task.
Middle distillates obtained by pyrolysis of oil shale and oil sands bitumen were denitrogenated by complex formation with CuCl2·2H2O, which reduced the nitrogen contents from 9900 to 2700 wtppm and from 1300 to 700 wtppm, respectively, without any change in the sulfur contents. The original and denitrogenated oils were hydrotreated over a conventional NiMo catalyst in a fixed-bed continuous flow reactor. The pre-removal of nitrogen compounds greatly enhanced hydrodenitrogenation (HDN) and hydrodesulfurization (HDS), and the rate constants were increased by 4.9-27 for HDN and 2.8-5.4 for HDS. As a result, the nitrogen and sulfur contents of the denitrogenated oils were reduced to < 1 and < 10 wtppm, respectively, under the conditions of H2 8 MPa, LHSV 1 h−1 and 350°C.
Bimodal porous Ru/SiO2 catalysts for the Fischer-Tropsch reaction were prepared by modifying the surface of macro-porous silica with Ru–SiO2 prepared by the alkoxide method. The Ru particle size estimated by H2 adsorption increased with the pore size of the macro-porous silica, whereas the Ru crystallite size evaluated by XRD line broadening did not show much variation. The bimodal catalysts showed high and stable activity in the slurry phase under the reaction conditions of T = 493-503 K, P = 1 MPa, H2/CO = 2/1, and W/F = 5 g-catal.h/mol, with reduction in the used amounts of the expensive alkoxide. Selectivity for higher hydrocarbons increased with increasing pore diameter of the catalysts, which can be explained in terms of diffusivity of the slurry solvent and/or the products in the pores, and the effect of the Ru particle size depending on the macro-pore size of the catalysts.