To develop a compact and low cost excess sludge reduction system, alkaline treatments were carried out using sludge from a petroleum refinery. Alkaline treatment with a concentration of 0.025-0.05 mol/L solubilized about 30% of the sludge after 1 h. Alkaline wastes from petroleum refinery such as sodium sulfide, sodium hydrosulfide, and diisopropanol amine could be used to solubilize about 10-30% of the sludge. Combination of alkaline solubilization (0.05 mol/L NaOH) and high speed mixing achieved about 50% solubilization rate after 1 h at 25°C. Application of this system in a petroleum refinery (600 m3 aeration vessel and 450 m3 sedimentation vessel, 3 m3 solubilization vessel) resulted in average solubilization rate of 44% and reduction rate of sludge of 47% during 64 days operation. Return of alkaline solubilized broth into the aeration vessel did not affect the treatment. In 40 L bench scale experiments, solubilization rate of 59% and sludge reduction rate of 94% were obtained when the amount of sludge solubilization was increased up to 2-3 times of excess sludge produced under the standard activated sludge treatment without the solubilization process.
As a new catalyst support, powdered diamond was first investigated. Although diamond has been considered to be a stable material, the surface carbon was found to react to give C–H and C–O–C or C=O bonds by hydrogenation and oxidation. Oxygen treated diamond (O-Dia) was evaluated as a catalyst support material, which was considered to be a pseudo solid carbon oxide phase corresponding to the well known catalyst support SiO2. Following reactions were successfully carried out using O-Dia supported metal oxides or metal catalysts: Dehydrogenation of light alkanes and ethylbenzene to give light alkenes and styrene on Cr2O3 and V2O5/O-Dia catalysts; direct oxidation of C2H6 and CH4 to aldehydes using CO2 as the oxidant over V2O5/O-Dia catalyst; oxidation of methane to syn-gas over Ni or Co/O-Dia catalysts; carbon nanofilament or nanotube synthesis over Ni and Pd/O-Dia catalysts; ammonia synthesis over Ru/O-Dia catalyst. This review article summarizes the characteristics of these reactions.
Carbon nanotube (CNT)-based composites have attracted a great deal of interest because of their potential application in catalysts. These composites are frequently prepared by the addition of metals or metal oxides to the outer surface of CNT. However, the surface modification of CNT is generally a challenging task, because their surface is chemically inert. In addition, metal or metal oxide particles on CNT are easily aggregated when these are used as catalysts. Recently, we developed CNT-supported metal nanoparticle catalysts covered with silica layers a few nanometers thick. The catalysts show high catalytic activity in spite of coverage of metal nanoparticles with silica layers. In addition, the silica layers which are wrapped around metal particles prevent the sintering of metal particles as well as the detachment of metal particles under severe reaction conditions. In addition, the CNT-supported metal particles covered with silica can be applied to catalysts for the oxygen reduction reaction at cathode in polymer electrolyte fuel cells (PEFCs). Pt catalysts supported on carbon black which are conventional catalysts in the state of the art PEFCs, are seriously deactivated under PEFC cathode conditions such as high potential, low pH and oxygen atmosphere due to the aggregation of Pt metal and the dissolution and re-deposition of Pt metal. We demonstrated that the silica-coated Pt/CNT is electrochemically active in spite of coverage of Pt metal with silica insulator. In addition, the coverage of Pt metal particles with silica layers inhibits the growth of Pt metal particles in size under cathode conditions in PEFCs. The silica-coated Pt/CNT thus shows high durability for the oxygen reduction reaction. The coverage with silica layers also prevents the dissolution of metals other than Pt under cathode conditions. Therefore, our silica-coating method is promising for the development of highly durable non-Pt metal catalysts for use in PEFC cathodes.
Through introducing the pressure function and apparent viscosity the expression of space potential is obtained based on the oil-water two-phase flow theory in this paper. The potential distribution in reservoir of herringbone branch well under the condition of oil-water two-phase steady flow has been studied based on the potential theory. Then the coupled model of flow in reservoir and wellbore pipe-flow is deduced according to wellbore pressure drop calculation model of the variable mass flow with the oil-water two phase in the horizontal pipe. And the anisotropic correction parameters are introduced to correct the model. The model can be used to calculate the productivity of branch well with different configurations at different water cut stage. The establishment of this model has provided a basis for the productivity prediction and the configuration optimization of herringbone branch well under the condition of oil-water two-phase flow.
Heavy oil upgrading technology using supercritical or subcritical water has been developed to produce low viscosity and vanadium-free reformed oil. This study investigated the vanadium removal mechanism from heavy oil using a continuous tube reactor. In particular, the relationship between vanadium removal and coke formation during the upgrading process was estimated. The experimental conditions were as follows: pressure 25 MPa, temperature 350-470°C, and water/oil ratio 0.5. The coke yield heavily depended on the operating temperature of the tube reactor. The vanadium content in heavy oil was expected to concentrate in the coke at higher temperatures of the reactor. Therefore, the concentration of vanadium in the reformed oil was lower with higher coke yield. The asphaltene fraction in the heavy oil included a high concentration of vanadium, and the asphaltene tend to form the coke at reactor temperature of 450°C. Supercritical water can be expected to absorb the light oil components and asphaltene fractions at this temperature.
A rapid analysis method is proposed to distinguish between gas oil and fuel oil discharged into sea area. The proposed analysis was performed on a FT-IR spectrometer. Because those oils could be distinguished from three peaks at 811, 742 and 723 cm−1, they were used as discrimination indices. Those peaks are assigned to CH bending modes for 2 and 4 hydrogens and methylene framework, respectively. As a result, the absorption intensities of gas oil was 742<811<723 cm−1, but those of the fuel oil was 723<742<811 cm−1. The absorption of 1603 cm−1 was larger in fuel oil than gas oil. And the absorption of 475 cm−1 was not observed in gas oil, while it was in fuel oil. Because the frequency intensities were peculiar to the oil types, the spectra offered the rapid type analysis of the discharged fuel oil and gas oil. However, the frequencies of 2955, 2925, 2854, 1462 and 1377 cm−1 of the gas oil were hardly distinguished from those of the fuel oil. This method was effective for the analysis of the discharged gas oil and fuel oil into sea areas.
Bis(imino)pyridinevanadium(III) complexes [2,6-(Ph’-N = C(CH3))2C5H3NVCl3, Ph’ = complex 1: 2,4,6-(CH3)3C6H2 and complex 2: 2,6-((CH3)2CH)2C6H3] supported on Mg2+-exchanged fluorotetrasilicic mica (Mg2+-Mica) and montmorillonite (Mg2+-Mont) were prepared as heterogeneous catalysts for ethylene polymerization. These catalysts combined with conventional alkylaluminum compounds were tested for the ethylene or ethylene/1-hexene polymerization. The catalysts supported on Mg2+-Mont showed a significantly higher activity compared to those supported on Mg2+-Mica during the polymerization of ethylene or ethylene/1-hexene. The catalyst based on complex 1 promoted the ethylene/1-hexene copolymerization to afford a linear low-density polyethylene. In contrast, no copolymerization took place using the complex 2-based catalyst because of the high steric bulk around the active center. A bimodal distribution was specifically observed in the GPC profiles of the ethylene/1-hexene copolymers, suggesting that multiple active species were formed by the reaction of the vanadium complex and the trialkylaluminum compound.
Friedel-Crafts alkylations are very important reactions which are widely used in the production of fine chemicals, intermediates, and petrochemicals. Solid catalysts should be developed for greening of these chemical processes. We previously developed a high-throughput screening system (HTS) and had been screening solid catalysts for benzylation of anisole by benzyl alcohol. In the present study, supports and additives for 12 tungstophosphoric acid (HPA) catalysts were screened by HTS and data mining tools using principal component analysis, radial basis function network, and support vector machine. These methods identified Re-HPA/activated carbon with the highest activity, which was experimentally confirmed.
Selective membrane separation of saturated water vapor from olefin gas such as ethylene and propylene has been investigated using two types of carbon hollow fiber membranes. One is prepared by the pyrolysis of sulfonated poly(phenylene oxide) (H-SPPO) at 600°C of which pore size is 0.4-0.45 nm, and another is prepared using sodium substituted SPPO (Na-SPPO) of which pore size is 0.3-0.35 nm. The membrane pore size was found to have a significant effect on the olefin gas dehydration performance and the latter carbon membrane showed superior performance due to the higher ideal selectivity of water vapor with respect to ethylene or propylene. This carbon membrane selectively permeated 95% of water vapor in feed stream (4.4 vol%) at a feed flow rate of 30 L · m−2 · min−1. It was revealed that the permeation amount of water vapor increased with increasing feed pressure. At a feed pressure of 0.5 MPa, more than 97% of the propylene gas dehydration ratio was obtained with good resistance against olefin gases.
Analysis of bio-oil derived from activated sludge using biomarkers was performed by spectroscopic methods. The method successfully determined the distinction between the oil derived from activated sewage sludge (bio-oil) and crude oil (heavy fuel oil).