Evaluation of different reaction strategies for the improvement of cetane number in diesel fuels

Cetane number improvement of diesel fuels is a difficult task that refiners will face in the near future. Aromatics saturation by deep hydrogenation is a necessary, but perhaps not sufficient step in the diesel treatment. Some researchers have proposed selective ring opening (SRO) as an additional step in the upgrading. In this work, we explore some possible reaction pathways of compounds typically found in diesel after different levels of hydrogenation, i.e. decalin (decahydronaphthalene), perhydrophenanthrene, tetralin (1,2,3,4-tetrahydronapthalene), as well as 1-ring and 2-ring aromatic phenanthrenes. We have estimated the cetane number (CN) of each individual compound involved in the reaction pathways, using an artificial neural network program that was trained with pure compound cetane numbers from a database. The results demonstrate the great challenge that reaching high CN represents. In the conversion of decalin, acidic catalysts alone are not able to yield products with CN significantly higher than the decalin feed. Similarly, no significant gain in CN can be expected with hydrogenolysis metal catalysts operating via the dicarbene mechanism. Only in the case of selective metal-catalyzed hydrogenolysis, with preferential cleavage at substituted C–C bonds, the predicted products have CN substantially higher than the decalin feed. As expected, branching has a strongly negative effect on the CN and it should be minimized. Both, metal-catalyzed di-carbenium C–C cleavage and acid-catalyzed ring contraction/ring opening combination leave branching groups in the product. Similarly, the acid-catalyzed ring opening of perhydrophenanthrene does not result in a significantly higher CN than the initial feed. The possibility of minimizing hydrogen consumption in the CN improvement process by an initial partial hydrogenation followed by ring opening was tested by using phenanthrene and tetralin as probe molecules. In the first reaction strategy, partially hydrogenated phenanthrenes (1-ring and 2-ring aromatics) were followed by ring opening of one of the saturated rings. Although this option would lead to lower overall hydrogen consumption, it results in products of much lower CNs than the ones obtained by full hydrogenation of phenanthrene. Similar results are obtained for tetralin. From this analysis, it is clear that upgrading CN of diesel requires extensive hydrogen consumption. For further upgrading, highly selective hydrogenolysis catalysts are needed in order to minimize branching and therefore obtain high CN products.     

Improving the low-temperature properties of alternative diesel fuels: Vegetable oil-derived methyl esters

This work explores near-term approaches for improving the low-temperature properties of triglyceride oil-derived fuels for direct-injection compression-ignition (diesel) engines. Methyl esters from transesterified soybean oil were evaluated as a neat fuel and in blends with petroleum middle distillates. Winterization showed that the cloud point (CP) of methyl soyate may be reduced to −16°C. Twelve cold-flow additives marketed for distillates were tested by standard petroleum methodologies, including CP, pour point (PP), kinematic viscosity, cold filter plugging point (CFPP), and low-temperature flow test (LTFT). Results showed that additive treatment significantly improves the PP of distillate/methyl ester blends; however, additives do not greatly affect CP or viscosity. Both CFPP and LTFT were nearly linear functions of CP, a result that compares well with earlier studies with untreated distillate/methyl ester blends. In particular, additives proved capable of reducing LTFT of neart methyl esters by 5–6°C. This work supports earlier research on the low-temperature properties; that is, approaches for improving the cold flow of methyl ester-based diesel fuels should continue to focus on reducing CP.     

On the way to understand the keys for the stabilization of the conductive phase in doped- NASICON-type materials

A family of doped-NASICON-type structures according to the chemical compositions: Li_1.2 Zr_1.9M_0.1(PO₄)₃ [with M = Ca²⁺, Mg²⁺, Zn²⁺]; Li_1.1 Zr_1.9Y_0.1(PO₄)₃ and Li_1.0 Zr_1.9Ce_0.1(PO₄)₃ have been synthesized by solid state reaction. The modification on the thermal treatment proposed in this work makes possible to obtain a high purity phase confirmed by XRD, SEM, microRaman-confocal and FTIR. Rietveld refinement evidences how the LZP lattice parameters are affected by each of those five different dopant cations incorporated into the pristine structure. Impedance spectroscopy proves how the relationship radius - charge of each dopant-ion affects the ionic conductivity. Unravelling that the partial replacement of Zr⁴⁺ in the LZP by a dopant improves the conductivity behavior. When the dopant cation has a lower charge and a larger size than the Zr⁴⁺ the developed structure favours the lithium-ion mobility at room temperature and the lithium conductivity increases.     

Using polyfurfuryl alcohol to improve the hydrothermal stability of mesoporous oxides for reactions in the aqueous phase

Hydrodeoxygenation (HDO) of bio-oils derived from the pyrolysis of woody biomass is required to improve the stability and heating value of the liquid hydrocarbon products. Since pyrolysis produces bio-oils having up to 30 vol% water, HDO catalysts must not only be active and selective, but also stable under hydrothermal conditions associated with HDO upgrading. We investigated the effect of carbon coatings on a variety of silica, mixed zirconia-silica oxides and alumina. Surface area and porosity changes from exposure to controlled steaming conditions were used to evaluate the effectiveness of carbon coating on support stability. Systematic studies of the effects of the composition and structure of the carbon precursor, the inclusion of a zirconium modifier, the carbon loading and carbonization conditions led to the development of highly stable carbon modified zirconium silicate and mesoporous alumina supports that substantially maintain pore size distribution and surface area after steaming at 493 K with 23 bar of steam pressure.     

硫基复合肥生产提高副产盐酸质量的方法

目前我国大部分硫基复合肥为了降低生产成本,主要采用硫酸与氯化钾反应来生产,而硫酸与氯化钾的反应是一个不太完全的复分解反应:     

Opening of the rings of aromatic and naphthene hydrocarbons: A new way of improving the quality of fuels

In recent years, the opening of the rings of aromatic and naphthene hydrocarbons has been considered as a way way of improving the quality of motor fuels. In gasolines, the opening of monocyclic compounds like di- and trialkylcyclohexanes allows the synthesis of high-octane components (C₇–C₁₀ iso-paraffins). In diesel fuels containing considerable amounts of bi- and trinuclear polycyclic compounds such as derivatives of naphthalene (decaline), phenanthrene, and indane, this allows the synthesis of monocyclic compounds and alkanes, thus leading to a reduction in the freezing temperature of the fuel and, when obtaining predominantly linear alkanes, to an increase in the cetane number. In this work, we conduct a brief analysis of accumulated data on the opening of cyclic compounds on oxide and zeolite supported catalysts.     

Determination of hydrocarbon compound class abundances in kerosine and diesel fuels: Chromatographic and nuclear magnetic resonance methods

Procedures for the determination of compound class abundances in kerosine and diesel fuels from diverse sources have been developed. Gas chromatography or ¹³C n.m.r. can be used to obtain the abundance of n-alkanes. For n-alkane contents > ≈ 15 wt% both g.c. and n.m.r. give similar results. Low n-alkane contents (< 10 wt%) are difficult to determine. An established h.p.l.c. nethod yields separate peaks for saturates and 1- and 2-ring aromatics. Fractions separated from whole fuels on a preparative scale have been studied to derive average response factors recommended for use in routine h.p.l.c. analysis. Samples from different sources show only minor variations in response factors for 1- and 2-ring aromatics. Larger variations found for saturates response factors present a potential problem for quantitative h.p.l.c. This variation arises in part from different relative abundances of n-alkanes in saturates. Particularly accurate abundances of all compound classes can be obtained if the wt% n-alkanes is first determined by g.c. or n.m.r. For a test set of 11 kerosines of various origins, the standard deviation of errors arising from variations in true response factors is only 1.6 wt% for saturates.     

Preparation of Ru metal nanoparticles in mesoporous materials: influence of sulfur on the hydrogenating activity

Hydrogenating catalysts were prepared by inserting Ru into the pores of mesoporous Al-MCM-41 materials by selective adsorption of [Ru(NH₃)₆]³⁺. Ru/support catalysts were obtained after reduction with H₂. The activities of these catalysts in hydrogenation reactions were compared to those of Ru/HY and Ru/SiO₂. The catalytic properties in the absence of sulfur were tested in benzene hydrogenation, and the intrinsic activities of all the catalysts (either supported on mesoporous materials or on zeolites) were identical. It was concluded from this result that the dispersion of the Ru metallic phase was similar for all these catalysts. These samples were tested in the tetralin hydrogenation in pure H₂ and in the presence of H₂S (330 ppm of H₂S in H₂). They were found to be much less active than the zeolite-supported catalysts in the presence of H₂S. It is proposed that the lower activity of the catalysts supported on mesoporous materials is either due to their milder acidity, as evidenced by NH₃-TPD, cumene cracking and pyridine desorption experiments, or to the localization of the Ru nanoparticles on alumina islands.     

An efficient way to improve the mechanical properties of polypropylene/short glass fiber composites

Enhancement of tensile strength, impact strength, and flexural strength of polypropylene/short glass fiber composites by treating the glass fibers with coupling agent, mixing with maleated polypropylene (MPP) for compatibilization and adhesion, and with nucleating agent for improvement of polypropylene crystallization was studied. The results showed that both the silane coupling agent and MPP enhance tensile strength, impact strength, and flexural strength. In the absence of MPP, the effect of silane coupling agent on the mechanical properties of the composites decreases in the following order: alkyl trimethoxy silane (WD‐10) > γ‐methacryloxypropyl trimethoxysilane (WD‐70) > N‐(β‐aminoethyl)‐γ‐aminopropyl trimethoxysilane (WD‐52), whereas in the presence of MPP, the order changes as follows: WD‐70 > WD‐10 > WD‐52. When the glass fibers were treated with WD‐52, 4,4‐diamino‐diphenylmethane bismaleimide (BMI) can further enhance the mechanical properties of the composite. The three kinds of strengths increase with MPP amount to maximum values at 5% MPP. As a nucleating agent, adipic acid is better than disodium phthalate in improving the mechanical properties, except for the notched impact strength. Wide‐angle X‐ray diffraction showed that the adipic acid is an α‐type nucleating agent, whereas disodium phthalate is a β‐type nucleating agent. Blending with styrene–butadiene rubber can somewhat improve the notched impact strength of the composites, but severely lowers the tensile strength and bending strength. Scanning electron micrographs of the broken surface of the composite showed greater interfacial adhesion between the glass fibers and polypropylene in the modified composite than that without modification. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1414–1420, 2005     

Novel isomerization of ω-phenylalkanals to phenyl alkyl ketones over cesium (lanthanum) oxide supported on mesoporous aluminosilicate molecular sieves and related materials

A novel rearrangement of the ω-phenylalkanals phenylacetaldehyde, 3-phenylpropionaldehyde and 4-phenylbutyraldehyde towards phenyl alkyl ketones is reported. The liquid-phase isomerizations are catalyzed by cesium oxide or binary cesium-lanthanum oxide supported on the mesoporous aluminosilicate molecular sieves MCM-41 and HMS and on amorphous supports like silica-alumina and γ-alumina. Beside the title reaction the aldol condensation is observed as a side-reaction. A mechanism is proposed in which the aromatic ring is involved in the rearrangement process. Factors governing the activities and product selectivities are presented. This revised version was published online in July 2006 with corrections to the Cover Date.     

碳硅介孔材料对水中Cr~(6+)和苯酚的吸附性能研究

以正硅酸乙酯(TEOS)为硅源,十六烷基三甲基溴化铵(CTAB)为模板和碳源,用水热合成法制备介孔氧化硅(MCM-41),再加浓硫酸,经过干燥、煅烧、水洗,得到介孔碳硅复合材料。考察其对环境水体中Cr⁽⁶⁺⁾和苯酚的吸附性能。结果表明,吸附苯酚的最适条件:30℃,pH=5,吸附时间24 h,此时饱和吸附量为7(6+)和苯酚的吸附性能。结果表明,吸附苯酚的最适条件:30℃,pH=5,吸附时间24 h,此时饱和吸附量为7¹1 mg/g;吸附Cr11 mg/g;吸附Cr⁽⁶⁺⁾的最适条件:20℃,pH=8,吸附时间24 h,饱和吸附量为15(6+)的最适条件:20℃,pH=8,吸附时间24 h,饱和吸附量为15²0 mg/g。用材料吸附微污染水中Cr20 mg/g。用材料吸附微污染水中Cr⁽⁶⁺⁾和苯酚,去除率分别达到70%和79.77%。     

碳硅介孔材料对水中Cr~(6+)和苯酚的吸附性能研究

以正硅酸乙酯(TEOS)为硅源,十六烷基三甲基溴化铵(CTAB)为模板和碳源,用水热合成法制备介孔氧化硅(MCM-41),再加浓硫酸,经过干燥、煅烧、水洗,得到介孔碳硅复合材料。考察其对环境水体中Cr~(6+)和苯酚的吸附性能。结果表明,吸附苯酚的最适条件:30℃,pH=5,吸附时间24 h,此时饱和吸附量为7~11 mg/g;吸附Cr~(6+)的最适条件:20℃,pH=8,吸附时间24 h,饱和吸附量为15~20 mg/g。用材料吸附微污染水中Cr~(6+)和苯酚,去除率分别达到70%和79.77%。     

Modern catalysts of deep hydrotreatment in the production of low-sulfur diesel fuels at Russian oil refineries according to Euro-3 and Euro-4 standards

The production of diesel fuels with sulfur contents according to Euro-3 and Euro-4 standards at Russian oil refineries requires the replacement of catalysts by more active ones without reconstructing the existing hydrotreating units. The majority of Russian catalysts can be used for the production of diesel fuels containing 350 ppm S and more. For the production of fuels with less than 50 and 10 ppm residual sulfur, however, last generation catalysts should be used, whose surface compounds are highly active Co(Ni)-Mo-S phases of the second type. A typical representative of these catalysts is the Russian IC-GO-1 catalyst, which has been manufactured since 2007 by ZAO Industrial Catalysts under the license of Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences. The characteristics of hydrotreatment ensured by the developer and producer were confirmed during the commercial use of the catalyst at OAO Saratov Oil Refinery. The production of IC-GO-1 can reach 600 t per year, which is sufficient for the re-equipment of 10 standard Russian hydrotreating units.     

On agglomeration phenomena in ball mills: application to the synthesis of composite materials

Composites of poly(vinyl acetate) filled with calcium carbonate (CaCO₃) have been synthesized in a ball mill. The different steps in fragmentation and agglomeration phenomena have been identified. The materials have first been ground separately to characterize their behaviour in the mill. Then, they were ground together. It has been shown that small CaCO₃ fragments cover PVA particles, limiting for a first time the agglomeration of these and permitting their size reduction. Then, when PVA fragments are small enough, a competition between size reduction and agglomeration occurs, which favours the dispersion of CaCO₃ in the matrix. It has also been observed that the presence of the filler does not modify significantly the molecular mobility of PVA.     

Inclusion and release of cytisine in mesoporous silicate materials: an agent for smoking cessation

Journal of Porous Materials - Cytisine is a natural compound obtained primarily from the seeds of the plant Cytisus laburnum. Cytisine has been used as a smoking cessation drug and has a mechanism...     

Metathesis of 1-butene and ethene to propene over mesoporous W-KIT-6 catalysts: the influence of Si/W ratio

Journal of Porous Materials - Mesoporous W-KIT-6 catalysts with various Si/W ratios were prepared by one-pot direct hydrothermal reactions and were studied in metathesis of 1-butene and ethene to...     

Oxidative desulfurization of diesel fuel by mesoporous phosphotungstic acid/SiO2: the effect of preparation methods on catalytic performance

Two kinds of mesoporous phosphotungstic acid/SiO₂ (HPW/SiO₂) have been synthesized by amino-functionalized (AF) method and evaporation-induced self-assembly (EISA) method, and their catalytic performance was investigated for deep oxidative desulfurization of benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) in diesel oil. Various analysis techniques such as XRD, TEM, N₂ adsorption/desorption isotherms, FT-IR and ³¹P MAS NMR spectra have been used to investigate the pore structure and chemical properties of the resultant catalysts. The structural and spectroscopic analysis indicates both catalysts have a highly ordered 2D hexagonal mesostructure. HPW/SiO₂-EISA can maintain the Keggin structure of HPW molecules and has a high BET surface area (403 m²/g). But in the AF method, the mesostructure of SBA-15 are partially blocked after the introduction of HPW molecules, and the Keggin structure of HPW molecules has been damaged. The catalytic performance results also show that HPW/SiO₂-EISA exhibits higher catalytic activity and stability compared to HPW/SiO₂-AF. As for HPW/SiO₂-EISA, the conversions of DBT, 4,6-DMDBT and BT are found to be 99.6, 97.6, 94.8 %, respectively. It shows a good maintenance of activity even after the 7th cycle of use. While corresponding conversions by using HPW/SiO₂-AF are found to be 90.2, 89.1 and 87.6 %, and the DBT conversion decreases to 75.7 % after the 5th cycle of use.