Jovan Jovanovic

Kinetics and modelling of oil shale pyrolysis

Abstract The pyrolysis kinetics of oil shales from Yugoslavia, Northern Korea and the USSR, were investigated under non-isothermal conditions using thermogravimetric analysis (TGA) and differential scanning calorimetry (d.s.c.). Additional kinetic investigations were performed on samples obtained by chemically and thermally treating each oil shale. The results obtained were incorporated into the multi-step kinetic model (MSM) which was adjusted according to the specific properties of particular oil shale samples, and tested by comparison of the experimental and simulated TGA, DTG and d.s.c. curves. The modelling procedure developed for Aleksinac oil shale was found to be useful in modelling the pyrolysis of other oil shales of the same kerogen type.

Thermogravimetrically and differential scanning calorimetrically derived kinetics of oil shale pyrolysis

Abstract Thermogravimetry (TG) and differential scanning calorimetry (d.s.c.) were used to investigate the kinetics of non-isothermal pyrolysis of Aleksinac oil shale from Yugoslavia. The samples used included oil shale, demineralized oil shale and bitumen extracted from the original, as well as from the thermally treated oil shale. Kinetic parameters were determined by assuming a single first-order kinetic model, using the integral method for TG analysis, and ASTM procedure E-698 for d.s.c. analysis. The influence of cracking catalyst addition was examined with respect to the overall kinetics and to conversion in particular temperature regions. Higher values of kinetic parameters were obtained by d.s.c. analysis, and the reasons for the differences between those and the TG results are discussed.

Composition of the sterol fraction in horse chestnut

Abstract The Δ7-and Δ5-sterol fractions were isolated from the unsaponifiable matter of ripe, air dried, chestnut seed. The Δ7-sterol fraction amounted to 18.4% and the Δ5-sterol fraction amounted to 8.2% of the unsaponifiable matter. In the Δ7-sterol fraction three components were identified as Δ7-campesterol, α-spinasterol and Δ7-stigmastenol. One component was probably Δ5,7-stigmastadienol and five components remained unidentified. Δ7-stigmastenol and α- spinasterol were the major components and amounted to 74.8% of the fraction. In the Δ5-sterol fraction at least ten components were found. Five of them were identified as cholesterol, campesterol, stigmasterol, sitosterol and Δ4-stigmasten-3-one. Stigmasterol and sitosterol amounted to 73.6% of the fraction.

Modelling and simulation of oil shale pyrolysis

Abstract The pyrolysis of a Yugoslavian oil shale was represented by three alternative mathematical models, based on single-step (SSM), two-step (TSM) and multistep (MSM) reaction schemes. The models were constructed using previously reported TG- as well as d.s.c.-derived kinetic parameters, obtained from the non-isothermal pyrolysis of different samples, assuming the influence of heat and mass transfer limitations could be neglected. The ability of the models to predict important effects of non-isothermal, as well as isothermal oil shale pyrolysis was investigated and compared. The complexity level of the pyrolysis representation is discussed with regard to the practical purpose of model application.

Oligomerization and alkylation products of the oil obtained by naphtha steam pyrolysis (RPO)

Abstract In the presence of Friedel–Crafts acids, residual pyrolysis oil (RPO) [Ullmanns encyclopedia of industrial chemistry, 4th ed. 1993: A23; p. 89; Kirk-Othmer encyclopedia of chemical technology, 3rd ed. 1990: 13; p. 717] is easily converted to a petroleum aromatic resin (PAR) [Jeremic K, Jovanovic JA. Erdoel and Kohle, erdgas petrochemie, 1993: 46; 430–434]. By using HPLC chromatography, GC-MS, HPLC-MS and APCI-MS/MS techniques and the reaction of indene and naphthalene in the presence of boron trifluoride for comparison, it was proved that the PAR sample investigated in this work represented a mixture of the components that remained from RPO, an oligomer with dimers, trimers and tetramers in, respectively, decreasing quantities, an alkylate with naphthalene being the main substrate and a polymer in which products with 7–32 monomer moieties prevailed. The monomers and alkylation agents present in the RPO were identified, as were the components that do not polymerize and could be alkylated. By taking into account all the possible oligomerization products including dimers, trimers and tetramers, both in the form of homopolymers and heteropolymers, and all the possible alkylation products, the molecular weights of compounds expected in the oligomer and the alkylate part of the PAR were calculated. All of them were detected in the PAR by using direct sample insertion APCI-MS/MS analysis. GC-MS and HPLC analysis of the PAR and GC-MS, HPLC and HPLC-MS analysis of a product mixture of the reaction of indene in naphthalene in the presence of boron trifluoride, were accomplished. By using the described analytical procedure, it has become possible to control and manage the reaction of the conversion of RPO to PAR, and to characterize this complex system in a very precise manner.

Hydrodenitrogenation of Aleksinac shale oil distillates in a pilot trickle-bed reactor

Abstract Hydrodenitrogenation (HDN) of the Aleksinac shale oil distillates was studied in a pilot trickle-bed reactor at 340–435°C, 8.0 MPa, 1–4.57 h−1 liquid hourly space velocity (LHSV) and 500 cm3 (STP) of H2/cm3 oil. The commercial Co  Mo Al 2 O 3 and Ni  Mo Al 2 O 3 presulfided catalysts were evaluated for the HDN of three different shale oil distillates. The initial HDN catalyst deactivation was followed using a linear catalyst deactivation model. The Ni  Mo Al 2 O 3 catalyst showed somewhat higher initial HDN activity and lower initial deactivation rate than the Co  Mo Al 2 O 3 catalyst for the first 30–45 h on shale oil feedstock. Nitriles in shale oil first undergo HDN reaction at mild operating conditions, much faster than five- and six-membered nitrogen heterocyclic compounds. The overall HDN kinetics of refractive nitrogen in shale oil was analyzed using a modified pseudo-first-order behavior. The on-line measured hydrogen consumption was in the range 200–300 cm3 (STP)/cm3 for HDN > 80% regardless of the catalyst type and feedstock.

Pyrolysis of oil shale in a microretorting unit

With the aim of investigating the dependence of shale oil composition on pyrolysis conditions (temperature and time), a laboratory microretorting unit was constructed which enabled experiments to be conducted under isothermal conditions with ~ 20 g of oil shale, and allowed the collection of four to six fractions of shale oil. The details of the microretorting unit are presented, as well as the results of preliminary investigations. The composition of shale oil and gas produced by pyrolysing Aleksinac oil shale under isothermal conditions (420–520 °C) was determined using column and gas chromatography, 13C n.m.r. spectroscopy and elemental analysis. The results showed that a pyrolysis temperature between 450 and 480 °C gave the highest quantity of aliphatics and the lowest quantity of aromatics in the product.

2,3,1′,3′-Tetrahydro-[1,2′]biindenylidene

In the crystal structure of the title compound, C18H16, the dihedral angle between the least-squares planes through the C atoms of the phenyl rings is 2.82 (4)°. The bond length of the central double bond is 1.3297 (15) A.

4α-methylergosta-8,24(28)-dien-3β-ol, a minor sterol in the seed of horse chestnut

Abstract From ripe horse chestnut seed the 4α-methyl sterol fraction was isolated representing 4.5% of the unsaponifiable matter, i.e. 3 mg% of the seed. This fraction was investigated by capillary GC and combined GC-MS. It contains at least 12 components, of which 5 were identified as: obtusifoliol 4α-methylergosta-8,24(28)-dien-3β-ol, gramisterol, cycloeucalenol and citrostadienol. The distribution of these five 4α-methyl sterols in the seed was also determined and they represent about 90% of the investigated fraction. 4α-Methylergosta-8,24(28)-dien-3β-ol up to now been found in higher plants only in traces, while in this fraction it was found in the amount of about 5%.

Landfill design: need for improvement of water and soil protection requirements in EU Landfill Directive

This paper deals with environmental policy issues related to a landfill design. The final product of numerous waste treatments should be placed on a landfill. Before waste disposal, the ground should be protected by a mineral layer with properties required by the related regulation. In order to prevent environment pollution, EU adopted the Landfill Directive 1999/31/EC. The most important technical requirements related to the characteristics of the layer material are water permeability and thickness. The performed comparative national regulatory analysis raised the question of the need for more uniform elaboration of the directive requirements over the whole European Union area (including EU candidates). The choice of the material for the impermeable mineral layer, which should be made during landfill design, is a very important decision. Methods for the determination of the permeability coefficient were analysed, showing that the Directive should define hydraulic gradient as a physical quantity and define its value through measurement of the permeability coefficient. The paper analyses whether some parts of the Directive, as landfill design BAT and base for national legislative acts, require further elaboration in order to provide sufficient information about proper protection of soil and water. Using integrated approach, seven amendments on the directive annex I were suggested related to (a) the meaning of the term artificially established geological barrier, (b) layer thickness, (c) water permeability coefficient determination, (d) mineral layer lifecycle, (e) the meaning of the term sealing and (f) leaching control of material joints.