Pierre Le Perchec

THERMOCATALYTIC HYDROCONVERSION OF HEAVY PETROLEUM CUTS WITH DISPERSED CATALYST

Abstract This report concerns the use of unsupported dispersed catalysts in upgrading heavy feeds. The conversion of heavy crudes and resids into valuable products requires an efficient hydrogen activation. A method recently investigated deals with the use of metallic or organometallic (water- or oil-soluble) compounds, which under a thermal treatment decompose and give rise to a slurry of fine solid particles. This active form of catalyst promotes locally the spill-over of the hydrogen and therefore enhances the conversion of resids to distillate, reducing the coke formation. The primary objective of this report is to assess the current state of knowledge on this field, in order to identify new directions and strategies for Research.

Polyoxyethylene di-phosphonates as efficient dispersing polymers for aqueous suspensions

Polyoxyethylenes having a di-phosphonate functional group at one of their chain ends strongly adsorb on calcium carbonate particles in aqueous colloidal suspensions. An enhanced colloidal stability of such suspensions results with a concomitant drastic reduction of the viscosity of concentrated aqueous suspensions. The viscosity of a 20 wt % CaCO3 colloidal suspension in water could be lowered to 2 mPa · s with low concentrations of polymer. The adsorption and viscosity reduction were studied as a function of the chemical nature of the end chain group and the polymer molecular weight. The di-phosphonate group was found the most efficient anionic group when associated with a polyoxyethylene of polymerization degree larger than 20. The main features of this di-block architecture of the polymer are discussed.

Visbreaking of Safaniya vacuum residue in the presence of additives

Visbreaking and hydrovisbreaking of an heavy oil (Safaniya VR) are optimized in term of conversion into light fractions (500+) using additives. H-donor diluents inhibit coke formation and reduce conversion. Addition of a small amount of thiol or disulphide allowed the transformation of the heavy oil at low temperature. Under more severe conditions, the association of H-donor diluents and sulphide additives gives high conversion yields (⩾50%) with moderate gas and coke production. This paper attempts to explain the synergism observed.

Oxidative pyroanalysis: elemental analysis in volatile and non-volatile fractions of coals and related materials

Abstract Oxidative pyroanalysis affords accurate and quantitative analysis of coals under various temperature programmes and gas flow conditions. When applied to coals of diverse origins, this technique allows samples and products to be classified from standard proximate and ultimate analyses and from the elemental composition of any fraction. Detection of thermally evolved products from coal (water, carbon dioxide, sulphur dioxide), produced in the absence of oxidation, is also possible. Comparison with other methods shows good agreement between measured values. Characterization of coal products exemplifies the possibilities of this technique.

Synthesis of new zwitterionic surfactants with improved solubility in water

Abstract New neutral zwitterionic surfactants of the sulfobetaine series have been synthesized in a preparative scale in a two steps procedure. Ring opening of propane or butane sultone is obtained by a 2-methyl-1,3-cycloiminoether in a first stage, and the resulting inner cycloiminium sulfonate salt is ring-opened by a fatty tertiary amine. The introduction of an acetamide group between the two charged groups of the zwitterion enhances the solubility in water and then allows the use of octadecyl chained surfactants in water at room temperature. This synthesis provides pure compounds, free of inorganic ions, in good yield addition reactions from commercially available starting materials.

Hydrogen-bonded complexes of pentaalkyl guanidines

The hydrogen-bonded complexes of strongly basic pentaalkylguanidines (G) with 4-fluorophenol as a proton donor reference (FP) have been studied in CDCl3 solution by means of 13C NMR spectroscopy. The equilibrium constants for formation and the chemical shifts of all the 13C NMR lines of the hydrogen-bonded complexes were determined. This rich spectroscopic characterization of the complexes allowed us to discuss their structure. The guanidines were found to be more basic than triethylamine, the bicyclic ones being the strongest bases, in accordance with expectations. The ion pair character of the hydrogen-bonded complexes was as high as 40% for the strongest bases. In addition to the expected GFP complex, a diassociation complex G(FP)2 was observed at high fluorophenol concentrations. In this latter complex, one fluorophenol molecule is ionized by full proton transfer to the guanidine and the second fluorophenol molecule is bound by hydrogen bonding to the fluorophenate anion. A linear relationship between the 13C NMR chemical shift variations of 4-fluorophenol and log(K1) was found, as in the original work of Gurka and Taft using 19F NMR.

Reaction paths of 1,3-oxazolinium saltz with stabilized carbanions

Abstract Reaction of stabilized carbanions with 3-methyl-2-phenyl-1,3-oxazolinium triflate occurs at both C 5 and C 2 sites with a regioselectivity depending partially on steric effects. The reaction at C 2 site can result in the formation of 1,4-oxazepin derivatives.

14C polyaromatics as radio isotope tracers for grafting analysis during heavy oil pyrolysis

Abstract Labelled polyaromatics, such as 14 C chrysene and 14 C acenaphthylene, have been used as tracers during pyrolysis of a heavy oil residue. Prior to this approach the thermal behaviour of 1:1 mixtures of chrysene and Safaniya vacuum residue (VR) were examined using mass spectrometry and ultraviolet (u.v.) analysis. Chrysene was found to be highly reactive, producing dimers and alkylated chrysene materials. From feedstocks with 14 C chrysene and 14 C acenaphthylene as radio tracers, the distribution of polyaromatics in the pyrolysed heavy oil fractions were determined. In this series, acenaphthylene was found to be more reactive than chrysene in grafting reactions on heavy oil components. The radical quenching propensity of polyaromatic additives towards small radicals has been confirmed, supporting their anticoke effect when used at high concentration. Interestingly, the diluted polyaromatic tracers did not accumulate in the coke fractions. This result points to weak and reversible bonding reactions of the polyaromatic additives onto the heavy oil components.

Thermal behaviour of oxidized Boscan atmospheric residue

Abstract Controlled and progressive chemical oxidation was performed on Boscan atmospheric residue, then the thermal behaviour of the samples was examined. Hydrogen peroxide-methanol gave specific sulphoxidation, while stronger oxidation of sulphur and large viscosity and solubility changes were observed with hydrogen peroxide-acetic acid and m-chloroperbenzoic acid. Thermal cracking sensitivity was reduced and coke production increased steadily with the strength of oxidation. Efficient visbreaking only occurred with H2O2-methanol from low temperature decomposition of sulphoxides to active radicals. In no case was the sulphur elimination at the level expected from model compound pyrolysis. Except with H2O2-methanol, carbonization of the oxidized residues followed by transmission electron microscopy showed deep degradation of the microstructural organization (decrease in the extent of the local molecular orientation). This altered the graphitization capacity, as confirmed by the sulphur concentration in the pre-graphites. All the results suggest that sulphone entities are mainly responsible for profound physical and thermochemical changes, with rapid destruction of the microstructural organization.

Long chain n-alkyl and n-alkylthio radicals: Reactivities towards hydrogen donor additives under gas phase condition

Abstract Fossil fuel model compounds such as didodecylsulphide 1 , 1-dodecanethiol 2 and didodecylsulphone 3 were thermally decomposed under gas phase and short contact time reaction conditions with defined medium composition. Intermolecular H-transfer occurs with sulphided species while intramolecular β-scissions and H-transfers are probably involved during decomposition of the dodecyl radical. The appearance of light alkyl radicals and the presence of thiyl and mercapto radicals clearly activate thermal conversion of the starting material. H-donor additives have a weak effect on the various intramolecular mode of fragmentation of the n-alkyl chains but they are able to inhibit the activity of light and thiyl radicals improving the yield of liquid n-olefins. In all cases only traces of n-alkanes are formed by intermolecular H-transfer.