Michel Thomas

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.

Reactive poly(2-vinyl-4,4-dimethyl-5-oxazolone) and poly[(2-vinyl-4,4-dimethyl-5-oxazolone)-co-(methyl methacrylate)]s. Synthesis, characterization and chemical modification with 4-methoxy-4'-(β-aminoethoxy)biphenyl

Poly(2-vinyl-4.4-dimethyl-5-oxazolone) (P 0 ) and poly[(2-vinyl-4,4-dimethyl-5-oxazolone)-co-(methyl methacrylate)]s with increasing content of methyl methacrylate units (P 1 -P 4 ) were synthesized and characterized. NMR spectra were discussed in terms of monomer sequence distribution and tacticity effects. The reaction of 4-methoxy-4-hydroxybiphenyl (1) with 2-ethyl-2-oxazoline was milized to prepare 4-methoxy-4-(p-aminoethoxy)biphenyl (3) through the intermediate 4-methoxy-4-[(N-propanoyl)-β-amino-ethoxy]biphenyl (2). The homopolymer P 0 and two copolymers P 2 and P 3 were functionalized with 4-methoxybiphenyl side groups by reaction with 3 via a ring-opening process in N,N-dimethylformamide (DMF) or 1,2-dichloroethane. The resulting copolymers P 5 -P 8 were characterized by 1 H and 13 C NMR. The highest degree of functionalized units was obtained in DMF at 80 C.

Synthesis and characterization of 4-cyanobiphenyl-4′-yloxy-functionalized poly(7-oxanorbornene-5,6-exo-dicarboximide)s via ring opening metathesis polymerization (ROMP)

N-[n-(4-cyanobiphenyl-4′-yloxy)alkyl]-7-oxanorbornene-5,6-exo-dicarboximide (CBON2–CBON8) with increasing number of methylene groups in the alkyl part (n = 2–8) were synthesized by Mitsunobu condensation between the appropriate alcohols (CBA2–CBA8) and 7-oxanorbornene-5,6-exo-dicarboximide (ON). The conditions for the ring opening metathesis polymerization of CBONn giving acceptable molecular weights and molecular distributions were established. Characterization of the resulting polymers (P2–P8) by 1H- and 13C-NMR has shown a high trans content. Differential scanning calorimetry and optical microscopy analysis have shown that the alcohols CBAn are thermotropic with some variations between the first and second heating-cooling cycles, the monomers CBONn melt with no evidence of any mesomorphic state, the polymers Pn show only the glass transition, and the glass transition temperature (Tg) decreases with increases in the spacer length.

Synthesis and characterization of frequency doubling nonlinear optical liquid crystalline polyepichlorohydrins and polyoxetanes functionalized with alkoxycyano-azobenzene and alkoxynitrostilbene dyes. Second harmonic generation in corona poled thin films

New copolyethers were prepared by chemical modification of polyepichlorohydrin and poly(3,3-bis(chloromethyl)oxetane) with the sodium salt of either 4-hydroxy-4-nitrostilbene or 4-hydroxy-4-cyanoazobenzene, employing the concept of having the nitrostilbene or cyanoazobenzene species serve concomitantly as both the nonlinear optical (NLO) chromophore and the mesogenic moiety in the polymer. Their thermal behavior was established by means of differential scanning calorimetry (DSC) and optical microscopy. The NLO properties of two nematic copolyethers were studied. The NLO mesogenic groups were oriented by the standard corona poling technique and the degree of axial ordering was determined as a function of poling conditions. The second harmonic coefficients d 31 and d 33 were measured. The results showed that liquid crystallinity enhances field-induced polar ordering. The ratio d 33 /d 31 was found to be much larger than 3, in agreement with the theoretical models for electric field poling of liquid crystals. We were able to obtain d 33 values up to 130 pm/V at λ = 1,064 μm, thus exceeding many values previously reported for second harmonic generation measurements on isotropic polymers containing similar side chain chromophores.

Characterization of heavy oil fractions obtained from thermal treatment in presence of sulfides and H-donor additives

Analytical studies have been performed on effluents issued from thermal conversion of Safaniya Vacuum residue (Arab Heavy) in presence of tetralin, thiophenol and methyldisulfide. In contrast to thermal behavior of the heavy oil alone, low coke amount was produced at high conversion level (up to 50%) beside good product qualities as demonstrated from analysis of the remained 500{degrees}C{sup +} fractions. H-donor diluent and sulfide additives help effectively in lowering the carbon residue values and maintaining the H/C ratios at the highest value compatible with the conversion. Microstructural parameters of the liquid effluents and their asphaltenic parts are obtained from {sup 1}H and {sup 13}C NMR spectroscopy and average molecular weight determination. Even at high conversion level results allow to assess a rapid dealkylation process at the first stage of the thermal treatments associated with a good control in the evolution of the size of polyaromatic units. Optical microscopy and X-ray analysis outline the specific effect of tetralin as a delayed coking additive.