Alain Favre-Réguillon

Ultra-deep desulfurization of transportation fuels via charge-transfer complexes under ambient conditions

Very stringent regulations on the maximum sulfur content of gas oil have led to intense research into all aspects of desulfurization. Deep desulfurization of diesel fuels is particularly challenging due to the difficulty of removing refractory sulfur compounds, particularly 4,6-dialkyldibenzothiophenes, using conventional hydrodesulfurization processes (HDS). A novel approach to the potential desulfurization of fuels such as diesel is proposed. It relies on the ability of 4,6-dialkyldibenzothiophene to form charge-transfer complexes (CTC) with π-acceptor molecules. We present the synthesis of a new π-acceptor molecule, 4,5-dicyano-2,7-dinitrofluorenone, solution redox behaviour and the crystal structure of the charge-transfer complex with the refractory 4,6-dimethyldibenzothiophene. This π-acceptor compound was then immobilized on a hydrophobic support (poly(styrene-co-divinylbenzene)). The selectivity of the CTC process was confirmed by the analysis of the sulfur compounds trapped from straight run Arabian Light (SR) containing 13600 ppm S. The functionalized polymer can be used in multiple cycles for the removal of refractory S-containing compounds from hydrotreated SR. It can also be regenerated with toluene. The high selectivity of this material permits diesel fuel to be desulfurized to a level that meets future regulatory requirements, i.e. less than 10 ppm S, at ambient temperature and without hydrogen consumption.

Cloud point extraction : An alternative to traditional liquid-liquid extraction for lanthanides(III) separation

Cloud point extraction (CPE) was used to extract and separate lanthanum(III) and gadolinium(III) nitrate from an aqueous solution. The methodology used is based on the formation of lanthanide(III)-8-hydroxyquinoline (8-HQ) complexes soluble in a micellar phase of non-ionic surfactant. The lanthanide(III) complexes are then extracted into the surfactant-rich phase at a temperature above the cloud point temperature (CPT). The structure of the non-ionic surfactant, and the chelating agent-metal molar ratio are identified as factors determining the extraction efficiency and selectivity. In an aqueous solution containing equimolar concentrations of La(III) and Gd(III), extraction efficiency for Gd(III) can reach 96% with a Gd(III)/La(III) selectivity higher than 30 using Triton X-114. Under those conditions, a Gd(III) decontamination factor of 50 is obtained.

A straightforward synthesis of unsymmetrical secondary phosphine boranes

A one-pot procedure for the synthesis of unsymmetrical alkyl-substituted secondary phosphine oxides is described. The sequential addition of N-benzylaniline to a solution of dichlorophenylphosphine and 1-methylimidazole in methylcyclohexane, separating of the protic ionic liquid formed, addition of Grignard reagent followed by hydrolysis gave unsymmetrical secondary phosphine oxides (SPOs) in high yield. The use of ionic liquids in the first step is essential and streamlined the synthesis. Unsymmetrical SPOs could be quantitatively reduced to secondary phosphine using a catalytic amount of Ti(OiPr)4 and tetramethyldisiloxane (TMDS) under mild reaction conditions.

Extraction of Cesium from an Alkaline Leaching Solution of Spent Catalysts Using an Ion-Exchange Column

The selective extraction of cesium from an alkaline leaching solution of spent catalysts using phenolic resins was studied. The resins were synthesized by alkaline polycondensation of formaldehyde by phenol, resorcinol, catechol, and phloroglucinol. Their ionoselectivities for five alkali metals were evaluated with a solid-liquid extraction, and their ion-exchange capacities were compared. The resin with the best selectivity for cesium was tested with a real solution at different pH values. An on-column extraction is proposed to obtain cesium with high purity.

Zirconium and hafnium separation, Part 1. Liquid/liquid extraction in hydrochloric acid aqueous solution with aliquat 336

Abstract The extraction of zirconium and hafnium from aqueous HCl solutions by means of Aliquat 336 in organic diluents was systematically studied. The following three aspects were discussed: the extraction dependence on HCl, the Aliquat 336 concentrations, and the nature of diluents. Both of the metals were stripped with deionized water and the influence of phase ratio on the efficiency of the stripping has been investigated. The stoichiometry of the extracted Zr and Hf species from single metal ion were studied and a possible extraction mechanism for the Zr‐Hf mixture is discussed in the light of the results obtained.

Combined process for the treatment of olive oil mill wastewater: absorption on sawdust and combustion of the impregnated sawdust.

Olive oil mill wastewater (OMWW) generated by the olive oil extraction industry constitutes a major pollutant, causing a severe environmental threats because of the high chemical oxygen demand and the high content of polyphenol. This work studied a combined process of absorption on sawdust, a low-cost renewable absorbents, and an energetic valorisation via combustion was studied. The thermal behaviour of different OMWW/sawdust blends was studied under inert and oxidative atmosphere from 20 to 900 degrees C using thermogravimetric analysis (TGA). Gaseous emissions such as CO(2), CO and volatile organic compounds (VOCs) were measured under oxidative conditions at 600 degrees C in a fixed-bed reactor. Kinetic parameters were obtained and compared for the different mixtures of OMWW and sawdust. The absorption of the organic content of OMWW on sawdust improves the decomposition of cellulosic compounds at low temperatures in both atmospheres. Compared to sawdust, absorption of the organic content of OMWW on sawdust favours a combustion process with lower molar ratio of CO/CO(2) in the exhaust. Combustion of an impregnated sawdust containing 40 wt.% of the organic content of the OMWW generates the same amount of gas in the exhaust as sawdust. OMWW/sawdust blends may therefore be a promising biofuel with low environmental impacts.

Regioselective synthesis of N-functionalized 12-membered azapyridinomacrocycles bearing trialkylcarboxylic acid side chains

Abstract Selective protection of primary amine moieties of diethylenetriamine by 2-nitrophenylsulfonyl chloride followed by alkylation of the central N atom generates functionalized disulfonamide building blocks. When reacted with 2,6-bis(bromomethyl)pyridine following the Richman–Atkins methodology, such compounds yield the corresponding pyridine-containing azamacrocycles. Smooth removal of the N-sulfonyl groups provides versatile azamacrocyclic intermediates with transannular secondary amine functions. Subsequent N-alkylation regioselectively leads to tri N-functionalized 12-membered azapyridinomacrocycles bearing a sequence of N-acetate and N-propionate side chains.

Zirconium and hafnium separation, Part 2. Solid/liquid extraction in hydrochloric acid aqueous solution with anion exchange resins

Abstract Sorption behavior of zirconium and hafnium on different commercial anion exchange resins with different amine functions; ammonium (Amberjet 4200Cl), pyridine (PVP) and pyridinium (HPQ) was investigated in hydrochloric acid by both batch and column methods. Experiments were studied as a function of the concentration of hydrochloric acid. For all resins, zirconium was preferably extracted. The highest separation factors at equilibrium conditions were obtained by poly(vinyl‐pyridine) (PVP) with a hydrochloric acid concentration of 9.5 M. It was observed that a single contact of the loaded resins with pure water completely back extracted the metal ions from the resins. On the basis of the significant difference between distribution coefficients of Zr and Hf, the separation was performed on a glass column (25×160 mm), packed with the resin. The breakthrough curves showed a competitive sorption and desorption process between Zr and Hf for the three resins studied.

Selective Separation of Lanthanides with Phenolic Resins: Extraction Behavior and Thermal Stability

Catechol, resorcinol, and their admixtures with 8-hydroxyquinoline were converted into polymeric resins by alkaline polycondensation with formaldehyde. The resins were characterized by FTIR spectroscopy, moisture regain, ion-exchange capacity, and distribution coefficient (D) for Eu3+. Thermogravimetric analysis of the polymer samples was studied, and the effect of the sorption of metal ions on their thermal stability was evaluated. Complexation of Eu3+ to the resins was modeled based on metal ion charge neutralization. The selective uptake of Eu3+ from aqueous solutions containing La3+ was investigated, and the ionoselectivities of the resins were compared. The incorporation of 8-hydroxyquinoline in the molecular matrix of the phenolic resins is shown to exert a significant influence upon the competitive sorption of La3+ and Eu3+, leading to their intragroup separation. The separation factors obtained by phenolic ion-exchange resins from aqueous solutions indicate ion-specific resins can be developed for the specific separation of actinide ions from nuclear waste.

SYNTHESIS AND EVALUATION OF RESORCINOL-BASED ION-EXCHANGE RESINS FOR THE SELECTIVE REMOVAL OF CESIUM

Control of the reaction conditions during the alkaline polycondensation of resorcinol with formaldehyde leads to polymeric resins with improved capacity toward caesium. The resins obtained are characterized by determining their moisture regain and ion-exchange capacity. The distribution coefficient (D) for alkali-metal cations are determined in a competitive extraction system at different pH. The alkali-metal cation sorption selectivity series is strongly influenced by the pH of the solution. Two kinds of mechanism can explain these selectivity series. Extraction of caesium from simulated radioactive waste was studied at different pH in the presence of a large excess of sodium. The study also includes the kinetic and the ion-exchange capacity for caesium of the sodium form of the resins.