J. B. Hyne

Chemistry of organosulphur compound types occurring in heavy oil sands:: 1. High temperature hydrolysis and thermolysis of tetrahydrothiophene in relation to steam stimulation processes

Abstract Studies have been made of the high temperature, high pressure hydrolysis and thermolysis of tetrahydrothiophene as part of a study of the reactivity of organosulphur compounds during in situ steam stimulation processes for heavy oil recovery. It was found that hydrolysis of tetrahydrothiophene produces hydrogen sulphide, carbon dioxide and hydrocarbon gases, together with a complex array of liquid products. A mechanism for this reaction is proposed and investigations into the aqueous decomposition of butanal have been carried out to support this mechanism. A comparative study of the dry thermolysis of tetrahydrothiophene has been carried out.

The corrosion of carbon steel by wet elemental sulphur

Abstract The corrosion behaviour of carbon steel in wet elemental sulphur under both aerobic and anaerobic conditions is reported. The corrosion reaction was studied as a function of the initial pH of the system and the particle size of sulphur. Catastrophic corrosion is observed after an induction period which is found to be a function of the initial pH of the system, the particle size of the sulphur and the presence or absence of oxygen. Corrosion potential measurements suggest that the observed catastrophic corrosion process is subject to catalysis of the cathodic reaction. A possible mechanism for the corrosion reaction is discussed.

Some chemistry of organosulphur compound types occurring in heavy oil sands: 2. Influence of pH on the high temperature hydrolysis of tetrahydrothiophene and thiophene

Abstract The hydrolysis of thiophene at high temperatures and pressures has been examined in relation to the steam-stimulated recovery of high-sulphur tar sands and heavy oils. The influence of pH has been examined in the hydrolysis of both thiophene and tetrahydrothiophene considered to be reasonable models for organosulphur molecular types in heavy oils. Mechanisms are proposed to account for the products observed under acidic, neutral and basic conditions.

The chemistry of organosulphur compound types occurring in heavy oils: 4. the high-temperature reaction of thiophene and tetrahydrothiophene with aqueous solutions of aluminium and first-row transition-metal cations

In the reactions of thiophene and tetrahydrothiophene with aqueous solutions of first-row transition-metal and aluminium cations at 240 °C and 3.4 MPa all the metal species accelerated the decomposition of the thiophenes in relation to equivalent reactions with pure water. Al3+, Sc3+, VO2+, Cr3+, Ni2+ and Cu2+ were most reactive towards thiophene and Al3+, VO2+, Cr3+ and Cu2+ were most reactive towards tetrahydrothiophene. Principal products were H2S and complex mixtures of organic products. The presence of CO2 and oxygen-containing organic products revealed that water was involved in direct chemical reaction with the substrates. It is likely that these model reactions parallel more complex processes that occur during the steam-stimulated recovery of oil-sand bitumen and other high-sulphur oils.

Chemistry of organosulphur compound types occurring in heavy oil sands: 3. Reaction of thiophene and tetrahydrothiophene with vanadyl and nickel salts

Abstract As part of a study of the chemistry of the steam-stimulated recovery of heavy oils, the hydrolysis and subsequent desulphurization of tetrahydrothiophene and thiophene by aqueous solutions of vanadyl and nickel salts was investigated. Vanadyl sulphate and vanadyl chloride were shown to behave very differently, emphasizing that these salts have different molecular species in aqueous solutions.

Chemistry of organosulphur compound types occurring in heavy oil sands: 5. Reaction of thiophene and tetrahydrothiophene with aqueous Group VIIIB metal species at high temperature

Abstract As part of a study of organosulphur compounds in heavy oil sands, the interaction of thiophene (1) and tetrahydrothiophene (10) with aqueous solutions of Group VIIIB metal species at 200–240 °C has been investigated. Thiophene was the more reactive and the greatest degree of reaction was observed with the second- and third-row members of the Group VIIIB metals. Aqueous Pt(IV) gave most reaction for both substances. Desulphurization of the sulphur compounds was significant, although conversion to more complex organic substances, including dithienyls and benzothiophene, account for > 50 wt % of the total reaction for most metal species. The presence of CO2 in the products showed that water was involved in the reaction. Reactions with thiophene produced only minor amounts of C1C4 hydrocarbons, but significant quantities were obtained from reactions with tetrahydrothiophene.

The influence of substituted alcohols on the temperature of maximum density of water

The influence of various substituted (including halogenated) alcohols on the temperature of maximum density (TMD) of water has been investigated. Evaluation of the structural contribution to the shift in the TMD demonstrates that trifluoroethanol, hexafluoroisopropanol, and neopentyl alcohol are “structure makers”, whereas trichloroethanol and tribromoethanol are “structure breakers”. The results are discussed in terms of an excluded volume model.

Heats of solution and the influence of solutes on the temperature of maximum density of water

The influence of N,N-dimethylformamide, N,N-dimethylacetamide, 2-pyrrolidinone, N-methyl-2-pyrrolidinone, and N-t-butyl-2-pyrrolidinone on the temperature of maximum density (TMD) of water has been investigated. Heats of solution for these compounds and for diethylsulfoxide, tetramethylene sulfoxide, tetramethylene sulfone, dimethyl sulfoxide, and tetrahydrofuran in water at 23°C are also reported. These data, together with published TMD and heat of solution data for other solutes, are used to examine the relationship between the enthalpy change on dissolution of a solute in water and the effect of the dissolved substance on the structure of water as reflected by changes in the temperature of maximum density of the system.

The influence of aliphatic diols on the temperature of maximum density of water

The influence of various aliphatic diols on the temperature of maximum density (TMD) of water has been investigated. 1,2-Propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 2,5-hexanediol were found to yield positive structural contributions to the solute-induced shift in the TMD, i.e., they are “structure makers”. Contrariwise, data from the literature indicate that 1,2-ethanediol is a “structure breaker”. Relationships between the structure making/breaking tendencies of the solutes and the relative positions of the two hydroxyl groups are discussed.

Corrosion of carbon steel during cyclical exposure to wet elemental sulphur and the atmosphere

Abstract The corrosion of carbon steel during cyclical exposure to wet elemental sulphur (four days) and the atmosphere (six days) has been investigated. The integral corrosion rate is found to decrease with successive cycles, thereby demonstrating that oxidation of the sulphide film confers protection to the underlying steel.