Synthesis of Carbon Nanomaterials and Their Applications in the Oilfield
Tour, James M.
Doctor of Philosophy
This dissertation explores the potential applications of nanotechnology in the oilfield including poly(vinyl alcohol) stabilized carbon black nanoparticles for oil exploration and temperature-responsive carbon black nanoparticles for enhanced oil recovery. Also, it describes the rational design of graphene nanoribbons via intercalating reactive metals into multi-walled carbon nanotubes followed by addition of vinyl monomers or haloalkanes. Efficient production and modification of these aforementioned nanomaterials will make them more attractive for applications in the oilfield and electronics materials. A method is reported for detecting the hydrocarbon in the porous media with stabilized nanoparticles that are capable of efficiently transporting hydrophobic molecules through oil-containing rocks and selectively releasing them when a hydrocarbon is encountered. Nano-sized carbon black was oxidized and then functionalized with poly(vinyl alcohol) via a coupling reaction between the polymer's hydroxyl groups and the carboxylic groups on oxidized carbon black. Breakthrough curves show that poly(vinyl alcohol)-coated oxidized carbon black was stable in synthetic sea brine at room temperature and could carry the 14C-labeled radioactive tracer 2,2ˊ,5,5ˊ-tetrachlorobiphenyl through rocks and then released the tracer upon exposure to hydrocarbon. Due to the temperature-sensitivity of hydrogen bonds, higher molecular weight poly(vinyl alcohol) was used to improve the stability of carbon black nanoparticles in synthetic sea brine at higher temperatures. After sulfation, high molecular weight poly(vinyl alcohol) could stabilized carbon black nanoparticles in American Petroleum Institute standard brine at high temperatures. Those nanoparticles could efficiently transport mass-tagged probe molecules through a variety of oil-field rock types and selectively released the probe molecules into the hydrocarbon-containing rocks. Those proof-of-concept chemical nanoreporters can potentially be used under conditions commonly observed in the reservoir, and aid in the recovery of oil that remains in place. Amphiphilic carbon nanoparticles have been prepared that are capable of reversibly transferring across the water/oil interface in a temperature-controlled manner. Nano-sized carbon black was oxidized and then functionalized with amphiphilic diblock polyethylene-b-poly(ethylene glycol) copolymers that were water-soluble at low-to-moderate temperatures but oil-soluble at higher temperatures. The correlation between the phase transfer temperature and the melting temperature of the hydrophobic block of the copolymers and the weight percent of hydrophilic block were investigated. The amphiphilic nanoparticles were used to stabilize oil droplets for demonstrating potential applications in reducing the water/oil interfacial tension, a key parameter in optimizing crude oil extraction from downhole reservoirs. Graphene nanoribbons free of oxidized surfaces can be prepared in large batches and 100% yield by splitting multi-walled carbon nanotubes with potassium vapor. If desired, exfoliation is attainable in a subsequent step using chlorosulfonic acid. The low-defect density of these GNRs is indicated by their electrical conductivity, comparable to that of graphene derived from mechanically exfoliated graphite. Additionally, cost-effective and potentially industrially scalable, in situ functionalization procedures for preparation of soluble graphene nanoribbons from commercially carbon nanotubes are presented. To make alkane-functionalized graphene nanoribbons, multi-walled carbon nanotubes were intercalated by sodium/potassium alloy under liquid-phase conditions, followed by addition of haloalkanes, while polymer-functionalized graphene nanoribbons were prepared via polymerizing vinyl monomers using potassium-intercalated graphene nanoribbons. The correlation between the splitting of MWCNTs, the intrinsic properties of the intercalants and the degree of graphitization of the starting MWCNTs has also been demonstrated. Those functionalized graphene nanoribbons could have applications in conductive composites, transparent electrodes, transparent heat circuits, and supercapcitors.
Carbon black; Graphene nanoribbons; Amphiphilic nanoparticles; Phase transfer