Development of composite amine functionalized polyester microspheres for efficient CO2 capture.

In order to reduce the impact of greenhouse gases on the environment, the development of various new CO2 capture materials has become a hot spot. In this work, a novel composite amine solid adsorbent was prepared by simultaneously using tetraethylenepentamine (TEPA) and 2-[2-(dimethylamino) ethoxy] ethanol (DMAEE) for amine functionalization on the polyester microsphere carrier. The introduction of methyl methacrylate (MMA) with high glass transition temperature into the polyester carrier makes the carrier microspheres have high hardness. At the same time, the carrier also contains active epoxy groups and hydrophobic glycidyl methacrylate (GMA, which can undergo ring-opening reaction with composite amines to achieve high-load and low-energy chemical grafting of amines on the carrier. The composite aminated polyester microspheres were used as an efficient adsorbent for CO2 in simulated flue gas. The results show that the synergistic effect of TEPA-DMAEE composite amine system in the adsorbent is beneficial to the improvement of CO2 capture capacity. When the total amine content in the impregnating solution is 45 wt% and the composite amine ratio is TEPA: DMAEE = 6: 4, the CO2 adsorption capacity can reach the optimal value of 2.45 mmol/ g at 70 °C. In addition, the composite amine microsphere adsorbent has cyclic regeneration performance. Importantly, through kinetic fitting, the Avrami kinetic model fits the CO2 adsorption better than the quasi-first-order and quasi-second-order kinetic models, which proves that physical adsorption and chemical adsorption coexist in the adsorption process. This simple, long-term stable and excellent selective separation performance makes amine-functionalized adsorbents have potential application prospects in CO2 capture.

Investigation of the Nonionic Acidizing Retarder AAO for Reservoir Stimulation.

In the process of matrix acidizing, reducing the reaction rate between hydrochloric acid and carbonate rock to increase oil and gas production has become one of the biggest challenges in reservoir stimulation. An adsorption film formed on rocks can effectively postpone the contact between the hydrogen ion and rock, which is of great significance in decreasing the rate of an acid-rock reaction. In this study, nonionic acidizing retarder AAO was synthesized by acrylamide, allyl poly(ethylene glycol), and octadecyl methacrylate. The structure of AAO was characterized by Fourier transform infrared (FT-IR) spectrometry and 1H nuclear magnetic resonance (1H NMR). The reaction of AAO retard acid and 20% hydrochloric acid with CaCO3 was studied at 50 °C, and the amount of CO2 generated at different times was recorded. The etching time of 0.8% AAO retard acid to CaCO3 could be up to 120 min, whereas 20% hydrochloric acid (without AAO) ended at 45 min, which showed that AAO had the potential to defer the acid-rock reaction. The adsorption behavior of AAO on CaCO3 matched the pseudo-second-order kinetic model well. Meanwhile, the addition of urea greatly reduced the adsorption amount of AAO on CaCO3, which showed that the hydrogen bond was the driving force for the adsorption process. Additionally, the results of X-ray photoelectron spectroscopy (XPS) showed that the N element from acrylamide appeared on the surface of CaCO3 after adsorption. Scanning electron microscopy (SEM) demonstrated that a smooth and dense thin film existed on the surface of CaCO3 treated with AAO retard acid. The change in the vibration peak of C=O from 1720 to 1650 cm-1 indicated that the ester groups in AAO had been hydrolyzed, which was beneficial to film desorption and the reduction of reservoir damage. Therefore, this paper could help with research on carbonate acidizing for reservoir stimulation.

Interaction between hydrophobic chitosan derivative and asphaltene in heavy oil to reduce viscosity of heavy oil.

The high viscosity of heavy oil made it difficult to exploit and transport heavy oil in pipeline. In this research, N-[(2-hydroxy-3-trimethylammonium) propyl] O-stearoyl chitosan tetraphenylboride (sc-CTS-st) was synthesized from chitosan, 2, 3-epoxy-propyl trimethyl ammonium chloride, sodium tetraphenylboron and stearyl chloride. sc-CTS-st contains long chain saturated aliphatic hydrocarbon, hydroxyl group and benzene ring, which could be dissolved in heavy oil fully and interacted with asphaltene. At 50 °C, the viscosity of heavy oil could be reduced to 13,800 mPa·s at most, with a viscosity reduction rate of 57.54 %. SEM and XRD showed that sc-CTS-st could affect the supramolecular accumulation structure of asphaltenes. Using FT-IR, sc-CTS-st could interact with asphaltene in the form of hydrogen bonds using the polar parts of the molecule, thereby weakening the self-association between asphaltene molecules. Molecular simulation was used to demonstrate the interaction mechanism between chitosan derivatives and asphaltenes. sc-CTS-st interacted with asphaltene through chemical bonding and influenced the self-association of asphaltene molecules. In addition, the non-polar portion of sc-CTS-st molecules could form a coating on the outside of the asphaltenes stacking structure, thus shielding or reducing the polarity of the stacking structure surface.

Soybean-Oil-Based CO2-Switchable Surfactants with Multiple Heads.

Oligomeric surfactants display the novel properties of low surface activity, low critical micellar concentration and enhanced viscosity, but no CO2 switchable oligomeric surfactants have been developed so far. The introduction of CO2 can convert tertiary amine reversibly to quaternary ammonium salt, which causes switchable surface activity. In this study, epoxidized soybean oil was selected as a raw material to synthesize a CO2-responsive oligomeric surfactant. After addition and removal of CO2, the conductivity analyzing proves that the oligomeric surfactant had a good response to CO2 stimulation. The viscosity of the oligomeric surfactant solution increased obviously after sparging CO2, but returned to its initial low viscosity in the absence of CO2. This work is expected to open a new window for the study of bio-based CO2-stimulated oligomeric surfactants.

Tuning CO2-induced reversible redispersion or irreversible destabilisation for latex separation.

HYPOTHESIS: The CO2-sensitive dispersion/precipitation transition of polymer latexes fabricated based on a responsive emulsifier is a promising way to conveniently acquire bulk polymer materials. Nevertheless, the tedious synthesis procedures for switchable surfactants and the harsh operating requirements for the sensitive latexes constrain the applicability of the approach for latex preparation. Therefore, a new strategy for generating latexes with tunable CO2 responsiveness in a maneuverable way is urgently needed. EXPERIMENTS: In this work, a CO2-switchable electrostatic interaction is introduced to construct responsive latexes. A series of lightly crosslinked poly(diethylaminoethyl methacrylate-styrene) [P(DEA-St)] latexes with different PDEA contents were fabricated via one-pot emulsion copolymerization, with divinylbenzene and sodium dodecylsulfate (SDS) used as the crosslinker and anionic emulsifier, respectively. The influence of the DEA feeding ratio on the resulting P(DEA-St) colloids was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. Then, a cyclic CO2/N2 input was introduced to verify the response transitions of polymer latexes. FINDINGS: Accompanied by the stepwise decrease of DEA feeding ratio, the morphology of the resulting copolymerized nanoparticles changed from an ambiguous bulge to the typical spherical pattern. In addition, the P(DEA-St) latexes treated by cyclic CO2/N2 exhibit four different types of response modes, namely (i) CO2-switchable swelling/deswelling transition, (ii) CO2-reversible dispersion/coagulation transition, (iii) CO2-induced irreversible destabilisation and (iv) CO2-insensitive latexes. The CO2-responsive destabilisation is highly applicable in the separation and transportation fields of commercial latex products, such as poly(methyl methacrylate), poly(n-butyl acrylate) and poly(butyl methacrylate) colloids.

The Thermoviscosifying Behavior of Water-Soluble Polymer Based on Graft Polymerization of Pluronic F127 with Acrylamide and 2-Acrylamido-2-methylpropane Sulfonic Acid Sodium Salt.

A new concept of thermoviscosifying polymers is proposed to address the problems about decreasing viscosity of polymer solution under high temperatures. However, existing thermoviscosifying polymers have complicated synthesis processes and high costs, and both of them restrict the wide practical applications of thermoviscosifying polymers. Although polyethers have the characteristics of thermal gelatinization, they just display thermoviscosifying behaviors only under extremely high concentrations (>15 wt %). Therefore, the graft copolymerization of the commercialized Pluronic F127 (PEO100-PPO65-PEO100) with acrylamide and 2-acrylamide-methylpropionic acid sodium salt was studied here. A series of graft modified polyether polymers were prepared and it was expected to get thermoviscosifying polymers with high molecular weights and low association temperatures. Several factors on thermoviscosifying behaviors were investigated, such as polymerization condition, polymer concentration, hydrophilic monomer, molecular structure and molecular weight. It was also proven that the apparent viscosity of polymer solution is influenced by polymer concentration, molecular weight of polymer, and content of anion groups.

Adsorption-desorption behavior of the hydrophobically associating copolymer AM/APEG/C-18/SSS.

In this study, acrylamide (AM), allyl polyethylene-1000 (APEG), octadecyl dimethyl allyl ammonium chloride (DMDAAC-18), and sodium styrene sulfonate (SSS) were chosen to synthesize a quadripolymer (HPAAT) in which a hydrophobic association exists between the molecules. The critical concentration of the hydrophobic association was determined using fluorescence spectrophotometry. Furthermore, HPAAT formed films by adsorbing onto a carbonate rock surface. The molecular structure of HPAAT was characterized using Fourier-transform infrared spectroscopy and 1H-NMR spectroscopy, the results showed that the obtained product was consistent with the target product. The intrinsic viscosity was determined using an Ubbelohde viscometer. The molecular weight and dispersion exponent of HPAAT were determined using gel permeation chromatography. Addition of HPAAT into 20% HCl decreased the reaction rate of the acid rock obviously, even at a low viscosity. Variation of the reaction rate with time with different amounts of HPAAT was investigated using the volume of carbon dioxide gas produced. The adsorption and desorption of HPAAT on a carbonate rock surface were demonstrated using infrared spectroscopy analysis, scanning electron microscopy and ultraviolet spectrophotometry.