Carbon dioxide (CO2) capture and storage (CCS) technologies and catalytic CO2 transformation may become extremely important for mitigating global warming, but still present major challenges. Poly(ethyleneimine) (PEI) contains a high density of amine moieties in its polymer chain, so is considered one of the promising adsorbents for CCS technology. This review describes the design, preparation, and applications of multi-functional adsorbents and catalysts using PEI as CO2 adsorbent and nanoporous materials as supports for efficient capture and catalytic transformation of CO2. A series of PEI-mesoporous silica composites were prepared for CO2 capture applications from simulated CO2 gas streams with concentrations of 10 % and 400 ppm. Tuning of the surface acid/base properties of the mesoporous silicas via incorporation of heteroatoms (such as Zr and Ti) strengthened the interaction between PEI and the silica, resulting in significantly increased CO2 adsorption capacities, improved CO2 adsorption/desorption kinetics, and enhanced regeneration characteristics. Furthermore, hybrid catalysts consisting of metal complex/nanoparticles and PEI confined in chemically-stable nanoporous materials (such as titanate nanotubes and hollow mesoporous organosilica spheres) were fabricated for use as heterogeneous catalysts for hydrogenation of CO2 to formic acid (HCOOH), which is a key reaction for sustainable hydrogen energy cycles. The CO2 capture characteristics of PEI and the stabilizing effect of the support materials achieved high catalytic activity and reusability under moderate reaction conditions.
Coordination chemistry has established the principle of “organometallic smart design: metal × ligand” for metal complexes with specific properties and functions based on empirical rules and quantum chemistry considerations. Numerous metal complexes have subsequently been synthesized to catalyze required chemical reactions. This review describes several representative studies, especially concerning the reactions of designed metal complexes with dioxygen, dihydrogen, and methane gases. Copper-mediated dioxygen activation and nickel–iron-mediated dihydrogen activation were inspired by the enzymatic activities of tyrosinase and nickel–iron hydrogenase. Hydroxylation of arene ring, epoxidation of styrene, and oxidation of carbon–hydrogen bonds of hydrocarbons have been achieved using a dinuclear copper peroxide complex derived from dioxygen modelled on tyrosinase. Biomimetic dihydrogen oxidation and dioxygen reduction have been promoted by nickel–iron and nickel–ruthenium complexes in organic solvent and water, based on the oxygen-tolerant nickel–iron hydrogenase. The transformation of methane to methanol and formaldehyde using dioxygen as an oxidant has been achieved by input of light energy into a designed diruthenium dioxide complex.
Electromagnetic methods are used for the accurate integrity assessment of buried pipelines. A non-invasive electromagnetic inspection method for metallic pipelines is described which uses magnetic field line variations (MFLV) to determine the position and thickness of faults in metal pipes. The skin effect is applied to solve the framework problem and establish the measurements for identifying the vector angle variations. A simulation case of the mathematical assumptions was performed to verify the presence of damage in a pipeline by comparing magnetic field measurements at different transmitted signal frequencies. Finally, the technical specifications of the required electronic equipment were defined to implement the technology.
Improved catalyst performance for diesel hydrodesulfurization and meeting various requirements from each refinery was investigated using the machine learning technique to effectively and efficiently estimate the optimized grading ratio of selected hydrodesulfurization catalysts. A catalyst grading optimization program was developed based on “design of experiment” and “multi-objective optimization,” in which virtual experiments and multi-objective optimization were carried out to estimate the grading ratio of the optimum catalyst to minimize the refined oil sulfur concentration under specific conditions. The calculated evaluation value of the optimized grading system obtained from our program showed quite good agreement with the pilot experimental results using the same system. In addition, the pilot evaluation showed superior HDS activity of the grading system obtained from our program compared to the single catalysts used for the grading system as well as other catalyst systems with other grading ratios.
Our previous studies showed that microwaves change the interfacial characteristic of the oil-water system because it is strongly absorbed in the interface. At the same time, it was predicted that surfactant molecule is desorbed from the interface by the energy concentration of the microwave absorbance and the desorption level depends on the irradiation mode. Therefore, the quick increase of the interfacial tension by microwave-induced surfactant desorption could be used for a new estimation method of surfactant capability besides the HLB (Hydrophilic Lipophilic Balance) value. This study used surfactants with different hydrophilic or hydrophobic lengths, and interfacial tension was measured during and after microwave irradiation. It was found that the quick increase caused by surfactant desorption after pulse irradiation depends on the hydrophilic or hydrophobic length, and the ratio is closely correlated with HLB values. Surfactant desorption is caused by the rotation of water molecules at the interface due to the microwave absorption, and maximum interfacial tensions after each pulse irradiation represent the actual adsorption capacity. Finally, it is expected that interfacial tension obtained by microwave irradiation will become a new evaluation method for surfactants in future.