The corrosion inhibition properties of 2-(1,3,4-thiadiazole-2-yl)pyrrolidine (2-TP) on mild steel in a 1 M HCl solution were investigated using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and open circuit potential (OCP) measurements. In addition, DFT calculations were performed on 2-TP. The polarization curves revealed that 2-TP is a mixed-type inhibitor. The results indicate that 2-TP is an effective inhibitor for mild steel corrosion in a 1.0 M HCl solution, with an inhibition efficiency of 94.6% at 0.5 mM 2-TP. The study also examined the impact of temperature, revealing that the inhibition efficiency increases with an increasing concentration of 2-TP and decreases with a rise in temperature. The adsorption of the inhibitor on the mild steel surface followed the Langmuir adsorption isotherm, and the free energy value indicated that the adsorption of 2-TP is a spontaneous process that involves both physical and chemical adsorption mechanisms. The DFT calculations showed that the adsorption of 2-TP on the mild steel surface is mainly through the interaction of the lone pair of electrons on the nitrogen atom of the thiadiazole ring with the metal surface. The results obtained from the weight loss, potentiodynamic polarization, EIS and OCP measurements were in good agreement with each other and confirmed the effectiveness of 2-TP as a corrosion inhibitor for mild steel in 1.0 M HCl solution. Overall, the study demonstrates the potential use of 2-TP as a corrosion inhibitor in acid environments.
Metal-based adsorbents with varying active phase loadings were synthesized to capture hydrogen sulfide (H2S) from a biogas mimic system. The adsorption-desorption cycles were implemented to ascertain the H2S captured. All prepared adsorbents were evaluated by nitrogen adsorption, Brunauer-Emmett-Teller surface area analysis, scanning electron microscopy-energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. From the results, modified adsorbents, dual chemical mixture (DCM) and a core-shell (CS) had the highest H2S adsorption performance with a range of 0.92-1.80 mg H2S/g. After several cycles of heat/N2 regeneration, the total H2S adsorption capacity of the DCM adsorbent decreased by 62.1%, whereas the CS adsorbent decreased by only 25%. Meanwhile, the proposed behavioral model for H2S adsorption-desorption was validated effectively using various analyses throughout the three cycles of adsorption-desorption samples. Moreover, as in this case, the ZnAc2/ZnO/CAC_OS adsorbents show outstanding performances with 30 cycles of adsorption-desorption compared to only 12 cycles of ZnAc2/ZnO/CAC_DCM. Thus, this research paper will provide fresh insights into adsorption-desorption behavior through the best adsorbents' development and the adsorbents' capability at the highest number of adsorption-desorption cycles.
There is growing interest in using corrosion inhibitors and protective treatments to limit the degradation of mild steel, leading to the development of numerous Schiff bases as cutting-edge inhibitors. In this study, the effectiveness of a Schiff base, 3-((5-mercapto-1,3,4-thiadiazol-2-yl)imino)indolin-2-one (MTIO), to prevent mild steel corrosion in HCl was investigated using weight loss measurements, potentiodynamic polarization measurements, electrochemical impedance spectroscopy techniques, and surface characterization. The experimental results showed that 0.5 mM MTIO exhibited a satisfactory inhibitor efficiency of 96.9% at 303 K. The MTIO molecules physically and chemically adsorbed onto the mild steel surface following the Langmuir model, forming a compact protective film attributed to the presence of a thiazole ring in the MTIO structure. Theoretical calculations were combined with experimental techniques to investigate the anticorrosion performance and mechanism of inhibition.
Carbon-intensive industries must deem carbon capture, utilization, and storage initiatives to mitigate rising CO2 concentration by 2050. A 45% national reduction in CO2 emissions has been projected by government to realize net zero carbon in 2030. CO2 utilization is the prominent solution to curb not only CO2 but other greenhouse gases, such as methane, on a large scale. For decades, thermocatalytic CO2 conversions into clean fuels and specialty chemicals through catalytic CO2 hydrogenation and CO2 reforming using green hydrogen and pure methane sources have been under scrutiny. However, these processes are still immature for industrial applications because of their thermodynamic and kinetic limitations caused by rapid catalyst deactivation due to fouling, sintering, and poisoning under harsh conditions. Therefore, a key research focus on thermocatalytic CO2 conversion is to develop high-performance and selective catalysts even at low temperatures while suppressing side reactions. Conventional catalysts suffer from a lack of precise structural control, which is detrimental toward selectivity, activity, and stability. Core-shell is a recently emerged nanomaterial that offers confinement effect to preserve multiple functionalities from sintering in CO2 conversions. Substantial progress has been achieved to implement core-shell in direct or indirect thermocatalytic CO2 reactions, such as methanation, methanol synthesis, Fischer-Tropsch synthesis, and dry reforming methane. However, cost-effective and simple synthesis methods and feasible mechanisms on core-shell catalysts remain to be developed. This review provides insights into recent works on core-shell catalysts for thermocatalytic CO2 conversion into syngas and fuels.
Hydrogen (H2) represents a promising avenue for reducing carbon emissions in energy systems. However, achieving its widespread adoption requires more effective and scalable synthesis methods. Herein, we investigated the isothermal carburization process of the MoO3 catalyst. This reaction was carried out at a constant temperature of 700 °C in a 60% CO/He stream, with hold reaction times varying (60-min, 90-min, and 120-min). This investigation was conducted using a micro-reactor Autochem with the aim of enhancing the yield of H2. The study focused on evaluating the chemical reduction and carburization behavior of the MoO3 catalyst through X-ray diffraction (XRD), transmission electron microscopy (TEM), and CHNS elemental analysis. The XRD analysis revealed the formation of carbides, Mo2C, and MoO2, serving as active sites for subsequent H2 production in the thermochemical water splitting (TWS) process. The carburization at a 60-min hold time exhibited enhanced H2 production, generating approximately ~ 6.60 µmol of H2 with a yield of up to ~ 32.90% and a conversion rate of ~ 54.83%. This finding emphasizes the essential role played by the formation of carbides, particularly Mo2C, in the carburization process, contributing significantly to the facilitation of H2 production. These carbides serve as exceptionally active catalytic sites that actively promote the generation of hydrogen. This study underscores that the optimized duration of catalyst exposure is a key factor influencing the successful carburization of MoO3 catalysts. This emphasizes how important carbide species are to increasing H2 efficiency. Additionally, it is noted that carbon formation on the MoO3 active sites can act as a potential poison to the catalysts, leading to rapid deactivation after prolonged exposure to the CO precursor.
Using traditional weight-loss tests, as well as different electrochemical techniques (potentiodynamic polarization and electrochemical impedance spectroscopy), we investigated the corrosion-inhibition performance of 2,2′-(1,4-phenylenebis(methanylylidene)) bis(N-(3-methoxyphenyl) hydrazinecarbothioamide) (PMBMH) as an inhibitor for mild steel in a 1 M hydrochloric acid solution. The maximum protection efficacy of 0.0005 M of PMBMH was 95%. Due to the creation of a protective adsorption layer instead of the adsorbed H2O molecules and acidic chloride ions, the existence of the investigated inhibitor reduced the corrosion rate and increased the inhibitory efficacy. The inhibition efficiency increased as the inhibitor concentration increased, but it decreased as the temperature increased. The PMBMH adsorption mode followed the Langmuir adsorption isotherm, with high adsorption-inhibition activity. Furthermore, the value of the ∆Gadso indicated that PMBMH contributed to the physical and chemical adsorption onto the mild-steel surface. Moreover, density functional theory (DFT) helped in the calculation of the quantum chemical parameters for finding the correlation between the inhibition activity and the molecular structure. The experimental and theoretical findings in this investigation are in good agreement.