Zeolites are crystalline materials composed of silica and alumina linked by oxygen bridges. They exhibit a highly ordered pore structure that allows them to be applied in a variety of ways, including as acid/base catalysts (e.g., strong acid catalysts in heavy oil fluidized catalytic cracking), adsorbents (e.g., high-performance moisture adsorbents in dehydration processes), and cation exchange resins (e.g., water softeners). Considerable research has been devoted to developing new zeolite structures and compositions that enhance their performance across these applications. Macro-level analytical techniques such as nitrogen adsorption measurements, X-ray diffraction, and electron microscopy have been traditionally performed for zeolite material characterization. However, as energy efficiency and carbon footprint concerns escalate, the focus has shifted towards engineering novel zeolite materials that have precise surface properties in order to optimize their performance. This shift underscores the need for advanced analytical techniques for the molecular or atomic-level structural and physicochemical characterization of zeolites. Solid-state nuclear magnetic resonance (ssNMR) spectroscopy provides high-resolution information at the atomic scale, making it a valuable tool for this purpose. This review comprehensively examines the application of ssNMR techniques for analyzing zeolite materials within clean technology research and details fundamental principles and usage cases to demonstrate ssNMR’s relevance and utility in the field. In addition, this review summarizes previous research that has demonstrated how to characterize the structural and acidic properties of zeolites and how to reveal the detailed mechanisms of methanol-to-olefin and ethylene-to-propylene reactions.

The demand for methanol as an alternative marine fuel is increasing. However, due to the high production costs and the instability of renewable energy supplies, green methanol currently accounts for less than 1% of the total methanol production. To address the challenges associated with green methanol, it is essential to improve the methanol yield and its energy efficiency in order to enhance the performance of the production process overall. This study proposes a novel green methanol production process that integrates solid oxide electrolyzer cell (SOEC)-based green hydrogen production with biogas partial oxidation. The proposed process minimizes carbon loss by injecting additional green hydrogen. As a result, this process achieved a methanol yield of 88.51%. Furthermore, by recovering waste heat from the biogas partial oxidation and methanol synthesis reactions and using it to produce steam, the energy efficiency of the proposed process was improved by 177% and 7% compared to the conventional e-methanol and bio-methanol processes, respectively.

The objective of this study is to investigate the characteristics and reaction properties of Pt/HY catalysts for hydro-upgrading reaction to produce bio-jet fuel from bio-oil. Pt catalysts supported on HY zeolite were synthesized, and their Si/Al₂ ratio was varied to evaluate catalyst properties and reactivity. BET, NH₃-TPD, and pyridine FT-IR analyses were conducted to characterize the catalysts. The hydro-upgrading reaction, which involves simultaneous hydrocracking and isomerization, was studied using n-octadecane as a model compound. This study aims to elucidate the influence of the structure and acid sites of Pt/HY catalysts on the hydro-upgrading performance of n-octadecane and to propose optimal catalyst conditions. It was observed that as the Si/Al₂ molar ratio of the synthesized Pt/HY catalysts increased from 5.2 to 60, the development of mesopores became more pronounced. NH₃-TPD analysis revealed that as the Si/Al₂ ratio increased, both the number and strength of acid sites decreased, and the ratio of weak to strong acid sites gradually declined. Furthermore, an increase in the Si/Al₂ ratio led to a reduction in Brønsted acid sites. The hydro-upgrading reaction of n-octadecane using Pt/HY catalysts was conducted in a continuous fixed-bed reactor. Pt/HY(60) exhibited the highest conversion, while a decreasing Si/Al₂ molar ratio resulted in lower conversion. The Pt/HY(60) catalyst also showed the highest selectivity and yield for jet fuel-range hydrocarbons (C8~C17), as well as excellent isomer selectivity. These results suggest that in the hydro-upgrading reaction of n-octadecane, the acid site density and strength of the Pt/HY(60) catalyst are optimal for achieving a suitable balance between cracking and isomerization to produce jet fuel fractions. Additionally, when evaluating the effect of reaction pressure on the hydro-upgrading of n-octadecane using Pt/HY(60), the highest jet fuel yield was obtained at 10 bar, while isomer selectivity was not significantly affected by pressure.

A new type of continuous microwave reformer was developed and high-quality reforming energy conversion characteristics were studied in order to solve this problem and the results are as follows; The reforming conversion rate was improved only when the residence time of biogas in the microwave carbide bed is sufficiently secured since the amount of biogas supplied is small, biogas is supplied in an appropriate ratio to eliminate the problem of carbon active layer failure, and steam is supplied in an appropriate amount to increase the cleaning effect and the temperature increase rate of the receptor layer was increased by supplying a portion of SIC to the carbon receptor from the microwave receptor. The optimal operating conditions of the microwave reformer are gas supply amount 10 L/min, reforming temperature 900oC, biogas CH4 60% : CO2 40%, steam supply 10 mL/min, receptor biochar 75% : SiC 25%, CH4 conversion rate and CO2 conversion rate are 96.6%, respectively, 96.7%, gas calorific value of 11.53 MJ/Nm3 and H2 selectivity of 72.2, making it possible to produce low-carbon, high-quality biofuel with high hydrogen yield.

Microplastics, particularly poly(ethylene terephthalate), have become a significant environmental concern due to their persistence in aquatic ecosystems. This study presents an ecofriendly approach for PET degradation using Vibrio natriegens (Vn)-derived outer membrane vesicles (OMVs) as carriers for immobilized PETase, a PET-degrading enzyme. Vn was engineered to express a membrane-anchored PETase, which was subsequently secreted as part of the OMVs upon cultivation. These PETase-immobilized OMVs (PETase-OMVs) were harvested via membrane filtration. They had a spherical structure with a size of 150 nm, and displayed significant PET degradation activity because they could effectively break down PET microplastics into monomeric units. This study highlights the potential of using OMVs as a versatile and stable platform for enzyme immobilization in order to create an environmentally friendly and sustainable solution to plastic waste in aquatic environments.

The development of organic thermoelectric (TE) materials with three-dimensional structures is essential to meet the growing demand for lightweight, flexible, and efficient energy-harvesting systems in wearable electronics. This study developed poly(3,4- ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) and ionic liquid (IL) composite foams with enhanced TE properties through the incorporation of ethyl-3-methylimidazolium dicyanamide (EMIM DCA) and a freeze-drying process. The electrical conductivity (v) increased by over 1000 times to 19 S cm–1, while the Seebeck coefficient (S) improved by 1.5 times to 26 nV K–1. These increases resulted in a power factor enhancement of over 3,000 times to 1.3 nW m–1 K–2. Scanning electron microscopy revealed larger pore sizes and a well-connected conductive network in the PEDOT:PSS/IL composite foams. The pores and conductive network improved the charge transport and σ. Raman spectroscopy further confirmed the role of EMIM DCA in inducing de-doping effects, thereby enhancing the S of PEDOT:PSS. These findings establish PEDOT:PSS/IL composite foams as promising lightweight and flexible materials for next-generation wearable TE devices because they offer practical solutions for efficient energy-harvesting.

The utilization of renewable energy and the development of low-carbon technologies are gaining attention in response to climate change. This study synthesized TiNi catalysts to mitigate the intermittency problems associated with renewable energy and improve the hydrogenation characteristics of MgH2, which can safely store hydrogen. In addition, the catalyst was dispersed with graphene oxide to reduce aggregation and the catalyst’s properties were evaluated. XRD, SEM, and BET analyses were performed to confirm the metallurgical properties of the hydrogen storage composite, and PCT (pressure-composition-temperature) was used to observe the hydrogen adsorption behavior. The results showed that the hydrogen adsorption rate of MgH2 was improved when more than 10 wt% TiNi was used as a catalyst, and the hydrogenation reaction rate was improved when 5 wt% graphene oxide was added. Therefore, the effect of graphene oxide on reducing the aggregation phenomenon of TiNi catalyst was confirmed.

In this study, the effect of adding Ce to Fe-based oxygen carriers on the ethylene selectivity of chemical looping oxidative dehydrogenation (CL-ODH) was investigated. A comparative analysis between the Ce-added oxygen carrier and the conventional Fe₂O₃ carrier revealed that the Ce-added oxygen carrier exhibited reduced COₓ selectivity and enhanced ethylene selectivity. Through X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H₂-temperature programmed reduction (H₂- TPR), and thermogravimetric analysis (TGA), it was confirmed that the addition of Ce regulates the reduction rate of Fe oxides. This regulation contributes to the stable control of oxygen mobility, thereby suppressing over-oxidation and improving the selectivity of the CL-ODH reaction. The results of this study suggest that Ce can serve as an effective additive for enhancing ethylene selectivity in Fe-based oxygen carriers for CL-ODH processes. The results also provide fundamental insights for further development of high- efficiency oxygen carriers in the future.

Developing high-performance solid-state electrolytes is being researched extensively because they are a viable alternative to the inflammable liquid-phase organic electrolytes used in lithium ion batteries (LIBs). In this study, the performance of solid-state LIBs using a Li7La3Zr2O12 (LLZO)/poly(ethylene oxide) (PEO) composite electrolyte in conjunction with SnO₂-based electrodes was systematically optimized. The LIB charge/discharge performances were initially evaluated as a function of LLZO:PEO mass ratios (e.g., 20:80, 40:60, 60:40, 80:20). The best performing 20:80 LLZO:PEO composite electrolyte was then integrated with high-surface-area SnO₂ nanowire electrodes to further enhance the fast-charging capabilities of solid-state LIBs.