Zeolites, with their exquisite microporous frameworks and tailorable acidities, serve as ubiquitous catalysts across a diverse spectrum of industrial applications, ranging from petroleum and coal processing to sustainable chemistry and environmental remediation. Optimizing their performance hinges on a thorough understanding of the structure-performance relationship. In situ solid-state nuclear magnetic resonance spectroscopy has emerged as a critical tool, providing unparalleled atomic-level insights into both structure and dynamic aspects of zeolite-catalyzed reactions. Herein, we review recent progress in the development and application of the in situ solid-state nuclear magnetic resonance technique to zeolite catalysis. We first review the in situ nuclear magnetic resonance techniques used in zeolite-catalyzed reaction, including batch-like and continuous-flow reaction modes. The conditions and limitations for these techniques are thoroughly summarized. Subsequently, we review the applications of in situ nuclear magnetic resonance techniques in zeolite-catalyzed reaction, focusing on some important catalytic reactions like methanol-to-hydrocarbons, ethanol dehydration, alkane activation, and beyond. Emphasis is placed on the strategies of specific in situ nuclear magnetic resonance methodologies to tackle critical challenges encountered in these fields, such as probing intermediates and unraveling reaction mechanisms. Additionally, we discuss the burgeoning opportunities and prospective challenges associated with in situ nuclear magnetic resonance studies of zeolite-catalyzed processes.
The urgent need for sustainable waste management has led to the exploration of upcycling waste plastics and biomass as viable solutions. In 2018, global plastic production reached 359 million tonnes, with an estimated 12000 million tonnes projected to be delivered and disposed of in landfills by 2050. Unfortunately, current waste management practices result in only 19.5% of plastics being recycled, while the rest is either landfilled (55%) or incinerated (25.5%). The improper disposal of plastics contributes to issues such as soil and groundwater contamination, air pollution, and wildlife disturbance. On the other hand, biomass has the potential to deliver around 240 exajoules of energy per year by 2060. However, its current utilization remains relatively small, with only approximately 9% of biomass-derived energy being consumed in Europe in 2017. This review explores various upcycling methods for waste plastics and biomass, including mechanical, chemical, biological, and thermal approaches. It also highlights the applications of upcycled plastics and biomass in sectors such as construction, packaging, energy generation, and chemicals. The environmental and economic benefits of upcycling are emphasized, including the reduction of plastic pollution, preservation of natural resources, carbon footprint reduction, and circular economy advancement.
Nowadays, global warming caused by the increasing levels of CO2 has become a serious environmental problem. Membrane separation technology has demonstrated its promising potential in carbon capture due to its easy operation, energy-efficientness and high efficiency. Interfacial polymerization process, as a facile and well-established technique for preparing membranes with a thin selective layer, has been widely used for fabricating commercial reverse osmosis and nanofiltration membranes in water treatment domain. To push forward such an interfacial polymerization process in the research of CO2 separation membranes, herein we make a review on the regulation and research progress of the interfacial polymerization membranes for CO2 separation. First, a comprehensive and critical review of the progress in the monomers, nanoparticles and interfacial polymerization process optimization for preparing CO2 separation membrane is presented. In addition, the potential of molecular dynamics simulation and machine learning in accelerating the screen and design of interfacial polymerization membranes for CO2 separation are outlined. Finally, the possible challenges and development prospects of CO2 separation membranes by interfacial polymerization process are proposed. It is believed that this review can offer valuable insights and guidance for the future advancement of interfacial polymerization membranes for CO2 separation, thereby fostering its development.
Metal-organic frameworks have a wide range of applications in the field of membrane separation, but the inherent flexible structure and the difficulty for scale-up hinder their further applications. Herein, the relatively rigid zeolitic imidazolate framework-8 particles prepared under an electric field (E-ZIF-8) were used as the fillers in polysulfone (PSF) to form series of mixed matrix membranes. It was found that the introduction of E-ZIF-8 improves both the C3H6 permeability and C3H6/C3H8 selectivity of the membranes. Compared with the bare PSF membrane, the C3H6/C3H8 selectivity of the 30 wt % E-ZIF-8@PSF membrane increased by ~230%, while the C3H6 permeability was enhanced by ~830%. In addition, time and pressure dependence analysis demonstrated that such E-ZIF-8@PSF membranes also exhibited good long-term stability and pressure resistance, offering significant industrialization advantages.
The dynamics of methanol within prototype methanol synthesis catalysts were studied using quasi-elastic neutron scattering. Three Cu-exchanged zeolites (mordenite, SSZ-13 and ZSM-5) were studied after methanol loading and showed jump diffusion coefficients between 1.04 × 10−10 and 2.59 × 10−10 m2·s–1. Non-Arrhenius behavior was observed with varying temperature due to methoxy formation at Brønsted acid sites and methanol clustering around copper cations.
Coal utilization, as a major energy source, raises sustainability concerns and environmental impacts, prompting researchers to explore blending it with other feedstocks. This study discusses hydrochar coal-water slurry (HC-CWS) preparation conditions, emphasizing apparent viscosity and exploring the influence of high ash content on char reactivity. The study highlights that the presence of free water in sludge is moderately influential, while high amounts of free water in raw sewage sludge (SS) and its near absence during hydrothermal carbonization (HTC) of SS are both unfavorable for enhancing the overall performance of coal-water slurry (CWS). HTC reduces the concentration of hydroxyl functional group, enhancing slurry performance and reducing ash content in HC-CWS, indicating that coal complements hydrochar (HC). High-temperature HC preparation is unsuitable for HC-CWS due to increased viscosity and decreased stability. In terms of ash content, the optimal pH and HC ratio for CWS are determined at 30% HC. The gasification reactivity of HC, prepared at 180 °C with a 30% HC ratio in CWS at R0.5 is 6 × 10−3 and at R0.9 is 9 × 10−3. However, increasing HC to 50% diminishes reactivity under CO2 atmosphere. The inhibitory effect was observed with an increasing percentage of HC in CWS and the synergy factor decreased in the following order: 10% HC > 30% HC > 50% HC, i.e., from 1.04 to 0.35. The possible reason is the presence of high ash content and their similar initial gasification rates during its early stages.
The rapid migration and separation of photoinduced carriers is a key factor influencing photocatalytic efficiency. Constructing an S-scheme heterojunction is a strategic technique to enhance the separation of photogenerated carriers and boost overall catalytic activity. Herein, a simple physical stirring technique was adopted to successfully fabricate a novel NiCo2S4/CoTiO3 S-scheme heterojunction photocatalyst. Upon exposure to light, the NiCo2S4/CoTiO3-10 specimen demonstrated an outstanding hydrogen evolution rate of 2037.76 μmol·g–1·h–1, exceeding twice the rate observed for the pristine NiCo2S4 (833.72 μmol·g–1·h–1). The experimental outcomes reveal that the incorporation of CoTiO3 significantly enhances the charge separation and transfer within the system. Concurrently, the formation of the S-scheme mechanism facilitates the separation of carriers while maintaining high redox capabilities. This work introduces an innovative approach to forming S-scheme heterojunctions based on bimetallic sulfides, thereby offering new prospects for the efficient utilization of solar energy.
