Nut-like MOF/hydroxylated graphene hybrid materials for adsorptive desulfurization of thiophene

Coupling Structural and Adsorption Properties of Metal-Organic Frameworks: From Pore Size Distribution to Pore Type Distribution

Metal-organic frameworks (MOFs) attract a rapidly growing attention across the disciplines due to their multifarious pore structures and unique ability to selectively adsorb, store, and release various guest molecules. Pore structure characterization and coupling of adsorption and structural properties are imperative for rational design of advanced MOF materials and their applications. The pore structure of MOFs represents a three-dimensional network comprised of several types of pore compartments: interconnected cages and channels distinguished by their size, shape, and chemistry. Here, we propose a novel methodology for pore structure characterization of MOF materials based on matching of the experimental adsorption isotherms to in silico-generated fingerprint isotherms of adsorption in individual pore compartments of the ideal crystal. The proposed approach couples structural and adsorption properties, determines the contributions of different types of pores into the total adsorption, and estimates to what extent the pore structure of the sample under investigation is different from the ideal crystal. The MOF pore structure is characterized by the pore type distribution (PTD), which is more informative than the traditional pore size distribution that is based on oversimplistic pore models. The method is illustrated on the example of Ar adsorption at 87 K on hydrated and dehydrated structures of Cu-BTC, one of the most well-known MOF materials. The PTD determined from the experimental isotherm provides an estimate of the crystal fraction in the sample and the accessibility and degree of hydration of different types of pore compartments. In addition, the PTD determined from the experimental adsorption isotherm is used to predict the isosteric heat of adsorption that provides important information on the specifics of adsorption interactions. The results are found to be in excellent agreement with experimental data. Such detailed information about the pore structure and adsorption properties of practical MOF samples cannot be obtained with currently available methods of adsorption characterization.

Research advancements in sulfide scavengers for oil and gas sectors

Sulfide species (inorganic and organic sulfides) are well known for their toxicity and corrosiveness. Several industries, including oil and gas, are prone to corrosive damage due to sulfides that necessitate their timely removal using appropriate methods. Employing chemical scavengers is the most suitable method where the scavenger combine with dissolved sulfides in aqueous/hydrocarbon phase and convert them to a nontoxic and less corrosive form that can be easily removed from the stream. Instead of direct chemical scavenger addition, different approaches, including absorption and adsorption methods, are employed in eliminating sulfide species from gas streams in different industrial applications. This review provides a detailed account of various sulfide scavengers used in oil and gas sweetening. Most recent research advancements in this area are highlighted. A brief account of the latest reported works on novel adsorbents for the desulfurization process for refinery fuels is also provided. The review ends with a short discussion on catalytic hydrodesulfurization.

Improved Chloride Ion Sensing Performance of Flexible Ag-NPs/AgCl Electrode Sensor Using Cu-BTC as an Effective Adsorption Layer

We designed the flexible chloride ion selective sensor that directly monitors electrochemical reactions of chloride ions without using a reference electrode. A flexible polytetrafluoroethylene (PTFE) substrate was utilized to provide bendability to the fabricated sensor. As an ion selective material, Ag nanoparticles were employed on the MWCNTs loaded on the PTFE substrate. Enhanced adsorption property of the fabricated sensor toward the chloride ions was given by incorporation of hydrophilic copper benzene-1,3,5-tricarboxylate (Cu-BTC) with great flexibility and stability. Accordingly, compared to the bare sensor the sensing performance of the Cu-BTC treated Ag NPs/AgCl electrode sensor was improved by indicating the decrease in response and recovery time about 4 times. It elucidated that the Cu-BTC layer could work as an effective medium between the Ag-NPs surface and electrolyte containing chloride ions. As a result of contact angle measurement, the hydrophilicity much increased in the Cu-BTC treated sensor because the exposed surface of the sensor not treated by the Cu-BTC largely consisted of hydrophobic MWCNTs. Furthermore, the Cu-BTC layer could hold the electrolyte for effective adsorption of analytes with large specific surface area.

Carbon Nanomaterials for the Adsorptive Desulfurization of Fuels

The increasing demand for cleaner fuels and the recent stringent regulations of commercial fuel specifications have driven the research of alternative methods to upgrade the current industrial desulfurization technology. Adsorptive desulfurization, the removal of refractory sulfur compounds using appropriate selective tailor-made adsorbents, has shown up as a promising alternative in the recent years. Carbon nanomaterials, namely, graphene, graphene oxide, carbon nanotubes and carbon nanofibers, show a significant potential as desulfurization adsorbents. Their surface area and porosity, their ability of easy functionalization, and their suitability to serve as a support of different types of adsorbents have rendered them attractive candidates for this purpose. In this review, after a presentation of the current industrial desulfurization practice and its limitations, the structure and properties of the carbon nanomaterials of interest will be described, followed by a detailed account of their applications in adsorptive desulfurization. The major literature findings and conclusions will be presented and discussed as a road map for future research in the field.