Toward Greener and Designed Synthesis of Zeolite Materials

Barros

et al. 2021

Silicon

The synthesis of mesoporous materials such as MCM-41 and SBA-15 requires large amounts of water to neutralize the resulting products. The ltrate (mother liquor) therefore contains unreacted components that can be recycled and reused. The addition of the mother liquor in consecutive syntheses was carried out in order to evaluate the different effects on the physical and chemical properties of the mesoporous materials. For this purpose, the mother liquor from the initial synthesis (1st Generation) was saved and used for the second synthesis (2nd Generation) and successively for the third synthesis (3rd Generation).The three generations of each material were then characterized using different techniques such as X-ray diffraction, X-ray dispersive energy uorescence, electron microscopy, infrared spectroscopy, Thermal behavior by thermogravimetric analysis and N 2 adsorption. The materials obtained showed similar diffractograms for the three generations and also showed similar percentages of silica through XRF. The SEM and IR results for molecular sieves showed the effectiveness of the processes of MCM-41 and SBA-15 synthesis using mother liquor. The results made it possible to observe that the structures of the materials had no signi cant differences in their physical and chemical properties, favoring the use of mother liquor for up to three generations.

Section: Introductionmentioning

confidence: 99%

Green Synthesis for MCM-41 and SBA-15 Silica Using the Waste Mother Liquor

Barros

et al. 2021

Silicon

Crystal Growth & Design

“…These upper bounds of performance for organic polymer membranes increase gradually with further development, but these do not approach the performances observed by other materials, for example, inorganic membranes. Efforts are being undertaken to pass this “Robeson upper bound” by the development of new polymeric materials, pure inorganic membranes like zeolites (crystalline, porous aluminosilicates), , metal–organic frameworks (MOFs), carbon molecular sieves (CMS), , carbon nanotubes (CNTs), and graphene or by combining different materials in so-called mixed-matrix membranes (MMMs) (see below).…”

Section: Introductionmentioning

confidence: 99%

Enhancing Mixed-Matrix Membrane Performance with Metal–Organic Framework Additives

Dechnik

Sumby

Janiak

2017

138

Metal–organic frameworks (MOFs), as porous fillers possessing molecular sieving properties, have been combined with polymers to give mixed-matrix membranes (MMMs) with enhanced separation performance. This field of research has produced a large number of different membranes, and many MOF/polymer combinations have been tested and reported to show potential application to industrial gas separation. Although MOFs have been proposed as novel additives with high porosity and tunable pore size, which were supposed to outperform other porous fillers, due to restrictions in separation performance of the filler and challenges concerning the compatibility of polymer and MOF, only a small fraction of these works report both improved permeability and selectivity. In this review these challenges are set into the context of MOF synthesis and membrane fabrication by the choice of appropriate polymer/MOF combinations, utilization of the MOF functional sites, modification of the MOF surface chemistry or pore texture and size, and also targeted influence of the size and shape of the filler particles. The effect of the highlighted MOF additives on the gas separation performance is analyzed and discussed by comparison of the gas permeability and selectivity. This emphasizes strategies by which high performing MMMs can be achieved through accessing the full potential of the porous MOF fillers.

“…The cathodic oxygen reduction reaction (ORR) process with sluggish reaction kinetics is critically linked to the overall performance of proton exchange membrane fuel cells (PEMFCs) and metal-air batteries. − Efficient electrocatalysts for ORR can boost the reaction, thus driving high current densities at low overpotentials. − However, Pt group metals as the most practical electrocatalysts suffer from prohibitive cost, significantly restricting the large-scale applications. − In this respect, tremendous strategies to highly expose Pt at the nanoparticle surface have been explored, such as high index facet, ultrathin nanowires, concave nanoframes, and specifically engineered alloy . Previous investigations have demonstrated that the performance is mainly affected by the spatial location, size distribution, metal–support interaction, and the microenvironment of Pt electrocatalysts. − Specifically, Pt supported on porous materials can have two distinct spatial locations: they are either attached to the outer surface or inside the support.…”

Section: Introductionmentioning

confidence: 99%

Regioselective Control of Ultralow Concentrations of Pt Nanoparticles on Zeolite-Templated Carbon for Oxygen Reduction Reaction

Li,

Ou,

Liu

et al. 2024

ACS Appl. Nano Mater.

Supported electrocatalysts on porous carbons show excellent electrocatalytic oxygen reduction reaction (ORR) performance, but there are few works about selectively controlling Pt locations on supports for an ultralow content and excellent properties. Herein, we demonstrated a Pt location-selective strategy using transformative support engineering to reduce the Pt content and tune the ORR performance. The electrocatalyst with the spatial location of Pt nanoparticles both on the outer surface and inside the zeolite-templated carbon (ZTC) supports containing an ultralow Pt content of 0.5 wt % exhibits an optimum mass activity of 1.75 A•mg Pt −1 , significantly outperforming the solely located Pt wthin ZTC and the commercial Pt/C electrocatalysts. This work offers insight into the precise placement control of active sites in electrocatalysis and holds promise for the large scale of low-cost ORR electrocatalysts.