Tag: zeolite

Users of ALBA create the most porous zeolite to date

Users of ALBA create the most porous zeolite to date

A team from the Materials Science Institute of Madrid -CSIC) leads an international research that synthetized a zeolite with extra-large pores by expanding and connecting silica chains. This material has applications in water and gas decontamination and catalysis. Experiments carried out at the MSPD beamline of the ALBA Synchrotron had a key role in determining the structure of the zeolite.

A team from the Materials Science Institute of Madrid (ICMM-CSIC) leads an international research that has succeeded in creating the world’s most porous zeolite. The study, published yesterday in the journal Nature, opens up new avenues for water and gas decontamination and “demonstrates that it is possible to make more porous materials that are stable,” says Miguel Camblor, researcher at the ICMM-CSIC and lead author of the study.

Zeolites are microporous crystalline silicates. These are materials with applications in decontamination, catalysis, gas adsorption, and cation exchange. For decades, obtaining stable zeolites with greater porosity and, therefore, capacity for absorption and processing of large molecules, has been an important scientific goal. However, this is not a simple challenge: “until recently, it challenged our synthetic capacity,” indicates Camblor.

The team already developed in recent years two zeolites with “extra-large” pores in the three spatial directions that also exhibited high stability. On this occasion, they have created a stable aluminosilicate zeolite with extra-large pores open through rings of more than 12 tetrahedra, capable of processing even larger molecules.

“The structure of this zeolite presents unprecedented characteristics and demonstrates that with different methods, things that were believed impossible can be found, such as this world record in porosity,” highlights Camblor, who indicates that they have already used the zeolite for the absorption of volatile organic compounds.

To determine the structure of the zeolite, the research team has combined electron diffraction techniques and powder X-ray diffraction, the latter available at the MSPD beamline of the ALBA Synchrotron. The X-rays produced at the ALBA’s accelerator provided crucial information on the position of the atoms in the zeolite structure.

Read more on the ALBA website

Image: Structure of the zeolite called ZEO-5

Credit: Nature

Control of zeolite microenvironment for biomass conversion

Control of zeolite microenvironment for biomass conversion

Pentadienes serve as key building blocks for the chemical and polymer industries and are widely used as monomers in the production of adhesives, plastics, and resins. However, state-of-the-art processes to produce pentadienes are based on steam cracking of naphtha (typically at 850ºC) and rely on fossil fuels with the attendant environmental impacts. Therefore, the sustainable production of pentadienes from renewable resources, such as biomass-derived materials, is a vitally important and urgent task. 

Methyltetrahydrofuran (2-MTHF) can be produced readily from lignocellulose-derived furfural via low-cost, high-yield processes and has been identified as a sustainable resource for making pentadienes via ring-opening, hydrogen transfer and dehydration processes. Leading catalysts for this reaction include amorphous SiO2/Al2O3, and Al or B- zeolites. However, these microporous catalysts often suffer from deactivation due to the formation of cokes. Furthermore, achieving effective selectivity control towards pentadienes in this reaction is still a significant challenge. 

MCM-41 is a mesoporous silica-based material used as a catalyst or catalyst support for a wide range of reactions; emerging niobium-based catalysts have shown exceptional performance for the hydrodeoxygenation of biomass under mild conditions. 

An international team of researchers studied whether MCM-41 materials containing weak acid sites and active niobium sites effectively address the challenges of pentadiene production. The reaction mechanism of conversion of 2-MTHF is complex, involving multiple reaction intermediates and products. The ring-opening of 2-MTHF is the rate-limiting step in this conversion. The research team aimed to determine the full molecular details of the catalytic mechanism through the use of operando X-ray Absorption Spectroscopy (XAS), combined with Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and in situ high-field solid-state Nuclear Magnetic Resonance spectroscopy. 

On Diamond’s I20-EDE beamline, they used the spectroscopy group’s recently commissioned high-temperature synchronous gas/vapour phase XAS/DRIFTS set-up coupled to the mass spectrometer and in-house developed gas dosing rig. This combination enabled them to propose a detailed reaction mechanism via temperature programmed spectroscopy. 

Read more on Diamond website

Image: The highly selective conversion of biomass-derived 2-methyltetrahydrofuran (2-MTHF) into pentadienes has been achieved over an aluminium and niobium bimetallic atomically doped on MCM-41. The Nb(V) sites enhance the catalytic performance by binding 2-MTHF.