Hierarchical mesoporous SSZ-13 chabazite zeolites for carbon dioxide capture

Artificial carbon dioxide capture is an alternative method to remove the carbon dioxide already accumulated in the atmosphere as well as to stop its release at its large-scale emission points at the source, such as at power plants. However, new adsorbents are needed to make the approach feasible. For this purpose, in this study, hierarchical mesoporous-microporous chabazite-type zeolites were synthesised by applying a dual-templating method. The microporous zeolite structure-directing agent N,N,N-trimethyl-1-adamantanammonium hydroxide was combined with an organosilane mesopore-generating template, 3-(trimethoxysilyl)propyl octadecyl dimethyl ammonium chloride. Materials were characterised for their structural and textural properties and tested for their carbon dioxide capture capacity both in their original sodium form and in their proton-exchanged form by means of breakthrough curve analysis and sorption isotherms. The influence of template ratios on their structure, carbon dioxide capture, and capacity have been identified. All mesoporous materials showed fast adsorption-desorption kinetics due to a reduction in the steric limitations via the introduction of a meso range network of pores. The hierarchical zeolites are recyclable with a negligible loss in crystallinity and carbon dioxide capture capacity, which makes them potential materials for larger-scale application

2D boron nitride nanosheets (BNNS) prepared by high-pressure homogenisation : structure and morphology

2D Boron Nitride Nano-sheets (BNNS) were prepared using a high-pressure homogenisation process to exfoliate bulk hexagonal boron nitride (h-BN). The effectiveness of this process was studied by characterising bulk h-BN and BNNS post-processing using numerous techniques. The BNNS produced was composed of a mixture of sheets having lengths on the nanometre (nm) scale, but lateral thicknesses on the micron (μm) length scale. The product was a macro-porous material containing slit-like pores with a surface area of 170 m2 g−1. It had a polycrystalline structure with d002 = 0.335 nm and L002 = 2 nm. From the sharp E2g peak in the Raman spectrum at 1360 cm−1 (FWHM = 12.5 cm−1), the sheets had a low defect density and were highly exfoliated. X-Ray photoelectron spectroscopy (XPS) studies detected B–OH and N–H groups on the BNNS surface and the presence of residual surfactant. Contact angle measurements (60° ± 3° (0 s); 40° ± 2° (10 s)) confirmed a hydrophilic surface. The BNNS was thermally stable under oxidative conditions up to 323 °C

Improving the quality of pyrolysis oil from co-firing high-density polyethylene plastic waste and palm empty fruit bunches

This study aimed to produce and improve the quality of pyrolysis oil as a source of bioenergy that is made by mixing palm empty fruit bunch (EFB) with high-density polyethylene (HDPE) plastic waste. The slow co-pyrolysis method was employed, and HDPE waste and EFB were fed into the pyrolysis reactor at HDPE amounts of 0, 10, 25, 50, 75, and 100% by weight. The pyrolysis oil product was obtained by co-firing EFB with HDPE using the slow co-pyrolysis method in a fixed bed reactor at 500°C with a flow rate of 750 mL/min and a heating rate of 5°C/min. The chemical compositions of pyrolysis oil were analyzed by gas chromatography-mass spectroscopy. A pyrolysis oil produced by HDPE 100 wt.% was dominated by the chemical compounds of phenols, aromatics, aliphatic, and acids, while for EFB 100 wt.% was dominated with aldehydes, acids, phenols, furan and aliphatic. The addition of HDPE reduced the amount of pyrolysis oil yield, increased the pH, reduced the viscosity, and reduced the oxygen content of the pyrolysis oil. These results proved that the HDPE affected the decrease in pyrolysis oil and the increase in gas production from co-firing HDPE and EFB using the slow co-pyrolysis method

ZIF-8 metal organic framework for the conversion of glucose to fructose and 5-hydroxymethyl furfural

Herein, Zeolitic imidazolate framework-8 (ZIF-8) is considered as an easy and cheap to prepare alternative catalyst for the isomerization of glucose and production of 5-hydroxymethyl furfural (HMF). For the synthesis of the ZIF-8 catalysts two preparation methods were evaluated, being room temperature and hydrothermal synthesis at 140 °C. Of these, the hydrothermal synthesis method yields a material with exceptionally high surface area (1967 m2·g−1). As a catalyst, the ZIF-8 materials generated excellent fructose yields. Specifically, ZIF-8 prepared by hydrothermal synthesis yielded a fructose selectivity of 65% with a glucose conversion of 24% at 100 °C in aqueous reaction medium. However, this selectivity dropped dramatically when the reactions were repeated at higher temperatures (~140 °C). Interestingly, greater quantities of mannose were produced at higher temperatures too. The lack of strong Brønsted acidity in both ZIF-8 materials resulted in poor HMF yields. In order to improve HMF yields, reactions were performed at a lower pH of 1.0. At 140 °C the lower pH was found to drive the reaction towards HMF and double its yield. Despite the excellent performance of ZIF-8 catalysts in batch reactions, their activity did not translate well to the flow reactor over a continuous run of 8 h, which was operating with a residence time of 6 min. The activity of ZIF-8 halved in the flow reactor at 100 °C in ~3 h, which implies that the catalyst’s stability was not maintained in the long run

PEI-coated Fe3O4 nanoparticles enable efficient delivery of therapeutic siRNA targeting REST into glioblastoma cells

Glioblastomas (GBM) are the most frequent brain tumors lacking efficient treatment. The increasingly elucidated gene targets make siRNA-based gene therapy a promising anticancer approach, while an efficient delivery system is urgently needed. Here, polyethyleneimine (PEI)-coated Fe3O4 nanoparticles (NPs) have been developed and applied for siRNA delivery into GBM cells to silence repressor element 1-silencing transcription factor (REST). The prepared PEI-coated Fe3O4 NPs were characterized as magnetic nanoparticles with a positive charge, by transmission electronic microscopy, dynamic light-scattering analysis and a magnetometer. By gel retardation assay, the nanoparticles were found to form complexes with siRNA and the interaction proportion of NP to siRNA was 2.8:1. The cellular uptake of NP/siRNA complexes was verified by prussian blue staining, fluorescence labeling and flow cytometry in U-87 and U-251 GBM cells. Furthermore, the REST silencing examined by realtime polymerase chain reaction (PCR) and Western blotting presented significant reduction of REST in transcription and translation levels. Upon the treatment of NP/siRNA targeting REST, the GBM cell viabilities were inhibited and the migration capacities were repressed remarkably, analyzed by cell counting kit-8 and transwell assay separately. In this study, we demonstrated the PEI-coated Fe3O4 nanoparticle as a vehicle for therapeutic siRNA delivery, at an appropriate NP/siRNA weight ratio for REST silencing in GBM cells, inhibiting cell proliferation and migration efficiently. These might represent a novel potential treatment strategy for GBM

Tuning the hydrophobicity and Lewis acidity of UiO-66-NO2 with decanoic acid as modulator to optimise conversion of glucose to 5-hydroxymethylfurfural

Glucose conversion to 5-hydroxymethylfurfural (HMF) is important to the success of a biorefinery. Herein, metal–organic frameworks (MOFs) with the UiO-66 structure were synthesised with decanoic acid as the modulator and used as the catalyst to optimise HMF yield. PXRD, FTIR, and TGA/DSC techniques were applied to characterise the materials. The analysis results show that the materials assembled from the ligand 2-nitroterephthalic acid and hexameric Zr-oxo clusters contain decanoic acid chemically bound in the framework that influences porosity, Lewis acidity, and hydrophobicity. The materials exhibit excellent catalytic performance for HMF production from glucose in DMSO as solvent, attributed to their abundant defects and high hydrophobicity due to the addition of the decanoic acid modulator. Influences of catalyst dosages, reaction duration, and temperature were comprehensively investigated, leading to 98.1% conversion of glucose and 54.5% HMF yield under optimised reaction conditions. The catalytic conversion shows some deterioration after four cycles, yet the reaction selectivity displays no significant decline

A hydrothermally stable Ytterbium metal-organic framework as a bifunctional solid-acid catalyst for glucose conversion

Yb6(BDC)7(OH)4(H2O)4 contains both bridging hydroxyls and metal-coordinated waters, possessing Brønsted and Lewis acid sites. The material crystallises from water at 200C. Using the solid as a heterogenous catalyst, glucose is converted into 5-hydroxymethylfurfural, via fructose, with a total selectivity of ~70 % after 24 hours at 140 C in water alone: the material is recyclable with no loss of crystallinity

Gasification and physical-chemical characteristics of carbonaceous materials in relation to HIsarna ironmaking process

HIsarna ironmaking process is one of the emerging technologies being developed to mitigate the increasing carbon footprint from the steel making industry. This innovative process offers flexibility with the type of reductants used in the smelting reduction vessel for the conversion of iron ore to liquid hot metal. Natural gas is well known for being a relatively clean fossil fuel producing carbon black and hydrogen when it undergoes thermal decomposition. The gasification reactivity of carbon black compared to the carbonaceous materials used in HIsarna process is investigated in this work using isothermal gravimetric analysis (TGA) method at 1250˚C, 1350˚C and 1450˚C under atmospheric pressure. Furthermore, physical-chemical characteristics of the individual carbonaceous materials, which may influence the reactivity, are evaluated systematically. The experimental results show that carbon black is the least reactive followed by thermal coal and charcoal. It was found that the effect of the morphology of the carbonaceous materials on the reactivity is dominant compared to the surface area of the materials. In addition, the reactivity increases with the alkali index (AI) and the level of the amorphousness of the material’s structure. Three well-known kinetic models, i.e. the volumetric model (VM), the grain model (GM) and the random pore model (RPM) were applied to predict the gasification behaviour of the three carbonaceous materials. The random pore model best describes the gasification reaction of the selected samples due to the influence of the pore diffusion on the reaction. It is observed that the activation energy of the samples are not following the order of reactivity, this can be explained by the kinetic compensation effect

Processing of agricultural apple fruit waste into sugar rich feedstocks for the catalytic production of 5-HMF over a Sn Amberlyst-15 resin catalyst

In this study we considered processes of treatment of agricultural apple waste which is normally discarded. We show the effect of various pre-treatment procedures on the final catalytic performance to produce 5-HMF from this real world biomass waste. Our study of the various potential pre-treatment steps, and their effect on the catalytic performance, provides valuable new insights which can be used for the development of new processes for the localised small scale valorization of agricultural fruit waste. The apple waste is aimed to be converted into a sugar rich feedstock stream for the catalytic conversion to 5-hydroxymethyl furfural (5-HMF) at low temperatures (∼120 °C). Filters with varying pore sizes were studied for the filtration of apple pomace after milling the rotten apples in order to reduce the solids content. The tested filters varied in pore sizes of 0.2 μm, 2 μm and 54 μm. The effect of heating, acid or base treatment of the apple slurry was evaluated for increasing the speed of filtration. The highest flow rate was obtained for the filter with 54 μm pores. The sugar rich filtrates were investigated in the catalytic conversion to 5-HMF over an easy-to-manufacture Sn exchanged resin (Amberlyst-15) catalyst. Results showed that filtrates obtained over a 2 μm filter lead to the highest 5-HMF yields (18 %) without extra additives. Adjustment of the reaction mixtures to pH 7 resulted in a lower catalytic activity. 5-HMF is proposed to be extracted from the aqueous layer by using an organic liquid layer (methyl isobutyl ketone, MIBK). In order to increase the diffusion of 5-HMF to the MIBK layer the addition of salts to the reaction mixture was investigated. This leads to lower catalytic activity, possibly due to catalyst deactivation. Our results showed that a relatively wide pore filter (54 μm) provides the fastest apple processing method and a filtrate reacting to the highest 5-HMF yield in catalytic conversion of the sugar rich product stream obtained from agricultural waste apples