Combination of Cu/ZnO Methanol Synthesis Catalysts and ZSM-5 Zeolites to Produce Oxygenates from CO2 and H2

Cu/ZnO methanol catalysts were deposited over several ZSM-5 acid zeolites to directly synthesise oxygenates (methanol and dimethyl ether) from a CO2/H2 feed. Catalysts were prepared by two different preparation methodologies: chemical vapour impregnation (CZZ-CVI) and oxalate gel precipitation (CZZ-OG). Chemical vapour impregnation led to Cu/ZnO being deposited on the zeolite surface, whilst oxalate gel precipitation led to the formation of Cu/ZnO agglomerates. For both sets of catalysts a higher concentration of mild and strong acid sites were produced, compared to the parent ZSM-5 zeolites, and CZZ-CVI had a higher concentration of acid sites compared to CZZ-OG. Nevertheless, CZZ-OG shows considerably higher oxygenate productivity, 1322 mmol Kgcat−1 h−1, compared to 192 mmol Kgcat−1 h−1 over CZZ-CVI (ZSM-5(50), 250 ℃, 20 bar, CO2/H2 = 1/3, 30 ml min−1), which could be assigned to a combination of smaller particle size and enhanced methanol mass transfer within the zeolites.

One-Pot Synthesis of Ultra-Small Pt Dispersed on Hierarchical Zeolite Nanosheet Surfaces for Mild Hydrodeoxygenation of 4-Propylphenol

The rational design of ultra-small metal clusters dispersed on a solid is of crucial importance in modern nanotechnology and catalysis. In this contribution, the concept of catalyst fabrication with a very ultra-small size of platinum nanoparticles supported on a hierarchical zeolite surface via a one-pot hydrothermal system was demonstrated. Combining the zeolite gel with ethylenediaminetetraacetic acid (EDTA) as a ligand precursor during the crystallization process, it allows significant improvement of the metal dispersion on a zeolite support. To illustrate the beneficial effect of ultra-small metal nanoparticles on a hierarchical zeolite surface as a bifunctional catalyst, a very high catalytic performance of almost 100% of cycloalkane product yield can be achieved in the consecutive mild hydrodeoxygenation of 4-propylphenol, which is a lignin-derived model molecule. This instance opens up perspectives to improve the efficiency of a catalyst for the sustainable conversion of biomass-derived compounds to fuels.

Adsorption of Methylene Blue Dye using Fe3O4 Magnetized Natural Zeolite Adsorbent

Preparation and characterization of Fe3O4 magnetized natural zeolite adsorbent for adsorption of methylene blue dye have been carried out. Natural zeolite/Fe3O4 adsorbent preparation was carried out using coprecipitation of Fe2+ and Fe3+ ions (1: 2 mol ratio) on the natural zeolite surface. Characterization was carried out using X-Ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR), and Scanning Electron Microscopy (SEM) to determine the effect of Fe3O4 on the natural zeolite surface. UV-Vis spectroscopy was used to determine the concentration of methylene blue after the adsorption process. The characterization results showed that Fe3O4 was successfully embedded in the natural zeolite without damaging the natural zeolite's crystallinity. Natural zeolite/Fe3O4 adsorbent showed easy separation from water medium after the adsorption process. The optimum conditions for adsorption were achieved at the contact time of 60 minutes, and the initial concentration of methylene blue was 30 ppm with an adsorbent mass of 25 mg. Adsorption kinetics followed pseudo-second-order reaction kinetics, and adsorption isotherm followed Langmuir isotherm with an adsorption capacity of 32.258 mg/g.

Kinerja Aktivasi dan Impregnasi Zeolit Alam sebagai Adsorben

Performance of natural zeolites can be improved through the process of activation and impregnation. Activation process using HCl and impregnation with Mg2+ have carried out in this study. The activation process was performed out for 30 minutes with a 0.5M HCl solution and impregnation of MgCl2.6H2O 2.5M for 2 hours. Natural zeolites which have been activated and impregnated are then analyzed by the Scanning Electron Microscope-Energy Dispersive Spectrophotometer (SEM-EDS). The results of zeolite surface profile characteristics activated and impregnated using SEM-EDS showed that there were changes in morphology and functional groups. Then, activated and impregnated zeolites were used to absorb ammonia at various contact times of 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes and 45 minutes. The equilibrium point was obtained at 25 minutes contact time with adsorption capacity of 30.444 mg/g and absorption efficiency of 85.2352%. The dosage of adsorbent varied with 0.01% size; 0.03%; 0.05%; 0.07%; 0.09%; 0.11%, 0.13% m/v. The concentration of ammonia absorbed was performed out using an Uv-Vis Spectrophotometer. The best efficiency of ammonia absorption is 90.106% with particle size 110-120 mesh, adsorbent dose 0.09% and adsorbent impregnation treatment.

Investigation of adsorption mechanism of phosphate(V) ions on the nanostructured Na-A zeolite surface modified with ionic polyacrylamide with regard to their removal from aqueous solution

The sorption properties of Na-A-type synthetic zeolite, obtained from fly ash with regard to the phosphate(V) ions, were determined. The Na-A zeolite was prepared using hydrothermal conversion of fly ash with aqueous sodium hydroxide. The effects of solution pH and zeolite surface modification by ionic polyacrylamide (PAM) were examined. Both anionic and cationic forms of PAM were applied. The adsorption and electrokinetic data were obtained by means of spectrophotometric measurements, potentiometric titrations and zeta potential determination. It was shown that the presence of ionic polyacrylamide adsorption layers modifies the surface properties of the solid. The resulting composite material (zeolite/polymer) can be applied for effective removal of phosphate(V) ions from the liquid medium. Its regeneration possibilities are also considerable. Additionally, the use of fly ash for zeolite preparation leads to management of hazardous waste material.