Isopropanol to Hydrocarbons Transformation Particularities on Hybrid Zeolite H-ZSM-5 and H-Beta Systems

The continuous depletion of hydrocarbon sources contributes to a wide study of the use of biorenewable raw materials to obtain synthetic hydrocarbons from them. Isopropyl alcohol is traditionally produced by chemical hydration of propylene, however, with the development of biotechnology, broad prospects have opened for its production by fermentation of glucose-containing substrates obtained from agricultural and forestry waste. This way, isopropyl alcohol can also be considered as a bio-renewable raw material and it can be widely used for the production of chemical synthesis products, including hydrocarbons. One of the possible ways of processing isopropyl alcohol is the catalytic transformation of alcohols on zeolites and zeotypes of various natures with the formation of hydrocarbons. Currently, zeolite H-ZSM-5 and zeotype SAPO-34 are the most frequently used catalysts for the transformation of alcohols into hydrocarbons, however, their rapid deactivation due to the formation of a carbon residue remains an unresolved problem. The formation of core-shell structures with H-ZSM-5 zeolite in center and an outer shell consist of H-Beta zeolite with large pores can reduce the deactivation of zeolite because of increase in reagents diffusion rate. In this article is devoted to synthesis of ZSM-5/Beta sample with a core-shell structure, as well as a study of its catalytic and physicochemical properties. To form the H-ZSM-5 zeolite, a colloidal solution of tetrapropylammonium hydroxide, a colloidal solution of silicon oxide, aluminum oxide, sodium hydroxide of distilled water was used. The colloidal solution was placed in an autoclave, heated to 140 °C and kept at this temperature for 48 hours, after which the crystals formed were centrifuged, washed with distilled water and kept in a 1M solution of ammonium nitrate for a day. Then, to form the H-Beta layer, H-ZSM-5 was suspended in a colloidal solution consisting of tetraethylammonium hydroxide, tetraethylammonium chloride, a colloidal solution of silicon oxide, sodium hydroxide, sodium chloride and distilled water. The suspension was placed in an autoclave and kept at a temperature of 140 °C for 48 hours, followed by centrifugation, washing in distilled water, suspended in a 1M solution of ammonium nitrate, with repeated washing with distilled water, drying and calcining at 600 °C. Testing of the synthesized of H-ZSM-5/Beta zeolite sample showed a significant decrease in the rate of deactivation compared to the synthesized sample of H-ZSM-5; it is also necessary to note a slight increase in the fraction of liquid hydrocarbons for the sample H-ZSM-5/Beta.

Bentonites in Southern Spain. Characterization and Applications

The objective of this work was to investigate and demonstrate the pozzolanic properties of the bentonites found at the San José–Los Escullos deposit, located in the southeast of the Iberian Peninsula, to be used in the manufacturing of more durable and environmentally compatible pozzolanic cements, mortars and concretes. These bentonites are mainly composed of smectites, with montmorillonite as the main clay mineral. They were formed by the hydrothermal alteration of tuffs, volcanic glasses, dacites, rhyolites and andesites. For this research, samples were taken from outcrops on the south, north and west side of the San José–Los Escullos deposit, and in the Los Trancos deposit located 19.3 km to the northeast. All samples consisted of bentonites, except for a zeolite sample taken from the northern flank of the San José–Los Escullos deposit, which was used to contrast and compare the behaviour of bentonite in some of the analyses that were done. An investigation of the mineralogical, petrological, chemical and thermogravimetric characteristics of the samples was carried out using various methods, such as XRD, OA (Oriented aggregates), TGA, XRF, SEM and thin section petrography (TSP). In addition, a chemical analysis of pozzolanicity (CAP) was done at 8 and 15 days to determine the pozzolanic capacity of the samples. XRD, XRF, SEM and TSP studies showed that these bentonites have a complex mineralogical constitution, composed mainly of smectites of the montmorillonite variety, as well as halloysite, illite, vermiculite, biotite, muscovite, kaolinite, chlorite, mordenite, feldspar, pyroxene, amphibole, calcite, volcanic glass and quartz. Thermogravimetric analysis (TGA) established the thermal stability of the bentonites studied at above 800 °C. Chemical analysis of pozzolanicity (CAP) confirmed the pozzolanic character of the bentonites, exhibited in their reactive behaviour with Ca(OH)2. The pozzolanic reactivity increased significantly from 8 to 15 days. These results show that the materials studied can be used as quality pozzolans for the manufacture of pozzolanic cements, mortars and concretes.

Physical and mineral characterisation of natural zeolites from Taiz, South-western Yemen

Aim: To investigate the physical, minerals and geochemical composition of Taiz natural zeolites. Methodology: Each zeolite sample were assessed for its characterization via optical microscopy, X-ray Diffraction (XRD) techniques, X-ray Fluorescence Methods (XRF), Inductively Coupled Plasma- Optical Emission Spectrometry (ICP-OES) to examine their mineral composition and geochemistry properties. Further, physical properties like pH, electrical conductivity (EC), plasticity, specific surface area, water content and brightness were estimated by standard methods. Results: Natural zeolite in the studied area occurs within pyroclast of volcanic tuffs. It consists mainly of perlite and rhyolite as lenses grey to light green in color with fine granulation texture. Petrography analysis showed that the Taiz zeolites are mainly classified as clinoptilolite – heulandite and are mixed with various types of others zeolite minerals such as analcime, chabazite and mazzite. Small amounts of impurities like K-.feldspar (orthoclase) and clay mineral such as montmorillonite, kaolinite and illite were also detected. The mean ratio of SiO2:Al2O3 for representative zeolite sample from the study area ranged between of 6.34-6.98. Interpretation: Zeolites showed fairly medium to high brightness and on comparing with the commercial zeolites, Taiz zeolite showed significant industrial potential to be used as a filler in paper industry.

Bifunctional cobalt catalyst for the Fischer – Tropsch synthesis of low-freezing diesel fuel – from development to implementation: Part 1. Selection of a commercial sample of the HZSM-5 zeolite component

The effect of the quality of various domestic commercial HZSM-5 zeolites on the properties of bifunctional cobalt catalyst represented by a composite mixture was studied in the Fischer – Tropsch synthesis. Activities and selectivities of the catalyst samples were compared. The fractional and hydrocarbon composition of the synthesis products was investigated; viscosity-temperature characteristics of the diesel fuel fraction were estimated. A promising HZSM-5 zeolite sample was selected for practical implementation of the catalytic technology.

Unprecedented CO2 adsorption behaviour by 5A-type zeolite discovered in lower pressure region and at 300 K

The NaCaA-85 zeolite sample which works as an efficient adsorbent for CO2 at RT and in low pressure range was found and its specificity is nicely explained by the model composed of CO2 pinned by two types of Ca2+ ions through far-IR and DFT studies.

Separation of Radionuclides from a Rare Earth-Containing Solution by Zeolite Adsorption

The increasing industrial demand for rare earths requires new or alternative sources to be found. Within this context, there have been studies validating the technical feasibility of coal and coal byproducts as alternative sources for rare earth elements. Nonetheless, radioactive materials, such as thorium and uranium, are frequently seen in the rare earths’ mineralization, and causes environmental and health concerns. Consequently, there exists an urgent need to remove these radionuclides in order to produce high purity rare earths to diversify the supply chain, as well as maintain an environmentally-favorable extraction process for the surroundings. In this study, an experimental design was generated to examine the effect of zeolite particle size, feed solution pH, zeolite amount, and contact time of solid and aqueous phases on the removal of thorium and uranium from the solution. The best separation performance was achieved using 2.50 g of 12-µm zeolite sample at a pH value of 3 with a contact time of 2 h. Under these conditions, the adsorption recovery of rare earths, thorium, and uranium into the solid phase was found to be 20.43 wt%, 99.20 wt%, and 89.60 wt%, respectively. The Freundlich adsorption isotherm was determined to be the best-fit model, and the adsorption mechanism of rare earths and thorium was identified as multilayer physisorption. Further, the separation efficiency was assessed using the response surface methodology based on the development of a statistically significant model.

Effect of using regenerated combined FAU and MOR zeolites as catalysts during the pyrolysis of kraft lignin

The SiO2/Al2O3 mole ratio, pore size, and acid sites are the key parameters of zeolite’s activity in lignin pyrolysis. In this study, the comparison of individual Y and M zeolites, the combined ‘Y + M’ sample after regeneration, and their effect on lignin pyrolysis were studied in five cycles (regeneration and reuse). The results were explained using Brunauer, Emmet, and Teller (BET), micropore surface area (MSA), and total acid sites (TAS) analyses. In comparison with the individual Y or M zeolite sample, the consistent higher catalytic activities of the combined ‘Y + M’ sample in repeated cycles were observed. Pyrolysis heavy oils were characterized by nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC). The NMR analyses revealed that with increased zeolite regeneration cycles, p-hydroxy phenyl and methoxyl groups increased. Decreases in guaiacyl phenolic hydroxyl were less for the combined ‘Y + M’ sample than the individual Y and M zeolites. Lower weight average (Mw) of heavy oil for the combined ‘Y + M’ sample indicated the enhanced cleavage of lignin structures in pyrolysis. These results support the higher catalytic activity of regenerated zeolites for the combined ‘Y + M’ sample compared with individual Y and M zeolites due to the improved MSA and TAS.

Generalized Methodology for Inserting Metal Heteroatoms into the Layered Zeolite Precursor RUB-36 by Interlayer Expansion

The incorporation of metal heteroatoms into zeolites is an effective modification strategy for enhancing their catalytic performance. Herein, for the first time we report a generalized methodology for inserting metal heteroatoms (such as Sn, Fe, Zn, and Co) into the layered zeolite precursor RUB-36 via interlayer expansion by using the corresponding metal acetylacetate salt. Through this generalized methodology, Sn-JHP-1, Fe-JHP-1, Zn-JHP-1 and Co-JHP-1 zeolites could be successfully prepared by the reaction of RUB-36 and corresponding metal acetylacetate salt at 180 °C for 24 h in the presence of HCl solution. As a typical example, Sn-JHP-1 and calcined Sn-JHP-1 (Sn-JHP-2) zeolite is well characterized by the X-ray diffraction (XRD), diffuse reflectance ultraviolet-visible (UV-Vis), inductively coupled plasma (ICP), N2 sorption, temperature-programmed-desorption of ammonia (NH3-TPD) and X-ray photoelectron spectroscopy (XPS) techniques, which confirm the expansion of adjacent interlayers and thus the incorporation of isolated Sn sites within the zeolite structure. Notably, the obtained Sn-JHP-2 zeolite sample shows enhanced catalytic performance in the conversion of glucose to levulinic acid (LA) reaction.

The removal of lead by natural zeolite

This study aimed to evaluate the ability of natural zeolite samples obtained from Gunungkidul, Yogyakarta, Indonesia in the removal of lead (Pb) in solutions. This study included mineralogical characterization as well as a batch test in the laboratory with parameters including grain size, the mass of natural zeolite sample, pH, and initial concentration of the solution. The results of mineralogical characterization showed that the natural zeolite sample have varied constituent on mineral components and relatively have high cation exchange capacity (CEC). The results of the batch test showed that the adsorption behavior depends on the mass of the zeolite sample which the increasing of the sample mass will increase the adsorption capacity. The results of the following batch testing showed that the variations in grain size had a limited effect on the adsorption capacity and the effect of the pH of the solution being a significant parameter. The results of the following batch test also showed that the increasing initial concentration of Pb solution caused a decrease in adsorption capacity. In general, natural zeolite samples in the study area have sufficient adsorption capacity as adsorbent material for Pb solution.

Effect of the NH4NO3 Addition on the Low-T NH3-SCR Performances of Individual and Combined Fe- and Cu-Zeolite Catalysts

We have measured NOx conversions and N2O productions over Fe-BEA and Cu-SAPO catalysts and over their sequential arrangements under Enhanced SCR conditions, resulting from the addition of an aqueous solution of ammonium nitrate (AN) to the typical Standard SCR feed stream, and we have compared them to those observed under Standard and Fast SCR conditions. The expected strong enhancement of the poor low temperature activity of the Fe-BEA catalyst was confirmed: both NH3 and NOx conversions and N2O formations similar to those of the Fast SCR reaction were achieved when cofeeding ammonium nitrate. On the other hand, the Cu-SAPO efficiency was drastically decreased by the addition of AN at low temperatures, possibly due to trapping of the ammonium nitrate salt within the SAPO zeolite, characterized by smaller pores than those of the BEA zeolite. The Cu-SAPO performances were recovered only at T > 250 °C with a huge release of N2O due to the thermal decomposition of AN. The combined system with the Fe-zeolite sample placed upstream of the Cu-zeolite also exhibited outstanding low temperature deNOx performances, with even lower N2O production than over the Fe-zeolite only at the same Enhanced SCR (E-SCR) conditions.