Heavy metal contamination in water remains a major environmental concern. In this work, ZSM-5 zeolites were synthesized by a microwave-assisted route and optimized by Design of Experiments to enhance adsorption performance. Structural and textural characterization by XRD, N₂-physisorption, and SEM confirmed the formation of crystalline micro–mesoporous ZSM-5 with hierarchical features. The zeolite synthesized under the optimized conditions (Si/Al ratio of 25, tetrapropylammonium bromide concentration of 0.08 mol, and crystallization time of 8 h) demonstrated a strong ability to selectively remove Cd2⁺ at 10 µg L−1 from aqueous solution even in the presence of a ten-fold excess of competing Ca2⁺ ions. The zeolite was further integrated into a pipette-tip microextraction format for Co2⁺ preconcentration, and the extraction procedure was independently optimized by a second DoE, assessing aspiration/dispensing strokes, sample volume, and temperature. Extraction consisted of a single procedure in which the same solution was repeatedly aspirated and dispensed through the zeolite bed to maximize contact. The regression model for tip extraction achieved R2 = 0.958 and Q2 = 0.892, confirming strong predictive performance and methodological robustness. These results support the use of engineered ZSM-5 as a reusable and low-impact material for monitoring and mitigating heavy-metal pollution in water.

The photochemistry of resveratrol with singlet oxygen ( 1 O 2 ) under blue‐LED irradiation is explored in the presence of three metal‐free porphyrins as photosensitizers. Irradiation at 450 nm yields products of CC bond scission, 6‐electron electrocyclic ring closure, and [4 + 2] cycloaddition, including benzaldehydes, 2,4,6‐trihydroxyphenanthrene, and resveratrol cyclic endoperoxide. The selectivity of the process is controlled by the structure of the metal‐free porphyrin and by the nominal capacity of the blue‐LED photon. The scope of the reaction is extended to sustainable heterogeneous photosensitizers produced by immobilization of metal‐free porphyrins on lignin, the most abundant polyphenol in nature characterized by beneficial photochemical properties.

Biomass-derived activated carbons play an important role in H2 storage applications since their structural and chemical properties can be modulated by adjusting the activating methods and experimental parameters as well as by functionalization with heteroatoms. However, unfavorable reaction conditions are usually required, which may compromise the carbonaceous framework, negatively impacting on the hydrogen storage performance. In this context, this work investigates the potential modification effects of different solvents on activated carbons (ACs) under mild conditions, with a focus on structural and textural rearrangements. ACs were treated, among others, with solvents such as toluene (TOL), tetrahydrofuran (THF), and isopropyl alcohol (IPA) at 353 K for a variable amount of time. Structural and textural analyses revealed that solvents might have a significant impact on the microporosity, chemical functionalization, and specific surface area (SBET) of ACs, thus potentially affecting their further chemical functionalization. TOL and IPA treatments demonstrated the solvent's role in framework reorganization, enhancing microporosity and storage capacity over reaction time. In contrast, THF exposure led to a decrease in textural properties and thermal stability, attributed to disruptive reaction conditions above the solvent's boiling point. Furthermore, the presence of atmospheric oxygen was found to induce the formation of oxygenated functional groups in the graphitic carbon structure, which contributed to structural instability even if facilitating the framework reordering during prolonged treatments. Although treated samples exhibited reduced hydrogen uptake compared to the parent AC, selected treatments with toluene and IPA demonstrated promising improvements in adsorption efficiency (i.e., H2 uptake/SBET). This study opens the possibility of an effective biomass-derived AC modification, without the need to employ high-energy-consuming thermal treatments, thus maximizing the potential of greener processes.

Acid catalysis is recognised as the most reliable industrial ì way to convert hydrocarbons into various products (methanol to olefins and aromatics, glycerol to olefins, methane dehydroaromatization, isomerization, etc.). In this concern, ZSM-5 is extensively used, also because of peculiar type of active sites of such zeolite. In this paper, a fine tuning of the acidity content and strength of ZSM-5 was investigated through a combination of post -synthesis treatments: desilication via alkaline solution and wet impregnation with Mg2+ ions followed by calcination. Results show that the insertion of Mg2+ has a large influence on the distribution and strength of Bronsted and Lewis acid sites of the hierarchical ZSM-5, as well as an improved crystallinity with respect to the desilicated-one. The hierarchical ZSM-5 zeolite incorporating Mg-species was tested in Methanol-to-olefins re-action and the reduction of acid strength of catalyst increased the selectivity toward light olefins (mainly pro-pylene) as well as it suppressed oligomerisation reactions delaying the coke formation.

In spite of the widespread range of hydrogen applications as one of the greenest energy vectors, its transportation and storage still remain among the main concerns to be solved in order to definitively kickstart a rapid takeoff of a sustainable H2 economy. The quest for a simple, efficient, and highly reversible release storage technique is a very compelling target. Many studies have been undertaken to increase H2 storage efficiency by exploiting either chemisorption or physisorption processes, or through entrapment on different porous solid materials as sorbent systems. Among these, biomass-derived carbons represent a category of robust, efficient, and low-cost materials. One question that is still open-ended concerns the correlation of H2 uptake with the kind and number of heteroatoms as dopant of the carbonaceous sorbent matrix, such as boron, aiming to increase whenever possible bonding interactions with H2. Furthermore, the preferred choice is a function of the type of hydrogen use, which may involve a short- or long-term storage option. In this article, after a brief overview of the main hydrogen storage methods currently in use, all the currently available techniques for the boronation of activated carbonaceous matrices derived from recycled biomass or agricultural waste are discussed, highlighting the advantages and drawbacks of each of them.

This review is focused on a number of issues that are essential for the industrial development of plastic waste pyrolysis technologies, including the role of catalysts, dehalogenation treatments, co-pyrolysis and process modelling and assessment.

The synthesis of high-silica BEA zeolite has attracted great attention from the zeolite scientific community, and several approaches have been proposed for the preparation of crystalline materials with a very low aluminum content. In this work, high-silica crystalline BEA zeolites were prepared starting from an Al-free synthesis gel, by using boron and iron as trivalent atoms. A Si/Fe molar ratio equal to 100, 200 or infinity was adopted, and crystallization was successful in the presence of tetraethy- lammonium (TEA+), with a low Si/B starting synthesis gel molar ratio, i.e. 8 or 12, and with a hydrothermal synthesis time of 6 days maximum at 150 degrees C. The Si/Fe ratio affects TEA+-zeolite interactions, crystallographic patterns, and surface acidity. In particular, the proposed synthesis procedure allowed obtaining BEA zeolites with a very low acidity, with a tunable Lewis/Bronsted acids site distribution. Liquid-phase etherification of 5- hydroxymethyl furfural (HMF) with ethanol highlighted the suitability of the obtained materials for the production of 5- (ethoxymethyl)furan-2-carbaldeyde (EMF), a green fuel additive. Particularly, a high EMF selectivity (>97%) was obtained in the presence of both iron and boron. As the main outcome, the presented results indicated that high-silica BEA zeolite can be easily obtained starting from a low Si/B ratio in the synthesis gel, with conventional tetraethylammonium as a template, and iron can be also incorporated for catalytic purposes.

Hydrogen is considered one of the energy carriers of the future due to its high mass-based calorific value. Hydrogen combustion generates only water, and it can be used directly as a fuel for electricity/heat generation. Nowadays, about 95% of the hydrogen is produced via conversion of fossil fuels. One of the future challenges is to find processes based on a renewable source to produce hydrogen in a sustainable way. Bioethanol is a promising candidate, since it can be obtained from the fermentation of biomasses, and easily converted into hydrogen via steam catalytic reforming. The correct design of catalysts and catalytic supports plays a crucial role in the optimization of this reaction. The best results have to date been achieved by noble metals, but their high costs make them unsuitable for industrial application. Very satisfactory results have also been achieved by using nickel and cobalt as active metals. Furthermore, it has been found that the support physical and chemical properties strongly affect the catalytic performance. In this review, zeolitic materials used for the ethanol steam reforming reaction are overviewed. We discuss thermodynamics, reaction mechanisms and the role of active metal, as well as the main noble and non-noble active compounds involved in ethanol steam reforming reaction. Finally, an overview of the zeolitic supports reported in the literature that can be profitably used to produce hydrogen through ethanol steam reforming is presented.

Catalytic pyrolysis of plastic wastes is a promising way for their conversion into valuable products. By modu-lating the catalyst properties and operating conditions, it is possible to direct the product distribution to obtain oils that may be suitable both as fuels and as chemicals. However, the efficient and safe removal of the halogens, often contained in plastic wastes, remains as a great challenge. In this work, the catalytic behaviour of ZSM-5 zeolites in the pyrolysis of a real chlorinated plastic waste of the electric and electronic equipment sector (WEEE), consisting of PE with about 3.4% of PVC, was investigated. To that end, three zeolite samples with different acidity and accessibility were synthesized and assayed. A thermal pre-treatment was applied to the plastic waste at 350 degrees C, which allowed a chlorine removal of 87% from the WEEE feedstock. The pyrolysis tests were carried out in a downdraft fixed-bed stainless steel reactor, with a catalyst/feedstock ratio of 0.2, at temperatures of 600 degrees C and 450 degrees C in the thermal and catalytic zones, respectively, of the reaction system. In comparison with thermal pyrolysis, that mainly produced waxes, the product distribution changed considerably by contacting the pyrolysis vapours with ZSM-5 zeolites, leading to a strong enhancement in the yield of oil and gases. The largest yield of oil (about 60 wt%), having a concentration of monoaromatics (mainly BTX) above 50 wt%, was attained over the desilicated ZSM-5 sample. Regarding chlorine distribution, about 90% was accu-mulated in the char fraction, probably captured by the inorganic components present in the raw WEEE waste. Coke was the second fraction in terms of Cl concentration, followed by wax and oil, whereas this halogen was almost not detected in the gases. The lowest concentration of Cl in the oil was attained with the desilicated zeolite, with a value below 90 ppm, which could facilitate the subsequent processing of this stream in refinery units.

Methanol (MeOH) dehydration for Dimethyl ether (DME) production is one of the possible pathways to produce a green, synthetic fuel that can substitute fossil/conventional ones in automotive/transportation applications. DME synthesis in gas phase usually occurs in presence of an acid catalyst at moderate temperature (up to 250 °C). This work deals with the use of MFI-type zeolitic catalysts. H form and desilicated zeolite samples were synthesized, characterized, and tested to investigate their catalytic activity in MeOH dehydration reaction. Ammonia temperature-programmed desorption (NH3-TPD) and Fourier-transform Infrared spectroscopy (FT-IR) analyses were carried out to elucidate the amount and the nature of acid sites. Zeolite sample desilicated for 60 minutes presented a higher amount of Bronsted acid sites (that can be correlated to the superior catalytic activity), while the Turnover frequency (TOF) referred to the amount of Bronsted acid sites is very similar for the investigated samples. Finally, preliminary kinetic investigation via linear fitting of experimental data on the Arrhenius plot was carried out for simple first and second order kinetic models.

The modification of the physicochemical properties of synthetic zeolites is an important element when these materials are applied as heterogeneous catalysts in the view of more sustainable and effective processes. In this work, desilicated ZSM5 samples were tested on the methanol to dimethyl ether dehydration. Desilication time strongly affects the textural and acidic properties of the samples, and those characteristics determined a different catalytic behaviour. Contact time of 60 min with NaOH solution (alkaline desilication) favourably impact on the activity of the catalysts and its stability against deactivation in terms of methanol conversion and yield to DME, in comparison with parent zeolite and sample prepared after 30 min of desilication. This effect is due to a combination of changes in the properties of acidic sites and mesoporous volume, as confirmed by stability test over 80 h of reaction. The analysis of formed coke confirmed this evidence since the most performing catalyst showed the lowest tendency to form coke as the main consequence of the improved accessibility to the acid sites determined by the induced mesoporosity.

In the last century, a series of problems related to the environment, mainly due to polluting emissions such as CO2, CH4, and N2O, led to revaluation of a series of factors, including that of emissions from motor vehicles. To overcome the problem, new types of less polluting biofuels based on ethanol blends with fossil fuels, have been developed. United States, with the production of ethanol from corn, and Brazil, with the production of ethanol from sugarcane, currently drive the market for the world production of bioethanol, thanks mainly to government subsidies. Despite this, some problems related to energy loss during industrial processes and to the linkage of the first-generation feedstock with both biofuel and food for human consumption, are leading to the development of new-generation feedstocks which exploit lignocellulosic or algal biomasses. This chapter is a brief review of the methods of production of ethanol in the United States and Brazil, giving the generic economical and statistical data of the processes.

Methanol, or methyl alcohol, is the simplest alcohol, appearing as a colorless liquid with a distinctive smell. Nowadays, it is considered one of the most useful chemical compounds. In fact, it is one of the most promising building blocks for obtaining more complex chemical structures, such as acetic acid, methyl tertiary butyl ether, dimethyl ether, methylamine, etc. Furthermore, methanol is also considered a promising clean-burning fuel with a high octane number. Knowing that CO2 and H2 are among the precursors in methanol synthesis, it is noteworthy that the conversion of CO2 to methanol can be considered a promising method for significantly reducing CO2 emissions, and that methanol production can also be used as a convenient energy carrier for hydrogen storage and conservation. In fact, methanol synthesis is the second source, after ammonia production, of hydrogen consumption (which has the highest energy content per weight) via several reactions, such as partial oxidation, steam reforming, autothermal reforming, methanol decomposition, or methanol-water solution electrolysis. Finally, among the recent attractive applications of methanol, the most promising for the future are the production of DME, the production of hydrogen, and the direct methanol fuel cell (DMFC). This chapter is an overview of not only common feedstocks used in the production processes for obtaining methanol (natural gases, CO2, or char/biomass), but also of the historical production processes (such as the BASF process, also known as the “high-pressure method,” and the ICI process, also known as the “low-pressure method”) and the most innovative trends for industrial applications.