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Selective hydrogenation catalysts play a key role in many industrial processes, but they are primarily based on supported noble metals, such as Pt and Pd, which are usually dispersed in nanoparticles. However, the production and recovery of these noble metal nanoparticles is a very energy-consuming and expensive procedure. Accordingly, replacing these metals by other inexpensive, transition metals such as Fe and Cu without sacrificing the activity and selectivity, will necessarily reduce their production costs. Moreover, zeolites as a support provide the advantage of shape selectivity to the desired product. In this study, we develop an alternative method for preparing hydrogenation catalysts composed of metallic nanoparticles encapsulated into zeolite frameworks through reductive demetallation of Fe-zeolites or Cu/Fe-zeolites with MFI topology. Particularly, the process of reductive demetallation is described using temperature-programmed reduction (TPR) and Mossbauer spectroscopy data. The reductive demetallation of Fe-MFI, consisting of Fe extraction from the zeolite framework and formation of Fe0 nanoparticles, starts at the temperatures above 800 ℃ and finishes at 1030 ℃, when sintering occurs strongly. In contrast, introduction of second metal leads to the decrease in the reduction temperature, as process of CuFe@MFI formation finishes at 800 ℃. Both Fe@MFI and CuFe@MFI show activity in p-nitrotoluene hydrogenation to p-toluidine. Conversion of the substrate grows with increase in the Cu and Fe loading. Thus, this synthesis method of encapsulation of Fe0 nanoparticles and Fe0-Cu0 bimetallic nanoparticles into the zeolite micropores through reductive demetallation of Fe-zeolites can be used to prepare hydrogenation catalysts.

Nanoporous crystalline aluminosilicates, zeolites, are synthesised by solvothermal method producing three-dimensional (3D) crystals. An alternative, more controllable approach of zeolite synthesis - ADOR – can be used for preparation of isoreticular zeolites with tuneable porosity. Zeolites porosity allows their wide use as isomerisation catalysts due to their shape selectivity effects. Selective isomerisation of m-xylene towards p-xylene is an industrially important reaction due to a high demand for the latter as a substrate for terephthalic acid production. In this work, we investigated the influence of pore size (shape selectivity effect) on the isomerization of m-xylene using a system of isoreticular Al-containing zeolites. These materials, prepared by ADOR approach (UTL, IPC-7, IPC-2, IPC-6, and IPC-4) had different layers connectivity, and therefore various channel systems. We tracked the influence of the pore systems of ADOR zeolites (8- up to 14-ring channels) on the catalytic performance in gas-phase m-xylene isomerisation. We investigated the crystallinity and interlayer distances, phase purity, textural properties of prepared materials, their crystals morphology, and aluminium content. M-xylene isomerisation was carried out in a fixed-bed reactor at 350 °C. ADOR catalysts were compared with standard ZSM-5 zeolite. We show the dependence of zeolite porosity on the performance in isomerisation of m- to p-xylene. Smaller pore zeolites: IPC-4 (8- and 10-ring channels) and IPC-6 (8-, 10- and 12-ring channels) exhibited the lowest conversions, while the highest conversion and p-xylene yields were observed for IPC-2 (10- and 12-ring channels). Presence of extra-large, 14-ring channels (IPC-7 and UTL) resulted in the drop of selectivity due to the xylene disproportionation.

Bulky epoxides are industrially produced by organic synthesis in multistep procedures, generating significant amounts of waste products in the process. Efficient catalyst in combination with a simple oxidant (H2O2 or O2) would significantly reduce the waste production. Four types of microporous titanosilicates with extra-large pores (Ti-UTL), and shortened diffusion pathways (L-TS, Ti-MCM-22, and Ti-SPP) were prepared and investigated in the epoxidation of cyclooctene with H2O2 and photocatalytic oxidation using O2. Ti-UTL is a zeolite possessing 14−12-ring channel system. l -TS-1 and Ti-MCM-22 are composed of aggregates of titanosilicate nanosheets with the thickness of ca. 2 nm and hexagonal thin platelets, respectively. Ti-SPP is composed of olive-like aggregates with approximately length of 0.88–1.12 μm and width of 0.44−0.68 μm consisting of intergrown (self-pillared) nanosheets having 13−70 nm in size. In the epoxidation with H2O2 as an oxidant, Ti-MCM-22 showed the highest catalytic activity due to the wide interlayer space, which enhanced the accessibility of cyclooctene to active titanium site. While, in the photocatalytic epoxidation in the presence of O2 instead of H2O2, Ti-UTL showed the highest activity. The incorporated germanium atoms, which is indispensable component for the construction of extra-large pores, may affect the electronic properties of active titanium species, leading to high photocatalytic activity.

Transitioning towards green chemistry requires designing sustainable processes to produce both inexpensive and environmentally friendly materials capable of catalyzing complex chemical transformations in fine chemistry. In this context, natural silicate-based catalysts stand out as some of the most promising alternatives, yet vermiculites have been mostly overlooked so far, despite their high potential as clay catalysts with high negative layer charge, high number of exchangeable interlayer cations and high Lewis and Bronsted acidity. Thus, this work reports a previously undescribed and unusual reaction between benzaldehyde and dioxane in the presence of natural and ion-enriched (Al3+, Fe3+, Mg2+, Ni2+, Sn4+) vermiculite catalysts. The effects of different vermiculites on the reaction were assessed both at different activation/calcination temperatures (150 °C, 300 °C and 450 °C) and without activation. Regardless of temperature activation, all vermiculites catalyzed C-C bond cleavage, decarbonylation/ decarboxylation and radical oxidative coupling of benzaldehyde and dioxane, albeit in different yields. Non-activated, natural vermiculite provided the highest benzaldehyde conversion (92 %) and benzaldehyde-based selectivity to the coupling product, 1,4-dioxan-2-yl benzoate (11 %). High benzaldehyde conversion rates were observed also in reactions with aluminum-enriched vermiculite (Al-VMT) activated at 150 °C (84 %), providing 10% selectivity to the coupling product, and with iron (III)-enriched vermiculite (Fe-VMT) (38 % benzaldehyde conversion, 12% selectivity). Catalyst calcination prevented the formation of the 1,4-dioxan-2-yl benzoate while simultaneously enhancing benzaldehyde degradation to benzene. Ultimately, this study shows, for the first time, that vermiculites catalyze radical-oxidative coupling, yielding complex structures such as 1,4-dioxan-2-yl benzoate, which can be used as building blocks in fine chemistry.

Titanium-containing zeolite-based catalysts have been synthesized and investigated as catalysts in methyl(phenyl)sulfide oxidation with hydrogen peroxide. A hierarchical TS-1 prepared by the secondary templating and a layered TS-1 without and with silica and silica-titania pillars have been studied. Conventional TS-1 was a benchmarking material. The study focuses on observation of the different catalytic performance with regard to textural properties; presence and volume of mesopores and different diffusion characteristics. Thus, a deficiency and excess of the oxidizing agent were used in the catalysed reactions and the progress of reaction and selectivity to products were studied. All tested catalysts have shown after 240 min almost total conversion of methyl(phenyl)sulfide with different selectivity (substrate/catalyst mass ratio 10). It was observed that the reactants ratio hydrogen peroxide/ methyl(phenyl)sulfide influences the selectivity to sulfoxide or sulfone over a particular catalyst. In the case of hydrogen peroxide deficiency experiments (H2O2/sulfide = 0.5 mol/mol) the catalysts exhibited different distributions of products. Lamellar catalyst provided 100% selectivity to sulfoxide, the others in range of 90–65% selectivity to sulfoxide; however, the selectivity was independent on the reaction time and substrate conversion. In the case of the excess of the oxidant, except for Ti-pillared TS-1, all the catalysts showed stabile selectivity of 65% towards methyl(phenyl)sulfoxide being independent of the catalyst. The Ti-pillared TS-1 has shown, during the reaction progress, a decrease in the selectivity to sulfoxide from initial 60% to final 20% of sulfoxide at almost total conversion. The only case when higher selectivity to sulfone was achieved was gradual dosing of hydrogen peroxide.

Lamellar and pillared ZSM-5 materials modified with Mg and Zn oxides were synthesized and tested for in-situ catalytic upgrading of eucalyptus woodchips fast-pyrolysis vapors. The introduction of silica pillars into the lamellar ZSM-5 support led to a higher BET area, but also reduced the overall catalyst acidity. The incorporation of MgO and ZnO occurred with a high dispersion over the zeolitic supports, causing also a significant reduction in the value of their textural properties due to a partial blockage of the zeolite pores. Likewise, the acid features of the zeolitic supports underwent sharp changes by the addition of both MgO and ZnO with a strong decrease in the concentration of the Bronsted and Lewis acid sites present in the parent zeolite, as detected by pyridine adsorption followed FTIR spectroscopy. However, additional Lewis acid sites were created associated to the metal oxides deposited onto the zeolitic supports. Pyrolysis tests were accomplished using a lab-scale downdraft fixed-bed reactor working at atmospheric pressure and a temperature of 500 °C. The use of zeolitic catalysts increased the gas yield, mostly due to the formation of CO and CO 2 , to the detriment of bio-oil production. However, the so obtained bio-oils presented higher quality in terms of H/C and O/C ratios, and larger heating values. The incorporation of MgO and ZnO allowed tailoring the zeolite activity to avoid an excessive cracking of the bio-oil, which in turn resulted in a higher yield of the organic compounds present in the bio-oil, and decreasing the formation of undesired polyaromatic hydrocarbons and coke.

The UTL titanosilicate was prepared together with related lamellar Ti-IPC-1PISi material and zeolites Ti-IPC-2 (OKO) and Ti-IPC-4 (PCR) via top-down synthesis. The titanium can be incorporated to the UTL framework by conventional hydrothermal synthesis and it does not affect the so-called ADOR chemistry of the UTL material. Silica-titania pillaring concept was successfully applied providing very active Ti-IPC-1PITi catalyst for bulky molecules epoxidation with hydrogen peroxide. The textural properties of catalysts prepared can be tuned widely keeping the same crystalline titanosilicate active phase. All the materials were characterised by XRD, nitrogen sorption measurement, SEM, and DR-UV/vis spectroscopy. Ti-IPC-1PITi was the most active catalyst in cyclooctene, norbornene, and linalool epoxidation due to the lowest diffusion constraints and sufficient titanium content. Ti-UTL showed activity similar to Ti-BEA in epoxidation of cyclooctene and it provided different products than other titanosilicates in oxidation of linalool with hydrogen peroxide.

Titanium containing extra-large pore zeolite CIT-5 (IZA code: CFI) was successfully prepared by direct synthesis using Cab-O-Sil M5 and titanium(IV) butoxide in the presence of LiOH. N -Methylsparteinium hydroxide was used as a structure directing agent. The product crystallized into thin plate crystals with an approximate size of 20 × 5 × 0.2 μm. The lowest achieved Si/Ti ratio was 23. The necessary duration of hydrothermal synthesis increased with increasing concentration of Ti in the reaction mixture from 11 days (Si/Ti = 63 in product) to 17 days (Si/Ti = 36) at 155 °C. Prepared Ti-CFI samples exhibit BET surface areas in the range of 308–346 m 2 /g and micropore volumes of 0.094–0.097 cm 3 /g. CFI possesses extra-large pores (14-ring, 7.2 × 7.5 A) accessible for bulky molecules, therefore, Ti-CFI is a useful catalyst for epoxidation of double bonds in bulky molecules used in perfumery and pharmacy. The Ti-CFI samples proved to be catalytically active in epoxidation of 1-octene, cyclooctene, α-pinene, and norbornene with hydrogen peroxide as oxidation agent.