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A catalytic phenol methylation study on two ferrospinel materials (Mg0.63Zn0.37)(Mn0.1Fe1.8)O3.85 (hereafter Mg–Zn) and (Mn0.55Zn0.35Fe0.1)Fe2O4 (hereafter Mn–Zn) was performed. The reaction was carried out in the gas phase in a continuous manner with the feed composition of phenol, methanol, and water in molar ratio 1:5:1. Both ferrites are active in the studied reaction. The alkylation of phenol with methanol led to the selective production of o-methylated phenol derivatives, i.e., o-cresol and 2,6-xylenol. However, both catalysts markedly differ in terms of activity. Different synergy effects on both catalysts cannot be a sufficient explanation. These materials do not differ significantly either in their susceptibility to reduction or in their Lewis type acidity. Because their microstructure differs significantly, a size effect may therefore be responsible for the differences in activity.

ZnFe2−xAlxO4 (x = 0, 1, 2) spinels were obtained by microwave-assisted solvothermal method using 1,4-butanediol as reaction medium. The results of XRD and HRTEM studies have indicated higher nanocrystallinity of aluminium containing spinels, and N2 adsorption–desorption measurements have revealed their enhanced textural properties, in particular much higher specific surface areas. NH3-TPD method and cyclohexanol test have shown the variation of surface acid–base properties with the changes in the spinel composition. All studied spinels were active in aniline methylation and proved to be selective for N-methylation leading to N-methylaniline and N,N-dimethylaniline. The main advantage of aluminium containing spinels is that N-alkylation with methanol is possible at significantly lower temperature (200–260 °C) when pure zinc ferrite is almost inactive.

Palladium catalysts containing Pd(0) or Pd(II) supported on alumina-based mixed oxides prepared by alkoxide sol–gel method (Al 2 O 3 , Al 2 O 3 –ZrO 2 , Al 2 O 3 –ZrO 2 –Eu 2 O 3 , Al 2 O 3 –MgO, Al 2 O 3 –CeO 2 , Al 2 O 3 –Fe 2 O 3 ) are very effective in the Heck coupling of bromobenzene with butyl acrylate in DMF solvent. In the presence of an excess of bromobenzene, butyl cinnamate (1) was formed as the main product after 4 h. With the same catalysts, good results, up to 97% yield of ethyl β-phenylcinnamate (3), were also obtained in the coupling of bromobenzene with ethyl cinnamate. The three most active catalysts, Pd(0)/Al 2 O 3 , Pd(II)/Al 2 O 3 , and Pd(II)/Al 2 O 3 –Fe 2 O 3 , were applied in the Heck cross-coupling of cinnamates with different bromobenzene and iodobenzene derivatives, leading to β-arylcinnamate products. The highest yield was observed when iodoanisole and cinnamic aldehyde were used as substrates. The formation of Pd(0) nanoparticles in the Heck reaction carried out with supported Pd(II) catalyst precursors was confirmed by TEM measurements.

Mixed oxides with perovskite-like structure and the same formal composition La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) were prepared by combustion synthesis and by reactive grinding method. Properties of these materials were compared with properties of a commercially available LSCF mixed oxide. The samples were characterized using XRD, ICP, XPS, TEM, SEM, TPR-H2, specific surface area (SSA) and acid–base measurements. It was found that although studied materials exhibit similar physicochemical properties they show different catalytic behaviour for phenol alkylation with methanol. Such behaviour can be attributed to differences in surface structure caused by different synthesis route. The main reaction product, i.e. ortho-cresol, was obtained with selectivity higher than 90% (in the whole studied temperature range) at conversion level up to 41% on the material prepared by reactive grinding.

Alumina-based oxides Al 2 O 3 , Al 2 O 3 –ZrO 2 (A, B, C) and Al 2 O 3 –ZrO 2 –Eu 2 O 3 (D) were prepared by alkoxide sol–gel method and used as supports for palladium nanoparticles obtained by reduction of PdCl 2 by methanol or hydrazine. As confirmed by XRD and TEM methods, such catalysts are composed of palladium nanoparticles well dispersed on the surface of the alumina matrix. The Suzuki coupling of 2-bromotoluene with phenylboronic acid, used as the test reaction, revealed that the obtained catalysts were quite efficient even at 40 °C and that their catalytic activity increased at 60 and 80 °C. Very good results (95% yield after 1 h) also were obtained when PdCl 2 supported on mixed oxides was used without earlier palladium reduction. It was confirmed that under the reaction conditions, Pd(0) nanoparticles of ca. 5 nm in diameter were formed on the support. Under the same conditions ( i PrOH + H 2 O used as a solvent, KOH as a base), a Pd(0)/PVP colloid exhibited slightly lower catalytic activity.

A composite oxide ZnAl2O4 was prepared by microwave-assisted hydrothermal treatment, a precursor mixture of hydroxides obtained by precipitation of aluminium and zinc nitrates. Characterization by TEM, XRD and textural studies shows that ZnAl2O4 is nanosized and is a micro/mesoporous material with large a surface area (140 m2/g). The gas phase catalytic methylation of 4-hydroxypyridine in the presence of the ZnAl2O4 catalyst was performed in a continuous process at atmospheric pressure in the temperature range of 240–360 °C. A mixture of O- and N-alkylated products, namely 4-methoxypyridine and N-methyl-4-pyridone were obtained. The alkylation of 4-hydroxypyridine with methanol at 345 °C offered 87.6% selectivity towards N-methyl-4-pyridone with about 89% 4-hydroxypyridine conversion.

The gas phase alkylation of 2-hydroxypyridine with methanol at atmospheric pressure, over ZnAl 2 O 4 , prepared via hydrothermal route, is reported. The catalyst was characterised by XRD, HRTEM, DTA-TG, BET surface area measurements, pore-size analysis and surface acidity. The catalyst indicates high selectivity (over 95%) in the reaction of methanol with 2-hydroxypyridine leading to N -methyl-2-pyridone and its activity does not change substantially in the temperature range of 325–340 °C.

The investigation presented attempts to apply the Zr-Mg-Y oxide system as a catalyst for phenol alkylation with methanol by a gas-phase reaction. The studies were carried out in a continuous process performed at atmospheric pressure. It was indicated that the catalyst obtained is active and ortho-selective in the methylation of phenol. At 370°C, in the presence of Zr-Mg-Y oxide catalyst under the experimental conditions studied, an interesting yield of ortho-cresol (over 46% with 66.5% selectivity) was attained. Zr-Mg-Y-O catalyst was prepared by low temperature method and it was characterised by X-ray powder diffraction, scanning microscopy and nitrogen physisorption. In addition, in this reaction the catalytic specificity of Zr-Mg-O, ZrO2, MgO and Y2O3 was examined.

Mg,Al-mixed oxide catalyst with molar ratio 1:2 was prepared hydrothermally from magnesium acetate and basic aluminium nitrate. The obtained sample was characterised by XRD, HRTEM and nitrogen adsorption. The basic sites density was determined by temperature-programmed desorption of CO 2 combined with mass spectrometry (TPD-MS). Moreover, test reactions for acid–base characterisation (i.e. 2-propanol and cyclohexanol transformations) were used. The prepared catalyst proved to be selective and active for monoalkylation of imidazole leading to 1-methylimidazole. The gas phase catalytic alkylation of imidazole with methanol on Mg,Al-mixed oxide catalyst was carried out in a continuous process at atmospheric pressure in the temperature range of 225–350 °C. 1-Methylimidazole was efficiently obtained with selectivity reaching up to 97.4% at an imidazole conversion of 93.0% (at temperature 340 °C).

Nanosized γ-Al 2 O 3 catalyst was prepared by the alkoxide sol–gel method and characterized by XRD and TEM. The porous nature of the catalyst was studied by nitrogen adsorption–desorption isotherms. Acidity of the synthesised material was analyzed by pyridine-adsorbed FT-IR spectroscopy. The gas phase alkylation of isomeric methylphenols (cresols) with isopropyl alcohol over sol–gel prepared alumina catalyst was studied. The reactions were carried out in a continuous process at the atmospheric pressure with dependence on temperature, starting at 210 °C up to the point when the amount of alkylated cresols dropped due to decomposition. Both, O- and C-alkylated products were obtained at lower temperatures, while at higher temperatures ortho -isopropylated derivatives of isomeric cresols were the main products. According to the present method isopropylated cresols can be efficiently obtained with selectivity higher than 90%.

The gas-phase catalytic transformations of anisole on two catalytic systems: ZnAl 2 O 4 ( A ) and 8%Fe 2 O 3 /ZnAl 2 O 4 ( B ) have been studied. Catalyst A was synthesised at hydrothermal conditions from Zn and Al nitrates; catalyst B was made from catalyst A by additionally impregnating with aqueous solution of ferric nitrate. Experimental data show that the addition of iron oxide (Fe 2 O 3 ) into zinc aluminate improves the catalytic activity i.e. anisole conversion and total ortho -selectivity to ortho -cresol and 2,6-xylenol. On the surface of both catalysts, Lewis acid sites are present. Catalyst A is characterised by higher concentration of Lewis acidity. The proposal of the reaction mechanism in the presence of catalysts was presented.

The gas phase catalytic alkylation of phenol with methanol over new Sn–Ce–Rh–O catalyst has been studied. Cerium dioxide, tin dioxide, Sn–Ce–O and Sn–Rh–O systems have been also applied as catalysts. The reaction was carried out in a continuous process at the atmospheric pressure in dependence on temperature—starting at 523 K up to the deflection of phenol conversion. According to the elaborated method ortho-methyl phenol derivatives can be efficiently obtained. The best results were received in the presence of Sn–Ce–Rh–O: a summarized selectivity to ortho-cresol and 2,6-xylenol at 643 K reached 93.5% at the 71% conversion of phenol. Over all the studied catalysts O-alkylation was an insignificant process.

Deactivation of the iron catalyst Fe-Si-Cr-K-O was investigated with the help of X-ray photoelectron spectroscopy and checked in reaction of phenol alkylation with methanol performed in gas phase at the atmospheric pressure. It was indicated that the catalytic action of the alkylation catalyst (active–inactive) could be correlated with the relative contribution of the oxidation states of iron (+2) and (+3). The intensity ratio of the Fe 3p individual components was found to be a good measure of the contribution. The catalyst as-prepared has the (+2)/(+3) ratio 1.7, active in reaction—1.9, calcined at 1000 °C—1.4 and deactivated during the reaction—2.7. The process accompanied other reasons for deactivation as carbon deposition on the surface and/or sintering of catalyst crystallites.

Europium-doped nanostructured monolithic alumina matrix was prepared by the alkoxide sol–gel method. The Eu 3+ ions were introduced by impregnation. The resulting γ-Al 2 O 3 :Eu 3+ samples were heat-treated in the presence of gaseous components from oxidative pyrolysis of polytetrafluoroethylene (PTFE). The textural properties and optical behavior of the samples obtained were investigated. It was found that after a subsequent heat-treatment in air at 1400 °C, a strong blue fluorescence of Eu 2+ was observed whereas in thermally sintered samples without fluorination only the Eu 3+ ions were present.

The gas-phase catalytic alkylation of m -cresol with isopropanol on ZnAl 2 O 4 catalysts of different properties has been studied. The reactions were carried out in a continuous process at atmospheric pressure in the temperature range of 473–583 K. Both, O- and C-alkylated products were obtained at lower temperatures while at higher temperatures thymol was the main product of the reaction. According to the elaborated method thymol can be efficiently obtained with selectivity reaching up to 88.4% at an m -cresol conversion of 78.2%.

Two samples (A and B) of zinc aluminate spinel were prepared and used as catalysts of phenol methylation. Both catalysts were synthesised at hydrothermal conditions from zinc acetate and from various aluminium precursors: aluminium isopropoxide (catalyst A) or basic aluminium nitrate (catalyst B). Catalyst A was pure ZnAl2O4 and B - besides ZnAl2O4 contained traces of γ-Al2O3. Reactions of phenol alkylation with methanol were carried out in the gas phase under atmospheric pressure in a standard flow reactor with fixed bed. Catalysts indicated different properties in dependence on the aluminium precursor used during preparation. In the presence of catalyst A higher selectivity of ortho-methylation of phenol was obtained. Catalyst B was active both in O-alkylation and C-alkylation.

The methyl ester mixture obtained from rape oil, and the mixture of butyl esters produced from animal fatty acids, were converted into mixtures of ketones with a total yield above 65%. The experiments were performed at atmospheric pressure in a temperature range of 300-400°C using a standard flow system, with an iron catalyst modified with silicon, chromium, and potassium oxides, in the molar ratio of 100:2:1:0.1. The described method may extend the prospects of using waste technical fats.

Pentamethylene and hexamethylene glycols over a catalyst consisting of iron, silicon, chromium and potassium oxides undergo intramolecular condensation at about 640 K, but considerably different products are obtained: 2,3-dihydropyran and cyclopentanone, respectively. Above 650 K, both glycols undergo intermolecular condensation forming corresponding 5-nonanone and 6-undecanone. Reactions were carried out in a standard flow system under atmospheric pressure in the gas phase.

The susceptibility to ketonization of oxidized derivatives of n -decane ( n -decanol, n -decanal, their equimolar mixtures, n -decyl n -decylate, and 3-hydroxy-2-octyl-dodecanal) in the gas phase at atmospheric pressure over Fe 3 O 4 catalyst was studied. Using those reactants, 10-nonyldecanone was the main product. Condensing n -decanal, n -decyl n -decylate, and 3-hydroxy-2-octyl-dodecanal, ketone is obtained with higher yields than from n -decanol.

A oxidizing condensation of normal alcohols C4 to C12 in the gas phase over Fe3O4 catalyst containing Cr, Si and K oxides was studied. The reactions were carried out in a continuous process at atmospheric pressure. Initially the alcohols undergo dehydrogenation to aldehydes and esters, and at higher temperatures symmetric ketones containing 2n - 1 atoms of carbon in a molecule are formed. A mechanism for the reaction is proposed.

Gas-phase alkylation of meta-cresol, 2,5-xylenol and 2,3-xylenol by methanol over a catalyst containing iron oxide as the main component was studied. The reactions were carried out in a continuous process at atmospheric pressure in the temperature range of 573–663 K. The yield of 2,3,6-trimethylphenol increases in the series: meta-cresol

The influence of gas-phase methylation of phenol on the state of the Fe-Si-Cr-K oxide catalyst surface was investigated by thermodesorption of K atoms and ions. Changes in potassium desorption energies, as determined from Arrhenius-like plots, varied from 3.07 eV to 1.21 eV for the atoms and from 2.59 eV to 2.89 eV for ion desorption from the active and deactivated samples, respectively. The results were discussed in terms of transformation of the catalyst surface and formation of β-ferrite.

Iron catalysts modified with chromium, silicon, potassium or caesium ions were investigated in the synthesis of 2,6-xylenol by alkylation of phenol wit

Zn1−x Co x Al2O4 (x = 0, 0.5, 1.0) spinels were synthesised under microwave-assisted solvothermal conditions using 1,4-butanediol as reaction medium. The results of XRD and HRTEM have indicated nanocrystallinity of prepared materials (average crystallite size in the range 6–16 nm), and N2 adsorption–desorption measurements have revealed high feature of their surface area and mesoporous nature. Acid–base properties of prepared materials were determined using TPD-NH3 method and cyclohexanol test. All studied spinels that underwent examination were active in phenol methylation but Co-substituted zinc aluminate (Zn0.5Co0.5Al2O4) was found to be the most efficient in the selective formation of ortho-methylated products. It could be ascribed to its dominant basic character and the presence of weak and strong acid centres, and the highest surface area as well.

Alkylation of phenol to ORTHO-cresol and 2,6-xylenol with methanol in the presence of iron and iron-magnesium oxide catalysts was investigated. The catalysts displayed high activity and stability. Addition of magnesium oxide to the iron catalyst increases its selectivity towards C-alkylation in ortho-position. It was found that the active phase in the investigated catalysts is highly dispersed magnetite or mixed spinel of Fe(MgFe)O4 type. It is noticed that if Fe+2 ions are replaced by Mg+2 ions in the spinel the basicity of the bifunctional catalyst is augmented, increasing ortho-selectivity of alkylation.