Elucidating the layered structure of the g-C3N4 nanomaterials using X-ray photoelectron spectroscopy and X-ray powder diffraction techniques is possible.

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We report herein HMF (5-hydroxymethylfurfural) and furfural oxidation to 2,5-furandicarboxylic (FDCA) and furoic acids, respectively, in water, under base-free conditions and using supported gold nanoparticles. Prepared catalysts showed high catalytic activity under environmentally friendly conditions. Especially, the use of base-free conditions enables getting rid of the most usually needed neutralization step generating salts that must be further handled/eliminated. We showed that the conversion and the selectivity to desired products depend on the basicity of the support. To this respect, the Au/MgO catalyst was the most active sample (100% and 90% yields to furoic acid and 2,5furandicarboxylic acid, respectively), although a partial leaching of Mg was observed (89 ppm). Novel Au/MgF 2 -MgO catalysts were also very active (97% yield of furoic acid) with a final pH of 7.5. High yields of acid were also obtained (78%) with an acid final pH of 3.8, actually enabling the isolation of products under their acid form directly from the reaction medium without a neutralization step.

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Thanks to a combination of the high activity of ruthenium and unique properties of a new support, magnesium fluoride, a system highly active in the hydrodesulfurization reaction was obtained.Communication 8/07002D Table 1 Selectivity of hydrogenation and isomerization Sample S hyd S iso MRu-S

Graphitic carbon nitride (g-C3N4) was obtained by thermal polymerization of dicyandiamide, thiourea or melamine at high temperatures (550 and 600 °C), using different heating rates (2 or 10 °C min−1) and synthesis times (0 or 4 h). The effects of the synthesis conditions and type of the precursor on the efficiency of g-C3N4 were studied. The most efficient was the synthesis from dicyandiamide, 53%, while the efficiency in the process of synthesis from melamine and thiourea were much smaller, 26% and 11%, respectively. On the basis of the results provided by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–vis), thermogravimetric analysis (TGA), elemental analysis (EA), the best precursor and the optimum conditions of synthesis of g-C3N4 were identified to get the product of the most stable structure, the highest degree of ordering and condensation of structure and finally the highest photocatalytic activity. It was found that as the proton concentration decreased and the degree of condensation increased, the hydrogen yields during the photocatalytic decomposition of water–methanol solution were significantly enhanced. The generation of hydrogen was 1200 µmol g−1 and the selectivity towards hydrogen of more than 98%.

Organosilicon compounds, because of their unique properties, are widely used in a variety of organic processes, and thus the constant improvement of current methods is still needed. We present slurry-phase hydrosilylation reactions using novel supported ionic liquid-phase (SILP) catalysts containing rhodium complexes immobilized in four phosphonium ionic liquids (ILs) on silica support. The obtained new SILP catalysts were analyzed by infrared technique, low-temperature nitrogen physisorption at 77 K, and scanning electronic microscopy with energy-dispersive X-ray spectroscopy to provide structural information on these materials. Moreover, the catalytic activity in hydrosilylation reactions was evaluated and compared with the catalytic activity of rhodium catalysts dissolved in the same ILs when using a biphasic reaction system (IL/catalyst as one phase and mixture of substrates as a second phase). The rhodium-based SILP catalysts proved to be much more efficient than when used in a biphasic system composed of a similar catalyst and reactants. Furthermore, as a result of the presented study, we have identified a highly active SILP catalyst ([{Rh­(μ-OSiMe3)­(cod)}2]/[P66614]­[NTf2] supported on silica) that allowed us to decrease the amount of catalyst used in the reaction by 1000 times in comparison with the amount of catalyst required while performing reaction using the biphasic catalytic system. The proposed method of utilization of SILP materials can become a significant step in reducing expensive organometallic catalyst consumption in organic chemistry and, when applied more broadly, lead to significant cost savings, eventually making the production of many organic molecules more sustainable.

Furfural (FF) is a strategic product for the development of highly valued chemicals from biomass. The oxidation product of FF, furoic acid (FA), is an important precursor for the synthesis of green esters, such as methyl furoate. Taking into account issues with the direct furfural oxidation, furfural derivatives, such as alkyl furoates, can be easily prepared via oxidative esterification.Here, Au nanoparticles that were immobilized on alkaline-earth metal oxide supports were studied for the oxidative esterification of furfural while using alcohol as both reactant and solvent. The formation of esters is favored by the presence of basic sites on catalyst surface, resulting in high selectivity, preventing the formation of the acetal as a by-product. The Au/MgO sample provided up to 95% methyl furoate (MF) yield, a fast reaction rate, and high performance for furfural:Au molar ratios between 50 and 300. Furthermore, this catalyst was stable during reuse, since both the selectivity and the activity were maintained after four cycles. Oxidative esterification products were achieved in the presence of other alcohols, leading to the formation of esters of up to C 5 (isopentyl furoate) with high selectivity (>99%). Linear and branched esters were formed, but the long-chain linear alcohols resulted in higher yields, such as n-butyl furoate in 94% yield.Catalysts 2020, 10, 430 2 of 14 considered to be one of the most important platform compounds in biorefineries of the future [8][9][10]. Several products that are obtained via HMF oxidation are of great interest for the polymer industry because their derivatives can be used as C6 monomers to replace petrochemical monomers [1-10]. For example, 2,5-furandicarboxylic acid (FDCA) is a monomer in the production of polyethylene 2,5-furandicarboxylate (PEF), being a green alternative to polyethylene terephthalate (PET) [11][12][13]. The direct use of FDCA in the industry is difficult due to its low solubility in most commonly used solvents. The furan-2,5-dimethylcarboxylate ester (FDMC) is actually more suitable for the subsequent polymerization reaction, thanks to its better solubility. For this reason, the development of catalytic systems that are capable of producing FDMC directly from the HMF has received much attention today. One alternative is the production of FDCA can be obtained from furoic acid (furfural oxidation product) via the Henkel reaction [13]. However, the use of Au catalysts can also be a viable alternative. FDCA can be obtained from furoic acid (furfural oxidation product) via the Henkel reaction [13]. Recently, Au catalysts have been successfully applied for the oxidative esterification of alcohols [14-17] and they have also been explored for the esterification of furfural and HMF [18][19][20][21][22][23][24][25][26][27][28]. The first example of HMF esterification to produce dimethyl-2-furoate (FDMC) required the use of a base (NaOMe) [29]. Although other catalytic systems have then been reported, there are few examples of successful Au catalytic systems for t...