Valentin Nikolaevich Parmon

Glycerol is a major by-product in biodiesel manufacturing, which accounts for around 10% of the biodiesel volume. A surplus of glycerol has led to the development of technologies for production of value-added products using glycerol as a raw material, following the “waste as a resource” strategy. Various techniques are available to carry out glycerol transformation, viz. carrying out processes under thermal heating, application of ultrasonic or hydrodynamic cavitation, microchannel technologies, etc. Microwave-assisted organic synthesis (MAOS) is a simple and innovative technology, which can be considered as a means of intensifying these processes. This review describes microwave irradiation as a valuable energy-efficient alternative to conventional heating for the production of value-added chemicals from glycerol via dehydration, hydrogenolysis, esterification, transesterification, etherification, and oxidation. In general, innovative and potential catalysts, approaches, and technologies are discussed and critically evaluated in terms of the possibilities and potential for further industrial implementation

The current trends in environment protection and sustainable development demand the investigations in the field of searching new perspective sources for any production. Oat husks seems to be a perspective resource. Cellulose isolated from oat wastes can be used for the production of different materials such as hydro and aerogels, bacterial, nanocrystal and nanofibrillated cellulose, cellulose based composites and ethers. All these materials can be spent in different industries: production of pharmaceuticals, medicine (including targeted delivery of drugs, sponges etc.), agriculture (controlled delivery of pesticides or fertilizers), electronics, production of films, membranes, plastics, coatings, paints, biodegradable packages. In this review, we will demonstrate prospects for using oat husks to obtain cellulose and for obtaining materials based on the main oat husk polysaccharide. This review will evaluate the main achievements in this area. The analysis will allow a reader to form an analytical opinion about the prospects for using oat husks as a source for obtaining valuable products.

Niobium oxide supported on ZrO₂ and mixed oxide of NbO_x-ZrO₂ was prepared and characterized. Mechanical treatment was followed by the microwave heating procedure of catalysts with more advanced textural parameters. The amount of Lewis (LAS) and Brønsted (BAS) acid sites rose with the increasing Nb content in the catalysts. The catalytic properties of samples of niobia-zirconia (NbZr samples, NbZr catalysts) were studied in a cellulose hydrolysis–dehydration reaction at 453 K under an inert Ar atmosphere in a batch reactor. Glucose and 5-hydroxumethylfurfural (5-HMF) were the major products. The initial reaction rate could be tuned by the density of acid sites on the surface of solid. At a low density of acid sites (0.1–0.3 µmol·m⁻²), the initial reaction rate had a pronounced inverse correlation. Increasing the LAS/BAS from 0.3 to 2.5 slightly stimulated the formation of the target products. The catalytic properties of NbZr catalysts prepared by microwave treatment were studied in cellulose transformation in a flow set-up. Glucose was found to be the major product. The maximum yield of glucose was observed in the presence of the sample of 17%Nb/ZrO₂. Increasing Nb content resulted in the formation of Nb-associated acid centers and, in turn, increasing catalyst acidity and activity.

A review of literature on current results from work in the field of obtaining microalgae biomass and processing it into high-value products (biofuel, ethanol, butanol, hydrogen and other products) by chemical and biotechnological means is performed. The review consists of three parts: Biomass Production Methods, Biofuel Production from Microalgae, and Obtaining High-Value Products via Biotechnology. The first part considers promising strains of microalgae that produce lipids and are used to obtain biofuels that meet standards ASTM D6751 and EN 14214. Information is also given on factors affecting the accumulation and composition of lipids in microalgae (composition, illumination, temperature, and salinity of the nutrient medium). Data are presented on ways of producing microalgae biomass that include the use of flue gases and wastewater.

The possibility of obtaining sorbitol from potato starch via one-pot hydrolysis-hydrogenation is demonstrated using bifunctional catalysts 0.3–3 wt % Ru/Cs₃HSiW₁₂O₄₀ (Ru/Cs-HPA). It is found that a catalyst with 1 wt % Ru is the one most effective, since it has the optimum ratio of the concentrations of Brønsted and Lewis acid sites on the support’s surface and a large specific surface area. The kinetics of the reaction with 1% Ru/Cs-HPA is studied and the observed energy of activation of the hydrolysis-hydrogenation of starch to sorbitol is found to be 80 ± 8 kJ/mol. A kinetic model is proposed on the basis of experimental and published data. The model accurately describes the hydrolysis-hydrogenation of starch. The yield of sorbitol was 88 mol % (99 wt %) after 3 hours of the reaction using a catalyst with the optimum composition (1% Ru/Cs-HPA) at the optimum temperature (150°C).

Platinum alloy gauzes are employed for the high-temperature oxidation of NH₃ to NO used in the industrial production of HNO₃ for application in agricultural fertilizers. To enhance the efficiency of NH₃ oxidation, various Pt–Pd–Rh alloys are employed for the production of such catalytic gauzes. To understand the role of these metals in NH₃ oxidation, scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction were applied to investigate the morphology, composition and structure of Pt, Pd and Rh foils after annealing in O₂ and oxidation of NH₃ with air at 1133 K. After annealing in O₂ and NH₃ oxidation, the metallic microgranular structure was detected on Pt(poly), whereas oxide layers of Rh₂O₃ and PdO were observed on Rh(poly) and Pd(poly). At the onset of NH₃ oxidation (t = 1 h), fibrous metal-oxide agglomerates of nanofibers formed on these oxide layers. The long-term (5–10 h) oxidation of NH₃ led to the formation of a continuous layer of pyramidal crystals on Rh(poly) and palladium “cauliflowers” on Pd(poly). The highly exothermic reaction of NH₃ with oxygen on metals and PdO or Rh₂O₃ initiates strong catalytic etching forming grains and facets on Pt, fibrous metal-oxide agglomerates, pyramidal crystals and metallic “cauliflowers” on Rh and Pd.

A series of tin oxides were synthesized with polystyrene microspheres (250 nm) as the template. It was shown that an increase in the template content led to increasing specific pore volume and to the formation of bimodal pore structure with pores of 9 and 70 nm in diameter. Addition of cetyltrimethylammonium bromide (CTAB) during synthesis led to the formation of friable structures (SEM data), to an increase in the average pore diameter from 19 to 111 nm, and to the formation of macropores of 80–400 nm in size. All materials had similar surface properties and cassiterite structure with 5.9–10.8 nm coherent scattering region (XRD data). Flat-band potentials of the samples were determined and their photoelectrocatalytic properties to oxidation of water and methanol were studied in the potential range of 0.4–1.6 V RHE. It was shown that the sample obtained using CTAB was characterized by lower flat-band potential value, but appeared significantly higher photocurrent in methanol oxidation, which resulted from enhanced macro-meso-porous structure to facilitate methanol pore diffusion.

The catalyst preparation route is well known to affect the copper loading and its electronic state, which influence the properties of the resulting catalyst. Electronic states of copper ions in copper-containing silicalites with the MFI-framework topology obtained by a solid-state transformation S (SST) were studied with using EPR, UV-Vis DR, XRD, H₂-TPR and chemical differentiating dissolution. They were compared with Cu-ZSM-5 and Cu-MFI (silicalite) prepared via the ion-exchange and incipient wetness impregnation. SST route was shown to provide the formation of MFI structure and favor clustering of Cu-ions near surface and subsurface of zeolite crystals. The square-planar oxide clusters of Cu²⁺-ions and the finely dispersed CuO nanoparticles with the size down to 20 nm were revealed in Cu-MFI-SST samples with low (0.5–1.0 wt.%) and high (16 wt.%) Cu-content. The CuO nanoparticles were characterized by energy band gap 1–1.16 eV. The CuO-like clusters were characterized by ligand-to-metal charge transfer band (CTB L → M) at 32,000 cm⁻¹ and contain EPR-visible surface Cu²⁺-ions. The low Cu-loaded SST-samples had poor redox properties and activity towards different solvents due to decoration of copper-species by silica; whereas CuO nanoparticles were easily removed from the catalyst by HCl. In the ion-exchanged samples over MFI-silicalite and ZSM-5, Cu²⁺-ions were mainly CuO-like clusters and isolated Cu²⁺ ions inside MFI channels. Their redox properties and tendency to dissolve in acidic solutions differed from the behavior of SST-series samples.

Bifunctional solid acidic quaternary ammonium salts of Keggin-type vanadium-containing heteropoly acids, such as R_3.5H_0.5PVMo₁₁O₄₀ (R: (C₂H₅)₄N, (C₄H₉)₄N, (C₆H₁₃)₄N), and [(C₄H₉)₄N]_4.5H_0.5SiW₁₁VO₄₀, are capable of one-pot hydrolysis-oxidationconversion (OxFA-processing) of starch to biogenic formic acid. The impact of the reaction conditions and catalyst type was revealed. The highest formic acid yield of 50% was achieved over the best [(C₂H₅)₄N]_3.5H_0.5PVMo₁₁O₄₀ catalyst, which was active and stable in seven reaction cycles. The kinetic computational model, which described formic acid formation well, was proposed in the presence of the most active [(C₂H₅)₄N]_3.5H_0.5PVMo₁₁O₄₀ catalyst.

High-temperature oxidation of NH₃ on Pt alloy gauzes to NO is widely employed in industry for the production of HNO₃, which is used to obtain agricultural fertilizers. Particular attention is paid now to the investigation of the chemical composition of gauzes used in NH₃ oxidation. X-ray photoelectron and energy-dispersive X-ray spectroscopies with the depth of analysis ca. 5 nm and ca. 500 nm were applied to investigate the chemical composition of surface and subsurface layers of the new and used in NH₃ oxidation with air at T = 1133 K Pt–Pd–Rh–Ru catalytic gauzes (81, 15, 3.5, 0.5 wt.%, respectively). For all the gauzes, adsorption (OH_ad, CO_ad), graphitic (C_gr) and oxide (Rh₂O₃) films were found on the surface of the metallic alloy. Under these films, C_ab, N_ab and O_ab atoms absorbed in the subsurface layers were detected on the gauzes used in NH₃ oxidation. The obtained data testify to the penetration of O_ab and N_ab atoms into deeper layers of the alloy during etching with elevation of the catalyst temperature. O_ab atoms were accumulated predominantly on dislocations, etch pits and grain boundaries, whereas N_ab atoms intercalated mostly into interstitial sites of the alloy lattice.