The Ni–Cu/Al2O3 catalysts used for the synthesis of carbon nanofibers and hydrogen were prepared by solution combustion synthesis using sucrose, urea, and oxalic acid as fuel. The resulting catalyst was a powder with a specific surface area of 60–128 m2/g. Catalyst samples were tested in a flow reactor at a temperature of 550°C in a methane medium at a pressure of 1 and 5 atm. The influence of organic fuel content on the composition and textural characteristics of resulting catalysts and their efficiency in the synthesis of carbon nanofibers and hydrogen was studied. The methane conversion was revealed to change within 5–17.5
Using chemical vapor deposition (CVD) and the traditional method of incipient wetness impregnation, new Pd–glass fiber catalysts (GFCs) for the oxidation of volatile organic compounds (VOCs) were synthesized. GFC samples were characterized by physicochemical methods (SEM, XPS), and the formation of metal particles on the surface of glass fibers was studied. The process of methane oxidation over the synthesized GFCs was studied, and the specific rates and activation energies of the methane oxidation reaction were determined. The comparative analysis of catalysts prepared by CVD and impregnation was carried out, and the potential of CVD as an efficient GFC synthesis method was demonstrated.
The paper is devoted to studying the process of thermal catalytic biomass processing in a fluidized-bed reactor for useful heat generation. Miscanthus, pine nut shells, and spent coffee were selected as initial biomass. The biomass crushed to a fraction smaller than 0.5 mm (coffee was not ground, as the size of its particles was initially 0.2–0.4 mm) was fed into a fluidized-bed reactor at processing temperatures of 650, 700, and 750°C, respectively. The objective of these experiments was to generate useful heat by burning the supplied biomass and utilize it, e.g., in maintaining an autothermal regime, as well as to investigate the resulting ash residues and analyze the flue gases emitted during the combustion process, followed by process simulation in Aspen Plus. The data of simulation show good agreement with experiment, and the proposed scheme can be used as one of the approaches to evaluating the feasibility of catalytic biomass combustion in a fluidized-bed in autothermal mode.
The results of studying the samples of efficient sorbents based on domestic natural raw materials, namely, ferromanganese nodules (FMNs) are presented. The use of these sorbents has significant potential for solving the pressing problem of environmental protection, such as the purification of gas flows from toxic sulfur compounds. The influence of the calcination temperature of sorbents on their physicochemical and sorption characteristics is studied. It is shown that the calcination temperature of a sorbent significantly affects its sorption capacity with respect to hydrogen sulfide, and optimal sorption characteristics are exhibited by the sorbent calcined at 300°C. SEM elemental mapping and DRIFT study results for spent samples allowed us to propose a temperature-dependent pathway of hydrogen sulfide sorption on the synthesized sorbents.
The studies of acid-catalyzed production of cellulose acetates derived from various types of biomass are reviewed in this work. Conventional acetylation methods in the presence of strong inorganic acids, transition metal salts, iodine or polyoxometalates are considered. Their disadvantages are corrosive activity and poor environmental performance (for example, formation of wastewater that requires disposal). The promising areas for further studies are the development of new regenerable catalysts and the regulation of the degree of substitution during acetylation in their use. Such systems may yield materials for their use in separators for energy storage devices, including supercapacitors.
