Oleg V. Manaenkov

Platform chemicals, also known as chemical building blocks, are substances that serve as starting materials for the synthesis of various value-added products, which find a wide range of applications. These chemicals are the key ingredients for many fine and specialty chemicals. Most of the transformations of platform chemicals are catalytic processes, which should meet the requirements of sustainable chemistry: to be not toxic for humans, to be safe for the environment, and to allow multiple reuses of catalytic materials. This paper presents an overview of a new class of heterogeneous catalysts based on nanoparticles of catalytically active metals stabilized by a polymer matrix of hypercrosslinked polystyrene (HPS). This polymeric support is characterized by hierarchical porosity (including meso- and macropores along with micropores), which is important both for the formation of metal nanoparticles and for efficient mass transfer of reactants. The influence of key parameters such as the morphology of nanoparticles (bimetallic versus monometallic) and the presence of functional groups in the polymer matrix on the catalytic properties is considered. Emphasis is placed on the use of this class of heterogeneous catalysts for the conversion of plant polysaccharides into polyols (sorbitol, mannitol, and glycols), hydrogenation of levulinic acid, furfural, oxidation of disaccharides, and some other reactions that might be useful for large-scale industrial processes that aim to be sustainable. Some challenges related to the use of HPS-based catalysts are addressed and multiple perspectives are discussed.

В данной работе предложена методика синтеза магнитных материалов на основе коммерческих цеолитов типа ZSM-5 и оксидной формы алюмосиликата SIRALOX 40/490. Синтезированные композиты были охарактеризованы различными физико-химическими методами. В частности, показано, что при введении в состав сорбентов наночастиц магнетита происходит блокировка кислотных центров, а удельная площадь поверхности и характер пористости исходных сорбентов не претерпевают критических изменений в ходе синтеза, что позволяет предположить также незначительное изменение их сорбционных свойств. Методом электронной микроскопии определён средний размер частиц магнетита, сформированных в порах сорбентов – в пределах 55- 65 нм. Высокое содержание в композитах железа (в составе магнетита) обусловливает их хорошие магнитные характеристики, что позволяет быстро и в полном объёме отделять их от жидкой фазы посредством внешнего магнитного поля. Синтезированные магнитные композиты могут быть использованы в качестве сорбентов, или носителей для синтеза гетерогенных каталитических систем. In this work, we propose a procedure for the synthesis of magnetic materials based on commercial zeolites of the ZSM-5 type and the oxide form of aluminosilicate SIRALOX 40/490. The synthesized composites were characterized by various physicochemical methods. In particular, it has been shown that the introduction of magnetite nanoparticles into the composition of sorbents results in the blocking of acid sites, and the specific surface area and porosity of the initial sorbents do not undergo critical changes during synthesis, which also suggests a slight change in their sorption properties. Using electron microscopy, the average size of magnetite particles formed in the pores of sorbents was determined to be within 55-65 nm. The high content of iron in composites (in the composition of magnetite) determines their good magnetic characteristics, which allows them to be quickly and completely separated from the liquid phase by means of an external magnetic field. The synthesized magnetic composites can be used as sorbents or carriers for the synthesis of heterogeneous catalytic systems.

Lignin obtained by hydrogenolysis of lignocellulose biomass is a prospective source of valuable green fuels and chemicals such as monophenols. One of the key factors in the chemical decomposition of lignin to monophenols is an efficient catalyst. Inert porous materials such as hypercrosslinked polymers are suitable catalytic supports for the immobilization of noble and transition metal nanoparticles. However, such polymers do not have acidic properties, which are crucial for catalyzing hydrolysis. In this work, we report novel, efficient catalysts for lignin hydrogenolysis to produce valuable monophenolic compounds. The synthesized catalysts contained Ni, Ru, and Ni–Ru nanoparticles supported on SiO₂-coated hypercrosslinked polystyrene (SiO₂@HPS). Ni-Ru/SiO₂@HPS demonstrated remarkable stability without any loss of the metallic phase and a high yield of monophenols (>42 wt.%) at close to full lignin conversion (>95 wt.%). This result was attributed to the synergy between the two metals and the support’s surface acidity. All catalysts were fully characterized by a series of physico-chemical methods.

Flaxseed mucilage and its derivatives have been extensively investigated over the last decade, mainly due to their inherent techno-functional (thickening, gelling, interface-stabilizing, and film-forming) properties that are relevant in the food industry. Hydrocolloids are used to modify food properties, such as for stabilization and emulsion, and are also used to control the microstructure of the food. Increasing research attention has been paid to the application of hydrocolloid materials in gel particles for encapsulation or texture control in food, pharmaceutical, cosmetic, and probiotic products. Thus, it is important to investigate the properties of hydrocolloids manufactured from various sources and explore their possible applications in the food industry. The applied nature of the study of plant mucus substances is associated with the ever-increasing demand for their use in the food, cosmetic, and pharmacological industries, determining the related research priorities, including the development of the most effective methods for the extraction of glycans and the search for highly productive raw materials for the production of polysaccharides. The aim of this work was to study varietal differences in the compositions of heteropolysaccharides in the mucus samples of oilseed and fiber flax varieties using a modern methodological approach for obtaining glycans based on the ultrasonic extraction of polysaccharides. The seeds of 10 flax varieties were studied, differing in their morphotype, place, and time of creation. The obtained results indicated significant differences in the quantitative and qualitative compositions of the heteropolysaccharides of flax seeds of various varieties. The contents of reducing sugars in the studied varieties ranged from 5.61 ± 0.01 to 18.81 ± 0.01 mg/g, indicating significant differences in the structural organization of glycans in different flax varieties. Additionally, the results obtained here allowed us to conclude that the range of reducing sugars for flax heteropolysaccharides is significantly less than this range for oilseed flax varieties. The obtained results of the study of the composition of flax seed heteropolysaccharides allowed us to consider them as selection trait and genetic markers.

Маннит – это важное сырье в производстве смол, смазочных материалов, покрытий, ПАВ, взрывчатых веществ, косметики и лекарств. Одним из перспективных способов его получения является каталитическая конверсия инулина – природного полифруктозана, в больших количествах содержащегося в некоторых сельскохозяйственных культурах. В данном исследовании впервые для процесса гидролитического гидрирования инулина до маннита был предложен полимерный Ru-содержащий катализатор на основе мезопористой матрицы сверхсшитого полистирола. При оптимальный условиях реакции (0,1167 ммоль Ru в составе катализатора на 1 г инулина; 30 мл H₂O; температура 150 °С; парциальное давление водорода 60 бар, время реакции 45 мин) была получена высокая селективность по манниту – 48,7% при 100%-ной конверсии исходного полисахарида. При этом производительность полимерного катализатора оказалась выше, чем производительность магнитного катализатора на основе мезопористого диоксида кремния, синтезированного нами в предыдущих исследованиях. В ходе работы были проведены кинетические эксперименты, выявлены закономерности реакции гидролитического гидрирования инулина с образованием маннита и ряда побочных продуктов. На основе полученных экспериментальных данных была предложена схема реакций, математическая модель процесса, наиболее адекватно описывающая экспериментально полученные данные, а также рассчитаны ее параметры. Полимерный магнитный катализатор оказался стабильным в гидротермальных условиях реакции, легко отделялся от жидкой фазы катализата внешним магнитным полем, что делает его перспективным, в частности, для использования в процессах конверсии растительной биомассы в сырье для химического синтеза и производства топлива. Для цитирования: Манаенков О.В., Кислица О.В., Матвеева В.Г., Косивцов Ю.Ю., Сульман М.Г. Кинетика процесса гидролитического гидрирования инулина до маннита на Ru-содержащем магнитном катализаторе. Изв. вузов. Химия и хим. технология. 2023. Т. 66. Вып. 8 С. 70-76. DOI: 10.6060/ivkkt.20236608.6898.

Studies of the processes of the hydrolytic oxidation of disaccharides are the first step towards the development of technologies for the direct conversion of plant polysaccharides, primarily cellulose, into aldonic and aldaric acids, which are widely used in chemical synthesis and various industries. In this study, heterogeneous catalysts based on a porous matrix of hypercrosslinked polystyrene (HPS) and noble metals (Pt, Au, Ru, and Pd) were proposed for the hydrolytic oxidation of cellobiose to gluconic and glucaric acids. The catalysts were characterized using low-temperature nitrogen adsorption, hydrogen chemisorption, electron microscopy, and other methods. In particular, it was shown that the Pt-containing catalyst contained, on average, six times more active centers on the surface, which made it more promising for use in this reaction. At a temperature of 145 °C, an O₂ pressure of 5 bars, and a substrate/catalyst weight ratio of 4/1, the yields of gluconic and glucaric acids reached 21.6 and 63.4%, respectively. Based on the data obtained, the mathematical model of the cellobiose hydrolytic oxidation kinetics in the presence of 3% Pt/HPS MN270 was developed, and the parameter estimation was carried out. The formal description of the kinetics of cellobiose hydrolytic oxidation was obtained.

Разработана методика синтеза полимерных сорбентов на основе сверхсшитого полистирола (СПС), обладающих магнитными свойствами. Методика основана на восстановлении солей железа многоатомными спиртами при высокой температуре в инертной атмосфере. Получаемые сорбенты сохраняют исходные характеристики: развитую удельную площадь поверхности, микро-мезопористый характер, приобретая магнитные свойства, что даёт возможность их использования в качестве магнитноотделяемых сорбентов, носителей активной фазы гетерогенных каталитических систем. A procedure for the synthesis of polymeric sorbents based on hypercrosslinked polystyrene (HPS) with magnetic properties has been developed. The technique is based on the reduction of iron salts with polyhydric alcohols at high temperature in an inert atmosphere. The resulting sorbents retain their original characteristics: a developed specific surface area, micro-mesoporous nature, acquiring magnetic properties, which makes it possible to use them as magnetically separable sorbents, carriers of the active phase of heterogeneous catalytic systems.