scholarly journals New Supports for Carbon-Metal Catalytic Systems Based on Shungite and Carbonizates of Plant Raw Materials

2015 ◽  
Vol 17 (3) ◽  
pp. 223 ◽  
Author(s):  
R.R. Tokpayev ◽  
A.A. Atchabarova ◽  
S.A. Abdullayeva ◽  
S.V. Nechipurenko ◽  
S.A. Yefremov ◽  
...  
Keyword(s):  
Active Sites ◽  
Raw Materials ◽  
Base Catalysis ◽  
Metal Catalyst ◽  
Active Centers ◽  
Catalytic Systems ◽  
Homogeneous Surface ◽  
Plant Raw Materials ◽  
Bet Method ◽  
Catalyst Systems

<p>In this paper, new carbon containing materials based on products of shungite ore enrichment and carbonizates of plant raw materials were studied. The phase transformations occurring during the carbonization process were studied. Scanning electron microscopy (SEM) was used to visualize the surface topography. It was established that supports based on plant raw materials have more developed and homogeneous surface. Specific surface area and porosity was studied by BET (Method of Brunauer-Emmet Taylor). It was found that supports based on plant raw materials have developed microporous surface (383–480 m<sup>2</sup>/g), with predominant micropores on the surface with dimensions of 1.8–2.5 nm. The mechanical strength of the obtained supports is higher than their industrial analogs and it equals 53–91%. Conversion of methylbutynol on active centers of supports was studied. Supports based on plant raw materials have basic active sites whereby they can be used in base catalysis. Supports based on carbon-mineral raw materials possess acid and basic active sites and they can be used to prepare bidirectional type action of catalysts. Conducted research have shown the possibility of using these materials as supports for creating carbon-metal catalyst systems.</p>

scholarly journals New methods of acid hydrolysis of cellulose and plant raw materials

2021 ◽  
Vol 57 (1) ◽  
pp. 119-128
Author(s):  
V. S. Boltovsky
Keyword(s):  
Acid Hydrolysis ◽  
Plant Biomass ◽  
Raw Materials ◽  
Agricultural Waste ◽  
Feed Additives ◽  
Process Conditions ◽  
Catalytic Systems ◽  
Plant Raw Materials ◽  
Hydrolysis Of Cellulose ◽  
Hydrolysis Of

Prospects for the development of hydrolysis production are determined by the relevance of industrial use of plant biomass to replace the declining reserves of fossil organic raw materials and increasing demand for ethanol, especially for its use as automobile fuel, protein-containing feed additives that compensate for protein deficiency in feed production, and other products. Based on the review of the research results presented in the scientific literature, the analysis of modern methods of liquid-phase acid hydrolysis of cellulose and various types of plant raw materials, including those that differ from traditional ones, is performed. The main directions of increasing its efficiency through the use of new catalytic systems and process conditions are identified. It is shown that the most promising methods for obtaining monosaccharides in hydrolytic processing of cellulose and microcrystalline cellulose, pentosan-containing agricultural waste and wood, are methods for carrying out the process at elevated and supercritical temperatures (high-temperature hydrolysis), the use of new types of solid-acid catalysts and ionic liquids. 

scholarly journals Accumulation of heavy metals and arsenic with medicinal herbal raw material of common shovel harvested in Voronezh region

2021 ◽  
Vol 21 (4) ◽  
pp. 478-487
Author(s):  
Nina A. Dyakova ◽  
Keyword(s):  
Heavy Metals ◽  
Crop Production ◽  
Raw Materials ◽  
Anthropogenic Pollution ◽  
Raw Material ◽  
Cobalt Chromium ◽  
Active Centers ◽  
Plant Raw Materials ◽  
Nickel Copper ◽  
Voronezh Region

The Voronezh region is traditionally the most important area of crop production and agriculture. The purpose of the research was to study the contamination with heavy metals of medicinal plant raw materials of the Voronezh region using the example of the roots of ordinary burdock, prepared in urbo- and agro-ecosystems, which have various anthropogenic effects on themselves. The accumulation of heavy metals (lead, mercury, cadmium, nickel, copper, zinc, cobalt, chromium) and arsenic in 51 samples of raw materials was studied. By comparing the heavy metal content in the upper soil layers of the region and the content of these elements in the roots of the bladder, it can be assumed that there are significant physiological barriers to the accumulation of ecotoxicants in the roots of the bladder, which is especially noticeable for elements such as lead, mercury, arsenic, cadmium, cobalt and chromium. At the same time, this type of medicinal vegetal raw material is able to selectively concentrate some heavy metals included in the active centers of enzyme systems (copper and zinc). Thus, for an ordinary bladder under conditions of anthropogenic load, an edaphotype is formed, which is as a result of selection in conditions of anthropogenic pollution of the external environment and the manifestation of adaptation to these conditions.

scholarly journals COMPARISON OF THE ADSORPTION CAPACITY OF CARBON SORBENTS FROM DIFFERENT PLANT PRECURSORS

2021 ◽  
pp. 345-350
Author(s):  
Andrey Aleksandrovich Spitsyn ◽  
Mariya Igorevna Minich ◽  
Dmitriy Andreyevich Ponomarev ◽  
Nikolay Ivanovich Bogdanovich
Keyword(s):  
Activated Carbon ◽  
Adsorption Capacity ◽  
Sorption Capacity ◽  
Raw Materials ◽  
Nitrogen Adsorption ◽  
Heating Time ◽  
Birch Wood ◽  
Plant Raw Materials ◽  
Bet Method ◽  
Pine Cones

The sorption capacity of activated carbon obtained from various plant precursors – apple wood, birch wood, pine cones and cellolignin was studied. The plant material was first subjected to carbonation by heating to a temperature of 700 °C and further exposure at this temperature. The total heating time was 8 hours. Charcoal was then subjected to steam activation at a reactor temperature of 950 °C and an activation time of 40–45 minutes. The yield of activated carbon estimated on charcoal was 42–46%. The characteristics of the porous structure were determined by the method of low-temperature nitrogen adsorption. The total specific surface area according to the BET method was (m2/g) 674, 594, 552, 552, 622 for apple wood, birch wood, pine cones, cellolignin and an industrial sample of activated carbon, respectively. Determination of the adsorption capacity by iodine adsorption methods showed that this value, depending on the source of raw materials, falls in the order: birch wood > cellolignin ≈ apple wood > pine cones. The data on the sorption of benzene characterize approximately the same range of sorption capacity: birch wood > cellolignin > pine cones ≈ apple wood. The data on the sorption capacity show that unconventional plant raw materials can be used to produce activated carbon.

What catalysis needs from the electron microscopist

1988 ◽  
Vol 46 ◽  
pp. 694-695
Author(s):  
Alexis T. Bell
Keyword(s):  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Catalyst Deactivation ◽  
Surface Composition ◽  
Internal Surface ◽  
Active Phase ◽  
Atomic Scale ◽  
Metal Catalyst ◽  
Internal Surface Area ◽  
Porous Support

Heterogeneous catalysts, used in industry for the production of fuels and chemicals, are microporous solids characterized by a high internal surface area. The catalyticly active sites may occur at the surface of the bulk solid or of small crystallites deposited on a porous support. An example of the former case would be a zeolite, and of the latter, a supported metal catalyst. Since the activity and selectivity of a catalyst are known to be a function of surface composition and structure, it is highly desirable to characterize catalyst surfaces with atomic scale resolution. Where the active phase is dispersed on a support, it is also important to know the dispersion of the deposited phase, as well as its structural and compositional uniformity, the latter characteristics being particularly important in the case of multicomponent catalysts. Knowledge of the pore size and shape is also important, since these can influence the transport of reactants and products through a catalyst and the dynamics of catalyst deactivation.

Computationally-Guided Investigation of Dual Amine/pi Lewis Acid Catalysts for Direct Additions of Aldehydes and Ketones to Unactivated Alkenes and Alkynes

2020 ◽  
Author(s):  
Eric Greve ◽  
Jacob D. Porter ◽  
Chris Dockendorff
Keyword(s):  
Lewis Acid ◽  
Density Functional ◽  
Acid Catalyst ◽  
Metal Catalyst ◽  
Catalyst Poisoning ◽  
Lewis Acid Catalysts ◽  
Metal Ligands ◽  
Aldehydes And Ketones ◽  
Lewis Acid Catalyst ◽  
Catalyst Systems

Dual amine/pi Lewis acid catalyst systems have been reported for intramolecular direct additions of aldehydes/ketones to unactivated alkynes and occasionally alkenes, but related intermolecular reactions are rare and not presently of significant synthetic utility, likely due to undesired coordination of enamine intermediates to the metal catalyst. We reasoned that bulky metal ligands and bulky amine catalysts could minimize catalyst poisoning and could facilitate certain examples of direct intermolecular additions of aldehyde/ketones to alkenes/alkynes. Density Functional Theory (DFT) calculations were performed that suggested that PyBOX-Pt(II) catalysts for alkene/alkyne activation could be combined with MacMillan’s imidazolidinone organocatalyst for aldehyde/ketone activation to facilitate desirable C-C bond formations, and certain reactions were calculated to be more exergonic than catalyst poisoning pathways. As calculated, preformed enamines generated from the MacMillan imidazolidinone did not displace ethylene from a biscationic (<i>t</i>-Bu)PyBOX-Pt<sup>2+</sup>complex, but neither were the desired C-C bond formations observed under several different conditions.

Computationally-Guided Investigation of Dual Amine/pi Lewis Acid Catalysts for Direct Additions of Aldehydes and Ketones to Unactivated Alkenes and Alkynes

2020 ◽  
Author(s):  
Eric Greve ◽  
Jacob D. Porter ◽  
Chris Dockendorff
Keyword(s):  
Lewis Acid ◽  
Density Functional ◽  
Acid Catalyst ◽  
Metal Catalyst ◽  
Catalyst Poisoning ◽  
Lewis Acid Catalysts ◽  
Metal Ligands ◽  
Aldehydes And Ketones ◽  
Lewis Acid Catalyst ◽  
Catalyst Systems

Dual amine/pi Lewis acid catalyst systems have been reported for intramolecular direct additions of aldehydes/ketones to unactivated alkynes and occasionally alkenes, but related intermolecular reactions are rare and not presently of significant synthetic utility, likely due to undesired coordination of enamine intermediates to the metal catalyst. We reasoned that bulky metal ligands and bulky amine catalysts could minimize catalyst poisoning and could facilitate certain examples of direct intermolecular additions of aldehyde/ketones to alkenes/alkynes. Density Functional Theory (DFT) calculations were performed that suggested that PyBOX-Pt(II) catalysts for alkene/alkyne activation could be combined with MacMillan’s imidazolidinone organocatalyst for aldehyde/ketone activation to facilitate desirable C-C bond formations, and certain reactions were calculated to be more exergonic than catalyst poisoning pathways. As calculated, preformed enamines generated from the MacMillan imidazolidinone did not displace ethylene from a biscationic (<i>t</i>-Bu)PyBOX-Pt<sup>2+</sup>complex, but neither were the desired C-C bond formations observed under several different conditions.

COMPARATIVE ANALYSIS OF BIOACTIVE SUBSTANCES CONTENT IN THE LEAVES AND FRUITS OF A ROWAN-TREE (SORBUS AUCUPARIA FRUCTUS) AND ASSESSMENT OF PROSPECTS IN MEDICINE AND PHARMACY

2020 ◽  
pp. 58-62
Author(s):  
Chernichkina A.D.
Keyword(s):  
Raw Materials ◽  
Wide Distribution ◽  
Biologically Active ◽  
Bioactive Substances ◽  
Plant Raw Materials ◽  
Mountain Ash ◽  
The Russian Federation ◽  
Materials Used ◽  
Active Substances ◽  
Pectin Substances

A large number of biologically active substances, organic acids, tannins, and pectin substances were detected during the study of fruits, leaves, and pulp of the fruits of mountain Ash. The content of these substances in leaves and pulp will significantly expand the arsenal of medicinal plant raw materials used. Given the wide distribution of mountain Ash in the territory of the Russian Federation, harvesting leaves from the same plants after harvesting the fruit and using pulp will make it possible to obtain new phytopreparations.

TECHNOLOGICAL ASPECTS OF HIGH QUALITY RAW MATERIAL OBTAINING FOR PECTIN PRODUCTION

1970 ◽  
pp. 47-50
Author(s):  
I. A. Ilina ◽  
I. A. Machneva ◽  
E. S. Bakun
Keyword(s):  
Raw Materials ◽  
Thermal Characteristics ◽  
Environmental Safety ◽  
Raw Material ◽  
High Quality ◽  
Temperature Conductivity ◽  
Drying Temperature ◽  
Plant Raw Materials ◽  
Gel Forming Ability

  The article is devoted to the study of the chemical composition, physical and thermal-pfysical characteristics of damp apple pomaces and the identifying patterns of influence of drying temperature the functional composition and gel-forming ability of pectin. The research is aimed at obtaining initial data for the subsequent calculation of the main technological, hydro-mechanical, thermal, structural and economic characteristics of devices for drying the plant raw materials, ensuring the environmental safety and high quality of pectin-containing raw materials, the reducing heat and energy costs. As a result of the study of the thermal characteristics of apple pomaces, the critical points (temperature conductivity – 16.5 x 10-8 m2/s, thermal conductivity – 0.28 W/m K, heat capacity – 1627 j/(kg K)) at a humidity of 56 % are determined, which characterizing the transition from the extraction of weakly bound moisture to the extraction of moisture with strong bonds (colloidal, adsorption). It was found that the pomaces obtained from apples of late ripening have a higher content of solids (21-23 %), soluble pectin and protopectin (2.5-4.5 %). Dried pomaces obtained from apple varieties of late ripening contain up to 25 % pectin, which allow us to recommend them as a source of raw materials for the production of pectin. The optimum modes of preliminary washing of raw materials are offered, allowing to the remove the ballast substances as much as possible. It is established that when the drying temperature increases, the destructive processes are catalyzed: the strength of the pectin jelly and the uronide component and the degree of pectin esterification are reduced. The optimum drying temperature of damp apple pomaces is 80 0C, at which the quality of pectin extracted from the dried raw materials is maintained as much as possible. It is shown that the most effective for the pectin production is a fraction with a particle size of 3-5 mm, which allow us to extract up to 71 % of pectin from raw materials.

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