D. Yu. Murzin

Evaluation of Mesoporous TCPSi, MCM-41, SBA-15, and TUD-1 Materials as API Carriers for Oral Drug Delivery

The feasibility of four mesoporous materials composed of biocompatible Si (TCPSi) or SiO2 (MCM-41, SBA-15, and TUD-1) were evaluated for oral drug delivery applications. The main focus was to study the effect of the materials different pore systems (unidirectional/2D/3D) and their pore diameters, pore size distributions, pore volumes on the maximal drug load capacity, and release profiles of a loaded active pharmaceutical ingredient. Ibuprofen was used as the model drug. The total pore volume of the mesoporous solid was the main factor limiting the maximum drug load capacity, with SBA-15 reaching a very high drug load of 1:1 in weight due to its high pore volume. Dissolution experiments were performed in HBSS buffers of pH 5.5, 6.8, and 7.4 to mimic the conditions in the small intestine. At pH 5.5 the dissolution rate of ibuprofen released from the mesoporous carriers was significantly faster compared with the standard bulk ibuprofen (86–63% versus 25% released at 45 min), with the fastest release observed from the 3D pore network of TUD-1 carrier. The utilization of mesoporous carriers diminished the pH dependency of ibuprofen dissolution (pKa = 4.42), providing an interesting prospect for the formulation of poorly soluble drug compounds.

Ruthenium-modified MCM-41 mesoporous molecular sieve and Y zeolite catalysts for selective hydrogenation of cinnamaldehyde

Abstract Ru-modified MCM-41 mesoporous molecular sieve and Y zeolite catalysts were synthesised and characterised using XRD, electrochemical voltammetry, ESCA (XPS), nitrogen adsorption and H2-TPD. Selective liquid-phase hydrogenation of cinnamaldehyde to cinnamyl alcohol was investigated over these catalysts and compared to hydrogenation on a commercial Ru/C catalyst. The effect of support (MCM-41, Y and C), solvent (cyclohexane, hexane and 2-propanol) and catalyst pre-treatment (calcination) on the conversion of cinnamaldehyde and selectivity to cinnamyl alcohol was studied. The zeolite structure, pore size, acidity, catalyst pre-treatment as well as the solvent influenced the activity and selectivity. Non-calcined Ru/Y exhibited the highest selectivity to cinnamyl alcohol. The activity of Ru/Y was highest with 2-propanol as a solvent.

Solvent effects in enantioselective hydrogenation of 1-phenyl-1,2-propanedione

Abstract Solvent effects in enantioselective hydrogenation of 1-phenyl-1,2-propanedione ( A ) were investigated in a batch reactor over a cinchonidine modified Pt/Al 2 O 3 catalyst. The effect of different solvents, binary solvent mixtures and solvent dielectric constant on regio- and enantioselectivity as well as on the hydrogenation rate were studied. The hydrogen solubility in different solvents and the dielectic constants of solvent mixtures were measured. The highest enantiomeric excesses (ee) of ( R )-1-hydroxy-1-phenylpropanone ( B ) (65%) were obtained in toluene. The ee decreased non-linearly with an increasing solvent dielectric constant being close to zero in methanol. The role of the reactant conformation in different solvents was evaluated by quantum chemical calculations and the role of the Open(3) conformer of the modifier, cinchonidine was discussed. The dependence of ee on the dielectric constant could not solely be attributed to the abundance of the Open(3) conformer of cinchonidine in the liquid phase. A possible involvement of additional factors was proposed and discussed. The non-linear dependence of the ee on the dielectric constant was included in a kinetic model to describe quantitatively the variation of the ee in different solvents.

Catalysis in biomass processing

Biomass has in recent years been considered as a raw material for the production of fuels and chemicals. This work discusses the reasons for the increased interest in mainly lignocellulosic biomass. Gasification, pyrolysis, and depolymerization by hydrolysis are analyzed as key biomass technology. We also discuss which of the sugars obtained via depolymerization by hydrolysis can be processed into fuel or key intermediates of the chemical industry. Lignocellulosic biomass contains such extractants as fatty acids and terpenes, and we therefore describe the catalytic reactions of these substances for the synthesis of fuels and chemicals. Some typical reactions of biomass processing (oxidation, hydrogenation, cracking, etc.) are conceptually close to the process widely known in the refining and chemical industries. There are, however, other considerations due to, e.g., the large number of functional (hydroxyl and other) groups, and the processing of biomass components therefore requires dehydration, aldol condensation, ketonization, decarboxylation, etc. We cover the fundamentals of the approaches to selecting catalysts for these reactions.

Pyrolysis of pine and gasification of pine chars - influence of organically bound metals.

Pyrolysis of pine and gasification of pine chars was studied in this work, focusing on the influence of organically bound metals. Selective leaching of the major ash-forming elements in pine wood was performed with different acids, namely, nitric, sulfuric, hydrochloric and oxalic acids. No other major changes in the chemical composition of the biomass were observed except the removal of the metals. The effect of organically bound sodium, potassium, magnesium and calcium was studied in both pyrolysis and gasification. Removal of the metals had a positive effect on the pyrolysis, resulting in higher bio-oil, lower char and gas yields.

Overview of catalytic methods for production of next generation biodiesel from natural oils and fats

Production of biodiesel from natural oils and fats can be achieved using various technologies briefly discussed in this review. A particular appealing concept for production of green diesel is selective catalytic deoxygenation of renewables leading to diesel fuel products. This reaction can be performed over Pd on active carbon supports with saturated and unsaturated fatty acids and their derivatives.

Formation of Furfural in Catalytic Transformation of Levoglucosan over Mesoporous Materials

Catalytic transformations of levoglucosan (1‐6‐anhydro‐β‐D‐glucopyranose) and furfural were carried out in a fixed‐bed reactor at 573 K over mesoporous materials. Proton forms of MCM‐41, MCM‐48, SBA‐15, and platinum form of MCM‐48 catalysts were tested in the reaction, whereas H‐Beta and quartz sand were used as reference materials. The yield of the transformation products was substantially influenced by the catalyst structures. Oxygenated species were the main liquid products, consisting mainly of aldehydes and furfural. The formation of furfural was the highest over MCM‐41 catalyst followed by SBA‐15, MCM‐48, and H‐Beta catalyst. All catalysts were to some extent deactivated due to coke formation. However, it was possible to successfully regenerate the spent catalysts without changing the structure.

Catalytic pyrolysis of low density polyethylene over H-β, H-Y, H-Mordenite, and H-Ferrierite zeolite catalysts: Influence of acidity and structures

Low-density polyethylene (LDPE) catalytic pyrolysis was investigated over H-β-25, H-β-150, H-β-300, H-Y-12, H-Mordenite-20, and H-Ferrierite-20 zeolite catalysts. The numbers denote the SiO2/Al2O3 molar ratios. The influence of the zeolite’s acidity on the transformation of LDPE was studied by varying the SiO2/Al2O3 molar ratios of the β zeolite. The influence of the zeolite structure was investigated by using the proton forms of Y, β, Mordenite, and Ferrierite zeolites. The catalysts were characterized using X-ray powder diffraction patterns, nitrogen adsorption, and FTIR spectroscopy with pyridine as the probe molecule. The large pore and least acidic H-β-300 catalyst showed the lowest activity in the catalytic pyrolysis of LDPE. The H-β-25 catalyst, with higher acidity than H-β-300, showed higher activity for LDPE pyrolysis than H-β-300, indicating the importance of strong acid sites for this reaction. The H-Ferrierite and H-Mordenite catalysts, with small pores, showed the lowest effect on LDPE pyrolysis, although the catalysts were more acidic than H-β-25 and H-β-150, indicating that not only acidity but also the structure and pore size of zeolites are important for pyrolysis of LDPE. However, the H-Y zeolite catalyst with large pores and cavities is not suitable for this reaction because of rapid deactivation due to coke formation.

A Novel Radioisotope Method for Studying Catalytic Transformations over Alumina, H-ZSM-5 and H-Beta Zeolite Catalysts: Investigation of Conversion of 11C-Labeled Methanol to 11C-Labeled Dimethyl Ether and Hydrocarbons

A novel radiochemical method for investigating the catalytic transformations of the 11C-radioisotope labeled methanol over H-ZSM-5 and H-Beta zeolite catalysts has been introduced. The catalysis process was monitored by gamma detectors and the 11C-labeled products were analyzed by radio-gas chromatography. The medium pore H-ZSM-5 and H-Beta zeolite catalysts were synthesized and characterized using X-ray powder diffraction, scanning electron microscope, nitrogen adsorption, X-ray fluorescency and FTIR spectroscopy. The investigations of 11C-labeled product distributions and reaction mechanism of the conversion of [11C]methanol over H-ZSM-5 and H-Beta zeolite catalysts have been elaborated in terms of structure and acidity of the catalysts. In microreactors the effect of natural carbon compounds from environment can be a disturbing effect for the detection of inactive carbon products. Applied radio detection method eliminates these disturbing effects and detects only 11C-labeled compounds during the whole catalytic process. In the study of the transformations of carbon compounds, besides the well known 14C tracer technique and 13C MAS NMR spectroscopy investigation, the 11C-method is a new, more sensitive and simple one to monitor the transformation of the starting 11C-labeled compound by radio detectors (gamma detector) and for analyzing the 11C-labeled products by radio-gas chromatography.

CO2 capture from biogas: absorbent selection

The development of proper biogas upgrading technology offers a viable means to utilize biogas in conventional power systems. In this paper, various molecular and ionic solvent systems were evaluated for CO2 removal from biogas in a loop reactor system. The performance of amine solutions, ionic liquids and their mixtures, amino acid salts and solutions blended with piperazine was compared in terms of their CO2 loading capacity. The experimental results revealed that addition of small amounts of piperazine can increase on average by 30 vol% the efficiency of above-mentioned solutions. The CO2 capturing capacity achieved for the most promising solvents was in the range of 50–60 L CO2/L absorbent. The regeneration of the solvent mixtures can be challenging since the solvents could loose 16–43 vol% of their initial efficiency upon CO2 release. The ionic liquid [C4mim][acetate] was found to be an efficient VOCs scrubbing media. Moreover, upon use of this ionic liquid, the amount of identified volatile organic compounds (VOCs) in the studied samples was reduced by 65 wt%, while the use of 15 wt% aqueous N-methyldiethanolamine (MDEA) resulted only in 32 wt% reduction in the amount of VOCs.