Stanisław Gryglewicz

Preparation of polyol esters based on vegetable and animal fats

The possibility of using some natural fats: rapeseed oil, olive oil and lard, as starting material for the preparation of neopentyl glycol (NPG) and trimethylol propane (TMP) esters is reported. The syntheses of final products were performed by alcoholysis of fatty acid methyl esters, obtained from natural fats studied, with the appropriate polyhydric alcohol using calcium methoxide as a catalyst. The basic physicochemical properties of the NPG and TMP esters synthesized were the following: viscosity at 40 degrees C in the range of 13.5-37.6 cSt, pour point between -10.5 and -17.5 degrees C and very high viscosity indices, higher than 200. Generally, the esters of neopentyl alcohols were characterized by higher stability in thermo-oxidative conditions in comparison to native triglycerides. Due to the low content of polyunsaturated acids, the olive oil based esters showed the highest thermo-oxidative resistance. Also, methyl esters of fatty acids of lard would constitute a good raw material for the synthesis of lubricating oils, provided that their saturated acids content was lowered. This permits synthesis of NPG and TMP esters with a lower pour point (below -10 degrees C) than natural lard (+33 degrees C).

Alkaline-earth metal compounds as alcoholysis catalysts for ester oils synthesis

Some esters of carboxylic acids and polyhydric alcohols are environmental friendly lubricants of superior properties. This work presents an attempt to use alkaline-earth metal compounds as catalysts for alcoholysis reaction in terms of synthesis di(2-ethylhexyl) adipate and an oligomeric ester of neopentyl glycol. Magnesium methoxide, calcium oxide, calcium alkoxides and barium hydroxide appear to be active catalysts for transesterification. The mechanism of catalytic activity of these compounds in alcoholysis reaction has been proposed. Synthesised esters possess suitable physicochemical properties as lubricant oils.

Enhanced reduction of graphene oxide by high-pressure hydrothermal treatment

A high-pressure assisted hydrothermal treatment is proposed as a facile, green and efficient route for the reduction of aqueous dispersions of graphene oxide. Reactions were performed in an autoclave at mild temperature (180 °C) using only water and nitrogen or hydrogen gas. No further separation or purification of the reduced products was required. X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction and thermogravimetric analysis revealed that the application of high pressure significantly enhanced oxygen removal. The C/O atomic ratio of the graphene oxide sheets increased from 1.65 to 5.29 upon conventional hydrothermal treatment using autogenous pressure. Higher C/O ratios of 6.35 and 7.93 were obtained for graphene oxides that were reduced under high-pressure of nitrogen and hydrogen, respectively. Specifically, the use of high-pressure hydrogen improved the removal of oxygen double-bonded to carbon. The introduction of covalently bonded heteroatoms, which is commonly observed for the use of reductants such as hydrazine, was not detected. Furthermore, high-pressure reduction led to a better restoration of the sp2 conjugation than was obtained by conventional hydrothermal treatment, as determined by XPS and Raman spectroscopies. These findings illustrate the promise of high-pressure hydrothermal treatments for the eco-friendly mass production of reduced graphene oxide.

Enzyme catalysed synthesis of some adipic esters

Lipases from Candida antarctica (Novozym 435) and Rhizomucor miehei (Lipozyme IM) showed good reactivity in the alcoholysis of dimethyl adipate by racemic 2-ethylhexanol as well as neopentyl glycol. Novozym 435 was found to be the more reactive biocatalyst but less enantioselective compared with Lipozyme IM in the synthesis of methyl-2-ethylhexyl adipate. Di-2-ethylhexyl adipate obtained was optically inactive. Using dimethyl adipate and neopentyl glycol as starting material, oligomer esters with different range of molecular mass were synthesised (Novozym 435). An attempted of alcoholysis of dimethyl adipate by non-linear trihydric trimethylolpropane was unsuccessful.

Hydrodechlorination of DDT and chloroalkanes over carbon-supported Ni-Mo catalyst.

Catalytic hydrodechlorination (HDC) is an efficient method for the elimination of chlorinated compounds from organic wastes. HDC allows for the recovery of parent hydrocarbons. Herein, we studied the dechlorination of chlorododecane (CDD), dichlorocyclohexane (DCH) and dichlorodiphenyltrichloroethane (DDT) over a sulfided Ni-Mo/C catalyst in a flow reactor. The Ni-Mo/C catalyst was prepared by the incipient wetness method using a granular activated carbon support. In contrast to alumina, which is a commonly used support for commercial catalysts, the carbon support is resistant to decomposition by HCl formed during the HDC reaction. The composition of the tested catalyst was 5 wt.% NiO and 15 wt.% MoO(3), and it was characterized by well developed both the micro- and mesoporosity (V(mic)=0.559 cm(3)g(-1), V(mes)=0.430 cm(3)g(-1)). The level of conversion of CDD, DCH, and DDT was directly related to reaction temperatures in the HDC process; the total chlorine removal was achieved at 200 degrees C. The tested catalyst was determined to have good thermal stability in the HDC process at 170 degrees C for 100 h. This corresponded to conversions of 85-72% for CDD and 81-79% for DCH. For CDD the hydrogen pressure affected the ratio of dodecane to dodecene in the reaction products.

Guanidine, amitrole and imidazole as nitrogen dopants for the synthesis of N-graphenes

Three N-containing organic compounds – guanidine, amitrole (3-amino-1,2,4-triazole) and imidazole were selected and evaluated as new nitrogen dopants for the preparation of N-graphene. A graphene oxide aqueous dispersion was subjected to hydrothermal treatment at 180 °C for 8 h in the presence of the selected N-compounds. The nitrogen contents in the resultant N-graphenes were as high as 13.4 at%, which is among the highest reported for graphene materials. The X-ray photoelectron spectroscopy revealed that pyridinic nitrogen was predominant in all of the N-graphenes, accounting for up to 47% of the total nitrogen content. Deoxygenation of graphene oxide under hydrothermal conditions was also improved through the use of the N-compounds. Possible reaction mechanisms between graphene oxide and each N-compound are proposed.

Performance of Carbon Nanofiber and Activated Carbon Supported Nickel Catalysts for Liquid-Phase Hydrogenation of Cinnamaldehyde into Hydrocinnamaldehyde

The herringbone and platelet carbon nanofibers and the activated carbon were used as the supports of nickel catalyst for the selective hydrogenation of cinnamaldehyde to hydrocinnamaldehyde (HALD). The hydrogenation of HALD and cinnamyl alcohol under the same experimental conditions was also performed to determine the susceptibility of the isolated and conjugated C=O and C=C bonds to hydrogenation. The catalytic activity and selectivity of the nickel supported on carbons of different structure were evaluated based on the determination of the rate constants of the hydrogenation reaction. The nickel particle size effect was found to be crucial for the catalyst performance.Graphical Abstract

Hydrodechlorination of dichlorobenzenes and their derivatives over Ni–Mo/C catalyst: Kinetic analysis and effect of molecular structure of reactant

The kinetics of the catalytic hydrodechlorination (HDC) process of selected dichlorobenzenes (DCBs), dichlorotoluenes (DCTs) and dichlorodiphenyls (DCDs) was studied in the presence of a sulphided carbon-supported Ni-Mo catalyst. The HDC runs were performed in a magnetic stirred batch reactor in the range of 210-230°C under the hydrogen pressure of 3MPa. The kinetic constants were evaluated and the reaction network was proposed assuming the pseudo-first order kinetics of dechlorination process. The HDC of aromatic dichloroderivatives proceeded via a network of sequential-parallel reactions. At 210°C DCBs, DCTs and DCDs followed mainly the pathway of direct transformation to respective aromatic hydrocarbon. At 230°C, the contribution of sequential dechlorination to monochloroderivative became more predominant.

Demetallization of heavy vacuum fraction

Abstract The hydrodemetallization of a heavy vacuum fraction from petroleum was studied in a fixed bed-reactor. Natural aluminosilicates and sulfides of Mo, Co, Ni,/γ-Al 2 O 3 are used as catalysts. The natural aluminosilicate activated by sulfuric acid appear to be best at removing vanadium and nickel. The effect of the capillary structure and the hydrogenation properties of a catalyst on its demetallization activity is considered.

Emission of the odour substances from fertilizer industry

Emission of the odour substances from fertilizer industry Mineral fertilizers are indispensable for the intensification of plant production in agriculture. This process can cause a significant odour nuisance for the environment due to organic compounds content in apatites and phosphorites converted into fertilizers. The following chemical compounds are emitted to the gas phase among others: hydrogen sulphide, organic sulphides and (methyl, ethyl, isopropyl, butyl) disulphides, chain hydrocarbons, organic oils, waxes and carboxylic acids. A method using gas chromatography analysis with the mass detector (TD-GS-MS), to determine trace concentrations, was developed and tested for the assessment of odour nuisant substances emission from these processes. Application of additional thermal desorber to enable the intense desorption of the investigated organic compounds (previously adsorbed on classical sorbents) in the industrial research has been taken into consideration. In effect it facilitates the accumulating substances to be analyzed at short time interval providing identifying measurements. The technique has been verified during the investigation of the substances emitted in fertilizers processes at Maroko phosphorite decomposition. The organic sulfur compounds, aliphatic and aromatic hydrocarbons have been detected.