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, Shanks BH, Dumesic JA. Bridging the chemical and biological catalysis gap: challenges and outlooks for producing sustainable chemicals. ACS Catal. 2014;4:2060-2069. DOI: 10.1021/cs500364y. [6] Nørskov JK, Studt F, Abild-Pedersen F, Bligaard T. Fundamental Concepts in Heterogeneous Catalysis. Hoboken, NJ, USA: John Wiley & Sons, Inc; 2014. DOI: 10.1002/9781118892114. [7] Loures CCA, Amaral MS, Da Rós PCM, Zorn SMFE, de Castro HF, Silva MB. Simultaneous esterification and transesterification of microbial oil from Chlorella minutissima by acid catalysis route: A

Abstract

Catalysis is an alternative way for reaching an immediate formation of a product, because of a lower energy barrier (between the molecules and the catalysts). Heterogeneous catalysis comprises the acceleration of a chemical reaction through interaction of the molecules involved with the surface of a solid. It is a discipline, which involves all the different aspects of chemistry: inorganic and analytical chemistry in order to characterize the catalysts and the forms of these catalysts. The industrial chemistry puts all these things together to understand the solid chemical handling, chemical reaction and energy engineering and the heat and mass transfer in these catalytic processes. Very often there are more than one, but several products, then the role of the catalyst is not so much related to activity, but to selectivity. The underlying elementary steps can now be investigated down to the atomic scale as will be illustrated mainly with two examples: the oxidation of carbon monoxide (car exhaust catalyst) and the synthesis of ammonia (the basis for nitrogen fertilizer). There is a huge market for the catalysts themselves despite of their high costs. A large fraction is used for petroleum refineries, automotive and industrial cleaning processes. The catalytic processes is a wide field and there are still many problems concerning energy conservation and energy transformation, so there is much to do in the future.

Abstract

In our studies montmorillonite (MMT) was used as the heterogeneous, natural catalyst. This material was previously prepared by bentonite purification with help of the sedimentation method. The obtained catalyst was characterized by: XRD, SEM, BET and EDX. Catalytic tests with montmorillonite as the catalyst were performed with the natural terpene – R-(+)-limonene. This compound was oxidized with hydrogen peroxide and, moreover, in the separate process it was also isomerized. As the main products of limonene oxidation were detected: (1,2-8,9)-diepoxide, perillyl alcohol, carvone, carveol, 1,2-epoxylimonene and 1,2-epoxylimonene diol. In the isomerization of R-(+)-limonene were formed: terpinenes, terpinolene and p-cymene. Conversions of limonene in these processes reached 70–80%. The application of montmorillonite (the natural of origin) in the studied processes (oxidation and isomerization) is environmentally friendly, it allows to reduce the cost of the studied processes. The resulting products of the processes of oxidation and isomerization of R-(+)-limonene have many applications.

Abstract

Magnetic material may be added to proppant, as the magnetic marker allows to determine the range and efficiency of hydraulic fracturing. However, magnetic proppant may be also used in flowback fluid treatment and monitoring of environmental pollution. As a result of shale gas hydraulic fracturing, large volume of flowback fluid is created. Flow back fluid have similar properties to fracturing fluid, but it is potentially enriched with large amount of salts and organic compounds leached from shale. Magnetic proppant may serve as a heterogeneous catalyst during organic pollutants decomposition. Additionally, in case of leakage and consequently the fracturing fluid pollution, magnetic proppant is placed into the soil environment. It can be detected using magnetometric methods. This article discusses the above-mentioned issues based on the knowledge and experience of the authors and the literature review.

Abstract

The students frequenting the program Chemical Engineering at the Department of Chemical and Environmental Engineering, Faculty of Chemical and Food Technology of the Slovak University of Technology in Bratislava are taught to be able to combine and develop their knowledge acquired in the area of chemical, energetic, environmental, and safety engineering. Prior to completing their study, they are obliged to develop a report regarding engineering, economic, and safety analysis of important chemical technology. This paper presents the most valuable outputs of the student’s Technology project aimed on simulation and optimization of the fuel additives production technology. 2-Ethoxy-2-methylpropane (ethyl-t-butyl ether, ETBE) production based on liquid-phase etherification of 2-methylpropene with ethanol in the presence of heterogeneous catalyst was studied. Different patented technologies were investigated in terms of their profitability and safeness. The first technology was an isothermal reactor with the product separation via distillation (Kochar & Marcell, 1981). The next ETBE production design assumed was a modification of the previous one; the product separation was carried out using liquid-phase extraction (Pucci et al., 1992). The last design considered in this study was a reactive distillation column with a pre-reactor (Bakshi et al., 1992). In all three technologies, etherification reaction was carried out using Amberlyst ion-exchange resin in its H+ form as the catalyst. Selected ETBE production designs were simulated using Aspen+ program. Their profitability was compared on basis of the investment and operation costs assessment taking into account both the produced ETBE yield and purity. Further, basic safety analysis of all chosen technologies was performed in order to identify possible hazards. Finally, individual and social risk connected with the plant operation was computed. Taking into account these economic and safety criteria, the best alternative for ETBE production was the reactive distillation.

Abstract

The paper presents a new model of the mechanism of mechanocatalysis and tribocatalysis. The reason for the increase in heterogeneous catalysis effect after mechanical activation of a catalyst has not been fully understood yet. There is no known theory, which would explain the mechanism of the influence of mechanical energy introduced to catalyst particles on the rate of chemical reaction. All existing theories are based on Arrhenius equation and assume that catalysts increase reaction rate due to decreasing of activation energy E a. We hypothesize that both for standard and catalyzed heterogeneous reactions the same E a (real activation energy) is needed to trigger the reaction processes and the catalytic effect is the result of energy introduced to the reaction system, its accumulation by a catalyst and then emission of high flux of energy to the space near the catalyst particles. This energy emitted by molecules of reagents can reach a value equal to the value of E a at lower ambient temperature than it would result from Arrhenius equation. This hypothesis is based on α i model described in previous papers by Kajdas and Kulczycki as well as the results of tribochemical research described by Hong Liang et al., which demonstrate that the reaction rate is higher than that resulting from temperature.

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