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[en] Interest in heterogeneous catalysis has increased dramatically in the last decade. The extent of interest in this and related field can be accessed from the newly coined terms like, semi-heterogeneous catalysis, for the processes and mechanisms that are amalgam of homogeneous and heterogeneous catalysis. Whereas the progresses made I the area of science and technology of nano materials has provided the main impetus, the innovative processing of carbon nano tubes has added to potential applications in process engineering and consumer applications. The graphene based catalysts are yet another emerging class of catalysts with huge potential. This technical review summarizes the developments made in the area of material developments, a better understanding of processes involved and role of computational chemistry in the recent achievements. The emerging applications in the areas of process engineering have also been discussed. (author)
[en] In this communication we present a theoretical study of chemical reactions in a system of solid particles, immersed in a fluid environment. Our primary concern here is investigation of the systems of catalytic particles in a liquid media; however with some slight modifications our results are applicable to aerosol systems as well. We consider a second-order reaction, which proceeds both homogeneously in the environment, and heterogeneously at surfaces of catalyst particles. The Langmuir adsorption-desorption kinetics is considered explicitly. For definiteness, we are considering the so-called 'three-step mechanism' of the heterogeneous reaction.
[en] The development of heterogeneous catalysts for oleochemicals reactions is becoming very important, because such catalysts possess well defined catalytic active sites, which will increase catalytic activity and process efficiency. The use of hydrotalcite as heterogeneous catalyst has shown potentials in transesterification reaction due to their physico-chemical properties, such as good thermal stability, good meso porous material, bigger surface area, good memory effect, and even balanced basicity/ acidity active points. The catalytic performance of the calcined Mg-Al catalyst in the green process was developed for the conversion of glycerol to glyceryl carbonate using ethylene carbonate. The X-ray diffraction confirmed the calcined materials exhibit hydrotalcite pattern structure with surface area of 179 m"2 g"-"1. The HT3.0c comprised of Mg:Al composition of 3:1 was the best catalyst. The catalyst is robust and reusable. (author)
[en] Four main projects at the interface between organometallic chemistry and homogeneous catalysis were pursued. All were designed to give increased understanding of the mechanisms of organometallic reactions related to homogeneous and heterogeneous catalysis. In addition, a minor study involving η5-to η1-cyclopentadienyl ring slippage in catalysis was completed
[en] Specific features of homogeneous, heterogeneous, and nanoheterogeneous catalysis in hydrogenation of polymers and the advantages and drawbacks of various catalytic systems are considered. Differences in hydrogenation of polymers and monomers are discussed. Specific features of the behavior of polymer molecules, complicating the heterogeneous catalysis, are noted, such as diffusion of macromolecules into catalyst pores, conformational limitations, and rheology of polymer solutions. The main catalytic systems studied in polymer hydrogenation are listed. A separate section deals with hydrogenless hydrogenation of polymers. The properties and application fields of hydrogenated polymers are analyzed. Promising directions of studying the catalysis of hydrogenation of macromolecular compounds are outlined.
[en] The current transesterification method to produce biodiesel from palm oil uses NaOH as the homogeneous catalyst. NaOH has several disadvantages. It is corrosive, can not be reused, and separation from biodiesel is time-consuming. The objective of the present work was to replace NaOH with a greener and efficient heterogeneous catalyst, calcium diglyceroxide. The potential contamination of biodiesel by Ca"2"+ was minimised by incorporating Na_2CO_3 into the transesterification mixture. The work aimed to identify the optimum reaction conditions which would minimise the production cost of biodiesel complying with the quality prescribed by ASTM standards. Optimum conditions were oil: methanol ratio of 1:6 (molar), catalyst 0.2 % (w/w oil), Na_2CO_3 2.5 % (w/w oil), and 3 hr reaction period at 65 degree Celcius. The yield was 92.2 %. All the studied properties of biodiesel except kinematic viscosity conformed with recommended levels by ASTM. Reusing the catalyst which was used twice previously, increased the biodiesel yield from 92.2 % to 94.3 %. The production of good quality biodiesel from palm olein by this novel method is greener. It is more efficient because the catalyst is not corrosive and easy to separate. Also, the catalyst can be reused at least twice, thus minimising the amounts of chemicals used. (author)
[en] This report summarizes the Workshop on Neutron Scattering Techniques for Studies in Catalysis, held at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) on September 16 and 17, 2010. The goal of the Workshop was to bring experts in heterogeneous catalysis and biocatalysis together with neutron scattering experimenters to identify ways to attack new problems, especially Grand Challenge problems in catalysis, using neutron scattering. The Workshop locale was motivated by the neutron capabilities at ORNL, including the High Flux Isotope Reactor (HFIR) and the new and developing instrumentation at the SNS. Approximately 90 researchers met for 1 1/2 days with oral presentations and breakout sessions. Oral presentations were divided into five topical sessions aimed at a discussion of Grand Challenge problems in catalysis, dynamics studies, structure characterization, biocatalysis, and computational methods. Eleven internationally known invited experts spoke in these sessions. The Workshop was intended both to educate catalyst experts about the methods and possibilities of neutron methods and to educate the neutron community about the methods and scientific challenges in catalysis. Above all, it was intended to inspire new research ideas among the attendees. All attendees were asked to participate in one or more of three breakout sessions to share ideas and propose new experiments that could be performed using the ORNL neutron facilities. The Workshop was expected to lead to proposals for beam time at either the HFIR or the SNS; therefore, it was expected that each breakout session would identify a few experiments or proof-of-principle experiments and a leader who would pursue a proposal after the Workshop. Also, a refereed review article will be submitted to a prominent journal to present research and ideas illustrating the benefits and possibilities of neutron methods for catalysis research.
[en] The kinetic regularities of the formation of gaseous products obtained by the conversion of n-hexane on the surface of nano-ZrO2 at room temperature under the influence of radiation were studied. It was found that in the range of absorption doses, ΔD = 0-14 kGy, the yield of molecular hydrogen in the gas phase increases linearly, and the radiation-chemical yield is G(H2) = 9 molecules/ 100 eV,which is 1.8 times more than the yield in the homophase.