Thermodynamyc modeling of hydrogenation reactions of aromatic hydrocarbons in various environments

Aqueous Mediated Heterogeneous Catalysis

Effects of syngas from semi-coke in situ gasification on yield and quality of tar from pyrolysis of Naomaohu coal

I. Activation of molecular hydrogen by electron impact. In this research we have undertaken to study the activation of hydrogen molecules by electron impact under conditions in which we know the energies of the impinging electrons. The experiments of Cario and Franck show that hydrogen molecules can be activated by excited mercury atoms by collisions of the second kind and that copper oxide and tungstic oxide can then be reduced. In their experiments the mercury atoms receive energy of 4.9 volts from the light source, which is sufficient to dissociate hydrogen molecules, the heat of dissociation of hydrogen being 3 to 4 volts. Furthermore, it has been known for some time that in a discharge tube hydrogen will disappear when a discharge is passed. Hughes, in particular, has investigated the electrical clean-up of hydrogen and nitrogen, and finds a definite decrease in the hydrogen pressure at 13.3 volts and higher. He adopts Langmuir’s conclusion that hydrogen is dissociated under these conditions, and that the decrease in pressure is due to the freezing out of atomic hydrogen on surfaces cooled by liquid air. His results will be referred to later in connection with our own experiments. In Hughes’ investigations no copper oxide was present, and the minimum electron energy at which hydrogen disappears was not accurately determined. A number of experimenters also have investigated the chemical reactivity of hydrogen activated by an electric discharge, but the energies of the impinging electrons were not known. We shall discuss four possible mechanisms by which electrons may be expected to activate hydrogen molecules. First, it might be that an electron having kinetic energy of 3 to 4 volts could transfer its energy to the hydrogen molecule and cause its dissociation into atoms. These in turn could then react with other substances. However, it is known that no kink occurs in current-potential curves of hydrogen near 4 volts, and it seems, therefore, that electrons having kinetic energy equal to the dissociation energy of hydrogen molecules cannot transfer their energy to these molecules. We then should expect to find no evidence of reaction when hydrogen is bombarded with 4-volt electrons, and our experiments actually do give no indication of reaction. This is in agreement with the commonly held idea that the dissociation of molecules does not occur as the direct result of electron impact. Second, electrons may have to possess sufficient energy to resonate the molecule, which may then dissociate if its heat of dissocitation is less than its resonance potential. The hydrogen molecule has, according to the latest results of spectroscopy, a resonance potential at 11.6 volts. Electrons of this energy can raise hydrogen molecules into an upper quantum state. These activated molecules would ordinarily return to the normal state after a short time. However, they may either dissociate into atoms upon impact with other molecules and the atoms thus react, or the resonated molecules may act directly on any oxide or other substance on which they impinge. A third mechanism of causing activation by electron impact might be that where the impinging electron transfers enough energy to the hydrogen molecule to cause its dissociation and resonance of one of the atoms. This process may be expected at 13 to 14 volts, which is the sum of the heat of dissociation and the resonance potential of the hydrogen atom. This is the mechanism postulated by Hughes. A fourth possibility may be considered. It may be necessary that an electron ionize a hydrogen molecule before the latter can be made to react. It was found by Anderson and Storch and Olson that nitrogen and hydrogen reacted to form ammonia when bombarded by 17-volt electrons. This voltage is near the ionization potentials of these molecules. We may state at once the results of our experiments. Electrons of 11.4 volts’ energy can activate hydrogen molecules, for we find that there is a definite pressure decrease when the accelerating voltage applied to our tube has this value. At the same voltage we also obtain a kink in the current-potential curves, using the Franck method. This research was aided financially by a grant made to Professor A. A. Noyes by the Carnegie Institution of Washington. II. Velocity distribution of electrons issuing from small holes. The velocity distribution of a beam of 50-volt electrons issuing from a hole 0.022 cm in diameter in a copper plate 0.02 cm thick has been measured. Seventy percent of the electrons were found to retain approximately their initial velocity. By coating the sides and edges of the hole with lampblack 95% of the electrons were transmitted without appreciable energy loss. Similar results were obtained with grids of 100 mesh copper gauze. III. Activation of gases by electron impact. The purpose of this research was to study the chemical behavior of gases activated by electron impact and to measure the energy necessary for their activation. The general plan was to use an apparatus similar to that employed in the study of the reaction between copper oxide and active hydrogen by Glockler, Baxter, and Dalton. The gases were introduced at pressures of 0.05 - 0.3 mm of mercury into a four electrode tube connected with a liquid air trap and a Birani pressure gauge. A four electrode tube was used in order that the energy loss of the electrons might be studied by making current potential curves as done by Franck and others. With this arrangement it was possible to follow the course of any reaction which involved a change in the number of molecules or produced a product condensible in liquid air. It was of course not possible to use gases which would undergo reaction when exposed the the hot filament. The systems studied were: oxygen and carbon, carbon monoxide and hydrogen, nitrogen and copper. Only the first gave definite positive results and for this reason it will receive the most attention. The author wishes to express his thanks to Professor Tolman, Dr. Glockler and Mr. Baxter for their assistance in this research; also to the Carnegie Institution of Washington for financial aid received through a grant made to Professor A.A. Noyes.

The chapter presents the results of studies of the catalytic properties of nanocarbon materials based on carbon nanotubes and reduced graphene oxide in the hydrogenation of ethylene, acetylene and ethylene-acetylene mixture by molecular hydrogen at atmosphere pressure. The current state of scientific approaches to the creation of nanocarbon metal-free catalysts for the hydrogenation reactions in both liquid and gas phases is presented. A possible nature of active center of the hydrogenation reaction located on the surface of the nanocarbon material is discussed. It is shown that the catalytic activity of the nanocarbon materials is not associated with metal impurities. The correlation between the structural characteristics of carbon nanomaterials and their catalytic properties in the hydrogenation reactions of unsaturated hydrocarbons is demonstrated. A comparative analysis of the catalytic activity of nanocarbon materials and catalysts that contain noble metals in the hydrogenation reaction of acetylene is presented. Finally, the fundamental possibility of creating a nanocarbon catalyst for selective hydrogenation of acetylene in excess ethylene is shown.

Thermal insulation materials are important for building energy conservation, but the inherent combustibility of these materials increases the fire risk of building facades. To better understand the fire behaviors of these materials, the study of the kinetics of thermal insulation pyrolysis is particularly important because it is the initial step in ignition and combustion during fire. In this paper, the pyrolysis behavior of expanded polystyrene (EPS), a typical non-charring insulation polymer, has been investigated by thermogravimetric analysis at five different heating rates. The model-free kinetic analysis showed that the obtained average values for E and lnA were 151.23 kJ/mol and 21.29 ln/s, respectively. Model-fitting CR and masterplot methods indicated that f(α) = [2(1-α)[-ln(1-α)]]1/2 is considered the pyrolysis reaction mechanism of EPS degradation. Based on these results, the equation of the kinetic compensation effect was further developed as lnA = −3.1955 + 0.1736 Eα. Finally, the reaction model was reconstructed with the result of the expression f(α) = 3.95335α0.24174 (1-α) [-ln(1-α)]1.64712. In addition, PY-GC-MS experiments were conducted to analyze the composition of EPS pyrolysis volatiles. The results showed that the products were mainly compounds of benzene, naphthalene, and biphenyl. The analysis of EPS pyrolysis behavior and evolved gas provides numerical guidance for the future treatment and fire protection of insulation materials.

Although water is a very stable substance, it is easily electrolyzed to produce hydrogen and oxygen molecules. Weak current produces only active hydrogen and hydrogen molecule without production of oxygen molecule. Active hydrogen is so small that almost all minerals adsorbs or absorbs it. These facts prompted us to propose “active hydrogen theory of reduced water”. We have demonstrated that electrolyzed reduced water (ERW) and ground waters such as Hita Tenryosui water in Japan, Nordenau water in Germany, Tracote water in Mexico, which are so called miracle water because of their improving activity on various diseases, are all antioxidative water containing active hydrogen and can scavenge intracellular reactive oxygen species (ROS). Reduced water stimulated glucose uptake into muscle and adipocyte cells as well as insulin. It also stimulated the secretion of insulin from pancreatic beta cells and improved the sugar tolerance damage in type 2 diabetes model mice. Reduced water impaired the tumor phenotypes such as rapid growth, anchorage independent growth in a soft agar, morphology, telomere maintenance, and abilities of invasion, metastasis, and angiogenesis. It activated the cancer immune systems, suppressing the tumor growth in vivo. Reduced water is expected for utilization for prevention and therapy of various diseases.

Although it is a mature way to discuss thermo-ionization in stellar atmosphere by means of thermodynamics and statistical physics, e.g., the mass action law, the same consideration to photo-ionization is difficult since many conclusions for ideal gases cannot be applied to the photon.By introducing the solar photon as a reactant into the ionosphere photochemical reaction the reaction degree and chemical equilibrium constant in the low ionosphere, and hence the electron density are obtained by means of the chemical thermodynamics method. Meanwhile, the chemical equilibrium constant can be deduced by means of statistical physics method. The results show that the electron density in the lower ionosphere derived by thermodynamics methods is nearly identical with that from the Chapman theory, proves the feasibility to study the ionosphere formation by the thermodynamics methods. However, the two equilibrium constants derived by thermodynamic and statistical physics methods independently are different. Further analysis indicates that not all photon energy is converted to ionization energy in the photochemical process, part of the energy is converted into heat or keeping the particles in the excited states. This difference hints a possibility to derive the ionospheric plasma temperature.

Investigations of correlation between nitro group charges and C-nitro bond strength, and amino group effects on C-nitro bonds in planar conjugated molecules

The relative H-donor capacity of the hydrogenated derivatives of aromatic compounds (benzene, naphthalene, anthracene and phenanthrene) depending on temperature and pressure was studied by the methods of chemical thermodynamics and of quantum chemistry.

Free radical chemistry of coal liquefaction: role of molecular hydrogen

Nb2O5 is known as good promoter for adsorption/desorption kinetics of hydrogen in magnesium hydride. In this article the interaction with hydrogen of bare Nb2O5, the oxidic component of the mixed MgH2/Nb2O5 system, is investigated in various conditions (i.e. employing atomic, molecular and nascent hydrogen). The state of the hydrogen-Nb2O5 system was monitored using various techniques including: X-ray Diffraction, Electron Paramagnetic Resonance, Diffuse Reflectance UV-Vis Spectroscopy, Thermal Desorption Spectroscopy -Mass Spectrometry, Differential Scanning Calorimetry and Thermal Programmed Desorption. Niobium (V) oxide is not at all inert while interacting with hydrogen. This oxide is partially reduced by hydrogen, which is incorporated in the solid and released as both molecular hydrogen and water. This peculiar behaviour, reminiscent of some properties of the bronze family, suggests an active chemical role played by Nb2O5 in the mixed MgH2/Nb2O5 system.

Solid food waste is a significant threat to the environment. Thermodynamic calculations allow determining theoretically possible metabolic pathways for degradation of organic compounds by microorganisms, and also to select the optimal one to increase efficiency of food waste recycling. The purpose of our work was application of thermodynamic calculations to find out suitable fermentation parameters for regulation of microbial metabolism to ensure high rate of waste decomposition and formation of valuable products. The following methods were used: for pH and oxidation-reduction potential (ORP) measuring – colorimetric and potentiometric, for volume and composition of synthesized gas study – volumetric and chromatographic, for fermentation parameters calculation – mathematical. Fermentation of multicomponent kitchen food waste under theoretically calculated optimal parameters pH = 7.0 and Eh = –250...–350 mV provided extremely high metabolic activity of hydrogen-producing microbial community which resulted in decrease in duration of batch fermentation from to 3 days, increase in hydrogen yield from 16 to 80-115 L/kg of dry waste. The coefficient of waste destruction (Kd) that is ratio of initial and final weight of waste reached 91. Obtained after fermentation unfermented lignocellulosic substrate was shown to be applied as plant probiotics and supply mineral nitrogen for plant nutrition in arid condition. Thus, high efficiency of application of thermodynamic prognosis method of microbial interaction with organic compounds was shown to become the base for biotechnology of destruction of environmentally hazardous solid food waste with simultaneous obtaining of valuable products: environmentally friendly energy carrier – molecular hydrogen, as well as lignocellulosic substrate to increase crop yields. DOI: http://dx.doi.org/10.5755/j01.erem.74.4.20723

This study unveils a novel property of polyaniline by establishing its catalytic activity in heterogeneous hydrogenation with molecular hydrogen. Polyaniline was activated by heat-treating at different temperatures in a hydrogen atmosphere. The sample treated at 300 °C exhibited the highest catalytic activity for ethylene hydrogenation in the gas phase at atmospheric pressure and for p-nitrotoluene or α-methylstyrene hydrogenation in the liquid phase. XRD, HRTEM, Raman, XPS, UV-VIS, FTIR, and elemental analysis data as well as electrochemical study indicate that catalytic activity is associated with the conjugated structure of undoped emeraldine base, whereas the polymer cross-linking or an increase in chlorine residues correlates with catalyst deactivation. These results pave the way to use conducting polymers as catalysts for hydrogenation with molecular hydrogen, opening new avenues for their application in catalysis.

The main objectives of the further downstream operations (product upgrading) of Fischer-Tropsch products are to i) improve yields and selectivities of the desired fractions, and ii) improve fuel properties to meet the fuel product specifications. The present study addresses the combination of low-temperature Fischer-Tropsch (FT) synthesis (with Co or Fe catalysts) and hydrocarbon modification reactions (hydroprocessing) in one reactor.In addition to earlier results with Pt/ZSM-5 in a dual-layer configuration in a fixed-bed reactor (Mena et al. 2007), the objective of the present investigation was to study the influence of CO during hydroprocessing and oligomerisation reactions of hydrocarbon model compounds (1-octene, ethene/propene) on two different bifunctional catalysts (Pt/ZSM-5, Pt/Beta). In addition, the influence of the catalyst-bed configuration for the combination FT synthesis and hydrocarbon reactions was investigated (dual layer/physical mixture).The achieved results indicate a potential of combining FT and hydrocarbons reactions in one reactor. Hydrogenation, isomerisation, cracking and oligomerisation reactions take place on a Pt/zeolite catalyst at FTS temperatures and in the presence of CO and H2O. The most critical point of this combination seems to be the deleterious effect of CO on the cracking reactions of isomers. For that reason, the wax fraction (C21+) was only partially cracked. The experimental results also indicate that the type of zeolite and the catalyst-bed configuration have an influence on the diesel/gasoline ratio obtained. It seems that the final fuel products will be a mixture of gasoline and diesel fuel and C1 to C5 compounds, as long as no diesel-selective hydroprocessing catalyst is found.

Hydrogen formation from biomass using solar energy