Thermodynamic Analysis of the Effect of Green Hydrogen Addition to a Fuel Mixture on the Steam Methane Reforming Process

Steam methane (CH4–H2O) reforming in the presence of a catalyst, usually nickel, is the most common technology for generating synthesis gas as a feedstock in chemical synthesis and a source of pure H2 and CO. What is essential from the perspective of further gas use is the parameter describing a ratio of equilibrium concentration of hydrogen to carbon monoxide H/C=xH2/xCO. The parameter is determined by operating temperature and the initial ratio of steam concentration to methane SC= xH2O0/xCH40. In this paper, the author presents a thermodynamic analysis of the effect of green hydrogen addition to a fuel mixture on the steam methane reforming process of gaseous phase (CH4/H2)–H2O. The thermodynamic analysis of conversion of hydrogen-enriched methane (CH4/H2)–H2O has been performed using parametric equation formalism, allowing for determining the equilibrium composition of the process in progress. A thermodynamic condition of carbon precipitation in methane reforming (CH4/H2) with the gaseous phase of H2O has been interpreted. The ranges of substrate concentrations creating carbon deposition for temperature T = 1000 K have been determined, based on the technologies used. The results obtained can serve as a model basis for describing the properties of steam reforming of methane and hydrogen mixture (CH4/H2)–H2O.

Mode of Action of Condensed- and Gaseous-Phase Fire Retardation in Some Phosphorus-Modified Polymethyl Methacrylate- and Polystyrene-Based Bulk Polymers

The aspects of fire retardation in some phosphorus-modified polymethyl methacrylate (PMMA) and polystyrene (PSt) polymers are reported in the present paper. Both additive and reactive strategies were employed to obtain the desired level of loading of the phosphorus-bearing compound/moiety (2 wt.% of P in each case). Test samples were obtained using bulk polymerization. The modifying compounds contained the P-atom in various chemical environments, as well as in an oxidation state of either III or V. With a view to gain an understanding of the chemical constitution of the gaseous products formed from the thermal decomposition of liquid additives/reactives, these materials were subjected to GC/MS analysis, whereas the decomposition of solid additives was detailed using the pyrolysis-GC/MS technique. Other investigations included the use of: Inductively-coupled Plasma/Optical Emission Spectroscopy (ICP/OES), solid-state NMR and FT-IR spectroscopy. In the case of PMMA-based systems, it was found that the modifying phosphonate ester function, upon thermal cracking, produced ‘phosphorus’ acid species which initiated the charring process. In the case of solid additives, it is more likely that the resultant phosphorus- and/or oxygenated phosphorus-containing volatiles acted as flame inhibitors in the gaseous phase. With the PSt-based systems, a probable process involving the phosphorylation of the phenyl groups leading to crosslinking and char formation is feasible.

Thermodynamic analysis on disproportionation process of cyclohexylamine to dicyclohexylamine

This work deals with a study of the effect of temperature on the cyclohexylamine disproportionation to dicyclohexylamine, conjointly with the thermodynamic analysis of this process. The laboratory experiments were carried out in a glass tubular continuous-flow reactor in a gaseous phase at the reaction temperature 433–463 K over a nickel catalyst. The results show, that the temperature has a trifling effect on equilibrium conversion of cyclohexylamine. However, temperature affects the formation of hydrocarbons, benzene and cyclohexane, and dehydrogenation products of dicyclohexylamine, i.e. N-cyclohexylidenecyclohexanamine and N-phenylcyclohexylamine. The latter one is the dominant product of dicyclohexylamine dehydrogenation. The disproportionation of cyclohexylamine has slightly exothermic character. At the experimental reaction temperature range, the cyclohexylamine disproportionation is spontaneous reaction and other reactions of this process are non-spontaneous.

Electromigration-induced formation of percolating adsorbate islands during condensation from the gaseous phase: a computational study

We provide a computational study of a change in the morphology of a growing thin film during condensation caused by electromigration effects. It will be shown, that separated circular adsorbate islands, realized in an isotropic system, become elongated in the direction of the applied electrical field. We discuss the dependence of the critical value of the strength of the applied electrical field, responsible for the formation of percolating adsorbate islands, on main control parameters. This study provides insight into details of electromigration effects during the self-organization of adatoms into percolating adsorbate islands during condensation from the gaseous phase. We will show that the elongated morphology of adsorbate islands remains stable if the electric field is turned off.

GENERATING A STREAM WITH A STABLE FORMALDEHYDE CONCENTRATION IN THE LABORATORY

A laboratory-scale bio-trickling filter (BTF) was initialized to evaluate the removal of formaldehyde biologically. However, generating formaldehyde gas in the lab is one of the grand challenges hindering research efforts. Formaldehyde was introduced into the gaseous phase by aerating the required air flowrate through a diluted formaldehyde solution mixed with methanol as a stabilizer by a bubbler. However, achieving stable gaseous influent concentrations of formaldehyde was challenging since it polymerizes while volatilizing. Resulting in paraformaldehyde. The resulting white powder clogged the pipes and generated uneven gaseous concentrations. To solve this problem, sodium hydroxide (NaOH) was added with a phosphate buffer to the aqueous formaldehyde solution to maintain the pH between 7.00-7.20. Additionally, the aqueous solution needed to be heated at 60℃ to eliminate the polymerization. The exhausted formaldehyde by volatilization was replaced by a continuous supply of aqueous diluted formaldehyde solution to keep the volume and mass of the aqueous solution and formaldehyde constant, respectively. Stable gaseous concentration was achieved for extended periods of time and verified by Fourier transform infrared (FTIR) spectroscopy.