No abstract

Poly(oxymethylene) dimethyl ethers (OMEs) are attractive components for tailoring diesel fuels. They belong to the group of oxygenates that reduce soot formation in the combustion when added to diesel fuels and can be produced on a large scale based on gas-to-liquid technology. This work deals with a particularly favorable route for their large scale production in which they are formed from methylal and trioxane. Reaction kinetics and chemical equilibrium of the OME formation via this route were studied in a batch reactor using the ion-exchange resin Amberlyst 46 as heterogeneous catalyst at temperatures between 323 and 363 K and for a wide range of feed compositions. An adsorption-based kinetic model is presented that represents both reaction kinetics and equilibrium well.

Poly­(oxymethylene) dimethyl ethers (OME) are attractive oxygenated fuel additives and physical solvents for the absorption of carbon dioxide. This works studies the synthesis of OME from formaldehyde and methanol in aqueous solutions. The reaction kinetics of OME formation is studied experimentally in a stirred batch reactor on a laboratory scale using the heterogeneous catalyst Amberlyst 46. The influences of the ratio of formaldehyde to methanol, the amount of water, and the temperature (303.15–363.15 K) are investigated. A model of the reaction kinetics is developed that differentiates two competing reaction mechanisms. The model explicitly accounts for the intermediates poly­(oxymethylene) hemiformals and poly­(oxymethylene) glycols.

Polyoxymethylene dimethyl ether (OME) are a high-potential and carbon-neutral synthetic e-fuel. This is the first comprehensive study to report the energetic efficiency of the production of OME from CO2 and electrical energy.

Mixtures that contain a known target component but are otherwise poorly specified are important in many fields. Previously, the activity of the target component, which is needed e.g. to design separation processes, could not be predicted in such mixtures. A method was developed to solve this problem. It combines a thermodynamic group contribution method for the activity coefficient with NMR spectroscopy, which is used for estimating the nature and amount of the different chemical groups in the mixture. The knowledge of the component speciation of the mixture is not required. Test cases that are inspired by bioprocess engineering applications show that the new method gives surprisingly good results.

Sufficient and necessary conditions for the occurrence of a Hopf bifurcation in chemical reaction mechanisms are presented using the formalism of stoichiometric networks. The conditions are applied to determine the mechanistic basis of chemical oscillations in isothermal surface reactions. Realistic examples are given for the different oscillatory mechanisms.

Mixtures of which the composition is not fully known are important in many fields of engineering and science, e.g. in biotechnology. Due to the lacking information on the composition, such mixtures cannot be described with common thermodynamic models. In the present work, a method is described with which this obstacle can be overcome for an important class of problems. The method enables the estimation of the activity coefficients of target components in poorly specified mixtures and is based on a combination of NMR spectroscopy with a thermodynamic group contribution method. present work as group contribution method, but NEAT can be extended to any other group contribution method. NEAT has been introduced recently by our group in a short communication, in which, however, only the basic ideas were presented. In the present work, NEAT is described in full detail. Different options of using NEAT are discussed and examples for the application of the method are given. They include a variety of aqueous and non-aqueous mixtures. The results show very good agreement of the activity coefficients that are predicted by NEAT with the corresponding results for the fully specified mixtures.

Liquid mixtures of formaldehyde, water, and butynediol are complex reacting multicomponent systems in which formaldehyde forms oligomers both with water and butynediol. ‐ and ‐NMR spectra of these mixtures are elucidated. The species distribution of the oligomers is quantitatively determined by ‐NMR spectroscopy. The measurements cover temperatures from 293 to 366 K, overall formaldehyde mass fractions from to , and overall butynediol mass fractions from to . A mole fraction‐based and an activity‐based model of the chemical equilibrium in the studied system are developed and chemical equilibrium constants are reported. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4442–4450, 2017