Oxymethylene Ether (OME) Fuel Catalyst Screening Using In Situ NMR Spectroscopy

Abstract

Online NMR measurements are introduced in the current study as a new analytical setup for investigation of the oxymethylene dimethyl ether (OME) synthesis. For the validation of the setup, the newly established method is compared with state‐of‐the‐art gas chromatographic analysis. Afterwards, the influence of different parameters, such as temperature, catalyst concentration and catalyst type on the OME fuel formation based on trioxane and dimethoxymethane is investigated. As catalysts, AmberlystTM 15 (A15) and trifluoromethanesulfonic acid (TfOH) are utilized. A kinetic model is applied to describe the reaction in more detail. Based on these results, the activation energy (A15: 48.0 kJ mol−1 and TfOH: 72.3 kJ mol−1) and the order in catalyst (A15: 1.1 and TfOH: 1.3) are calculated and discussed.

Investigation of the cooperative-effects of Lewis- and Brønstedt acids in homogeneously catalyzed OME fuel synthesis by inline-NMR monitoring

“… 23 The anhydrous synthesis of OME fuels based on DMM and TRI was chosen not only due to its lower tendency to form byproducts but also to ensure the comparability with previous results. 39 Within this synthesis a two-step reaction mechanism ( Scheme 1 ) is widely assumed in literature. 17 In the first step trioxane decomposition takes place resulting in the release of three formaldehyde (FA) molecules.…”

“…As previously reported, more than one catalytic role of the catalyst is assumed, which will be addressed in this study by investigating the synergetic effects of Lewis- and Brønsted acids. 39 In all experiments of this study in which a Lewis acid was utilized, the acid was added to the reaction medium directly after loading the reactor with TRI (44.4 g) and DMM (150 g). Afterwards, the reaction setup was tempered to 20 °C and the reaction medium was stirred to guarantee a homogeneous solution.…”

“…In a recent study published by our groups, a new system to monitor the OME fuel synthesis via inline NMR measurements was introduced. 39 This system is based on a benchtop NMR device, which already gained much interest in academic research. [40][41][42][43] By the use of ow cells, a continuous circulation of the reaction solution through the analytical capillary is possible.…”

“…45 Within the OME fuel reaction, rst insights into the catalytical system were obtained by determining the order in catalyst of a liquid and solid acid. 39 In the present study we follow up on our initial results and use the developed setup to study the highly debated cooperative effects of BAs and LAs during OME synthesis. Therefore, different LAs were utilized for the OME fuel synthesis and the inuence of different LA : BA ratios on the catalytic performance was investigated using inline NMR spectroscopy.…”

“…Within the OME fuel reaction, first insights into the catalytical system were obtained by determining the order in catalyst of a liquid and solid acid. 39 …”