No abstract

Oxymethylene dimethyl ethers (OME ; CH (-OCH -) O-CH , n=3-5) are a novel class of sustainable synthetic fuels, which are of increasing interest due to their soot-free combustion. Herein a novel anhydrous OME synthesis route is presented. Catalyzed by trimethyloxonium salts, dimethoxymethane takes up monomeric gaseous formaldehyde instantaneously and forms high purity OME at temperatures of 25-30 °C. This new anhydrous approach using molecular formaldehyde and catalytic amounts of highly active trimethyloxonium salts represents a promising new step towards a sustainable formation of OME emanating from CO and H .

The influence of a mild difluorine treatment on Cu/ZnO precatalysts for methanol synthesis was investigated. It led to the incorporation of 1.2…1.3±0.1 wt % fluoride into the material. Fluorination considerably increased the amount of ZnOx related defect sites on the catalysts and significantly increased the space‐time yields. Although the apparent activation energy EA,app for methanol formation from CO2 and H2 was almost unchanged, the EA,app for the reverse water‐gas shift (rWGS) reaction increased considerably. Overall, fluorination led to a significant gain in methanol selectivity and productivity. Apparently, also the quantity of active sites increased.

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Oxymethylene dimethyl ethers (OME n ; CH 3 (-OCH 2 -) n O-CH 3 ,n= 3-5) are anovel class of sustainable synthetic fuels,w hich are of increasing interest due to their soot-free combustion. Herein an ovel anhydrous OME n synthesis route is presented. Catalyzed by trimethyloxonium salts, dimethoxymethane takes up monomeric gaseous formaldehyde instantaneously and forms high purity OME n at temperatures of 25-30 8 8C. This new anhydrous approach using molecular formaldehyde and catalytic amounts of highly active trimethyloxonium salts represents ap romising new step towards asustainable formation of OME n emanating from CO 2 and H 2 .Oxymethylene dimethyl ethers (OME n )o ft he general formula CH 3 (-OCH 2 -) n O-CH 3 are an ovel class of non-toxic compounds,w hich attract increasing interest due to their versatile applications.W ith their diesel-like properties in combination with soot-free combustion, OME n are considered as diesel additives or even as an ovel class of synthetic fuels (for n = 3-5). [1] In addition, OME n are discussed as solvents or for the absorption of CO 2 . [2] ForOME n formation, two structural building units are necessary:Onthe one hand molecules are required, which extend the oxymethylene chain by providing CH 2 O-units (e.g., para-formaldeyhde (para-FA), 1,3,5-trioxane (TRI)). On the other hand, molecules are needed, which contain methoxy groups for the chain termination (e.g.,m ethanol, dimethoxymethane,d imethyl ether). Currently,e stablished OME n syntheses are either based on aqueous syntheses routes via the reaction of methanol (MeOH) and aF A-source,o ra nhydrous by the reaction of dimethoxymethane (OME 1 )a nd TRI. [3][4][5][6][7][8][9][10][11][12] However,t he synthesis of dry TRI is complex and very energy demanding.In addition, the presence of water in OME n syntheses initiates the formation of large amounts of side-products [13] and OME n conversion decreases with increasing water content. The product separation for aqueous syntheses routes is evolving, [ * ] but remains av ery energy-intensive key step largely increasing the CO 2 footprint of the thereby produced OME n (ca. 7-10 MJ kg À1