Chemical Equilibrium and Reaction Kinetics of the Heterogeneously Catalyzed Formation of Poly(oxymethylene) Dimethyl Ethers from Methylal and Trioxane

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.

Kinetics of synthesis of polyoxymethylene dimethyl ethers from paraformaldehyde and dimethoxymethane catalyzed by ion-exchange resin

“…A set of relative mass correction factors of PODE n compounds (with DMM as reference) were measured using standard samples PODE 2 -PODE 5 . It was found that the relative mass correction factors for PODE n (n¼ 2-5) is a geometrical series, which was similar to the results Burger et al (2012) found during their PODE n quantitative analysis. The relative mass correction factors for PODE n with longer polymerization degree were calculated by extrapolation.…”

“…Different from Burger's attempt in PODE n system from DMM and trioxane (Burger et al, 2012), the titration by the sodium sulfite method used in this work could be calibrated and had a good reproducibility. The difference was attributed to the different depolymerization properties of trioxane and PF in sodium sulfite solution (Kiernan, 2000;Maurer, 1986).…”

“…Polyoxymethylene dimethyl ethers (CH 3 -O-(CH 2 -O) n -CH 3 , PODE n , where n 41), which are environmental benign alternative components for diesel fuels, are receiving increasing attentions in recent years Burger et al, 2010Burger et al, , 2012Lumpp et al, 2011). Compared with the reference diesel fuel, the PM emissions are reduced by 18% with 10% blend and by 77% with pure PODE n (Pellegrini et al, 2013).…”

“…Various acidic catalysts, including acidic ionexchange resins Zheng et al, 2013Zheng et al, , 2014Burger et al, 2012), ionic liquids , molecule sieves (Zhao et al, 2011), and solid superacids (Li et al, 2015;Zhang et al, 2014), have been employed in synthesis of PODE n . Burger et al (2012) proposed that water reacts with ethers and form alcohols during the synthesis of PODE n from DMM and trioxane in the acidcatalyzed system. To illustrate the effect of water on the synthesis of PODE n from DMM and PF, we investigated the product distribution with different dosages of water added in this work, as shown in Table 1.…”

“…However, the studies on the kinetics of synthesis of PODE n are very limited. Burger et al (2012) reported the reaction kinetics of the heterogeneously catalytic formation of PODE n from DMM and trioxane, and proposed an adsorptionbased kinetic model to describe the results. Zhang et al (2014) synthesized PODE n from methanol and formaldehyde solution and proposed a kinetic model based on an elimination mechanism.…”