Synthesis of Polyoxymethylene Dimethyl Ethers from Dimethyl Ether Direct Oxidation over Carbon‐Based Catalysts

Abstract

The synthesis of polyoxymethylene dimethyl ethers (DMMx) with a selectivity of 84.3 % by direct oxidation of dimethyl ether (DME) was realized over 30 %Ti(SO4)2/active carbon (AC) catalyst. This process also significantly promotes the growth of the C−O chain. The catalytic performances of Ti(SO4)2/AC and Ti(SO4)2/graphene (G) catalysts differ largely for DME oxidation reaction, although both AC and G are carbon materials. The carbonyl and hydroxyl groups on the surface of the carbon‐based catalysts play an important role in DME direct oxidation to DMMx. Owing to the differences of surface structure and chemical properties of AC and G materials, the different interaction between the Ti(SO4)2 and supports remarkably affects the sulfate structures on the supports surface and leads to the large differences in the acid and redox properties of catalysts.

The Synergistic Effect of Acidic Properties and Channel Systems of Zeolites on the Synthesis of Polyoxymethylene Dimethyl Ethers from Dimethoxymethane and Trioxymethylene

“…The identification of a highly efficient and clean fuel additive that could enhance diesel oil combustion efficiency and reduce pollutant emissions would be an economical and practical solution. Recently, polyoxymethylene dimethyl ethers (PODE n , CH 3 –O–(CH 2 –O) n –CH 3 , n > 1) have exhibited much potential as diesel additives, due to their high oxygen content, cetane number, good miscibility, and absence of C–to–C bonds [1,2,3,4,5]. Compared with CH 3 OH (MeOH), CH 3 OCH 3 (DME), CH 3 OCH 2 OCH 3 (DMM), and CH 3 OCOOCH 3 (DMC), PODE n , especially PODE 2–8 , can directly blend into traditional diesel without any fuel system modifications and can reduce the release of NO x and particulate emissions effectively [6,7,8].…”

Hierarchical H-MOR Zeolite Supported Vanadium Oxide for Dimethyl Ether Direct Oxidation

“…However, the activation In comparison, oxidizing DME directly to synthesize DMMx is considered as a very competitive and environmentally friendly route for the synthesis of clean fuel additives due to the advantages of short process, low investment, low CO2 emissions, and high energy efficiency. However, the activation of the DME molecule is very difficult at lower temperature because of its high stability, while higher temperature easily leads to deep oxidation of DME along with the formation of byproducts and makes product complex [8][9][10]. Especially, the synthesis of the larger DMMx molecules with longer C-O chain from small DME molecule is very complicated and difficult.…”

“…Thus, the activation and the highly efficient conversion of DME are very challenging. The appropriate redox and acid sites have been proved to be crucial factors and investigated systemically for the synthesis of DMMx [7][8][9][10][12][13][14][15], but to date, the effect of transport constraints due to the pore structure of support on product distribution has not been investigated. Given that the H-MOR has two pore systems consisted of 12-MR channels with the dimensions of 0.65 × 0.70 nm connected via 8-MR side pocket of 0.26 × 0.57 nm as shown in Scheme 1, it is expected to be a promising model for us to investigate the catalytic performance of DME direct oxidation as a function of pore structure.…”

Recent Progress in the Production, Application and Evaluation of Oxymethylene Ethers

“…Compared to reactions starting from DMM or methanol, OME synthesis from dimethyl ether (DME) is much less explored and recent investigations focused on the oxidation of DME , , , , . Alternatively, DME can be converted to OMEs employing formaldehyde sources.…”