Dimethoxymethane as a Cleaner Synthetic Fuel: Synthetic Methods, Catalysts, and Reaction Mechanism

Abstract

The increasing concerns regarding exhaust and CO 2 emissions from fossil-based transportation fuels have propelled intensive research aimed at finding alternative fuel candidates to realize a clean and renewable fuel system. In this context, dimethoxymethane and its derivatives oxymethylene ethers, a class of oxygenated synthetic fuel, have recently attracted increasing interest because of their fascinating characteristics as a diesel blend compound to significantly reduce soot and nitrogen oxide formation. At present, dimethoxymethane production primarily relies on an established two-step process comprising methanol oxidation and methanol condensation with formaldehyde. Several new synthetic routes based on methanol or CO 2 /H 2 have been proposed by adopting a reaction coupling strategy, which enables the production of dimethoxymethane in one step. A large variety of bi-and multifunctional catalysts have been developed for each synthetic route. This Review comprehensively summarizes the latest advances in synthetic approaches, catalyst systems, structure−activity relationships, and reaction mechanism for the catalytic synthesis of dimethoxymethane. Comparisons regarding the features and limitations of different synthetic approaches as well as the related catalytic materials are also provided in order to indicate possible directions for future research, especially on the rational design of catalysts, a vital factor for the commercial production of dimethoxymethane.

A Perspective on Biofuels Use and CCS for GHG Mitigation in the Marine Sector

“…It must be said that ethers other than DME are also promising biofuel candidates. These include the class of oligomers called oxymethylene dimethyl ethers (OMEs), of which dimethoxymethane (DMM) is the simplest member ( Sun et al., 2019 ). Although DMM has a cetane number of only 28, the polyoxymethylene dimethyl ethers OME 3-5 exhibit physico-chemical and combustion characteristics similar to conventional diesel fuels ( Hackbarth et al., 2018 ; Baranowski et al., 2017 ).…”

Challenges and Opportunities in the Production of Oxymethylene Dimethylether

“…They are mainly composed of vanadium pentoxide (V 2 O 5 ) and well established in industrial oxidation processes. [43] The excellent oxidation properties of vanadium-based catalysts have to be combined with an acidic function, either by using an acidic support material or via the addition of acidic additives. [47,48], sol-gel (SG) [49,50], and mechanical grinding (MG) [49] presenting the most efficient methodologies.…”

Processes for the production of OME fuels

“…Although the thermodynamic equilibrium is favorable for the reaction, the reaction rates are still small and have to be greatly improved. Sun et al [38] reported a heterogeneous catalyst that is able to produce OME1 and H2 from pure methanol in the gas phase. The reaction is fast with good selectivity toward OME1.…”