Polyoxymethylene dimethylethers (known as PODME or DMMn), also known as polyoxymethylene dimethylether, polyoxymethylene dimethylether, polymethoxymethylethers, is a generic term for a class of homologues. Its chemical formula can be expressed as: CH3O(CH2O)nCH3 (where n≥1, general value < 10).

DMMn has the properties of alkane and ether with high solubility, low viscosity and toxicity. In recent years, it has been used as an environment-friendly organic solvent to replace the traditional solvent with high pollution, toxicity and cost.

DMMn is used as a solvent and thinner in the paint industry and can replace solvents such as 200# and 150#. See table 2.1-1 for comparison of DMMn and 200# solvent properties, and table 2.1-2 for comparison of DMMn and 150# solvent properties.

Comparison of DMM_3-4 and 200# environmental solvent properties

Comparison of DMM_2-3 and 150# environmental solvent properties

DMMn has high oxygen content (wt% : 42%~51%) and high hexadecane value (≥60). The experiment shows that adding DMMn with a mass fraction of 10-15% in diesel vehicles can make diesel fuel with full combustion and improve the thermal efficiency. At the same time, incomplete combustion of carbon and nitrogen oxides was reduced by more than half. DMMn is recognized as the most promising diesel additive (see table 2.1-3 for comparison of some physical and chemical properties of DMMn and diesel).

Comparison of basic physical and chemical properties of DMMn and diesel oil

Product Applications

Production process 

Production process diagram

General formula of reaction mechanism

The synthesis of DMMn is a linear polymerization reaction whose degree of polymerization is easily affected by reaction conditions, where Q=m(DMMn-1)/m(DMMn). Q (Q∈ (1.1-5)) value is proportional to the ratio of raw material methylal and formaldehyde, and inversely proportional to water content.

By adjusting the ratio of reaction materials, reaction time and temperature, and changing the type of catalyst to achieve different Q, the product structure can be adjusted. Different Q values correspond to different product structures, as shown in the figure below (illustrated by Q=1.5 and 4) :

Secondary reactions in the process flow are as follows:

 Note: reaction (9) will obviously takes place when reaction temperature is higher than 200 ℃. A definite concentration of formic acid is required for the reaction (10) to occur appreciably.

Advantages of Dolton process:

1,Using formaldehyde solution as raw material, the process is short.
2,High process elasticity and mild reaction conditions.
3,The process wastewater meets the clean discharge standard, and the biochemical treatment of sewage is simple with low consumption.
4,Catalytic distillation reaction system, high conversion rate, low reaction material circulation.
5,Low equipment requirement and low investment.
6,The catalyst has mild service condition and long service life.
7,High energy utilization rate and low energy consumption (see table 2.4-1 for consumption index).
8,In this process, the product structure of M2/ M3-5 / M6-8 can be adjusted by adjusting the composition of raw materials, reaction time, type of catalyst and the product can be changed in line with market demand.

Consumption index

Consumption index of raw materials and utilities

Technology research

Lab photos

Experimental Plant

Patents: Dolton has a complete and independent patent intellectual property system, in which DMMn synthesis technology has applied for 8 patents. 
Note: some of the patents have been transferred to Helipont, the overseas sales company of Dolton, both companies share the patents. 

Dolton patent list