Methylal (methylal, also known as dimethoxymethane, short as DMM), has a molecular formula C3H8O2, structural formula CH3-O-CH2-O-CH3, molecular weight 76.09. It is a colorless, volatile and flammable liquid with a smell similar to chloroform, and can be mixed with alcohol, ether, acetone and other organic solvents.

Methylal has excellent physical and chemical properties, good solubility, low boiling point and good water solubility. Therefore, it can be widely used in cosmetics, pharmaceuticals, household products, industrial automotive supplies, pesticides, leather glazing agent, detergent, rubber industry, paint, ink and other products. At the same time, methylal has good degreasing ability and volatility, and can be used as a cleaner to replace F11 and F113 and chlorine-containing solvent, replacing freon, reducing the emission of volatile organic compounds (VOCs) and pollution to the air.
High concentration of methylal is mainly used in molecular weight regulator produced by paraformaldehyde, plasticizer of resin, hypnotic, analgesic, perfume and high-grade cosmetics, solvents for Grignard reaction and Reppe reaction, etc.
As a formaldehyde derivative, methylal has a wide market demand; especially high concentration methylal has a great market application and high added value.
Methylal process of Dolton has been widely recognized as low consumption, good quality and stable operation.

Sulfuric acid has been used as catalyst in the synthesis of methylal, which causes serious corrosion to the equipment. With the development of methylal technology, the catalyst has been changed to solid resin, and the combined reaction distillation process is developed. The output and quality are greatly improved, but the regeneration of the catalyst is very difficult, the COD content in the wastewater exceeds 2000ppm.
By many years practice, Dolton has developed a new process technology with independent intellectual property rights; The catalyst regeneration and replacement is convenient, and the conversion rate and output are further improved. The COD content in wastewater is reduced to below 200ppm.

Methanol and formaldehyde solution are pumped into the fixed bed reactor in certain proportion, control reaction temperature at 60 ~ 85 ℃. The methylal generated enters the reaction column along with unreacted raw materials. Reaction column is equipped with wire packing, evenly filled between solid acid catalysts. The feed components are separated while reacting in the reaction column. The reacted methylal with a low boiling point vaporizes out of the reaction bed, thus promoting the transfer of reaction equilibrium to the target product.
Methylal product is enriched on top of the column while the recombinant is extracted from the bottom. At the top of the column, the methylal condenses in the condenser and flows into the reflux tank, partial reflux for column top, part extracted as product.
Dolton provides three process solutions to meet different regional product standards and sewage discharge standards.

 Methylal process flow chart in column 1

 Methylal process flow chart in column 2

 External methylal process flow chart

High methylal concentration 

Firstly, low concentration methylal is produced with normal concentration production process, and 92% methylal goes into differential distillation column for pressurized rectification. A high concentration of methylal will be extracted from the bottom of the column, and reflux fraction at the top goes to the reaction column and the pressurized distillation column.

High concentration methylal process flow chart with 2 columns

High concentration methylal process flow chart with 3 columns

1, This process keeps the lower consumption level in the industry.
2, The catalyst has a long activity time and can be regenerated.
3, The waste water quantity is small and the formaldehyde content is lower than the environmental requirements and energy saving, greatly reduces the sewage discharge.
4, It has the advantages of high conversion rate, good selectivity, low energy consumption, high product purity, easy operation and small investment.

Main raw material consumption

Product Quality