The disclosure relates to a process for continuously producing polyoxymethylene dimethyl ethers at low temperature, pertains to the technical field of polyoxymethylene dimethyl ether preparation processes, and solves the technical problem of continuous production of polyoxymethylene dimethyl ether. A membrane separation element with precisely controlled pores in membrane is used to realize a direct separation of the feedstocks from the catalyst within the reactor, and effectively reduce the permeation resistance of the separation membrane tube. By oppositely switching the flowing direction of liquid reaction materials, the adhesion of the catalyst to the separation membrane tube is inhibited, and some particles stuck in separation membrane tube are removed, which ensures the continuous operation of the reaction process and allows a molecular sieve catalyst to exhibit its advantage of long catalytic life.

The disclosure relates to a process for continuously producing polyoxymethylene dimethyl ethers at low temperature, pertains to the technical field of polyoxymethylene dimethyl ether preparation processes, and solves the technical problem of continuous production of polyoxymethylene dimethyl ether. A membrane separation element with precisely controlled pores in membrane is used to realize a direct separation of the feedstocks from the catalyst within the reactor, and effectively reduce the permeation resistance of the separation membrane tube. By oppositely switching the flowing direction of liquid reaction materials, the adhesion of the catalyst to the separation membrane tube is inhibited, and some particles stuck in separation membrane tube are removed, which ensures the continuous operation of the reaction process and allows a molecular sieve catalyst to exhibit its advantage of long catalytic life.

A method of producing dimethoxymethane oligomers (DMMn), the method comprising: reacting a formaldehyde source and dimethoxymethane monomer (DMM1) in the presence of an acidic catalyst to produce a reaction effluent comprising DMMn and unreacted DMM1; and separating, from the reaction effluent, DMM1-2 including unreacted DMM1 and DMMn having a chain length n equal to 2 (DMM2), dimethoxymethane oligomers having a chain length n in the range of from 2-5 (DMM2-5), dimethoxymethane oligomers having a chain length n of ≥5 (DMM5+), or a combination thereof, wherein the separating comprises distillation in the presence of at least one alcohol, a distillate fuel, or both.

A method of producing dimethoxymethane oligomers (DMMn), the method comprising: reacting a formaldehyde source and dimethoxymethane monomer (DMM1) in the presence of an acidic catalyst to produce a reaction effluent comprising DMMn and unreacted DMM1; and separating, from the reaction effluent, DMM1-2 including unreacted DMM1 and DMMn having a chain length n equal to 2 (DMM2), dimethoxymethane oligomers having a chain length n in the range of from 2-5 (DMM2-5), dimethoxymethane oligomers having a chain length n of ≥5 (DMM5+), or a combination thereof, wherein the separating comprises distillation in the presence of at least one alcohol, a distillate fuel, or both.

A method of producing dimethoxymethane oligomers (DMMn), the method comprising: reacting a formaldehyde source and dimethoxymethane monomer (DMM1) in the presence of an acidic catalyst to produce a reaction effluent comprising DMMn and unreacted DMM1; and separating, from the reaction effluent, DMM1-2 including unreacted DMM1 and DMMn having a chain length n equal to 2 (DMM2), dimethoxymethane oligomers having a chain length n in the range of from 2-5 (DMM2-5), dimethoxymethane oligomers having a chain length n of ≥5 (DMM5+), or a combination thereof, wherein the separating comprises distillation in the presence of at least one alcohol, a distillate fuel, or both.

A method of manufacturing a cetane-boosting fuel additive includes reacting formaldehyde and 2-ethylhexanol at a mole ratio of 10:1 to 1:1, or 5:1 to 1.5:1, or 4:1 to 2:1, or 3.5:1 to 2.5:1 in the presence of a heterogeneous acid catalyst at a temperature of 300 to 375 K to obtain a cetane-boosting product mixture comprising H.sub.3C(CH.sub.2).sub.3CH(CH.sub.2CH.sub.3)CH.sub.2(OCH.sub.2).sub.nOH, H.sub.3C(CH.sub.2).sub.3CH(CH.sub.2CH.sub.3)CH.sub.2(OCH.sub.2).sub.nOCH.sub.2CH(CH.sub.2CH.sub.3)(CH.sub.2).sub.3CH.sub.3, or a combination thereof, wherein n has an average value of 2.8 to 3.2, preferably an average value of 3.

A method of manufacturing a cetane-boosting fuel additive includes reacting formaldehyde and 2-ethylhexanol at a mole ratio of 10:1 to 1:1, or 5:1 to 1.5:1, or 4:1 to 2:1, or 3.5:1 to 2.5:1 in the presence of a heterogeneous acid catalyst at a temperature of 300 to 375 K to obtain a cetane-boosting product mixture comprising H.sub.3C(CH.sub.2).sub.3CH(CH.sub.2CH.sub.3)CH.sub.2(OCH.sub.2).sub.nOH, H.sub.3C(CH.sub.2).sub.3CH(CH.sub.2CH.sub.3)CH.sub.2(OCH.sub.2).sub.nOCH.sub.2CH(CH.sub.2CH.sub.3)(CH.sub.2).sub.3CH.sub.3, or a combination thereof, wherein n has an average value of 2.8 to 3.2, preferably an average value of 3.

A method of manufacturing a cetane-boosting fuel additive includes reacting formaldehyde and 2-ethylhexanol at a mole ratio of 10:1 to 1:1, or 5:1 to 1.5:1, or 4:1 to 2:1, or 3.5:1 to 2.5:1 in the presence of a heterogeneous acid catalyst at a temperature of 300 to 375 K to obtain a cetane-boosting product mixture comprising H.sub.3C(CH.sub.2).sub.3CH(CH.sub.2CH.sub.3)CH.sub.2(OCH.sub.2).sub.nOH, H.sub.3C(CH.sub.2).sub.3CH(CH.sub.2CH.sub.3)CH.sub.2(OCH.sub.2).sub.nOCH.sub.2CH(CH.sub.2CH.sub.3)(CH.sub.2).sub.3CH.sub.3, or a combination thereof, wherein n has an average value of 2.8 to 3.2, preferably an average value of 3.

The disclosure relates to a process for continuously producing polyoxymethylene dimethyl ethers at low temperature, pertains to the technical field of polyoxymethylene dimethyl ether preparation processes, and solves the technical problem of continuous production of polyoxymethylene dimethyl ether. A membrane separation element with precisely controlled pores in membrane is used to realize a direct separation of the feedstocks from the catalyst within the reactor, and effectively reduce the permeation resistance of the separation membrane tube. By oppositely switching the flowing direction of liquid reaction materials, the adhesion of the catalyst to the separation membrane tube is inhibited, and some particles stuck in separation membrane tube are removed, which ensures the continuous operation of the reaction process and allows a molecular sieve catalyst to exhibit its advantage of long catalytic life.

The disclosure relates to a process for continuously producing polyoxymethylene dimethyl ethers at low temperature, pertains to the technical field of polyoxymethylene dimethyl ether preparation processes, and solves the technical problem of continuous production of polyoxymethylene dimethyl ether. A membrane separation element with precisely controlled pores in membrane is used to realize a direct separation of the feedstocks from the catalyst within the reactor, and effectively reduce the permeation resistance of the separation membrane tube. By oppositely switching the flowing direction of liquid reaction materials, the adhesion of the catalyst to the separation membrane tube is inhibited, and some particles stuck in separation membrane tube are removed, which ensures the continuous operation of the reaction process and allows a molecular sieve catalyst to exhibit its advantage of long catalytic life.