The present invention discloses a process for the synthesis of aromatic carbamates from amine with dialkyl carbonate in the presence of binary or ternary mixed metal oxide catalyst. The present invention further discloses the yield of said aromatic carbamate in the range of 60 to 99%. Further, the ratio of amine to dialkyl carbonate is in the range of 1:2 to 1:30.

The present invention discloses a process for the synthesis of aromatic carbamates from amine with dialkyl carbonate in the presence of binary or ternary mixed metal oxide catalyst. The present invention further discloses the yield of said aromatic carbamate in the range of 60 to 99%. Further, the ratio of amine to dialkyl carbonate is in the range of 1:2 to 1:30.

The present invention relates to a method for preparing an aliphatic isocyanate capable of suppressing the occurrence of side reactions and the production of by-products. The method for preparing an aliphatic isocyanate comprises a step of reacting a salt of an aliphatic amine with phosgene, wherein the reaction step comprises a first reaction step in which phosgene is primarily added and reacted with the salt of an aliphatic amine salt at a temperature of 80 to 100 C., and a second reaction step in which phosgene is secondarily added and reacted with the resultant product of the first reaction step at a temperature of 120 to 160 C., and wherein the amount of the primarily added phosgene is a certain ratio of the total amount of the phosgene.

The present invention discloses a process for the synthesis of aromatic carbamates from amine with dialkyl carbonate in the presence of binary or ternary mixed metal oxide catalyst. The present invention further discloses the yield of said aromatic carbamate in the range of 60 to 99%. Further, the ratio of amine to dialkyl carbonate is in the range of 1:2 to 1:30.

A method and a continuous process for producing two isocyanates by reacting a first amine with phosgene in a stoichiometric excess in the gas phase to produce a first isocyanate. The excess phosgene is subsequently recovered and recirculated back to react with a second amine to produce a second isocyanate. In an embodiment, both fresh and recycled phosgene may be used in reacting each respective amine to produce an isocyanate. The amine streams contain two different concentrations of hydrogen chloride: one may be between 0.0 and 0.1%, and another may be between 1 and 5% by weight.

A method and a continuous process for producing two isocyanates by reacting a first amine with phosgene in a stoichiometric excess in the gas phase to produce a first isocyanate. The excess phosgene is subsequently recovered and recirculated back to react with a second amine to produce a second isocyanate. In an embodiment, both fresh and recycled phosgene may be used in reacting each respective amine to produce an isocyanate. The amine streams contain two different concentrations of hydrogen chloride: one may be between 0.0 and 0.1%, and another may be between 1 and 5% by weight.

An isocyanate production method according to the present invention is a method in which an isocyanate is produced by subjecting a carbamate to thermal decomposition, and includes: a step of preparing a mixture liquid containing the carbamate, an inactive solvent and a polyisocyanate compound; a step of conducting a thermal decomposition reaction of the carbamate by continuously introducing the mixture liquid into a thermal decomposition reactor; a step of collecting a low-boiling decomposition product by continuously extracting the low-boiling decomposition product in a gaseous state from the reactor, the low-boiling decomposition product having a boiling point lower than the polyisocyanate compound; and a step of collecting a high-boiling component by continuously extracting, from the reactor, a liquid phase component which is not collected in a gaseous state at the step of collecting the low-boiling decomposition product.

An isocyanate production method according to the present invention is a method in which an isocyanate is produced by subjecting a carbamate to thermal decomposition, and includes: a step of preparing a mixture liquid containing the carbamate, an inactive solvent and a polyisocyanate compound; a step of conducting a thermal decomposition reaction of the carbamate by continuously introducing the mixture liquid into a thermal decomposition reactor; a step of collecting a low-boiling decomposition product by continuously extracting the low-boiling decomposition product in a gaseous state from the reactor, the low-boiling decomposition product having a boiling point lower than the polyisocyanate compound; and a step of collecting a high-boiling component by continuously extracting, from the reactor, a liquid phase component which is not collected in a gaseous state at the step of collecting the low-boiling decomposition product.

An isocyanate production method according to the present invention is a method in which an isocyanate is produced by subjecting a carbamate to thermal decomposition, and includes: a step of preparing a mixture liquid containing the carbamate, an inactive solvent and a polyisocyanate compound; a step of conducting a thermal decomposition reaction of the carbamate by continuously introducing the mixture liquid into a thermal decomposition reactor; a step of collecting a low-boiling decomposition product by continuously extracting the low-boiling decomposition product in a gaseous state from the reactor, the low-boiling decomposition product having a boiling point lower than the polyisocyanate compound; and a step of collecting a high-boiling component by continuously extracting, from the reactor, a liquid phase component which is not collected in a gaseous state at the step of collecting the low-boiling decomposition product.

The invention relates to a method for producing two isocyanates by reacting a first amine with phosgene in a stoichiometric excess in the gas phase to produce a first isocyanate, wherein the excess phosgene is subsequently recovered and recirculated back to react with a second amine to produce a second isocyanate. In another embodiment, both fresh and recycled phosgene may be used in reacting each respective amine to produce an isocyanate. The amine streams may be optimized to contain different concentrations of hydrogen chloride, as required for the production of two different isocyanates.