Council of Scientific and Industrial Research

Dhananjay Ravindra Mote

Ashutosh Anant Kelkar

Vilas Hari Rane

Vivek Vinayak Ranade

Anil Kisan Kinage

Savita Kiran Shingote

Lalita Sanjib Roy

The present invention discloses a process for recovery and regeneration of rare earth metals or salts thereof used as catalyst and which is conveniently integrated within the overall flow sheets of manufacturing dialkyl carbonates. Alkyl carbamate, alcohol and a rare earth metal salt as catalyst selected from the lanthanide series are added in a reactor to afford dialkyl carbonate. The rare earth metal catalyst is selected from samarium, cerium, lanthanum, neodymium, ytterbium, europium and gadolinium. Ammonia is added to a portion of the reaction mixture to precipitate the catalyst and the separated deactivated catalyst is dissolved in acid to afford regenerated catalyst, e.g., in triflic acid in the case of samarium triflate catalyst.

Process for recovery and regeneration of deactivated catalysts used in dialkyl carbonate synthesis

The present invention discloses an improved catalyst free process for synthesis of alkyl carbamates in an integrated system comprising a tubular reactor and a striper. The process comprises reacting urea and an alcohol in said tubular reactor under autogeneous pressure; wherein said process provides &#x3e;90% selectivity towards alkyl carbamate. The mixture of urea and alcohol is N fed to the tubular reactor at a particular feed rate. The tubular reactor is heated externally under autogeneous pressure to carry out a synthesis reaction producing alkyl carbamate and ammonia. The ammonia is removed from the tubular reactor by the striper. The tubular reactor and the stripper are arranged in series to reduce the equilibrium limitations of the reaction and drive the reaction in forward direction.

Configuration and its use in process for synthesis of alkyl carbamates from alkyl alcohol and urea in a tubular reactor

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Dhananjay Ravindra Mote