Council of Scientific and Industrial Research

Anil Kisan Kinage

Ashutosh Anant Kelkar

Vilas Hari Rane

Vivek Vinayak Ranade

Lalita Sanjib Roy

Savita Kiran Shingote

Dhananjay Ravindra Mote

Vasant Ramchandra Choudhary

Tushar Vasant Choudhary

Pralhad Arjun Burate

Balasaheb Rajendra Javale

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 invention relates to synthesis of methyl carbamate (MC) and dimethyl carbonate (DMC) in presence of stripping inert gas or superheated methanol vapors using packed column reactor and bubble column reactor.

Synthesis of methyl carbamate and dimethyl carbonate (DMC) in presence of stripping with inert gas or superheated vapours and a reactor for the same

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

The patent discloses a process for the synthesis of dialkyl carbonates catalyzed by a catalyst composition AB oxides, wherein A and B are rare earth metals or A and B are combination of rare earth and transition metals with ratios ranging from 0.5:10 to 10:0.5.

Process for the synthesis of dialkyl carbonates

The present invention discloses chiral siliceous composition comprising chiral or achiral silane moiety 'A', substituted in another moiety 'B' with tetrahedral metallo-silica or silica framework with mesoporous and microporous structure, useful as chiral heterogeneous catalyst and in enantioselective separations. The invention further discloses a method for introducing molecular level chirality in crystalline framework of silicate and metallosilicate with mesoporous or microporous structure thereof.

Chiral siliceous composition useful as chiral heterogeneous catalyst and a process for the preparation thereof

The invention relates to synthesis of methyl carbamate (MC) and dimethyl carabonate (DMC) in presence of stripping inert gas or superheated methanol vapors using packed column reactor and bubble column reactor.

The present invention describes a process for the conversion of a lower alkane or a mixture of lower alkanes or a feed containing lower alkane(s) to aromatics or higher hydrocarbons, which comprises (i) treating a bifunctional pentasil zeolite catalyst, optionally containing one or more transition elements, having strong dehydrogenation and acid sites with a mixture of H.sub.2, steam and optionally the presence of an inert gas at a gas hourly space velocity of at least about 500 cm.sup.3 g.sup.-1 h.sup.-1 at a temperature in the range of 400.degree.-800.degree. C. and pressure in the range of 1-5 atm. for a period of at least 0.5 h; (ii) treating the catalyst obtained in step (i) with air or O.sub.2 at a gas hourly space velocity of at least about 200 cm.sup.3 g.sup.-1 h.sup.-1) at a temperature in the range of 400-800.degree. C. and pressure in the range of 1-5 atm for a period of at least 0.2 h, and (iii) contacting the catalyst obtained in step (ii) with a lower alkane or mixture of lower alkanes and at least one olefin or at least one higher paraffin or both, at a gas hourly space velocity in the range of 1000-100000 cm.sup.3 g.sup.-1 h.sup.-1 at a temperature in the range of 300.degree.-600.degree. C. and pressure in the range of 1-5 atm, (iv) separating the aromatics formed from the reaction mixture by known methods and if desired, (v) recycling the unconverted lower alkanes and non-aromatics to step (iii) for further conversion.

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Anil Kisan Kinage