A catalyst-free novel synthesis of diethyl carbonate from ethyl carbamate in supercritical ethanol

Diethyl carbonate has been synthesized via the alcoholysis of ethyl carbamate in supercritical ethanol under catalyst-free conditions.The influences of various parameters such as reaction temperature,reaction time,reaction pressure,ethanol/ethyl molar ratios and reaction loading volume on the yield of DEC were studied systematically.The experimental results indicated that the alcoholysis of ethyl carbamate was greatly improved in supercritical ethanol.The optimal reaction conditions were as follows：a reaction temperature of 573 K,a reaction time of 30 min,a reaction pressure of 13.2 MPa,an ethanol/ethyl carbamate molar ratio of 10 and a reactor loading volume of 285 μL respectively.The optimal yield of DEC was 22.9%.

Catalytic depolymerization/degradation of alkali lignin by dual-component catalysts in supercritical ethanol

Depolymerization of lignin is an important step to obtain lignin monomer for the synthesis of functional bio-polymers.In this paper,catalytic degradation/depolymerization of an alkali lignin was investigated in a supercritical ethanol system.The process conditions were optimized in terms of lignin monomer yield,and the liquid products and solid residue were characterized.Results show that the conversion rate of the alkali lignin was improved in both the Ni7Au3 catalyzed and Nickel-catalyzed systems with supercritical ethanol as the solvent.The maximum lignin conversion rate was 69.57%and 68%respectively for the Ni7Au3 and Nickel-based catalysis systems.Gas chromatography/mass spectroscopy(GC/MS)analysis indicated that the catalytic depolymerization products of alkali lignin were mainly monomeric phenolic compounds such as 2-methoxyphenol.The highest yield of 2-methoxyphenol(84.72%)was achieved with Ni7Au3 as the catalyst.