Zn-Co bimetallic supported ZSM-5 catalyst for phosgene-free synthesis of hexamethylene–1,6–diisocyanate by thermal decomposition of hexamethylene–1,6–dicarbamate

Formation and Depolymerization of Oligomers during Thermal Cracking of Silicon‐Containing Carbamates

“…The yield of CPTS increased from 79 % to 96 % as the ethanol amount charged from 50 mmol to 150 mmol, and then the yield of CPTS increased tinily with further increase the alcohol amount to 200 mmol. Besides, the oligomers prepared at various conditions were also depolymerized under the optimized conditions (entries [10][11][12][13][14]. The oligomers obtained at high temperature show a decrease in the yield of CPTS, declaring that the depolymerization of oligomers obtained at high temperature became difficult.…”

“…One possible reason was that too much NH 3 inhibits the reaction from going in the positive direction. To further prove the role of NH 3 , a strong base C 2 H 5 ONa was added in the reaction system, and the yields of CPTS were also improved (entries [9][10][11]. The purpose of oligomers depolymerization was to obtain pure CPTS for the secondary cracking.…”

“…With the development of pyrolysis technology, carbonylation of nitrogenous compounds to carbamate for pyrolysis has become the most promising route for the preparation of isocyanates. [8][9][10][11] In order to improve the rate of pyrolysis, this process usually conducted at high temperatures. Probably because the higher cracking temperature, the polymerization reactions between N-substituted carbamates and isocyanates were easy to occur.…”

“…For this reason, the research and development of non‐phosgene technology for isocyanate chemicals has become a focused issue. With the development of pyrolysis technology, carbonylation of nitrogenous compounds to carbamate for pyrolysis has become the most promising route for the preparation of isocyanates . In order to improve the rate of pyrolysis, this process usually conducted at high temperatures.…”

A Novel High-Activity Zn-Co Catalyst for Acetylene Acetoxylation

“…Co was selected as a promoter in bimetallic Zn-Co catalyst for the thermal decomposition of hexamethylene-1,6-dicarbamate to hexamethylene-1,6-diisocyanate, which had a positive effect on the acidic sites, thus improving the catalytic performance [20]. The Zn-Co catalyst also exhibited a good performance for the selective catalytic reduction of NO X by methane because the interaction between Zn and Co largely inhibited the combustion of methane and increased its utilization [21].…”