A 1000 t/a urea-based indirect dimethyl carbonate (DMC) production pilot plant, co-developed by ICC and Shanghai Weifu Chemical Engineering Technology Development CO Ltd, was successfully operated by one shot in November. Located at Qinghai Salt Lake Group, Golmud City, Qinghai, the pilot plant has produced DMC with a purity of 99.8wt%.
The result of 500 hrs’ operation shows that: in the first step reaction between urea and 1, 2 - propylene glycol for production of propylene carbonate(PC), the urea conversion rate hits 100%, with PC yield coefficient over 95% ; and in the second step ester exchange reaction between PC and methanol for the production of DMC, the PC conversion rate reaches 100%, with DMC selectivity above 99% and the reactor tower top exit concentration of DMC above 30wt%. 1, 2 - propylene glycol produced in the second step reaction has no negative influence when recycled as the first step feedstock.
As a green and non-toxic chemical, DMC is regarded as a new base block for organic synthesis. It is expected that the domestic annual demand for DMC will be around 4.3 million tons in the near future. With low feedstock price, mild reaction condition, high yield, easy recycle of ammonia and low energy consumption, indirect production of DMC from urea is economically competitive as compared with other processes.
Based on the above-mentioned achievement, two patents have been applied and the scale-up to 50000 t/a plant is considered feasible.