Brief introduction
The technology for synthesizing ethylene glycol from synthesis gas/industrial vent gas, instead of petro-ethylene, is a major part of the C1 chemical industry, whose use of raw materials is a more scientific, more reasonable, and economically superior to the use of petroleum.
Our development of the catalyst and process for ethylene glycol production through the hydrogenation of oxalate was a key National Science and Technology Support Program project under the 11th Five-Year Plan. And it led to the successful development of Pd-type CO coupling catalysts and Cu-based hydrogenation catalysts and supporting technology. A 15t/a ethylene glycol pilot test showed the conversion rate of oxalate to be nearly 100 percent, the selectivity of ethylene glycol no less than 90 percent, and the space-time yield no less than 300g/(L·h), while the test unit performed stably. The reasonableness of the process, equipment, catalysts, and other aspects of this test unit have been thoroughly inspected. The test unit has been found to be safe and reliable, with all the basic conditions needed for an industrial scale-up. There are three patents on the technology, and technical indicators are China’s most advanced.
PROCESS ROUTE
The H2 in coal-based synthesis gas/industrial vent gas is separated through PSA technology and, after drying, the dehydrogenated, purified CO enters a preheater, then an oxidative coupling reactor, where it reacts with nitrite sent from an esterification and regeneration process to generate oxalate and NO. After the vapor-liquid separation, the NO is sent through the esterification and regeneration process to complete the self-closed circulation and zero emission of NOx. The intermediate product oxalate enters the hydrogenation process.
The oxalate generated from the oxidative coupling is pumped into a vaporizer and, after the input of H2, heating, and gasification, it goes to a fixed bed reactor, where a hydrogenation reaction is used to generate ethylene glycol and ethanol. After the heat exchange and passing through a partial condensation tower, the gaseous ethanol product is reused in the esterification and regeneration process. The liquid product is pumped into a rectification tower to obtain product ethylene glycol.
This is an efficient, energy-saving process and the two components -- CO and H2 in the synthesis gas are properly utilized.
Technical indicator
|
Raw and auxiliary materials and utilities |
Amount |
Unit |
Consumption quota |
|
CO |
≥98.5% |
Nm3 |
800 |
|
H2 |
≥99.5% |
Nm3 |
1650 |
|
O2 |
≥99% |
Nm3 |
245 |
|
NO |
≥99% |
kg |
18 |
|
Ethanol |
≥99% |
kg |
156 |
|
Cooling water |
|
t |
310 |
|
Steam |
1.50MPa |
t |
4.75 |
|
Compressed air |
|
Nm3 |
60 |
|
Electricity |
|
kWh |
1020 |