The carbide-based carbon-to-acetylene (C₂H₂) process is a simple pathway to convert various sources of carbon into acetylene and carbon monoxide directly. However, the current industrial process based on calcium carbide (CaC₂) is restricted by high energy consumption, significant amount of carbon dioxide and industrial solid waste emission.

Recently, a research team led by Prof. ZHAO Hong and Prof. JIANG Biao from the Shanghai Advanced Research Institute of the Chinese Academy of Sciences has proposed a sustainable acetylene and carbon monoxide coproducing process based on BaCO₃-BaC₂-Ba(OH)₂-BaCO₃ barium cycle, which can simultaneously realize CO₂ capture and acetylene-carbon monoxide co-production at mild dynamic conditions with lower energy consumption and less waste emission.

The results were published in Green Chemistry on Aug. 16.

The researchers found that BaC₂ could be efficiently solid-phase synthesized at about 1,500 ℃ by using carbon and BaCO₃ as raw materials without CO₂ emission, which is more than 600 ℃ lower than the production temperature of CaC₂. 

In addition, Ba(OH)₂ produced by the gasification of calcium carbide into acetylene was easily recovered and converted into BaCO₃ by absorbing CO₂, which was then used to synthesize carbide, verifying the coupling process between carbon-to-acetylene and carbon dioxide capture based on Ba loop, reducing the waste of carbide slag.  

The results suggested that BaC₂ was the more suitable intermediate for carbon-to-acetylene process than CaC₂, because of the milder formation temperature, the faster reaction rate, and the more convenient barium recover to carbide production. 

Featuring low cost, less wastes and high efficiency of co-producing of acetylene and carbon monoxide, this technology is expected to synthesize various of chemicals by using C₂H₂ and CO as platform chemicals instead of CO and H₂ produced by carbon gasification.