CO₂-Free Calcium Carbide Manufacturing: Demanded Strategy in the Carbon-Neutral Chemical Industry

Calcium carbide is considered a possible key component in the sustainable carbon cycle, including convenient recycling of carbon wastes to industrial uptake. However, currently employed CaC₂ manufacturing process produces significant amounts of CO₂. One of the main factors of its appearance is the formation of carbon oxide during the reaction. The reaction of lime ore with coal inevitably results in the formation of CO and the loss of one carbon atom. CO is usually burnt, forming CO₂ to maintain the required high temperature during synthesis – 2200 °C. In the present study, we discuss that the use of calcium metal instead of lime represents a good opportunity to prevent CO₂ emission since the reaction of Ca with carbon occurs in an atom-efficient manner and results in only CaC₂ at a much lower temperature of 1100 °C. Here, the reaction of Ca with carbon was successfully tested to synthesize CaC₂. The desired product was isolated in gram-scale amounts in 97.2% yield and 99% purity. The environmental friendliness of the proposed method originates from the calculations of the E-factor. Rationalization is provided concerning the cost factor of Ca within the considered process.