Reductive calcination of mineral magnesite: hydrogenation of carbon dioxide without catalysts

This paper discusses the conversion of mineral magnesite to magnesium oxide, methane, carbon dioxide, and carbon monoxide in hydrogen atmosphere between 748 K and 778 K at ambient to 1.2 MPa overpressure without catalysts. Low temperature and elevated pressure facilitate methane formation, whereas moderate to high temperature and low pressure facilitate carbon monoxide formation. Methane is formed directly without any additional catalyst. Carbon dioxide emissions are decreased substantially in reductive calcination. Additional experiments revealed that reductively calcined magnesium oxide is a highly active reverse water gas shift catalyst. Carbon monoxide formation from gaseous carbon dioxide and hydrogen at catalytically active magnesium oxide has been reproducibly confirmed. Further reduction of carbon monoxide to methane is not catalyzed by reductively calcined magnesium oxide.