Reducing the CO2 and H2S contents of biogas is a prerequisite to raise its quality to that of natural gas. The chemical capture of carbon dioxide was accomplished with non-aqueous single 2-amino-2-methyl-1-propanol (AMP), 2-(tert-butylamino)ethanol (TBMEA), 2-(isopropylamino)ethanol (IPMEA), and N-methyl-2,2'-iminodiethanol (MDEA), with their 1:1 blends dissolved in either an ethylene glycol/1-propanol mixture or single diethylene glycol monomethyl ether. The gas mixtures used contain either 15 or 40% CO2 in air, sometimes added with 50 ppm H2S. We designed two different experimental procedures: (1) separate experiments of CO2 absorption and desorption aimed at selecting the most efficient amines and (2) continuous cycles of CO2 absorption (20 degrees C) and desorption (90-95 degrees C) featuring CO2 removal efficiency in the range of 89-96%. The CO2/amine/alcohol equilibria were analyzed by C-13 nuclear magnetic resonance (NMR) spectroscopy, which allowed us to identify and quantify the carbonated species in solution originated from both amine and alcohol carbonatation. In some continuous cycles of CO2 absorption, H2S was selectively captured by aqueous H2O2 and separated as either elemental sulfur or CaSO4.