Supporting Information The polarity effect upon the methane solubility in ionic liquids: A contribution for the design of ionic liquids for enhanced CO 2 /CH 4 and H 2 S/CH 4 selectivities Pedro J. Carvalho 1 and João A.P. Coutinho 1 * 1 Departamento de Química, CICECO, Universidade de Aveiro, 3810-193, Aveiro, Portugal * To whom all correspondence should be addressed. Email: jcoutinho@ua.pt . 1