T,p dependence of intradiffusion in binary fluid mixtures with carbon dioxide as one component

Intradiffusion coefficients D-ii were measured by the pulsed field gradient NMR technique for five binary systems with carbon dioxide as one component , the second component being benzene, hydrogen, palmitic acid methyl ester, acetic acid or methanol. The studies are limited for most systems to low t emperatures because of the onset of crystallisation. They are extended to a maximum pressure of 200 MPa. The concentration dependence of the hydrogen- containing mixtures shows, at the carbon dioxide rich side of the D-ii vs. x diagram, a fairly steep increase in diffusivity with hydrogen concentrati on. The analysis of the methanol/carbon dioxide system is complemented by s tudies of the hydroxyl proton chemical shift. The x, T, p dependence of the chemical shift is described by a linear association model. These data show clearly that the carbon dioxide molecule does not form any hydrogen bonds with the methanol hydroxyl group.