Comparative analysis of sorption of small molecule hydrocarbons and polar substances in polish hard coals

Abstract

The subject of the article is the thermodynamic analysis of the sorption of aliphatic hydrocarbons in hard coals from polish mines. The analysis is based on a Multisorption model designed for describing small molecule sorption in different types of carbonaceous materials (e.g. hard coals, lignites or active carbons). Experimental isotherms of hydrocarbons: hexane, heptane, octane and benzene, in hard coals of different rank, together with water and methanol vapor isotherms measured at room temperature (25 C), are taken as comparative data for simulations. Results of the analyses reveal the complicated behavior of linear molecules in the sorption system. The location of molecules on the sorbent surface brings a spectrum of problems associated with the incomplete filling of pores, the coiling up of chains, the formulation of plates or globules, and the blocking of micropores. All these effects have an influence on the level and character of sorption, often in opposing ways. The sorption of small inorganic molecules is taken into account in the objective of achieving a more precise identification of the structure of coal. Semi-simultaneous computations for all types of sorbates have already been carried out. © 2013 The Author(s).