Distribution and comparing of volatile products during slow pyrolysis and hydropyrolysis of Turkish lignites

Abstract

Lignite samples obtained Ermenek and Uzunköprü coal plants in Turkey have been pyrolysed under specific conditions and the temperature effect on the final product distribution was elucidated by the use of GC and TGA. The temperature has been found to have a remarkable effect on the product distribution and evolution rate. The pyrolysis was carried out with the use of a fixed bed reactor equipped with a special sampling system to collect the organic volatile products to be analyzed by capillary gas chromatography (GC). The maximum product formation rate was found to be about 440°C for both of the samples. The formation rate of n-paraffins was higher than that of 1-olefines at each temperature employed. The hydrocarbons obtained by pyrolysis of lignite from Ermenek and Uzunköprü coal plants were observed to contain 43wt% and 40wt% n-paraffins at the maximum formation rate, respectively. The 1-olefins determined at the maximum product formation rate were found to be 15wt% for both lignite samples. Additionally, the effect of temperature on pyrolysis product distribution of Turkish lignites has been compared with those hydropyrolysed at different pressures and temperatures. The formation curves of hydropyrolysis differed from those obtained under inert pyrolysis conditions. Hydrogen was found to have an appreciable effect on pyrolytic decomposition especially at high temperatures and pressures. There were higher tar formation and less gas yield at higher hydrogen pressures.