Pyrolysis of Leather Trimmings in a Fixed Bed Reactor

Abstract

The leather industry, in spite of using by-products of the meatindustry, is also a potential pollutant, as it generates solid andliquid wastes. In the traditional manufacturing process,chromium may be present in a large part of such wastes. A lot ofresearch has been made in order to find ways to valorize thesewastes, although for crust and finishing leather trimmings morework is needed to show their potential. The aim of the presentinvestigation is to create useful products through the pyrolysis ofwaste leather trimmings. The experiments were performed in avertical semi-batch reactor with ID of 9.7 cm. The influence ofoperating temperature (490 – 800°C) and heating rate on thecomposition and distribution of the different phases (solid,liquid and gas) was studied. The gas and the liquid fractions wereanalyzed by gas chromatography and FTIR, respectively. Thechar obtained was characterized in terms of its higher heatingvalue and proximate analysis. In addition, the thermaldegradation of the leather waste was followed usingthermogravimetric analysis.As the temperature increased, the yields of char and gas phasedecreased and increased, respectively. The yield of the liquidphase was almost constant for 490 and 610°C, and decreased forhigher temperatures. The effect of heating rate on the yields ofpyrolysis products was almost negligible. The amount ofchromium oxide in the char tended to increase with increasingtemperatures. The FTIR analysis of bio-oils indicated thepresence of phenols and alcohols, alkanes, aldehydes, ketones,carboxylic acids and aromatic compounds. GC analysis of thegas phase indicated that CO2 was the most abundant gas at490°C, while hydrogen presented higher concentrations at bedtemperatures of 610, 700 and 800°C.