INVESTIGATION OF DIPENTENE ISOLATION POSSIBILITY FROM TIRES PYROLYSIS OIL IN LEAD MELT

Abstract

The work is aimed at experimental substantiation of dipentene (dl-limonene) extraction from pyrolysis liquid obtained by pyrolysis in the lead melt of tires of different brands. Pyrolysis liquid was isolated under conditions that reduce the sulfur content and increase the proportion of dipentene in the direct-contact reactor in the lead melt and in the temperature range of 400-470 °C. A method for extracting dipentene from pyrolytic liquid by distillation at normal pressure, in vacuum, and two-stage distillation (first with water vapor, then vacuum distillation) to obtain fractions enriched with dipentene was tested. The results obtained demonstrate that at this stage of the study the chemically unstable fraction of polyene hydrocarbons in the pyrolysis liquid is actively polymerized during distillation. The chromatographic analysis of the initial samples and distillation fractions was carried out, which showed that the feedstock contains more than 100 chemicals with a dipentene content of not more than 17%. Based on the evaluation of the obtained quantitative characteristics, distillation parameters providing the maximum yield of dipentene were determined. Under the proposed conditions, the enrichment of individual fractions with dipentene by ~4-6 times compared to its initial content in pyrolysis liquid was achieved. During distillation in vacuum, a fraction with a yield of 19.6% with a content of dipentene up to 40.8% was isolated, a narrow fraction with an yield of 4.8% with a maximum content of dipentene of 49.9% was isolated. During distillation with steam and subsequent vacuum distillation with a total yield of 17%, fractions with a dipentene content of 24-36 % were isolated. Further concentration of dipentene will obviously require more complex chemical synthesis and fractionation operations. The data obtained may be of interest in the development of a new process of pyrolysis of tires in the melt of heavy metals (lead), improving its efficiency by identifying economically important components for the production of commercial products.