Hyperbranched poly(amidoamine) as an efficient macroinitiator for steam cracking of naphtha

Abstract

The water-soluble and oil-soluble amidoamine-structured hyperbranched polymers (PAMAM & PPAMAM) were synthesized as initiators for steam cracking of naphtha to promote the production of light olefins. Within 740–840 °C, both PPAMAM and PAMAM significantly improved the gas yield and yields of light olefins, and the PPAMAM showed better performance. The effect of PPAMAM increased with the molecular weight. At 800 °C, when adding 570 ppm PPAMAM with the molecular weight of 12,500 , yields of ethylene and propylene increased from 29.81 wt% and 17.47 wt% to 33.06 wt% and 17.70 wt% respectively, which were even higher than those obtained by cracking pure naphtha at 840 °C (32.72 wt% and 16.08 wt%). Combined with the simulated pyrolysis reaction network and measured thermal decomposition products of PAMAM and PPAMAM, it was found that three active free radicals (•H, •NH2, •CH3) generated by the additives played important roles in the initial cracking stage of hydrocarbons.