Catalyst discrimination for olefin production by coupled methanol/n-butane cracking

The joint transformation of n-butane and methanol has been studied on catalysts prepared based on HZSM-5 zeolites (with different SiO2/Al2O3 ratios and doped with Ni) and SAPO-18. A methanol/n-butane molar ratio of 3 has been used, which corresponds to an energy-neutral integrated process. The kinetic behaviour of the catalysts has been compared based on C2–C4 olefin yield, deactivation by coke deposition for 5 h time on stream and hydrothermal stability by operating in reaction–regeneration cycles. The results show a good performance of the catalyst prepared based on HZSM-5 with SiO2/Al2O3 = 30, which has high levels of acidity and acid strength (≥120 kJ mol NH3−1). This catalyst allows obtaining 24.4% of C2–C4 olefin yield (11.5% of propene), with a selectivity of 43% at 575 °C and a space time of 1.1 gcat h molCH2−1. The catalyst fully recovers its initial kinetic behaviour after 10 reaction–regeneration cycles.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (95 K)Download as PowerPoint slideResearch highlights▶ Production of olefins from row materials alternative to oil and secondary interest streams in refineries. ▶ Performance of an autothermic process through the integration of two processes, one endothermic and the other one exothermic. ▶ Improvement of olefin yield by the synergy of the two reactions. ▶ Production of a hydrothermically stable catalyst, required in a reaction medium with a high water content.