Energy efficient simultaneous oxidative conversion and thermal cracking of ethane to ethylene using supported BaO/La 2O 3 catalyst in the presence of limited O 2

Abstract

An energy efficient conversion of ethane to ethylene involving simultaneous oxidative conversion (which is exothermic) and thermal cracking (which is endothermic) reactions of ethane in the presence of steam (steam/C 2H 6 mol ratio=1.0) and limited O 2 (C 2H 6/O 2 mol ratio ⩾ 4.0) over a BaO-promoted La 2O 3 supported on low surface area macroporous silica-alumina commercial catalyst carrier has been thoroughly investigated. Influence of various process parameters such as temperature (700–850°C), C 2H 6/O 2 feed ratio (4.0–8.0) and space velocity (50,000–200,000 cm 3 g −1 h −1) on the conversion, product selectivity and net heat of reactions in the process has also been studied. At all the process conditions, there was no coke deposition on the catalyst. High selectivity (⩾ 85%) for C 2+ olefins (at 50–60% conversion) can be obtained in the process at a low contact time (<10 ms), particularly for the higher C 2H 6/O 2 ratios (⩾ 6.0) and temperatures (⩾ 800°C). The process exothermicity is decreased appreciably with increasing the temperature and/ or the C 2H 6/O 2 ratio. The net heat of reaction in the process can be controlled by manipulating the C 2H 6/O 2 ratio and reaction temperature. Also, because of simultaneously occurring endothermic and exothermic reactions, the process is highly energy efficient and non-hazardous.