High performance noble-metal-free NiCo/AC bimetal for gasification in supercritical water. (9th March 2017)

• Record Type: Journal Article
• Authors: Guan, Qingqing; Chen, Shanshuai; Chen, Yuan; Gu, Junjie; Li, Bin; Miao, Rongrong; Chen, Qiuling; Ning, Ping
• Is Part Of: International journal of hydrogen energy. Volume 42:Number 10(2017)
• Page Start: 6511
• Page End: 6518
• Publication Date: 2017-03-09
• Subjects: Phenol -- Gasification -- Supercritical water -- NiCo/AC; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2016.11.191
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: We report high performance Noble-metal-free NiCo/AC bimetal for gasification in supercritical water by the polyol reduction method with chloroplatinic acid as nucleation seed. At 475 °C and 20 min, the carbon efficiency (CE) for gasification of phenol with NiCo/AC has reached about 65%, which represents a more than 20-fold enhancement of carbon efficiency compared to the Co/AC and 6-fold compared to the Ni/AC. The CE of commercial noble Ru/C (5 wt%) catalyst is only about 15% higher than that of NiCo/AC catalyst. The catalyst was characterized by BET, XRD, XPS and TEM. The results indicate smaller and higher disperse of NiCo alloy has been achieved. By using NiCo/AC catalyst, the CE can reach about 90% at 525 °C and 60 min with a 5 wt% phenol, 0.098 kg/m 3 density and catalyst loading of 0.5 g/g (the mass of NiCo/AC catalyst/the mass of phenol). The results of GC–MS indicate NiCo/AC can suppress tar successfully. A kinetic modeling was also proposed to describe gaseous product and tar formation, which gives the activation energy (Ea) 123.56 ± 31 kJ/mol and the frequency factor 16.93 ± 0.48 for gaseous products. While for tar formation, the Ea is 112.95 ± 24 kJ/mol and the frequency factor is 13.99 ± 0.37. The successful use of noble-metal-free NiCo/AC shows the potential to replace noble Ru-catalysts in SCWG process for gases fuels by bimetal. Highlights: The first report on supercritical water gasification of phenol over noble-metal-free NiCo/AC bimetal catalysts. Phenol has been effectively gasified in supercritical water using noble-metal-free NiCo/AC bimetal catalysts. Higher than 80% carbon efficiency achieved in a moderate temperature 500 °C. A kinetic modeling was proposed.