Dry Reforming Assisted Nonthermal Plasma Catalytic Reactor

Dry reforming assisted nonthermal plasma catalytic reactor

Shaik Mahammadunnisa, P. Manoj Kumar Reddy, B. Ramaraju, Ch.Subrahmanyam

Department of Chemistry, IIT Hyderabad-502205, India

csubbu@iith.ac.in

The negative effect of global warming of carbon dioxide (CO₂) is well established and there is an immediate need to develop large scale CO₂ utilization techniques. Catalytic CO₂ reforming of natural gas also has drawbacks such as high reaction temperature and clogging caused by coke formation. Hence, alternative technologies for CO₂ utilization are much warranted [1]. In this context, non-thermal plasma generated under ambient conditions seems to be the best choice, where CO₂ can act as an oxidant due to the fact that its deoxygenation proceeds rapidly in the absence of O₂. CO₂ reforming of aliphatic hydrocarbons, especially methane also contributes to the co-processing of two potential global warming compounds [2].

The experimental set up used for CO₂ reforming  consists of plasma generation in a quartz tube of length 30 cm and diameter was 21 mm and effective discharge area was 15 cm. Stainless steel rod was used as an inner electrode and the outer electrode was Cu wire wound around the quartz tube. The discharge gap was 3.5 mm. In order to understand the influence of catalyst, 500 mg NiO/Al₂O₃ was placed at the end of plasma zone. The AC voltage in the range 10 to 22 kV at 100Hz was applied. The discharge power (W) of the DBD reactor was calculated by V-Q Lissajous method [3]. Products were identified by using an online GC-2014 and confirmed with a GC-MS. The influence of various parameters like input power, total feed flow rate, dilution and catalyst on the conversion and product selectivity were studied.

Typical results indicated that NiO catalyst partially reduced to Ni showed highest conversion and methane conversion was always higher than that of CO₂. As seen from Fig. 2, increasing voltage showed higher conversion and selectivity towards syngas (Fig. 2). At 22 kV and 11 W, selectivity to H₂ and CO was 30% and 55%, respectively with plasma, whereas, plasma combining NiO catalyst increased the selectivity to 55% and 65%. It was observed that partial reduction of NiO further improved the conversion and selectivity.

Fig. 1. Effect of applied voltage  on  conversion

Fig. 2. Effect of Applied voltage on H2 and CO selectivity

1.      Xinli Zhu, PeipeiHuo, Yue-ping Zhang, Dang-guo Cheng, Chang-jun Liu, Applied Catalysis B: Environmental 81 (2008) 132–140.

2.      Chang-junLiu , Gen-huiXu , Timing Wang, Fuel Processing Technology 58  1999  119–134.