Effect of carbon deposition over carbonaceous catalysts on CH₄ decomposition and CH₄-CO₂ reforming

Abstract

An investigation was made using a continuous fixed bed reactor to understand the influence of carbon deposition obtained under different conditions on CH₄-CO₂ reforming. Thermogravimetry (TG) and X-ray diffraction (XRD) were employed to study the characteristics of carbon deposition. It was found that the carbonaceous catalyst is an efficient catalyst in methane decomposition and CH₄-CO₂ reforming. The trend of methane decomposition at lower temperatures is similar to that at higher temperatures. The methane conversion is high during the initial of stage of the reaction, and then decays to a relatively fixed value after about 30 min. With temperature increase, the methane decomposition rate increases quickly. The reaction temperature has significant influence on methane decomposition, whereas the carbon deposition does not affect methane decomposition significantly. Different types of carbon deposition were formed at different methane decomposition reaction temperatures. The carbon deposition Type I generated at 900°C has a minor effect on CH₄-CO₂ reforming and it easily reacts with carbon dioxide, but the carbon deposition Type II generated at 1000°C and 1100°C clearly inhibits CH₄-CO₂ reforming and it is difficult to react with carbon dioxide. The results of XRD showed that some graphite structures were found in carbon deposition Type II.

Keywords

carbon deposition / carbonaceous catalyst / CH₄-CO₂ reforming

References

[1] Yang L, Dong Y, Zhang Y F, Xie K C. Chinese coke oven gas utilization status and development prospects. Shanxi Energy and Conservation, 2006, 1: 1-4 (in Chinese)

[2] Zheng W H, Zhang X Z. Present situation and prospect on application of coke oven gas. Fuel & Chemistry Processes, 2004, 4: 1-3

[3] Shi K Y, Xu H Y, Fan Y M, Shang Y C, Xu G L. Studies of reforming natural gas with carbon dioxide to produce synthesis gas. V. Characteristics of carbon deposition for methane dehydrogenation. Journal of Molecular Catalysis (China), 1996, 1: 41-47

[4] Li Y B, Jin B S, Xiao R. Carbon dioxide reforming of methane with a free energy minimization approach. Korean Journal of Chemical Engineering, 2007, 24(4): 688-692

[5] Liu S Y, Ding Y H, Jin P. Studies on catalyst of resisting carbon deposition for CH₄ reforming with CO₂ to syngas. Journal of China Coal Society, 1999, 24: 194-197

[6] Liu G M, Qiu F L, Guo S D. Mechanism of an improvement on the resistance to carbon-deposit of CH₄-H₂O reforming catalysts by the addition of heavier rare earth oxides. Chinese Journal of Catalysis, 1990, 11: 45-50

[7] Tang S B, Qiu F L, Lu S J, Zhao M Y. Effect of supports on carbon-deposition resistance of nickel catalysts for methane reforming with CO₂. Natural Gas Chemical Industry, 1994, 6: 10-14

[8] Cheng H Y, Shen B, Zhang Z Z. Progress in studying the resistance to carbon deposition of methane reforming with carbon dioxide. Shanghai Chemical Industry, 2005, 30: 25-29

[9] Shang Y C, Ge S H, Hou S F. Investigation of carbon deposition on Ni/γ-Al₂O₃ catalyst by using TG technique. Natural Gas Chemical Industry, 1998, 4: 25-27

[10] Wang Z. Latest advances methane catalytic reforming with carbon dioxide to synthesis gas. Industrial Catalysis, 2005, 13: 14-18

[11] Wei J M, Li W Y, Xie K C. A review of carbon deposits on the surface of catalyst for CH₄ reforming with CO₂. Coal Conversion, 1997, 20: 32-38

[12] Zhang W D, Zhang Y F. The catalytic effect of both oxygen-bearing functional group and ash in carbonaceous catalyst on CH₄-CO₂ reforming. Frontiers of Chemical Engineering in China, 2010, 4(2): 147-152

[13] Zhang G J, Zhang Y F, Zhang M, Zhao W. Methane decomposition over carbonaceous catalyst and kinetic characteristics. Modern Chemical Industry, 2009, 29(S1): 29-32

[14] Saito Y, Yoshikawa T, Bandow S, Tomita M, Hayashi T. Interlayer spacings in carbon nanotubes. Physical Review B: Condensed Matter and Materials Physics, 1993, 48(3): 1907-1909

Acknowledgements

The authors were grateful to the National Basic Research Program of China (Grant No. 2005CB221202) and Shanxi Provincial Natural Science Foundation (20051020) for financial support of the present study.

RIGHTS & PERMISSIONS

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg