1. School of Chemical and Metallurgical Engineering, University of the Witwatersrand, 1 Jan Smuts Avenue, Braamfontein, Johannesburg 2000, South Africa
2. Gas and Fuels Research Center, Texas A&M Engineering Experiment Station, College Station, Texas 77843, United States
3. Department of Chemical Engineering, University of Texas Permian Basin, Odessa, Texas 79762, United States
4. Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843-3122, United States