from first principles PP-I-1

PP-III-116Theoretical Calculation of Hydroxyl Mechanism for Reforming of CH 4 withSupercritical CO 2 over Ni CatalystXu W.-Yu., Li M.Department of Chemistry and Chemical Engineering, East China Jiaotong University,Nanchang, Chinaxwy1027@sina.comThe reforming reaction of CH 4 and CO 2 can not only transform natural gas into syngas, butalso reduce the emission of a large number of CO 2 , which can achieve the goal oftransforming the trash into treasure. Supercritical CO 2 is a common supercritical fluid, itscritical temperature is 304.13 K, critical pressure is 72.90 atm.The hydroxyl mechanism of CH 4 -Supercritical CO 2 reforming reaction was studied usingDFT method at B3LYP/Lanl2dz level. The imaginary vibration mode of the transition statesand Curves of IRC pathway were obtained. The process of hydroxyl reforming reaction overNi catalyst were as follows:It was found that the mechanism included 13 steps, the beginning of hydroxyl reforming wasthe reaction of methane with Ni catalyst. -OH, CH 3 Ni, CHNi and -CH 2 OH were importantintermediate products. We chose step 3, 4 , 5, 6, 7 for further exploration. Hydroxyl couldattack CH 3 Ni group from the side and the back, respectively. Hydroxyl was easier to attackCH 3 Ni from para-position.The activation energies of step 3, 4 , 5, 6, 7 were 201.1664, 360.1252, 102.6259, 61.5419,126.3132 kJ·mol -1 , respectively. The rate determining step was hydroxyl's generative processas shown in step 4, hydroxyl played a significant role in the process of reforming reaction. Itwas competing that hydroxyl reacted with CH 3 Ni, CHNi groups, respectively. Undersupercritical CO 2 condition, the hydroxyl reforming reaction could proceed smoothly.References:[1] A. T. Vaso, E. V. Xenophon, Catalysis Today. 64 (2001) 83.[2] M. Yasuyuki, N.Toshie, Applied Catalysis A: General. 258 (2004) 107.[3] Z. B. Yang, Y. W. Zhang, Acta Phys. Chim. Sin. 26 (2010) 350.[4] P. G. Jessop, T. Ikariya, Noyori R. Nature. 368 (1994) 231.276