(6f) Light Alkanes Transformation through Ammonia-Assisted Reforming | AIChE

(6f) Light Alkanes Transformation through Ammonia-Assisted Reforming


Xiang, Y. - Presenter, Mississippi State University
Hydrogen is a clean energy carrier. It is expected to play a pivotal role in a clean, secure, and affordable energy future and is currently enjoying unprecedented political and business momentum worldwide. Currently, steam reforming stands for more than 90 % of H2 supply, which, however, produces stoichiometric amounts of CO and CO2 from hydrocarbons. Consequently, it requires additional water-gas-shift reactors and a methanation reactor to obtain COx-free H2. Here, we show that COx-free H2 can be produced from ammonia assisted reforming (ammoreforming) of natural gas liquids (CnH2n+2 + nNH3 = nHCN + (2n + 1) H2, n = 2 or 3) at the same conditions as the steam reforming. Such a process co-produces HCN, which can be easily separated (through absorption by water) from H2 and used as value-added chemicals (for polymer synthesis) or for NH3 recycling through hydrolysis.

The proposed ammoreforming of ethane and propane was realized over the Re-modified HZSM-5 zeolite rather than the traditional Pt-based catalyst for the BMA process (methane ammoreforming). The specific activity of the Re/HZSM-5 catalysts at 650ºC is up to 1 molH2/gRe/min (or 180 min-1) during ethane ammoreforming, which is significantly higher than the steam reforming of ethane or propane and ammonia decomposition for H2 production. Additionally, the Re/HZSM-5 catalyst is highly coke-resistant for the ethane and propane ammoreforming, no significant catalyst deactivation was observed with time-on-stream up to 20 h. Characterization of the fresh and used catalysts by X-ray absorption and Raman spectroscopies suggested that the isolated ReOx site grafted by AlO4‒ tetrahedral in the zeolite framework is responsible for the outstanding catalytic performance.

The present catalytic system demonstrated superior performance to the conventional steam reforming (for H2) and the commercial BMA and Shawinigan processes (for HCN), so appears to have considerable potential for industry application.