Ammonia-Assisted Light Alkane Anti-coke Reforming on Isolated ReOx Sites in Zeolite

Abstract

The conventional reforming produces H2 with stoichiometric amounts of CO and CO2 from hydrocarbons. 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 from H2 and used as value-added chemicals or for NH3 recycling through hydrolysis. The 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 650 °C is up to 1 molH2/gRe/min (or 180 min–1) during ethane ammoreforming. The catalyst is highly coke resistant and shows only slight deactivation with a 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 activity and coke resistibility.