Non-oxidative decomposition of propane: Ni-Cu/Al2O3 catalyst for the production of CO2 -free hydrogen and high-value carbon nanofibers

A Ni-Cu/Al2O3 catalyst was tested in the thermal decomposition of propane to produce CO2-free hydrogen and high value-added carbon nanofibers (CNF), the quantity and quality of which are key to making the process economically viable. The effect of temperatures in the range 550-750 degrees C and space velocities from 24 to 240 l g(Cat)(-1) h(-1) on the product distribution, conversion, H-2 selectivity and carbon formation rate (CFR) was evaluated. In addition to H-2, CH4 and C2H4 together with small amounts of C2H6 were detected in the reaction gases. While propane conversion overpassed 90% at 700 degrees C and higher temperatures, H-2 selectivity reached 40% for low space velocities (24 l g(Cat)(-1)h(-1)). Likewise, the CFR increased with temperature to 50 gC g(Cat)(-1) h(-1) at 700 degrees C, doubling the rates reported for methane or ethane as the feedstock and same reaction conditions. The CNF, thoroughly characterized by XRD, N-2 physisorption, SEM and TEM, exhibited bimodal and wide diameter distribution (6-120 nm) and fishbone morphology with high graphitic order (interplanar distance: 0.339-0.347 nm, and crystal sizes around 5 nm) and good textural properties (specific surface area: 100-190 m(2) g(-1) and total pore volume: 0.23-0.45 cm(3) g(-1)).

Automated summary

Using Ni-Cu/Al2O3 catalyst, the thermal decomposition of propane was studied to produce CO2-free hydrogen and high value-added carbon nanofibers. It was found that under specific temperature and space velocity conditions, high-quality CNF and H2 without CO2 can be efficiently produced.