Catalysis Today, Vol.349, 106-116, 2020
Hydrogen production by methane decomposition on Pt/ gamma-alumina doped with neodymium catalysts and its kinetic study
This paper presents results for the catalytic decomposition of methane using Pt/ ?-Al 2 O 3 and Pt/ ?-Al 2 O 3 -Nd 2 O 3 catalysts for the hydrogen production. All catalysts were prepared by wet impregnation using Nd(NO 3 ) 3 ?6H 2 O and H 2 PtCl 6 .6H 2 O as precursor salts. The concentrations of the catalysts were Pt, 1.0 wt%, and Nd, 1.0 and 10.0 wt%. The reaction was carried out from 400 to 750 ?C. All the catalysts reduced methane decomposition temperature by 400 -750 ?C relative to noncatalytic thermal decomposition, which is carried out at 1300 ?C. The Pt catalysts supported on ?-alumina doped with neodymium exhibited higher activity than Pt supported on alumina alone. All catalysts showed high activity and selectivity at 750 ?C, with conversions around 57 -80%vol and hydrogen productions of 0.29, 0.27 and 0.19 mmoles of H 2 / min*g cat for PtANd10, PtANd1 and PtA catalysts respectively also were observed in the output stream, traces of C 2 H 4 y C 2 H 6 (less than 1%) and unconverted methane. This work includes a kinetic study of methane cracking, for this purpose two experiments were carried out, the first one consisted of varying the amount of catalyst, keeping the feed flow constant, in the second ex- periment the flow rate was varied, keeping the mass of the catalyst constant. The activation energy of methane cracking is estimated at 35.5, 37.9 and 33 kJ/mol for the Pt/A, Pt/ANd1 and Pt/ANd10 catalysts, respectively. The characterization was done by X-ray di ffraction, N 2 adsorption -desorption, H 2 -TPR, FTIR of CO adsorption, FTIR of Pyridine adsorption, XPS, HRTEM, catalytic activity and TPO (Temperature programed Oxidation) analysis after reaction.