Natural gas is an efficient energy carrier. But due to its poor reserves, the production of synthetic natural gas (SNG) from coal and biomass thus becomes an important step. So many methanation catalysts, such as Ni/Al2O3, have been developed, but most are not suitable and still need to be improved.
Researchers with Institute of Process Engineering (IPE) reported a systematic investigation of Ni nanoparticles supported on barium hexaaluminate (BHA) as CO methanation catalysts for SNG production.
In the experiments, BHA with a high thermal stability was synthesized by a coprecipitation method using aluminum nitrate, barium nitrate, and ammonium carbonate as the precursors. The Ni catalysts supported on the BHA support (Ni/BHA) were prepared by an impregnation method.
Ways including X-ray diffraction, nitrogen adsorption, transmission electron microscopy, thermogravimetric analysis, H2 temperature-programmed reduction, O2 temperature-programmed oxidation, NH3 temperature-programmed desorption and X-ray photoelectron spectroscopy, were used to characterize the experimental samples.
The catalyst activity was also measured. The CO methanation reaction was carried out at pressures of 0.1 and 3.0 MPa, weight hourly space velocities (WHSVs) of 30 000, 120 000, and 240 000 mL·g–1·h–1, with a H2/CO feed ratio of 3, and in the temperature range 300–600 °C.
The results showed that although the BHA support has a relatively low surface area, Ni/BHA catalysts displayed much higher activity than Al2O3-supported Ni catalysts (Ni/Al2O3) with a similar level of NiO loading even after high temperature hydrothermal treatment. Nearly 100% CO conversion and 90% CH4 yield were achieved over Ni/BHA (NiO, 10 wt %) at 400 °C, 3.0 MPa, and a WHSV of 30 000 mL·g–1·h–1.
Lifetime tests demonstrated that Ni/BHA was more stable and was highly resistant to carbon deposition, compared to Ni/Al2O3 catalyst. The superior catalytic performance of the Ni/BHA catalyst was probably related to the relatively larger Ni particle size (20–40 nm), the high thermal stability of BHA support with nonacidic nature, and moderate Ni–BHA interaction.
The work shows that BHA is a promising support candidate for methanation catalysts. More information please consult Industrial & Engineering Chemistry Research.
