Stabilizing Ni on honeycomb-structural Al2O3 with enhanced coke tolerance for dry reforming of methane

Sintering and carbon deposition of Ni-based catalysts limit dry reforming of methane (DRM) reaction. Herein, honeycomb-structural Al2O3 was prepared and supported with Ni (Ni/Al2O3) to enhance coke tolerance during the DRM reaction. Compared to Al2O3-CT obtained from Al(NO3)3·9H2O treated with citric acid and triethanolamine, the Al2O3-AN obtained from Al(NO3)3·9H2O treated with amide still has a stable honeycomb structure at high temperatures and can inhibit the sintering of Ni particles and sufficiently expose the active sites. TEM results showed that the average particle sizes of Ni/Al2O3-CT and Ni/Al2O3-AN were 9.1 nm and 7.6 nm, respectively. After a 100-hour reaction, the conversion of CH4 and CO2 on Ni/Al2O3-CT decreased by approximately 13%, while on Ni/Al2O3-AN, the conversion of CH4 and CO2 decreased by approximately 6%. The SEM results showed that the average particle sizes of Ni/Al2O3-CT and Ni/Al2O3-AN were 24.2 nm and 14.3 nm, respectively. The thermogravimetric (TG) curves indicated that carbon deposition on Ni/Al2O3-AN mainly occurred in the early stage of the DRM reaction with excellent coke tolerance. In situ DRIFT spectra showed that the stable honeycomb structure on Ni/Al2O3-AN enhanced the activation efficiency of CO2 on the catalyst.