Biogas dry reforming using Ni–Al-LDH catalysts reconstructed with Mg and Zn

Abstract The reconstruction of NiAl-LDH by incorporating Mg or Zn using a memory effect was investigated aiming to improve the basic properties of the catalysts and evaluated in the dry reforming of Biogas. Samples were characterized by XRD, CO2−TPD, N2-physisorption, TPR, and TPO. Biogas dry reforming experiments were carried out using a feed of CH4/CO2/N2 = 1.5/1/7.5 in the temperature range of 500–750 °C with in situ reduced samples. The washing step strongly influences the LDH reconstruction. The unwashed samples showed the reconstruction of the LDH structure, presented a low specific area, and high basicity, responsible for decreasing carbon formation during reactions. The washed samples did not exhibit the LDH reconstruction property but showed a high specific area and low basicity. The metal used in the reconstruction influences the crystallinity, basicity, and reducibility of the materials. Samples with Zn showed higher crystallinity and reducibility, whereas the samples with Mg showed higher basicity. Among all the catalysts, reconstruction with Zn and subsequent washing leads to the best results with CH4 and CO2 conversion of 73% and 90%, respectively, and an H2/CO ratio of approximately 2. This can be attributed to the Ni–Zn alloy formation and to the reducing properties suitable for the range between 600 and 700 °C. This catalyst showed the highest resistance to sintering in the stability test at 700 °C.