Search

The efficient utilization of renewable biogas has attracted ever-increasing interest in the past few decades. Ni–Ce1−xZrxO2 supported on monolithic SiC-F (named Ni–Ce1−xZrxO2/SiC-F) is developed and applied in biogas reforming. Monolithic Ni–Ce1−xZrxO2/SiC-F catalysts were comprehensively characterized by ICP-AES, XRD, SEM, HR-TEM, CO2-TPD, etc. The promotional roles of Ce1−xZrxO2 in coke elimination as well as CO2 activation were deeply analyzed via in situ CH4-TPSR/CO2-TPO and in situ H2-TPR/CO2-TPSR. Ni–Ce1−xZrxO2/SiC-F exhibits satisfactory catalytic activity and ability to inhibit sintering and coke-deposition due to (a) the homogeneous dispersion of Ni nanoparticles (NPs) and (b) the strong interaction between Ce1−xZrxO2 solid solutions and Ni NPs. At 900 °C and a weight hourly space velocity (WHSV) of 24 000 mL gcat−1 h−1, an excellent CH4/CO2 conversion of 90/92% was initially achieved over the Ni–Ce1−xZrxO2/SiC-F catalyst, followed by a slight decrease after 150 h, but remained basically stable for the next 250 h.

Bio-fuels have been proposed as an ideal alternative fuel to conventional fossil fuel due to the advantages of renewability and low pollution. Herein, to greatly enhance the catalytic activity and selectivity of for the production of second generation biodiesel, designed and developed five kinds of catalysts with different ratios (3/1, 5/3, 1/1, 3/5, 1/3) of Co to Ni. The composite catalyst was characterized by XRD, XPS and HRTEM techniques. The activity and selectivity of the catalyst were evaluated by the hydrodeoxidization of oleic acid. It was found that the hydrodeoxygenation activity and selectivity of CoxNi1−xP/SiO2 catalyst was closely related to the proportion of Co/Ni. The selectivity of C17 followed the decreasing order: 3/5 > 1/3 ≈ 1/1 > 5/3 > 3/1 (Co/Ni ratios). Clearly, among all the samples, the catalyst with 3/5 Co/Ni ratio exhibits the best conversion rate and selectivity of 97% and 86% for the production of C17, respectively. The high activity and selectivity of CoxNi1−xP/SiO2 were dominantly attributed to the synergistic effects and the uniform dispersion of Co and Ni species on the SiO2 supports. In particular, the CoxNi1−xP/SiO2 shows the more advantages than the high activity for Ni-based catalysts and high selectivity for Co-based catalysts. It is expected that the catalyst has the great potential to be used in the practical industrial production.

The efficient conversion of renewable biogas has attracted ever-increasing interest in past decades. Ni-CeO2-Al2O3 supported on monolithic SiC-foam (denoted as Ni/CeO2-Al2O3/SCF) is designed and applied in biogas reforming. The monolithic Ni/CeO2-Al2O3/SCF catalysts were deeply characterized by XRD, ICP-AES, SEM, HR-TEM, CO2-TPD, etc. The cycle between CeO2-Al2O3 and CeAlO3 was verified by in-situ CH4/CO2-TPSR, and the catalytic role of CeAlO3 in coke elimination and CO2 activation was further confirmed. Due to the uniform distribution of Ni nanoparticles (NPS) and the activation of CO2 by CeAlO3, Ni/CeAlO3-Al2O3/SCF shows excellent catalytic stability to inhibit sintering and eliminate carbon deposition. At 900 °C and a gas hourly space velocity (GSHV) of 24000 mL gCat-1h−1, excellent CH4/CO2 conversion of 86/99% are initially achieved over Ni/CeAlO3-Al2O3/SCF catalyst, followed by slight decrease after 140 h, and remain basically stable for the next 260 h.

A monolithic silicon carbide foam (SiC-foam) structured nickel and lanthanum oxide (Ni-La2O3) nanocomposite catalyst is developed via reducing the nickel oxide and lanthanum oxide (NiO-La2O3) precursor that can be grown onto SiC-foam surface by depositing the needed citric acid gel followed by calcination at 750 °C. By taking the advantages of homogeneous component-distribution and strong Ni-La2O3 interactions in the Ni-La2O3 nanocomposites, this catalyst delivers much enhanced coke-depositing/Ni-sintering resistance than the unmodified counterpart of Ni-La2O3/alumina (Al2O3) in the titled reaction. At 850 °C, a weight hourly space velocity (WSHV) is set as 24,000 mLCH4-CO2 gCat−1 h−1, methane/carbon dioxide (CH4/CO2) conversions of 71/85% are initially achieved on the Ni-La2O3/SiC-foam catalyst followed by progressively decreased to 60/72% within 50 h (h), but remain almost unchanged for the next 50 h. On the contrary, the CH4/CO2 conversions on the Ni-La2O3/Al2O3 catalyst rapidly drop from 49/71% to 24/40% within only 25 h due to its serious Ni-sintering and coke deposition.