Xiaodong Li,Yanli Huang,Qian Zhang,Zhijun Zuo,Xiaodong Wang,Vladimir A. Vinokurov,Zheng Wang,Wei Huang
Ni-MoCeZr-MgAl(O) mixed oxide catalysts were successfully prepared from the Ce, Zr and Mo promoted hydrotalcite-like compounds (HTLcs) precursors using the simple and effective hexamethylenetetramine(HMT)-assisted hydrothermal synthesis method by tuning the molar ratio of n(HMT)/n(NO 3 − ). The influence of Ni content (3, 4.8, 6, 9 and 12%) on the catalytic performance of these catalysts in dry reforming of methane (DRM) was focused. Adjusting the content of Ni was able to change the metal dispersion and metal particle size, and small-sized (around 7 nm) and evenly dispersed Ni particles were obtained at Ni content of 6%. The catalyst with 6% Ni loading stood out for the high activity and stability, the CH 4 conversion of which fluctuated around 95% continuously for 610 h under GHSV of 60,000 mL·g cat −1 ·h −1 , and it was still above 92.8% throughout the 36-h-duration DRM experiments under GHSV of 80,000 mL·g cat −1 ·h −1 . This research may provide a simple and effective methodology for the synthesis of stable and efficient DRM catalysts.
Zhang Wenlong,Wang Bin,Xu Yuxin,Chen Xiao,Zhang Kuibao,Hao Yan
To enhance the thermal stability of SiO 2 aerogels at high temperature, this study proposes a method involving the incorporation of MgAl 2 O 4 nanoparticles into SiO 2 aerogels to improve their high-temperature stability. By comparing the performance of MgAl 2 O 4 -SiO 2 aerogel with pure SiO 2 aerogels after heat treatment at high temperatures, it is demonstrated that the MgAl 2 O 4 nanoparticles significantly enhances the thermal stability of SiO 2 aerogels at elevated temperatures while almost no effect on thermal conductivity, about 0.0312 and 0.0322 W/(m·K). The MgAl 2 O 4 -SiO 2 aerogels exhibit superior thermal stability and insulation performance compared to pure SiO 2 aerogels at temperatures exceeding 800 ℃. Notably, even after heat treatment at 1100℃, a condition that causes pure SiO 2 aerogels to nearly lose their porous structure, the MgAl 2 O 4 -SiO 2 aerogels retain a specific surface area of 81.95 m 2 /g and thermal conductivity of 0.0584 W/(m·K).
Shan Feng,Xinghua Zhang,Qi Zhang,Yuan Liang,Xuelai Zhao,Chenguang Wang,Longlong Ma
Production of aviation fuel is promising but challenging in the field of biomass utilization. Here we proposed a route to produce highly branched alkanes by the self-aldol condensation of methyl isobutyl ketone (MIBK), followed by the one-step hydrodeoxygenation (HDO). The catalytic activities of magnesium-aluminum mixed oxides (MgAl-O) were carefully explored in the self-aldol condensation of MIBK using cyclohexane as the solvent. The basic sites with moderate and strong strength play a key role in the self-aldol condensation of methyl isobutyl ketone, which can capture α-H, promoting the aldol condensation . Under an optimal condition, the yield of condensation product C12 oxygenate is 70.3%. Furthermore, the regeneration ability of 500-MgAl-O catalyst is tested in the self-aldol condensation of MIBK. In addition, hydrodeoxygenation of condensation products was also conducted over 2 wt% Pd/HZSM-5 catalysts. These obtained HDO products are highly branched alkanes with low freezing point (<−60 °C).
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