Mg-Al-hydrotalcite with alkaline sites protects Ni/KIT-6 from formation of amorphous coke in glycerol steam reforming via tailoring reaction intermediates  

作　　者：Yunyu Guo Yiran Wang Yuewen Shao Shu Zhang Yi Wang Song Hu Jun Xiang Xun Hu 

机构地区：[1]School of Material Science and Engineering,University of Jinan,Jinan 250022,China [2]Joint International Research Laboratory of Biomass Energy and Materials,College of Materials Science and Engineering,Nanjing Forestry University,Nanjing 210037,China [3]State Key Laboratory of Coal Combustion,Huazhong University of Science and Technology,Wuhan 430074,China

出　　处：《Frontiers of Chemical Science and Engineering》2024年第4期25-39,共15页化学科学与工程前沿（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant No.52276195);the Program for Supporting Innovative Research of Jinan(Grant No.202228072);the Program for Agricultural Development of Shandong(Grant No.SD2019NJ015).

摘　　要：During steam reforming,the performance of a catalyst and amount/property of coke are closely related to reaction intermediates reaching surface of a catalyst.Herein,modification of reaction intermediates by placing Mg-Al-hydrotalcite above Ni/KIT-6 catalyst in steam reforming of glycerol was conducted at 300 to 600°C.The results revealed that the catalytic activity of Ni/KIT-6 in the lower bed was enhanced with either Mg1-Al5-hydrotalcite(containing more acidic sites)or Mg5-Al1-hydrotalcite(containing more alkaline sites)as upper-layer catalyst.The in situ infrared characterization of steam reforming demonstrated that Mg-Al-hydrotalcite catalyzed the deoxygenation of glycerol,facilitating the reforming of the partially deoxygenated intermediates over Ni/KIT-6.Mg-Al-hydrotalcite as protective catalyst,however,did not protect the Ni/KIT-6 from formation of more coke.Nonetheless,this did not lead to further deactivation of Ni/KIT-6 while Mg5-Al1-hydrotalcite even substantially enhanced the catalytic stability,even though the coke was much more significant than that in the use of single Ni/KIT-6(52.7%vs.28.6%).The reason beneath this was change of the property of coke from more aliphatic to more aromatic.Mg5-Al1-hydrotalcite catalyzed dehydration of glycerol,producing dominantly reaction intermediates bearing C=C,which formed the catalytic coke of with carbon nanotube as the main form with smooth outer walls as well as higher aromaticity,C/H ratio,crystallinity,crystal carbon size,thermal stability,and resistivity toward oxidation on Ni/KIT-6 in the lower bed.In comparison,the abundance of acidic sites on Mg1-Al5-hydrotalcite catalyzed the formation of more oxygen-containing species,leading to the formation of carbon nanotubes of rough surface on Ni/KIT-6.

关 键 词：steam reforming of glycerol Mg-Alhydrotalcite sacrificial catalyst reaction intermediates property of coke 

分 类 号：TQ116.2[化学工程—无机化工] TQ426