摘要
用硝酸镍对磷钨酸(TPA)进行改性制得NiPW12O40催化剂.采用ICP、XRD、TG-DTA、IR、TPD-MS和微反技术研究了催化剂的化学组成、分子结构、化学吸附性质和催化反应性能.在350℃下,NiPW12O40催化剂仍保持原有的Keggin结构,其表面存在两种活性基元.CO2在Lewis酸位Ni( )和Lewis碱位Ni-O-W的桥氧协同作用下可生成CO2桥式吸附态Ni( )←O-(CO)-(O-Ni).丙烯以中间碳上的氢和甲基上的氢分别在两种活性基元吸附.在氢转移和碳插入作用下得到了相应的反应产物即甲基丙烯酸(MAA)和3-丁烯酸(β-butenicacid).在290℃,1MPa的反应条件下,丙烯的摩尔转化率2.7%,MAA选择性96%.
NiPW12O40 catalyst was prepared using the method of TPA reacting with nickel nitrate . Chemical composition, molecular structure, chemisorption character and catalytic reaction performance were determined by the techniques of ICP? XRD? TG\|DTA? IR? TPD\|MS and microreactor respectively. At the temperature of 350 ℃, the catalyst still remain the original Keggin structure of TPA. Two kinds of active structure units were formed on the surface of catalyst. The experimental results show that CO\-2 chemisorbs at bridging oxygen of Ni\|O\|W(Lewis base site) and Ni\+\{2+\}(Lewis acid site) to form bridged absorption Ni(Ⅱ)←O\|(CO)\|(O\+-\|Ni), that propylene chemisorbs on the surface of catalyst to form molecular absorption states, and that the main reaction products of CO\-2 with propylene on the catalysts are MAA and β\|butenic acid, with propylene conversion of 2.7%, MAA selectivity of 96%, at the reaction temperature of 563 K and 1 MPa.MAA andβ\|butenic acid were synthesized by route of transhydrotion and Carbon\|inserted.
出处
《分子催化》
EI
CAS
CSCD
北大核心
2003年第5期347-352,共6页
Journal of Molecular Catalysis(China)
基金
国家重大基础研究前期研究专项(2001CCA03600).
