双金属改性ZSM-5分子筛上甲醇合成二甲醚的DFT研究

DFT Study of Dimethyl Ether Synthesis from Methanol on HZSM-5 Modified with Double Metals

采用密度泛函理论的广义梯度近似(DFT-GGA)方法,研究了双金属改性HZSM-5的ZrOZn、ZrOAl、ZrOMg和ZrOGa等4种双5T构型对甲醇合成二甲醚的影响。4种构型中的合成二甲醚活化能分别为1.09,0.89,0.93,0.90eV,均有利于二甲醚的合成。存在3种可能的反应路径,两甲醇直接反应生成二甲醚反应路径3(CH_3OH+CH_3OH→CH_3O(H)CH_3+OH→CH_3OCH_3+H_2O)为最佳反应路径。实验对寻找改性双金属催化剂具有一定的指导意义。

In the present work,we employed periodic DFT-GGA calculation method and double 5Tcluster model to compare the influence of ZrOZn,ZrOAl,ZrOMg and ZrOGa models on methanol dehydration to dimethyl ether.It was found that：the activation energies on four configurations are 1.09,0.89,0.93,0.90 eV,being helpful for dimethyl ether synthesis;path 3（CH_3OH＋CH_3OH→CH_3O（H）CH_3＋OH→CH_3OCH_3＋H_2O）for direct methanol dehydration to dimethyl ether in three possible paths is the best path.The research has some guidance for searching modified double-metal catalysts.